ML14339A044

Enclosuresponses to Requests for Additional Information Re Environmental RAI AQ-11 to AQ-15 (as Amended by Exelon Generation Letter # RS-14-283)

ML14339A044
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Site:
Issue date:	04/30/2014
From:	Exelon Generation Co
To:	Division of License Renewal
Shared Package
ML14122A064	List: ML14122A065 RS-14-138, Enclosuresponses to Requests for Additional Information Re Environmental RAI AQ-11 to AQ-15 (as Amended by Exelon Generation Letter RS-14-283)
References
RS-14-138
Download: ML14339A044 (322)

Text

RS-14-138 Enclosure Page 1 of 322Enclosure Byron and Braidwood

Stations, Units I and 2License Renewal Application Braidwood Station Environmental ReportResponses to Requests for Additional Information Environmental RAls AQ-11 to AQ-15AS AMENDED BY EXELON GENERATION LETTER # RS-14-283 (ML14281A019)

DATED 10/08/2014 RS-14-138 Enclosure Page 2 of 322Enclosure Table of ContentsRAI Number Enclosure PageA Q -l aa .......................................................................................................................................

3A Q -1 1 b .......................................................................................................................................

7A Q -1 2 a .......................................................................................................................................

9AQ-1 2a, Attachment

1. 1 ........................................................................................................

10AQ-12a, Attachment

1. 2 .............................................................................................................

75A Q -12 b ...................................................................................................................................

15 2AQ-1 2b, Attachment

1. 1 ...........................................................................................................

154AQ-12b, Attachment

1. 2 ...........................................................................................................

236A Q -12 c ...................................................................................................................................

3 19A Q -13 .....................................................................................................................................

3 2 0A Q -14 .....................................................................................................................................

3 2 1A Q -15 .....................................................................................................................................

3 2 2 RS-14-138 Enclosure Page 3 of 322RAI #: AQ-11a Category:

Aquatic Resources Statement of Question:

Section 2.2.5, Page 2-15 of the Environmental Report (ER) discusses fish kill events in theBraidwood cooling pond.a. The ER states that five fish kills occurred between 2001 and 2007. NRC staff is aware ofthe fish kill events that occurred on July 22, 2001 (Agencywide Documents Access andManagement System (ADAMS) Accession No. ML012390121),

August 27, 2001(ADAMS Accession No. ML012680140),

and June 28, 2005 (ADAMS Accession No.ML052160140).

Provide the dates of the remaining two events as well as copies of thenon-routine event reports associated with each event.Response:

In addition to three fish kill events in the Braidwood cooling pond for which non-routine eventreports were submitted to the NRC, two other events that resulted from observations of deadfish were investigated between 2001 and 2007. All five events occurred under conditions ofhigh water temperatures and low dissolved oxygen levels, but two of the five events weredetermined to be non-reportable under the Braidwood Environmental Protection Plan (EPP)(Appendix B to Facility Operating License Nos. NPF-72 and NPF-77),

Section 4.1, whichdefines the requirement for reporting fish kill events to the NRC as follows (emphasis added):4.1 Unusual or Important Environmental EventsAny occurrence of an unusual or important event that indicates or could result insignificant environmental impact causally related to plant operation shall berecorded and reported to the NRC within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> followed by a written report inaccordance with Subsection 5.4.2. If an event is reportable under 10 CFR 50.72,then a duplicate immediate report under this subsection is not required.

However,a follow-up written report is required in accordance with Subsection 5.4.2. Thefollowing are examples:

excessive bird impaction events, onsite plant or animaldisease outbreaks, mortality or unusual occurrence of any species protected bythe Endangered Species Act of 1973, fish kills, increase in nuisance organisms or conditions, and unanticipated or emergency discharge of waste water orchemical substances.

The two events judged to be non-reportable were recorded in the station's corrective actionsystem for trending purposes and were included in the total number of fish kills mentioned inSection 2.2.5 of the ER. These two events-one on June 3, 2004 and the other on August 21,2007-are further described below.June 3. 2004Event Description At approximately 6:00 PM on June 3, 2004, a plant employee performing roving inspections noted what appeared to be an abnormal number of dead fish along the bar racks at the LakeScreen House (LSH). Chemistry/Environmental personnel immediately performed a check ofthe area adjacent to the LSH in search of evidence of a fish kill. The immediate inspection RS-14-138 Enclosure Page 4 of 322found no evidence that a fish kill was in progress.

There was no accumulation of dead fishalong the shorelines adjacent to the LSH nor were fish floating into the intake bays from thecooling pond at the LSH. An estimated 500 dead fish were observed along the bar racks infront of the LSH, with the greatest accumulation being in front of the 2A intake bay and rapidlydecreasing accumulations in front of the other five bays toward the west.It was observed that the fish basket receiving back wash from the traveling screens was filledand overflowing into the pit from which the screen back wash water returns to the lake. Thishad caused fish from the traveling screens to flow back out into the cooling pond andaccumulate predominantly along the 2A and 2B intake bay bar racks.It was determined that plant operations were not being impacted.

Therefore, since darknesswas coming, it was decided that further investigation would continue the next morning.Analysis and Evaluation On the morning of June 4, 2004, Chemistry/Environmental personnel continued to search forevidence of a fish kill caused by plant operations.

The fish observed in front of the intake bays(with the majority at the 2A and 2B intakes) were estimated to be 99+% gizzard shad. Thesefish were judged to have been dead for some time because most were already beginning todecompose.

The fish basket had been emptied that morning, and the contents were observedto contain significantly decomposed matter, which appeared to have caused the mesh in the fishbasket to become plugged.

This plugging had caused the basket to overflow into the return pitthe night before, which caused fish collected in the basket to be washed back into the coolingpond at the east end of the intake structure.

An inspection of the cooling pond shoreline revealed an occasional gizzard shad here andthere, but no accumulation of dead fish, as would be expected from a fish kill. One areaspecifically viewed was the northeast corner of the area of the cooling pond in front of the LSH.With winds primarily out of the west on the preceding few days, if a fish kill had occurred there,a major accumulation of shad along this portion of the shoreline should have occurred.

However, no such accumulation was present.

Also, no evidence of dead fish was observed inthe main body of the cooling pond.Chemistry Department personnel reviewed lake parameters, chemical feeds, and temperature data for the five days preceding the event to check for abnormal trends that could have causeda fish kill. No abnormal data trends were found.Probable Cause of EventThe absence of dead fish along the shore and in the cooling pond water on the night of June 3,2004 and the following day, combined with the decomposed state of the dead fish observed atthe LSH intake as well as the absence of any abnormal water parameter trends, suggested thatthe dead fish near the intake resulted from an accumulation of fish over time, rather than a fishkill event. Shad are very sensitive to changing conditions, and dead numbers appear in theintake bays and fish basket year-round.

Hence, although the reason for so many dead fish tohave accumulated at once near the intake trash racks could not be definitively established, itwas concluded that a fish kill event had not occurred.

RS-14-138 Enclosure Page 5 of 322Agencies NotifiedAfter reviewing the evidence, Braidwood personnel determined that the observed conditions didnot constitute a fish kill event and therefore did not trigger reportability requirements.

Hence, nonon-routine event report was filed.August 21, 2007Event Description During the early morning on August 21, 2007, a plant employee performing roving inspections noted a large number of dead gizzard shad in the circulating water intake at the Braidwood LakeScreen House (LSH). An inspection of the intake area and cooling pond banks revealed asignificant number of fish floating against the trash racks, near the North Boat Ramp, and alongshorelines in the eastern part of the cooling pond. Some fish were also noted floating in themain body of the cooling pond.Plant operating conditions were reviewed, but no plant-related cause for a fish kill event onAugust 21 could be identified.

All chemical injection systems were in proper operating condition with no leaks. Circulating water total residual oxidant concentrations for the preceding twomonths were all lower than the lower limit of detection.

Thermal data from the preceding twoweeks indicated that circulating water intake temperatures at the LSH had peaked at 96.5degrees Fahrenheit (F) on August 12, but had fallen to 84.6 degrees F on August 20 afterseveral days of overcast and rainy weather conditions.

Inspections conducted for dead fishduring the same two-week period showed none to low numbers of dead fish before the morningof August 21, and the event was effectively over by the afternoon of August 22.Analysis and Evaluation Beginning at approximately 12:00 Noon on August 21, 2007, an Exelon Fishery Specialist performed dissolved oxygen (DO) measurements at various locations in the cooling pond andobserved several thousand dead gizzard and threadfin shad floating across visible areas of thecooling pond. Dozens of channel catfish were also observed, but no other species wasobserved that counted more than 2 individuals.

DO concentrations ranged from 3.1 parts permillion (ppm) early in the afternoon to 6.7 ppm at approximately 3:30 PM following several hoursof direct.sunlight.

By 5:00 PM, however, the DO concentration had fallen again to 5.9 ppm.Unlike similar previous fish kill events in the Braidwood cooling pond, which predominantly occurred at peaks of periods of elevated circulating water intake temperatures, the circulating water intake temperature on August 21, 2007 was not at a peak.

RS-14-138 Enclosure Page 6 of 322Probable Cause of EventBased on the observed late afternoon decline in DO concentrations on August 21 and theabsence of either a circulating water intake temperature peak or any other plant-related contributing factor, the Exelon Fishery Specialist, in consultation with an Illinois Department ofNatural Resources (IDNR) biologist, concluded that the fish kill event occurred because theseveral days of overcast and rainy weather conditions preceding August 21 caused die off anddecay of phytoplankton in the cooling pond, which triggered a rapid decline in DOconcentrations during overnight hours, thus suffocating a large number of fish.Agencies NotifiedAfter reviewing the evidence, Braidwood personnel determined that the observed fish kill eventwas not reportable because it was not caused by plant operations and did not involve anendangered species.

Hence, no non-routine event report was filed.List of Attachments Provided:

None.

RS-14-138 Enclosure Page 7 of 322RAI #: AQ-11b Category:

Aquatic Resources Statement of Question:

Section 2.2.5, Page 2-15 of the Environmental Report (ER) discusses fish kill events in theBraidwood cooling pond.b. Provide the dates of all fish kill events for the period 2008 through present as well ascopies of the associated non-routine event report. The NRC staff is aware of theJune 24, 2009, fish kill event and associated non-routine event report (ADAMSAccession No. ML092390348).

Response

In addition to the fish kill event in the Braidwood cooling pond on June 24, 2009 for which anon-routine event report was submitted to the NRC, one other event that resulted fromobservations of dead fish has been investigated since January 2008. The second event wasdetermined to be non-reportable under the Braidwood Environmental Protection Plan (EPP)(Appendix B to Facility Operating License Nos. NPF-72 and NPF-77),

Section 4.1, whichdefines the requirement for reporting fish kill events to the NRC as follows (emphasis added):4.1 Unusual or Important Environmental EventsAny occurrence of an unusual or important event that indicates or could result insignificant environmental impact causally related to plant operation shall berecorded and reported to the NRC within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> followed by a written report inaccordance with Subsection 5.4.2. If an event is reportable under 10 CFR 50.72,then a duplicate immediate report under this subsection is not required.

However,a follow-up written report is required in accordance with Subsection 5.4.2. Thefollowing are examples:

excessive bird impaction events, onsite plant or animaldisease outbreaks, mortality or unusual occurrence of any species protected bythe Endangered Species Act of 1973, fish kills, increase in nuisance organisms or conditions, and unanticipated or emergency discharge of waste water orchemical substances.

The non-reportable event, which occurred during July 2012, was recorded in the station's corrective action system for trending purposes and is further described below.July 7-8. 2012Event Description Following the weekend of July 7-8, 2012, Braidwood personnel estimated that totals ofapproximately three thousand small gizzard shad and one hundred bass, catfish and carp haddied in the cooling pond.Monitoring results indicated that, on July 7, 2012, water temperature near the Braidwood Lake Screen House exceeded an average of 100°F for several hours while dissolved oxygen(DO) levels in the cooling pond remained at between 7 and 8 mg/L. The temperature excursion above 1 OOF in the ultimate heat sink due to prolonged hot weather was approvedby the NRC in a Notice of Enforcement Discretion issued orally on July 7, 2012 anddocumented in writing by letter dated July 12, 2012 (ML12194A681).

By July 12, 2012,cooling pond temperatures had significantly decreased and the rate of fish deaths hadslowed, although it was expected that some additional fish losses might occur.

RS-14-138 Enclosure Page 8 of 322Analysis and Evaluation For the following

reasons, Braidwood personnel concluded that fish were dying as a result of thesustained elevated water temperatures in the cooling pond.* DO levels in the cooling pond were noticeably higher than 3 mg/L, which is the level atwhich fish mortality due to low DO levels typically occur. Therefore, low DO did notappear to be the cause of fish mortality in this event.* The vast majority of the dead fish were juvenile gizzard shad, which are particularly susceptible to fluctuations in water thermal conditions.

• On July 8, the air temperature moderated and local wind speeds increased resulting in acorresponding decrease in cooling pond water temperature.

As water temperatures decreased, the rate of fish deaths slowed noticeably.

Probable Cause of EventFrom July 4 through July 8, 2012, northern Illinois experienced unprecedented weatherconditions, with no precipitation and air temperatures at or above 100°F for three consecutive days. As a result, cooling of the water in the Braidwood cooling pond that would typically occurdue to precipitation inflow and lower nighttime air temperatures was minimal during that time,which caused a sustained elevation of the water temperature.

Agencies NotifiedAfter reviewing the evidence, Braidwood personnel determined that the observed fish kill eventwas not reportable because it was not caused by plant operations and did not involve anendangered species.

Hence, no non-routine event report was filed. Nevertheless, courtesynotifications were made verbally to the NRC Resident Inspector and Illinois Department ofNatural Resources.

List of Attachments Provided:

None RS-14-138 Enclosure Page 9 of 322RAI #: AQ-12a Category:

Aquatic Resources Statement of Question:

Section 2.2.5, Page 2-16 of the ER states that "HDR [HDR Engineering]

assessed water qualityand fish populations in the cooling pond in late summer 2009 and 2010 to develop a betterunderstanding of the factors contributing to fish kills and design a water quality or fishmonitoring program that could be used to predict (and conceivably mitigate) fish kills in thepond."a. Provide copies of the 2009 and 2010 HDR studies mentioned in the ER.Response:

The HDR studies mentioned in the ER are provided.

List of Attachments Provided:

1. (Exelon Nuclear 2010) Exelon Nuclear, 2010. Braidwood Station -Braidwood LakeAdditional Biological Sampling

Program, 2009. Prepared by HDR Engineering, Inc.Copyright by Exelon Corporation.

2. (Exelon Nuclear 2011) Exelon Nuclear.

2011. Braidwood Station -Braidwood LakeAdditional Biological Sampling

Program, 2010. Prepared by HDR Engineering, Inc.Copyright by Exelon Corporation.

RS-14-138 Enclosure Page 10 of 322Attachment

1. 1 to Response

-- RAI # AQ-12a RS-14-138 Enclosure Page 11 of 322BA ID'WOOD STATIONBRAIDWOOD LAKE ADDITIONAL BIOLOGICAL SAMPLINGPROGRAM, 2009Prepared forEXELON NUCLEAR.FebWruaY 201.0HDRkEngineering,.

Inc.Environmental

Science

& Engineering Consultants 10207 Lucas Road.Woodstock, Illinoi§s,.

.60098:

RS-14-138 Enclosure Page 12 of 322BRAIDWOOD STATION.BRAIDWOOD LAK ADDITIONAL BIOLOGICAL SAMPLINGPROGRAM, 2009Preparedfor EXELON NUCLEARWarrenviliIe, ilinois;IIHDR Enginering, bdc.Environmental Science & Engineering.Consultants.

10207 LUicýas RoadWoodstock,1

'lios' 60098I, RS-14-138 Enclosure Page 13 of 322ACKNOWLEDGMENTS The field work and data analysis for this project was conducted by HDR Engineering, Inc.(HDR). Particular appreciation is extended to Rob Miller of the Illinois Department of NaturalResources (IDNR), Jim Smithson of Strategic Environmental

Actions, Inc. (SEA), and John Petroof Exelon Nuclear for providing historical fisheries and water quality data.This report was prepared by HDR and reviewed by Exelon Nuclear.

A special debt of gratitude is owed to the environmental staff at Braidwood Station and in particular Mr. Jeremiah Haas ofExelon Nuclear for his technical assistance, cooperation, and guidance during the preparation ofthis document and the study plan. Mr. Haas's experience and insight has been invaluable and isgreatly appreciated by the authors.HDR Engineering, Inc.

RS-14-138 Enclosure Page 14 of 322ABSTRACTHDR Engineering, Inc. (HDR) was contacted on March 12, 2009 by Braidwood NuclearGenerating

Station, requesting HDR to design and conduct a fish sampling program in theBraidwood Cooling Lake. The information gathered during this study was to be used by Exelonto develop an effective sampling program and set of procedures that could potentially predict fishdie-offs in the cooling lake. Large die-offs of fish challenge the integrity of the traveling screensat the Station.

With advanced

warning, the Station could be informed of a potential reportable event; regulatory agencies could be notified in advance; and crews responsible for fish disposalcould be put on alert to help manage the risk associated with a substantial fish die-off.

Currently, there are no practical or simple methods that can be used to predict or prevent the occurrence offish die-offs at Braidwood Cooling Lake.Sampling has been conducted at Braidwood Lake by the IDNR since 1980. From 1980 through2007 IDNR has collected 47 taxa of fish. Twenty-six taxa representing seven families wereincluded among the 2143 fish collected by HDR by electrofishing, trap netting, and gill netting atBraidwood Lake during July and August 2009. Several taxa listed as collected by IDNR since1980 were not captured by HDR in 2009. Many of those species were only rarely captured, havenot been captured during recent years, or represent taxa that were stocked.

However, five specieswere captured by HDR in 2009 that were not listed as collected during IDNR sampling efforts.They include shortnose gar, blue catfish, bigmouth

buffalo, fathead minnow, and rosyface shiner.A single specimen of each species was collected.

Dominant species collected in 2009 in terms ofboth numbers and weight were similar to results reported by IDNR in recent years. Braidwood Lake is dominated by warmwater species including gizzard shad, threadfin shad, carp, channelcatfish, flathead

catfish, largemouth bass, bluegill, and cyprinid species such as spotfm shiner andbluntnose minnow.Water quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection.

Water temperature (QC), dissolved oxygen (ppm), pH, andconductivity (prnhos/cm) measurements were taken 0.5 m below the water surface.

Watertemperatures during both the July and August sampling periods were similar ranging from 28.5I-DR Engineering, Inc.

RS-14-138 Enclosure Page 15 of 322'C at Location E-5 (near the make-up water discharge into the lake from the Kankakee River) to35.5 "C at Location E-1 (the most southern location closest to the Braidwood Station discharge).

Diurnal swings in dissolved oxygen (DO) were observed at the lake with DO ranging from 4.1 to9.5 ppm, Dissolved oxygen readings were generally slightly lower during the August samplingperiod. Examination of pH data collected during these studies show pH ranged from 8.7 to 9.1 inJuly and from 8.5 to 8.7 in August. Conductivity ranged from 760 to 899 anhos/cm in July andfrom 908 to 931 pnhos/cm in August.Review of historical water quality data reported in 2002 by Strategic Environmental

Actions, Inc.(SEA Inc.) at Braidwood Lake indicates that abnormally high levels of total dissolved solids(TDS), alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus exist throughout the cooling loop. This is not unexpected based upon the evaporation that takes place within thecooling loop coupled with the relatively low make-up and blow-down rates associated with theoperation of Braidwood Station.

These elevated levels within the lake were measured at two tonearly eight times higher than those of the make-up water from the Kankakee River. Elevatedlevels of water hardness are of concern to the Station because high levels have the potential toincrease problems associated with scaling at the Station.Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Studies conducted by SEA in 2002 indicated that nutrients within the cooling lake were at levels high enough tocontinue to cause problems associated with phytoplankton blooms. These blooms result in oxygenproduction via photosynthesis during daylight hours and oxygen depletion through respiration during darkness.

When algal populations crash and decompose they can produce severe oxygendepletion within the water column. Diurnal swings in oxygen readings have been routinely observed at Braidwood Lake during the past several years. In addition, DO levels of less than 3ppm have been recorded at the lake immediately following fish die-offs.

Dissolved oxygen levelsof 3 ppm and less cannot be tolerated for an extended period of time by most fish species.

Deeperportions of the lake were also reported to stratify in 2002. In the deeper zones of the lake, DOlevels approaching 0 ppm and reduced water temperatures were measured below the thermocline.

Review of historical fisheries information that was provided to HDR indicated that five separatefish kills were reported from 2001 to 2007. Numerically, the majority of fish observed duringiiiHDR Engineering, Inc.

RS-14-138 Enclosure Page 16 of 322these events were either gizzard shad or threadfin shad. These two species have typically comprised over 90% to 95% of all fish observed.

Remaining species included carp, freshwater drum, bluegill, channel catfish, flathead

catfish, quillback and largemouth bass. Each of thereported fish die-offs was attributed to oxygen depletion at the lake and not any result of Stationoperation.

ivHDR Engineering, Inc.

RS-14-138 Enclosure Page 17 of 322TABLE OF CONTENTSPage No.ACKNOWLEDGEMENTS iABSTRACT iiTABLE OF CONTENTS vLIST OF TABLES viLIST OF FIGURES vii1.0 Introduction 1-12.0 Methods 2-12.1 Electrofishing 2-12.2 Trap Netting 2-32.3 Gill Netting 2-32.4 Sample Processing 2-42.5 Water Quality Measurements 2-43.0 Results and Discussion 3-13.1 Species Occurrence 3-13.2 Relative Abundance and CPE 3-13.3 Physicochemical Data 3-83.4 Historical Information 3-103.4.1 Water Quality 3-103.4.2 Fish Kills 3-114.0 Summary and Recommendations 4-14.1 Summary 4-14.2 Recommendations 4-35.0 References Cited 5-1VHDR Engineering, Inc.

RS-14-138 Enclosure Page 18 of 322LIST OF TABLESTable No. Title Page No.3-1 Species Occurrence of Fish Collected by the Illinois Department of Natural Resources at Braidwood Lake from 1980 through2007. 3-23-2 Total Catch by Method for Fish Species Collected from theBraidwood Station Cooling Lake, 2009. 3-43-3 Fish Captured by Electrofishing at Braidwood Lake, 2009. 3-63-4 Fish Captured by Trap Netting in Braidwood Lake, 2009. 3-7IAivHDR Engineering, Inc.

RS-14-138 Enclosure Page 19 of 322LIST OF FIGURESFigure No.CaptionPage No.2-2Sampling Locations at Braidwood Lake during July andAugust, 2009.2-2!tviiHDR Engineering, Inc.

RS-14-138 Enclosure Page 20 of 32

21.0 INTRODUCTION

The Braidwood Lake Fish and Wildlife Area is comprised of approximately 2640 acres ofterrestrial and aquatic habitat that is located in Will County, Illinois.

Braidwood Lake is ownedby Exelon and is a partially

perched, cooling lake that was constructed in the late 1970s. The lakewas filled during 1980 and 1981 with water pumped from the Kankakee River. Several surfacemined pits existed at the site prior to the filling of the impoundment.

Fisheries management activities began in these surface mine pits in 1978, prior to the creation of Braidwood CoolingLake. Originally the lake was considered a semi-private area used by employees ofCommonwealth Edison Company until the end of 1981 when the Department of Conservation (now the Illinois Department of Natural Resources).

Braidwood Lake is currently used for fishing,waterfowl

hunting, fossil hunting, and acquired a long-term lease agreement from the companywhich allowed for general public access as a waterfowl refuge. From the late 1970's to thepresent time, Braidwood Lake has been stocked with a variety of warm- and coolwater fishspecies.

These stockings include largemouth and smailmouth bass, blue catfish, striped bass,crappie,

walleye, and tiger muskie. Monitoring programs have documented the failure of thecoolwater stockings to create a meaningful fishery.

This is attributed to the extreme watertemperatures that occur within the cooling lake during the warm summer months.Construction of the Braidwood Nuclear Generating Station and its associated riverside intake anddischarge structures provided an opportunity to gather fisheries information from the KankakeeRiver and Braidwood Lake. These studies were initiated to determine the effects of construction and plant operation on the river and the lake. Units I and II began commercial operation on 29July and 17 October, 1988, respectively.

Fisheries surveys at Braidwood Lake were conducted annually by the Illinois Department of Natural Resources (IDNR) from 1980 through 1992. Since1992, fishery surveys have been conducted by IDNR every other year except 1995 and 1996.Fishery surveys on the Kankakee River near the Station's intake have also been conducted annually since the late 1970's by the Illinois Natural History Survey (1977-1979 and 1981-1990),

LMS Engineers (1991-1992 and 1994-2004),

Environmental Research and Technology (1993),HDR/LMS (2005-2007),

and HDR (2008-2009).

i 1-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 21 of 322The objectives of the 2009 Braidwood Lake Additional Sampling Program were to:1. Conduct fish surveys at Braidwood Lake for comparison with historical data thathas been collected by IDNR.2. Summarize any existing data related to fish kills that have occurred at Braidwood Lake.3. Develop a sampling procedure or protocol that will help anticipate fish die-offs inthe cooling lake that could potentially effect Station operations.

1-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 22 of 3222.0 METHODS2.1 Electrofishing Electrofishing was conducted using a boat-mounted boom-type electrofisher utilizing a 5000 watt,230 volt AC, 10 amp, three-phase Model GDP-5000 Multiquip generator equipped with volt/ampmeters and a safety-mat cutoff switch. The electrode array consisted of three pairs of stainless steel cables (1.5 m long, 6.5 mm in diameter) arranged 1.5 m apart and suspended perpendicular to the longitudinal axis of the boat 1.5 m off the bow. Each of the three electrodes was poweredby one of the phases. Electrofishing samples were collected on 22 and 23 July during the firstsampling effort and on 20 August during the final survey period.Eight locations around the dike and islands at Braidwood Lake were electrofished during both thefirst and second sampling periods (Figure 2-1). Electrofishing was conducted near the shoreline at each location to collect fish utilizing shallow water zones. Each electrofishing area wassampled for 30 minutes.

Voltage and amperage of the electrofishing unit was recorded at eachlocation at the beginning and end of each sampling effort. Sampling was restricted to the periodof time ranging from one-half hour after sunrise to one-half hour before sunset.The electrofishing crew consisted of two people. One crew member operated the boat while thesecond crew member dipped fish from the bow of the boat. The boat operator also dipped fishwhenever necessary.

When fish surfaced behind the boat the boat operator backed up to retrieveall stunned fish. All stunned fish were collected without bias of size or species.Fish at each location were put into barrels of water in the front of the boat for analysis at the endof each 30 minute collection period. All fish were processed in the field immediately following collection at each location.

Special emphasis was placed on the return of all collected game fishspecies to the water as quickly as possible following field analysis.

Catches were standardized tocatch-per-effort (CPE) from actual fishing time (30 nin) to numbers caught per hour by dividingthe total numbers of fish collected by the actual fishing time in hours.2-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 23 of 322FIGURE 2-1. SAMPLING LOCATIONS AT BRAIDWOOD LAKE DURING JULYAND AUGUST, 2009.2-2 RS-14-138 Enclosure Page 24 of 3222.2 Trap NettingTrap nets were set at eight separate locations in Braidwood Lake (Figure 2-1). Each trap netconsisted of a 25-ft. lead that was 4-ft. deep and attached to a series of rectangular frames. Thelast rectangular frame was attached to a hoop net constructed of 1.5-in. (bar) mesh nylon webbingon hoops 3.5 ft in diameter.

Two separate throats were contained within each trap net. One waslocated in the series of rectangular frames at the front end of the net, while the second throat waslocated toward the back of the net inside the 3.5 ft diameter hoop net. Trap nets were set duringlate afternoon or early evening and were allowed to fish overnight for approximately 12 hrsbefore being retrieved the following morning.

Trap nets were set on 21 July and retrieved on 22July during the first sampling period and set on 17 August and retrieved on 18 August during thesecond sampling period.3 Fish at each location were put into barrels of water in the front of the boat for analysis at the endof each collection period. All fish were processed in the field immediately following removalfrom the trap net. Special emphasis was placed on the return of all collected game fish species tothe water as quickly as possible following field analysis.

Catches were standardized to catch-per-effort by dividing the total number of fish caught by the total number of hours the nets wereallowed to fish (fish/12-hr set).2.3 Gill NettingTwo 125-ft. long and 6-ft. deep monofilament experimental gill nets were used to collect fishfrom two locations in Braidwood Lake (Figure 2-1). Each net consisted of five separate panelsthat were 25-ft long by 6-ft deep. Bar mesh sizes of each panel were 0.5, 0.75, 1.0, 2.0, and 3.0inches, respectively.

Nets were set in water depths of approximately six to ten feet deep. Gillnet samples were collected on 21 July during the first sampling period and on 17 and 18 Augustduring the second sampling period.Gill nets were set for 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at Location GN-1 and for one hour at Location GN-2 before theywere lifted and fish were removed during both the July and August sampling period. Elevated2-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 25 of 322water temperatures in the cooling lake prohibited longer set times due to the high mortality thatoccurred shortly after the fish became entangled in the monofilament netting.

Gill net samplingwas conducted either early in the morning (0630 to 0800 hrs) or late in the afternoon (1600 to1910 hrs).All fish were processed in the field as they were removed from the net. Special emphasis wasplaced on the return of game fish species to the water as quickly as possible.

Catches werestandardized to catch-per-effort (CPE) from actual fishing time the nets were in the water tonumbers caught per hour by dividing the total numbers of fish collected by the actual fishing timein hours.2.4 Sample Processing All fish were identified to the lowest positive taxonomic level and enumerated.

For each geartype, up to 25 individuals of a species were measured for total length (mm) and weight (g) at eachlocation.

Any remaining individuals of that species were counted and weighed en masse.Minnow species (excluding carp) were counted and weighed en masse. Specimens that could notbe positively identified in the field were either photographed in the field or returned to thelaboratory for identification.

References used to facilitate identification included Pflieger (1975),Smith (1979), and Trautman (1981).2.5 Water Quality Measurements Four physicochemical parameters (temperature, dissolved oxygen [DO], pH, and conductivity) were measured in conjunction with the sampling program.

These data were collected at eachstation prior to each sampling effort. Physicochemical measurements were taken a half meterbelow the water surface at shallow water locations (electrofishing).

At deeper locations, temperature, conductivity, and DO were measured 0.5 m below the surface and 0.5 m off thebottom (gill and trap nets). Temperature

(*C), dissolved oxygen (ppm), and conductivity (pnihos)were measured using an YSI Model 85 handheld oxygen, conductivity,

salinity, and temperature 2-4HDR Engineering, Inc.

RS-14-138 Enclosure Page 26 of 322meter. A Cole-Parmer pH Tester1 was used to determine pH. All instruments were calibrated prior to each monthly sampling event.2-5HDR Engineering, Inc.

RS-14-138 Enclosure Page 27 of 3223.0 RESULTS AND DISCUSSION 3.1 Species occurrence.

Fish surveys have been conducted at Braidwood Lake by the IllinoisDepartment of Natural Resources (IDNR) since 1980 when the cooling lake was first impounded with water pumped from the Kankakee River. Sampling was conducted annually from 1980-1992, again in 1994, and every other year from 1997-2007 (Table 3-1). During these 20 years ofsampling, 47 taxa of fish have been collected including 45 species and two hybrids (hybrid sunfishand tiger muskie).

Gizzard shad, carp, channel catfish,

bluegill, and largemouth bass have beenthe dominate species collected during these surveys.

The total number of taxa collected by theIDNR has ranged from 12 in 1980 to 27 in 1989. Several species have been rarely collected oronly occasionally observed during this 30 year period. These include, yellow bass, rock bass,redear sunfish, orangespotted

sunfish, tiger muskie, grass pickerel, longnose gar, goldfish, highfincarpsucker, silver redhorse, river redhorse, blackstripe topminnow, emerald shiner, commonshiner, striped shiner, redfin shiner, slenderhead darter, johnny darter, and bullhead minnow,which have been collected in five or fewer of the 20 years of sampling conducted by the IDNRfrom 1980 through 2007. The only protected species (one fish collected in 1999) collected duringthese surveys has been river redhorse (Moxostoma carinatum),

which is currently listed asthreatened in Illinois (Illinois Endangered Species Protection Board 2004). River redhorse havebeen collected in the Kankakee River in the past (HDR, 2009). Eighteen of the taxa identified bythe ILDR have not been captured since 1999.Braidwood Lake has been stocked with a variety of warmwater and coolwater fish species sincethe late 1970's. Some of these species, such as striped bass, tiger muskie, and walleye, have notbeen collected in recent years following the discontinuance of those stocking programs.

Currently, the fish community is dominated by warmwater species that are more tolerant of theelevated water temperatures that exist in the cooling lake during summer months.3.2 Relative Abundance and CPE. In 2009, 26 taxa representing seven families were includedamong the 2143 fish collected by electrofishing, trap netting, and gill netting (Table 3-2). Severalspecies that were listed as being collected by the IDNR during surveys conducted between 1980and 2007 were not captured by this program in 2009. Each of these taxa were either rarelycaptured during previous years, represent taxa that were stocked, or have not been capture during3-1HDR Engineering, Inc.

TABLE 3-1SPECIES OCCURRENCE OF FISH COLLECTED BY THE ILLINOIS DEPARTMENT OF NATURAL RESOURCES" AT BRAIDWOOD LAKE FROM 1980 THROUGH 2007.SAMPLING YEARTaxa 80 81 82 83 84 85 86 87 88 89 90 91 92 94 97 99 01 03 05 07Longnose garThreadfin shadGizzard shadGrass pickerelTiger muskicGoldfishCarpGolden shinerEmerald shinerCommon shinerStriped shinerSpotfin shinerSand shinerRedfin shinerBluntnose minnowBullhead minnowQuillback Highfin carpsueker Silver redhorseGolden redhorseShorthead redhorseRiver redhorseBlack bullheadYellow bullheadChannel catfishFlathead catfishBlackstripe topminnowv Brook silverside Yellow bassStriped bass356427 2545 972 143 143 182 1412 5 24 7 17 1020 4248 1296 1382 30185831311 230412 925 925 786 1031 872122 3 1 I285 853 385 929 620 204I I I48122195405]275 365 414 616 785 532 666 675 511 1915 626 108 2274 82 I I l212 23114I14I9 3 37 75 5 41 1 26 11 2 I5 6 35 32 6 3I I198 3513 1327 24975I 46I126 39 6 42 37 39 29 53 39 20 42 26 66 20 37 5 32Iis 102 1673 I19 212 1 21 4 101I2 25 334 3125836612I1913773391161 2 I 179 177 362 3571 3 3 1 1463 136 364 866 384 129 2281 2 10 I 14 145II64 171 17 8 9 13 6 12 50 3 5 I 2 I 1 5 4 I 1 15 I= Ir ") c TABLE 3-1 (Continued).

SAMPLING YEAR80 81 82 83 84 85 86 87 88 89 90 91 92 94 97 99 01 03 05 07TaxaRock bassGreen sunfishOrangespotted sunfishBluegillLongear sunfishRedear sunfishHybrid sunfishSmallmoutli bassLargemouth bassWhite crappieBlack crappieJohnny darterYellow perchLogperchSlenderhead darterWallvycFreshwater drumII I24 57 163 12513 458 620 19116 71 13 13 2 7 1 10 8 23 13 37 139 26 10 771 1 I69 81 21 9 31 277 121 698 247 252 241 998 1754 1393 1369 275825 1 7 3 11 31 16 12 6 20 II 6 1 2 I 4 9 13 8 5 7i 3 42 24 17 42 17 9 3 523 473 385 390 298 265 241 150 142 142 192 175 91 337 202 711 351 334 88 26341 19 30 17 6 5 4 6 3 10 2 32 36 4 2 7 6 3 i 4 3 II 6 I 20 2 2 I 122 66 42 20 35 69 93 74 61 10 312 71 472 2Ii 727 88 156 7I 36 213 7113 21 24 53 30 62 38 37i1 7 14 12 11 61 1514 14 349 1Total fishTotal taxaTotal species400 5044 2840 1629 1489 1351 1305 1099 1942 7008 2730 2882 4165 1875 2536 3521 5193 3862 2957 440312 23 19 18 20 18 14 21 25 27 24 26 23 23 20 21 20 17 16 2012 22 is 16 18 17 13 20 25 26 24 25 21 22 19 20 19 16 15 19'Information provided by Rob Miller, District Fisheries Biologist with the Illinois Department of Natural Resources.

CoMo XroM .,CO M TABLE 3-2TOTAL CATCH BY METHOD FOR FISH SPECIES COLLECTED FROM THE BRAIDWOOD STATION COOLING LAKE, 2009.ELECTROPISHING TRAP NETTING GILL NETTING TOTALTAXON NUMBER WEIGHT NUMBER WEIGHTNUBE WEIGHT NUMBER WEIGHTNo. % (g) % No. % (g) % No. % (g) % No. % (g) %Threadfin shadGizzard shadSbortnose garLongnose garCarpStriped shinerRosyface shinerSpotfin shinerSand shinerFathead minnow.Bluntnose minnowBullhead minnowBigmouth buffaloBlue catfishChannel catfishFlathead catfishBrook silverside Sunfish spp.Green sunfishRedear sunfishBluegillLongear sunfishHybrid sunfishSmallmouth bassLargemouth bassBlack crappieTotalsTotal taxaTotal species59 4.2 522 0.2123 8.7 9730 3.3100 7.0 165,657 56.434 2.4 59 < 0.11 0.1 3 <0.1176 12.4 475 0.227 1.9 41 < 0.11 0.1 2 < 0.1164 11.5 332 0.1153 10.8 335 0.11 0.1 2550 0.996 6.8 34,352 11.73 0.2 38,750 13.21 0.1 2 <0.11 0.1 1 <0.120 1.4 857 "0.316 1.1 518 0.2338 23.8 18,098 6.216 1.1 373 0.110 0.7 162 0.12 0.1 1793 0.678 5.5 20,464 7.018 3.9 4211 2.6I 0.2 1750 1.14 0.9 9900 6.242 9.2 52,220 32.71 0.2 1000 0.673 16.0 57,416 36.0191 71.5 1964 13.33 1.1 469 3.23 1.1 4450 30.270 26.2 7870 53.3250 11.7 2486 0.5144 6.7 14,410 3.1I < 0.1 1750 0.44 0.2 9900 2.1145 6.8 222,327 47.534 1.6 59 < 0.1I <0.1 3 <0.1176 8.2 475 0.127 1.3 41 < 0.11 < 0.1 2 < 0.1164 7.7 332 0.1153 7.1 335 0.1I < 0.1 2550 0.51 < 0.1 1000 0.2239 11.2 99,638 21.33 0.1 38,750 8.31 <0.1 2 <0.11 < 0.1 I < 0.120 0.9 857 0.216 0.7 518 0.1649 30.3 48,014 10.316 0.7 373 0.110 0.5 162 < 0.12 0.1 1793 0.483 3.9 23,569 5.0 'CaI <0.1 147 <0.1 om0o.2143 468,247 Z26 0024311 68.2 29,916 18.7545691.1 3105 1.90.2 147 0.114202220293,829159,665267414,7539 4 RS-14-138 Enclosure Page 31 of 322recent years. However, five species were captured in this program during 2009 that were notlisted as collected during earlier sampling efforts.

They include shortnose gar, blue catfish,bigmouth

buffalo, fathead minnow, and rosyface shiner. A single specimen of each of these fivespecies was collected in 2009. The bigmouth

buffalo, fathead minnow, and rosyface shiner werecollected by electrofishing, while the shortnose gar and blue catfish were collected by trap netting.Species that numerically dominated the catch in 2009 included bluegill (30.3 %), threadfin shad(11.7%),

channel catfish (11.2%),

spotf'm shiner (8.2%), bluntnose minnow (7.7%), bullheadminnow (7.1%), carp (6.8%), gizzard shad (6.7%), and largemouth bass (3.9%). All of thesespecies were included among the catch during the 2007 survey conducted by IDNR. Biomass offish captured by electrofishing, trap netting, and gill netting in 2009 was dominated by carp(47.5 %), channel catfish (21.3%),

bluegill (10.3%),

largemouth bass (5.0%), and gizzard shad(3.1%). These results are similar to data collected by the IDNR and indicate that Braidwood Lakeis best suited to support warmwater species.Electrofishing resulted in the collection of 1420 individuals representing 22 taxa (Table 3-3). Thecatch was dominated numerically by bluegill, which comprised 23.8% of all fish captured.

Spotfin shiner (12.4%),

bluntnose minnow (11.5%),

bullhead minnow (10.8%),

gizzard shad(8.7%), carp (7.0%), channel catfish (6.8%), and largemouth bass (5.5%) were the only otherspecies to individually comprise greater than 5 % of the total catch by number. The total numberof fish collected by location ranged from 139 at Location E-2 to 250 at Location E-5 near themake-up water discharge.

The total number of taxa collected ranged from nine at Location E-2 to16 at Location E-6. In general, more fish and greater numbers of taxa were collected at locations located on the cooler end of the Braidwood Lake cooling loop (Locations E-5, E-6, and E-7).Electrofishing biomass was dominated by carp, which constituted 56.4% of the 293.8 kg collected (Table 3-2). Other species that individually contributed more than 5% of the total biomassincluded flathead catfish (13.2%),

channel catfish (11.7%),

largemouth bass (7.0%), and bluegill(6.2%).A total of 456 fish including nine species was collected by trap net (Table 3-4). Bluegill was thedominant species captured, comprising 68.2% of all fish taken. The second most abundantspecies collected was channel catfish (16.0%),

followed by carp (9.2%), gizzard shad (3.9%), andlargemouth bass (1.1%). The total number of fish collected by location ranged from nine at3-5HFDR Engineering, Inc.

TABLE 3-3FISH CAPTURED BY ELECTROFISHING IN BRAIDWOOD LAKE, 2009.Lo&SAMPLING LOCATIONS TAXON E-I E-2 E-3 E-4 E-5 E-6 E-7 E8 TOTALThreadfin shad 1 12 1 3 11 31 59 4.2Gizzard shad 72 14 7 16 5 2 2 5 123 8.7Carp I1 6 22 13 14 6 14 14 100 7.0Striped shiner 34 34 2.4Rosyface shiner I 1 0.1Spotfin shiner 27 9 34 2 12 52 17 23 176 12.4Sand shiner 16 11 27 1.9Fathead minnow I 1 0.1Bluntnose minnow I 19 22 19 16 31 18 38 164 11.5Bullhead minnow I 11 3 19 5 57 35 22 153 10.8Bigmouth buffalo I 1 0.1Channel catfish 10 25 5 23 13 3 5 12 96 6.8Flathead catfish 1 1 I 3 0.2Brook silverside 1 I 0.1Sunfish spp. I 1 0.1Green sunfish I 1 13 4 1 20 1.4Redear sunfish I 3 3 3 4 2 16 1.1Bluegill 18 22 42 30 133 20 31 42 338 23.8Longear sunfish 10 3 3 16 1.1Hybrid sunfish 4 3 3 10 0.7Smallmouth bass 2 2 0.1Largemouth bass 12 21 I1 4 8 I1 8 3 78 5.5Total fish 156 139 149 166 250 241 157 162 1420Total Taxa 12 9 iI I1 15 16 15 10 22 C mCPE (fish/hr)l 156.0 139.0 149.0 166.0 250.0 241.0 157.0 162.0 177.5 o 0Based on 1.00 hrs electrofishing effort.

TABLE 3-4FISH CAPTURED BY TRAP NETTING IN BRAIDWOOD LAKE, 2009.SAMPLING LOCATIONS TAXON TN-i TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-8 TOTAL %Gizzard shad 4 7 3 2 1 1 18 3.9Shortnose gar 1 I 0.2Longnose gar 3 1 4 0.9Carp 24 I 4 4 2 4 3 42 9.2Blue catfish I 1 0.2Channel catfish 13 6 II 1! 12 3 9 8 73 16.0Bluegill 41 21 37 64 46 4 51 47 311 68.2Largemouth bass I 1 2 1 I 5 1.1Black crappie 1 0.2Total fish 83 36 52 83 68 9 66 59 456Total Taxa 5 5 4 5 7 3 5 4 9CPE (fish/trap net set)' 41.5 18.0 26.0 41.5 34.0 4.5 33.0 29.5 28.5'Based on two over night sets of approximately 12 hr duration.

CD(0 0)K.) OD-RS-14-138 Enclosure Page 34 of 322Location TN-6 to 83 at Locations TN-i and TN-4. The total number of species collected bylocation ranged from three at Location TN-6 to seven at Location TN-5. Total biomass of fishcaptured by trap net was 159.7 kg (Table 3-2). Species collected by trap netting that comprised greater than 5% of the catch by weight included channel catfish (36.0%),

carp (32.7%),

andbluegill (18.7%).Gill netting resulted in the collection of 267 individuals representing four species (Table 3-2).Threadfin shad dominated the catch by comprising 191 (71.5%) of the 267 total fish collected.

Seventy channel catfish (26.2%),

three carp (1.1%), and three gizzard shad (1.1%) comprised theremainder of the gill net catch. Channel catfish comprised 7.9 (53.3 %) of the total 14.8 kg of fishcollected by gill netting (Table 3-2), followed by carp at 4.4 kg (30.2%),

threadf'm shad at 1.9 kg(13.3%),

and gizzard shad at 0.5 kg (3.2%).The mean electrofishing catch-per-effort (CPE) for all locations combined was 177.5 fish/hr(Table 3-3). CPE ranged from 139.0 fish/hr at Location E-2 to 250.0 fish/hr at Location E-5.Mean trap netting CPE was 28.5 fish/net (12-hr sets) and ranged from 4.5 fish/net at LocationTN-6 to 41.5 fish/net at Locations TN-1 and TN-4. Gill net CPE at Location GN-1 was 39.0fish/hr based on 117 fish collected during three hours of sampling time during the July and Augustsampling efforts.

CPE at Location GN-2 was 75.0 fish/hr based on 150 fish collected during twohours of total sampling effort during the July and August sampling periods.

Mean CPE forLocations GN-1 and GN-2 was 53.4 fish/hr based on 267 fish collected during 5 total hours offishing effort.3.3 Physicochemical DataWater quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection (Appendix Tables A-1 to A-3). During July 21-23, water temperature at Braidwood Lake ranged from 28.5 at Location E-5 (near the make-up water discharge into thelake from the Kankakee River) to 35.5 'C at Location E-1 (the most southern location locatedcloses to Braidwood Station discharge).

Make-up water from the Kankakee River was beingpumped into the lake at Location E-5 during the time water quality parameters were beingmeasured.

Water temperatures during the second sampling period (August 17-20) were similar to3-8HDR Engineering, Inc.

RS-14-138 Enclosure Page 35 of 322those measured in July. Temperatures during this period ranged from 30.4 0C at Location E-3 to35.3 'C at Location E-1. As expected, the temperature gradient generally declined as the coolingwater in Braidwood Lake moved toward the Braidwood Station intake.Dissolved oxygen (DO) ranged from 6.1 to 9.5 ppm at Locations E-1 and TN-5, respectively, during the July sampling period and from 4.1 to 9.5 ppm at Locations E-1 and TN-5,respectively, during the August sampling period. Diurnal variations in the lake led to increased dissolved oxygen reading from early morning to late afternoon.

These variations were directlyrelated to the intense phytoplankton blooms that were prevalent within the lake during the Julyand August sampling schedule.

Braidwood Lake is a very productive system with heavy oxygen demand (respiration anddecomposition) occurring during the night and intense oxygen production (photosynthesis) occurring during clear sunny days. Currently, the majority of the photosynthetic activity withinBraidwood Lake is attributable to phytoplankton, which has decreased water clarity and replacedaquatic macrophtyes as the primary producer.

In a report submitted to Exelon by SEA in 2001(Appendix Report B-i); it states that "Several perched cooling ponds in the Midwest have hadhigh macrophyte densities in their earlier years but usually become dominated by phytoplankton ifthey have heavy thermal loading.

A switch to phytoplankton dominance is usually accompanied by a reduction in water transparency."

Braidwood Lake appears to be relatively well buffered with only minor diurnal variation in pHreadings.

Examination of pH data collected during the present surveys show that pH ranged from8.7 to 9.1 during the July sampling period and from 8.5 to 8.7 during the August samplingperiod. The pH of water typically increases with increasing photosynthetic activity and oxygenproduction that may explain upward shifts in pH readings during the course of bright sunny days.During the July sampling period, conductivity ranged from 760 pnmhos at Location E-5 to 899'mhos at Location E-1. Conductivity during the August sampling period ranged from 908 arnhosat Location TN-7 to 931 Anhos at Location E-1.Make-up water was being pumped into Braidwood Lake from the Kankakee River during someportion of each sampling period during July and August, 2009. As a result, water quality3-9I-DR Engineering, Inc.

RS-14-138 Enclosure Page 36 of 322parameters were generally more favorable near the make-up water discharge (Location E-5)compared to the remainder of the sampling locations.

However, the affects of the make-up waterdischarge were quickly dissipated because of the relatively low volume of make-up flow beingpumped into the lake. During the July sampling period, water quality parameters were within therange of values acceptable for warmwater fish species.

During the August sampling period, watertemperatures, pH and conductivity were all relatively similar to the values recorded during July.However, dissolved oxygen readings in August were exhibiting greater diurnal variation rangingfrom 4.1 ppm in the morning to 9.5 ppm during the late afternoon.

The early morning dissolved oxygen readings that were measured during the August 20 sampling date were approaching valuesthat begin to adversely affect most fish species.

As previously described, these diurnal oxygenfluctuations can be attributed to oxygen depletion (respiration and decomposition) during the nightand oxygen production (photosynthesis) during the day. On cloudy calm days, photosynthesis andoxygen production can be slowed to levels that cannot compensate for the oxygen depletion thatoccurs throughout the night. If this occurs over an extended period of time, an oxygen deficit canbuild up and cause substantial fish die-offs if suitable refuges within the system are not available.

3.4 Historical Information 3.4.1 Water QualityWater quality parameters were measured on seven separate occasions at Braidwood Lake fromMay 29, 2001 through 8/27-28/2002 (Appendix Reports B-1 through B-7). The purpose andscope of these investigations varied, but the most intensive sampling was conducted during theAugust 27-28, 2002 sampling event. Results of these investigations indicated that abnormally high levels of total dissolved solids (TDS), alkalinity,

hardness, sulfates, magnesium, calcium,and total phosphorus existed throughout the cooling loop. This data was not unexpected based onthe evaporation that occurs within the cooling loop coupled with the relative low make-up andblow-down flows associated with the operation of the Station.

The cooling lake exhibited elevatedvalues for these parameters at levels of two to nearly eight times higher than those of the make-upwater from the Kankakee River. These elevated levels of water hardness can be of concern tothe Station because they have the potential to intensify problems associated with scaling.3-10HDR Engineering, Inc.

RS-14-138 Enclosure Page 37 of 322Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Concentrations ofthese nutrients are typically low in water because phytoplankton and aquatic macrophytes quicklyassimilate and utilize these nutrients for growth and reproduction.

The studies conducted by SEAin 2002 indicated that the high levels of these nutrients within the cooling lake would continue tocause problems associated with phytoplankton blooms. Unlike most water bodies, phosphorus levels within Braidwood Lake were in excess and nitrates were the limiting factor. Bluegreen algae appeared to be the dominant summer form of algae within Braidwood Lake because they arenot as limited by low nitrate levels as other algal species.Water quality analysis has indicated that dissolved oxygen levels within the cooling lake canexhibit large diurnal variation in response to algal blooms that are most problematic during thesummer months (June through August).

The nutrient rich water of Braidwood Lake is ideal forthe development of algal blooms that produce large amounts of oxygen during the day(photosynthesis) and oxygen depletion in the dark (respiration and decomposition).

As oxygen isproduced through photosynthesis, pH tends to increase if the water is not well buffered.

Dissolved oxygen levels of 4-5 ppm (levels that most fish species become stressed) and lowerhave been recorded throughout the cooling loop 0.5 m below the waters surface.

The lowest DOreadings occur during the early morning period and they typically increase throughout the day.Increases in DO of 4 to 5 ppm or more have been observed from morning to late afternoon atBraidwood Lake. In addition, stratification of the water column has also been reported during thesame period of time when DO readings are measured at less than 3 ppm. During these events,DO readings in the hypolimnion (the zone below the thermocline to the bottom of the lake) canapproach zero. When this occurs, it further limits the refuge available for fish and other aquaticorganisms.

3.4.2 Fish KillsHistorical fisheries data summarizing fish kills that have occurred at Braidwood Lake wasprovided to HDR by Exelon Nuclear, IDNR, and SEA (Appendix Reports B-2 through B-7).Five fish kills that occurred from 2001 through 2007 were identified in the information providedto HDR. Each of these events occurred during June, July, or August. Two of the kills occurred3-11HDR Engineering, Inc.

RS-14-138 Enclosure Page 38 of 322in 2001. The first took place in late July and the second on August 27-28. A third kill wasreported on July 30, 2004, the fourth on June 28, 2005, and the fifth on August 27-28, 2007.Little information was provided for the fish kills that occurred in late July and August, 2001. Thespecies involved and the extent of dead fish observed during the first event in July were notincluded in the information received by HDR. The second fish die-off in late August wasdominated primarily by gizzard shad that comprised more than 95 % of all the fish observed.

Theremaining species involved in the die-off in decreasing order of relative abundance

included, freshwater drum, quillback, carp, largemouth bass, channel catfish, redhorse spp., smallmouth bass, and bluegill.

With the exception of gizzard shad, the majority of the fish were located fromthe mid-point of the cooling loop to the intake. A report submitted by SEA indicated that warmwater temperatures and/or low dissolved oxygen levels were the most likely factors thatcontributed to the fish die-off in July. SEA also indicated that the die-off in late August was mostlikely the result of depleted dissolved oxygen levels that occurred in the lake following anextensive phytoplankton bloom collapse, which is a natural phenomenon that can occur in highlyproductive waters during summer months. Dissolved oxygen measurements throughout themajority of the lake were at or below minimum levels necessary to support most fish species.A third fish die-off at Braidwood Lake was investigated on July 30, 2004. Gizzard shad was thedominant species involved, although channel catfish were also observed.

The gizzard shadappeared to be in an advanced state of decay suggesting that the actual die-off occurred earlier inthe week. Water quality parameters at the time of the incident were not included in the briefsummary report provided to HDR, which suggest they were not measured concurrent with thefish die-off.

Water quality measurements were taken in early October following the fish die-off.During this period of time DO levels of 3.8 ppm and a water temperature of 29.2 'C wererecorded at a depth of one foot below the surface just north of the south boat ramp. At a locationseveral hundred feet from the lake make-up discharge, more favorable dissolved oxygen (7.6ppm) and water temperatures (26.5 'C) were measured.

DO readings at this location werestratified exhibiting a decline to 5.3 ppm at 40 feet, while water temperature showed minimaldecrease with water depth.3-12HDR Engineering, Inc.

RS-14-138 Enclosure Page 39 of 322In 2005, an inspection of a fish die-off ywas conducted on 28 June. Formal counts of fish were notconducted at this time, but field assessments indicated that a fairly substantial die-off involving several species had occurred.

Gizzard shad was again the most numerous species affected andfish carcasses were observed throughout the majority of the lake. Additional species observedincluded threadfin shad, quillback, largemouth and smallmouth bass, carp, and channel catfish.Water quality measurements during this event were not provided to HDR and are assumed to beunavailable.

Rob Miller of IDNR and Jeremiah Haas of Exelon Nuclear investigated another fish die-off thatwas first reported at Braidwood Lake on August 21, 2007. The majority of the dead fishobserved were either large gizzard shad or threadfin shad up to five inches in length. Channelcatfish were also prevalent, with only a few carp, largemouth bass, and flathead catfish beingobserved.

Most of the fish were distributed in close proximity to the north boat ramp due toprevailing south winds. The number of dead fish observed decreased towards the south (hot) endof the cooling loop. During the afternoon of 21 August, surface water temperature was 35.3 'Cand DO was near 3 ppm at a sampling point several hundred yards from the south ramp. Fourseparate water temperature and DO readings were also conducted at the north ramp between 1210hrs and 1658 hrs. Water temperature increased from 30.3 to 33.9 OC over the course of that timeinterval.

Dissolved oxygen was measured at 3.1 ppm at 1210 hrs and increased to 6.7 ppmduring the third reading at 1530 hrs. DO levels decreased during the last reading at 1658 hrs to5.9 ppm. Oxygen depletion appeared to be the factor responsible for the August fish kill thatoccurred at Braidwood Lake in 2007.3-13HDR Engineering, Inc.

RS-14-138 Enclosure Page 40 of 3224.0 SUMMARY AND RECOMMENDATIONS 4.1 Summary.

Braidwood Lake is a 2640 acre, partially perched cooling lake that was firstimpounded in 1980-1981 after several old strip-mine pits were inundated with water from theKankakee River. The lake has received supplemental stockings of both warm and coolwater fishspecies since the late 1970's. However, stocking efforts of species including

walleye, tigermuskie, smailmouth bass, and hybrid stripped bass have not produced a sustainable qualityfishery, which is most likely because of the warm water temperatures that are presently commonin the cooling lake during summer months. Water quality, particularly water temperature, improves as the water moves from the southern (hot) end of the cooling loop toward the northern(cool) end of the lake.Fisheries surveys have been conducted by IDNR at Braidwood Lake annually from 1980 through1992, in 1994, and at two year intervals from 1997 through 2007. Forty-five species of fish andtwo taxa (tiger muskie and hybrid sunfish) have been included among the 12 families of fishcollected.

River redhorse (one individual captured in 1999) is the only species that has beencollected which is currently listed as protected in Illinois.

Several of these species were rarelycollected, were the result of supplemental stocking

efforts, or have not been collected during thepast ten years of sampling.

In 2009, HDR collected 24 species and two taxa (hybrid sunfish andsmall unidentified young-of-year sunfish species) among the 2143 fish collected.

Several taxa thatwere collected during previous surveys were not collected in 2009. However, five species(shortnose gar, blue catfish, bigmiouth

buffalo, fathead minnow, and rosyface shiner) that had notbeen captured during previous sampling efforts were collected.

A single specimen of each specieswas collected by either electrofishing or trap netting.

No threatened or endangered species wereencountered in the 2009 lake surveys.

Since 1980, 50 species of fish and two hybrids (tigermuskie and hybrid sunfish) have been collected at Braidwood Lake by the IDNR and HDR.The Braidwood Lake Fish and Wildlife Area has evolved through three distinct phases since itsinception prior to the 1980's. Originally, several surface mined pits existed at the site until thelake was impounded with water from the Kankakee River during 1980 and 1981. The lakecontinued to function in this capacity until July 29 and November 17, 1988 when Braidwood Station began commercial operation of Unit I and Unit II, respectively.

From 1980 through July4-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 41 of 3221988, Braidwood Lake did not receive any thermal loading from Braidwood Station.

Since 1988,the lake has functioned as a cooling loop for the operation of the Station.

Currently, the lake isbest suited to support a warmwater fishery due to the warm temperatures prevalent in the lakeduring summer months. Dominant species currently found in Braidwood Lake include gizzardshad, threadfm shad, bluegill, channel catfish, and carp. Additional species such as largemouth bass, green sunfish, flathead

catfish, spotfm shiner, bluntnose minnow, and sand shiner are alsocommonly encountered.

Excluding several of the stocked taxa that have been introduced into thelake, the taxa encountered have also been collected from the Kankakee River, which is the sourceof make-up water for the lake. With the possible exception of common carp, these species arebetter suited to conditions that exist within the river. Survival of individuals that may beintroduced into the lake with the make-up water is limited by the elevated water temperatures thatexist within the cooling loop particularly during summer months.Braidwood Lake can be currently described as a well buffered body of water with elevated watertemperatures, high levels of total dissolved solids (TDS), phosphates, and nitrates.

Primaryproductivity in the lake can be very high in conjunction with algal blooms that occur throughout the lake, especially during the June through August period. These blooms are driven by the highnutrient levels that occur within the lake. In recent years, phytoplankton has replaced aquaticmacrophytes as the principal source of primary production.

The lake can also display relatively large diurnal fluctuations in dissolved oxygen measurements, particularly during the summerwhen oxygen is produced in large quantities by photosynthesis during the day and used in largequantities by respiration and decomposition during the night. In addition, Braidwood Lake canalso stratify during certain portions of the year, which has led to anoxic (oxygen depletion) ornear anoxic conditions throughout the hypolimnion (stratified bottom layer of water below thethermocline) as a result of respiration and decomposition from a collapsing algal bloom. Even inthe surface waters of the epilimnion, dissolved oxygen readings of 4 ppm and below have beenreported following an extensive and rapid die-off of an existing phytoplankton bloom. It is duringthese periods when water temperatures are elevated and dissolved oxygen levels are low that fishdie-offs occur within lake. The conditions described in this paragraph should not be expected tochange at Braidwood Lake in the foreseeable future.4-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 42 of 3224.2 Recommedations.

Five separate fish die-offs attributed to low DO levels were observedat Braidwood Lake between 2001 and 2007. It is expected that the conditions which led to thosefive events will not change or improve in the foreseeable future. Therefore, it should be assumedthat fish die-offs will continue to occur and be problematic for the Station when algal bloomscrash and oxygen depletion occurs. Substantial fish die-offs within the cooling loop couldadversely affect both the operation and maintenance of Braidwood Nuclear Station.Currently, there are no practical or simple solutions that could prevent the occurrence of fish die-offs at Braidwood Lake. It should be anticipated that fish die-offs will continue to occur at thelake on a fairly regular basis. Therefore, it would be advantageous if a reliable sampling programor set of procedures were developed that would reasonably predict fish die-offs which mayadversely affect the operation and/or maintenance of the Station.

With advanced warning theStation would be informed of a potential reportable

incident, regulatory agencies could benotified, and crews responsible for fish disposal could be put on alert to help manage the riskassociated with a substantial fish die-off.

HDR believes this can be accomplished by conducting routine visual inspections of the lake, monitoring dissolved oxygen levels, and by having a basicunderstanding of environmental conditions that may trigger these events, especially weatherconditions.

HDR recommends a two tier sampling procedure that may be utilized to help predict the onset ofa possible reportable fish die-off.

We recommend that visual inspections of the lake and waterquality measurements be conducted routinely throughout the year, particularly during the warmweather months, if budget constraints and staff are available to monitor the lake. The frequency of observations and the intensity of the water quality measurements should be discussed by themanagement at Braidwood Station who would analyze risk management.

Historically, all the fishdie-offs at Braidwood Lake have occurred during the warm weather period of June throughAugust. This is the period of time when water in the cooling loop is the warmest and dissolved oxygen levels can fall substantially following die-offs of extensive phytoplankton booms.Therefore, this is the most critical period of time to monitor existing conditions that could result ina potential problem (May through September).

Sampling on a less frequent basis throughout theremainder of the year may provide additional information that could be useful to the Station andpossibly alert the Station of an impending problem which may not have been identified in the past.4-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 43 of 322Water quality measurements should include dissolved oxygen readings at a minimum becausefisheries biologists that have investigated these events in the past have concluded that the mortality of fish was the result of oxygen depletion.

The most effective way to monitor dissolved oxygenlevels within the lake would be through the use of a permanently fixed continuous water qualitysampler and data logger that could be programmed to take measurements at predetermined timeintervals, The number of water quality samplers purchased or the type of sampler utilized wouldbe dependent upon the desired results and cost of the equipment.

Ideally, the best system wouldallow the sampling unit to take measurements at programmed time interval (perhaps every 15minutes to daily), would measure at least DO, water temperature, and pH, could provideinstantaneous readouts to Braidwood staff without having to manually go into the field todownload data, and would require minimal maintenance or calibration to operate.

The pricerange of this type of equipment is highly variable depending on the unit selected, the anchoring mechanism for the unit if required, battery life, the number of parameters

measured, etc. Analternative to this approach would be to utilize a technician to manually take these measurements.

The disadvantage of this approach is the number of readings that could be taken on a daily basisand the time involved to conduct the water quality analysis in the field.Water quality at Braidwood Lake should be monitored on some predetermined routine basis. Thatcould be at least weekly throughout the year or perhaps only through the more critical time periodof approximately May through September.

The two tiered sampling approach would be initiated when dissolved oxygen readings hit a pre-determined trigger point (perhaps 5 to 6 ppm). OnceDO readings decrease to the trigger point, sampling frequency should be increased to at least daily(preferably hourly).

If automatic samplers are not used, field technicians should be in the field bysunrise when DO readings are typically the lowest. If automatic samplers were utilized, dissolved oxygen, temperature and other water quality parameters could be tracked throughout the day.This would become important if DO reading ranged from 4 or 5 ppm in the morning to 7 or 8ppm in the afternoon.

This information would indicate that photosynthesis is still occurring during the daylight period, which would replenish DO levels in the water and reduce the risk of afish die-off.

However, if DO levels were 4 or 5 ppm in the morning and only increased slightlythroughout the day, this would indicate very little oxygen production due to photosynthesis.

Thiscondition would lead to a greater oxygen deficit during the evening, and could indicate the onsetof a phytoplankton bloom die-off that could trigger a fish kill. Once DO levels approach 3 ppm4-4HIDR Engineering, Inc.

RS-14-138 Enclosure Page 44 of 322Station management could be notified of a potential

problem, increased visual inspections of thelake could be conducted, and fish disposal crews could be notified and put on standby status.Additionally, Braidwood staff should be aware of weather patterns that can influence these events.When phytoplankton blooms are prevalent and several cloudy days with little or no wind areforecast, massive dies offs of the bloom and subsequent oxygen depletion throughout the watercolumn may be anticipated.

Increased sampling of DO during these weather patterns is advisable in conjunction with an increase in the frequency of visual inspections at the lake for moribund ordead fish. An increase in water clarity or transparency within the lake would also be expected tooccur as the phytoplankton population crash is in progress.

Visual inspections for fish die-offs should be conducted around the entire cooling loop asprevailing winds may push most of the fish toward one end of the lake. HDR recommends waterquality measurements be conducted at a depth of approximately one meter, if multiple depths arenot sampled.

If only one sampling location is selected, that location should be located near theapproximate mid-point of the cooling loop. The number of water quality stations sampled shouldbe determined by Exelon management or an advisory staff. It is further recommended that anadvisory team should be formed to devise an effective sampling program and set of procedures that can effectively monitor conditions within the lake. HDR is willing to participate and interactwith the advisory team to provide expertise in the development of an effective sampling program.4-5HDR Engineering, Inc.

RS-14-138 Enclosure Page 45 of 32

25.0 REFERENCES

CITEDBecker, G.C. 1983. Fishes of Wisconsin.

The University of Wisconsin Press. Madison, Wisconsin.

Environmental Science & Engineering.

1993. Kankakee River Fish Monitoring Program Braidwood Station 1993. Report to Commonwealth Edison Company,

Chicago, Illinois.

HDR Engineering, Inc. 2009. Braidwood Station Kankakee River Fish Monitoring

Program, 2008.Report to Commonwealth Edison Company,

Chicago, Illinois.

HDR/LMS 2006. Braidwood Station Kankakee River Fish Monitoring

Program, 2005. Report toCommonwealth Edison Company,

Chicago, Illinois.

HDR/LMS 2007. Braidwood Station Kankakee River Fish Monitoring

Program, 2006. Report to.Commonwealth Edison Company,

Chicago, Illinois.

HDRILMS 2008. Braidwood Station Kankakee River Fish Monitoring

Program, 2007. Report toCommonwealth Edison Company,

Chicago, Illinois.

Illinois Endangered Species Protection Board. 2004. 2004 Checklist of Endangered and Threatened Animals and Plants of Illinois.

Illinois Department of Natural Resources, Springfield, Illinois 22 pp.Lawler, Matusky and Skelly Engineers (LMS). 1992. Braidwood Station Kankakee River FishMonitoring

Program, 1991. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1996. Braidwood Station Kankakee River FishMonitoring

Program, 1995. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1999. Braidwood Station Kankakee River FishMonitoring

Program, 1998. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2001. Braidwood Station Kankakee River FishMonitoring

Program, 2000. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2005. Braidwood Station Kankakee River FishMonitoring

Program, 2004. Report to Commonwealth Edison Company,

Chicago, Illinois.

Pflieger, W.L. 1975. The Fishes of Missouri.

Missouri Department of Conservation.

Jefferson City, Missouri.

Smith, P.W. 1979. The Fishes of Illinois.

University of Illinois Press, Urbana, Illinois.

314 pp.Trautman, M.B. 1981. The Fishes of Ohio. Ohio State Press in Collaboration with the Ohio SeaGrant Program Center for Lake Erie Area Research.

782 pp.5-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 46 of 322APPENDIX APIHYSICOCHEMICAL DATA RS-14-138 Enclosure Page 47 of 322LIST OF TABLESTable No. Title Page No.A-i Physicochemical Measurements Recorded Concurrently withElectrofishing Samples Collected from Braidwood Lake, 2009. A-IA-2 Physicochemical Measurements Recorded Concurrently withTrap Netting Samples Collected from Braidwood Lake, 2009. A-2A-3 Physicochemical Measurements Recorded Concurrently withGill Netting Samples Collected from Braidwood Lake, 2009. A-3lHDR Engineering, Inc.

TABLE A- IPHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH ELECTROFISHING SAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2009PARAMETER E-1 E-2 E-3 E-4 E-5 E-6 E-7 E-8Date (First Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)> PhConductivity (Wnhos/cm)

JUL 22095535.56.19.1899JUL 22105032.78.99.1894JUL 22122530.58.58.8892JUL 22132031.97.58.7892JUL 22153028.58.28.7760JUL 23082030.56.48.8891JUL 23092530.76.58.7884JUL 22142032.18.68.8888Date (Second Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (prnhos/cm)

AUG 20104531.74.18.6931AUG 20115031.14.98.6927AUG 20125530.46.48.5923AUG 20150531.58.18.6923AUG 20071030.94.38.6926AUG 20083030.64.58.6914AUG 20093030.54.78.6914AUG 20134531.26.28.69200, 0-0 i)-00 TABLE A-2PHYSICOCIEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH TRAP NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2009PARAMETER TN-1 TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-8Date (First Sample Period)JUL 21 JUL 21JUL211715JUL 21 JUL 21JUL21 JUL21JUL 211855Time>Ib,3Temperature (0 C)Dissolved oxygen (ppm)PhConductivity (nimhos/cm)

Date (Second Sample Period)164532.6'32.6b9.1'7.eb9.1'9.1lb895'895b170032.532.58.98.79.19.189589532.132.29.49.09.19.1895894173032.031.98.68.68.98.9894894180029.929.39.59.48.88.8893893182030.730.89.49.38.78.7897896184030.130.27.67.48.78.78.887887729.629.78.68.68.88.8883884AUG 17 AUG 17AUG 17 AUG 17 AUG 17 AUG 17 AUG 17 AUG 17Time1655Temperature (0 C)Dissolved oxygen (ppm)35.3'35.3b8.9'8.918.7'9.72920"920'164534.334.38.98.98.78.7920920164033.633.68.68.58.68.6921922163033.633.68.08.08.68.6921921162032.632.69.59.58.78.7917917160033.133.09.08.98.68.6920919155031.731.76.86.88.58.5908908153532.032.07.07.18.7 -'8.7 (D912 -912pHConductivity (pmhoslcm)

'Top number represents subsurface readings taken 0. 5 meter below the surface.bBottom number represent bottom readings taken 0.5 meter above the bottom.

TABLE A-3PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH GILL NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2009PARAMETER Date (First Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)PhGN-1Surface BottomJUL 21 JUL 211600 160032.0 32.18.8 8.8GN-2SurfaceJUL 21 ]181030.88.8BottomFUL 21181030.98.98.98.78.78958.9896Conductivity (pmhos/cm)

Date (Second Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (pmhos/cm) 895AUG 18063033.75.28.5929896AUG 18063033.65.18.5928AUG 17160533.19.08.6920AUG 17160533.18.98.6920(DM C()2.C.,N) OD RS-14-138 Enclosure Page 51 of 322APPENDIX BHISTORICAL WATER QUALITY AND FISHERIES DATA RS-14-138 Enclosure Page 52 of 322LIST OF TABLESReport No. Title Page No.B-i Results of Initial Braidwood Cooling Pond Survey by SEA Inc.,2001. B-IB-2 Investigation of Fish Kill on Braidwood Cooling Pond August27-28, 2001. B-5B-3 Results of Braidwood Cooling Pond Water Quality Analysisfrom August 27 and 28, 2002. B-9B-4 Fish Kill Reports going back to 2003. B-17B-5 Braidwood Lake Fish Kill, August 21, 2007. B-19B-6 Braidwood Fish Kill August 21, 2007. B-21B-7 Braidwood Fish Kill Clean-up August 21, 2007. B-22HDR Engineering, Inc.

RS-14-283 Enclosure Page 2 of 9APPENDIX REPORT B-I.Results of Initial Braidwood Cooling Pond Survey by SEA Inc.SEA Inc. was asked to conduct an initial water quality and ecological assessment of Braidwood Cooling Pond. The objective was to determine if the densemacrophytes were contributing to an increasing trend toward a higher pH in thepond. The results and discussion presented in this report are primarily basedupon the samples taken and observations made on May 29 and 30, 2001, and ona preliminary review of water quality data from three sites taken on May 18, andJune 14, 2001. SEA Inc. was also asked to investigate a fish kill on Braidwood Cooling Pond on August 27 and 28. The results of that investigation are in aseparate report but some of that information is referenced in this report.Overview of Methods and Results Presentation.

SEA's initial survey (May 29-30) consisted of:" water quality parameters at several key sites with a Hydrolab Surveyor Il,during both daylight and night conditions,

" measuring phytoplankton community respiration (light & dark bottle method)," identification of macrophytes and observations on their distribution andabundance, and" monitoring temperatures throughout the cooling loop.The survey results are summarized in Tables 1,2, 3, and 4. Table 1 provides theresults from key sampling sites that were selected to characterize the coolingpond. These sites were sampled three to four times over a 36-hour period.Parameters sampled with the Hydrolab included:

Depth, Temperature, Dissolved Oxygen (D.O.), pH, Specific Conductance, and Redox Potential.

Sample timesincluded midday, just before sunset, and prior to sunrise.Table 2. includes results from two sites for depth profiles, 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration light& dark bottles, and the SX discharge.

Table 3. provides D.O. and temperatures sequentially around the cooling loop at midday. Table 4. lists the D.O. levels and% saturation at four sites prior to sunrise.

Table 5 list the water quality analysispreformed by Test America at three locations on two dates. Figure 1. is a mapidentifying the sample locations listed in the tables.Discussion of Results and Observations:

Braidwood Cooling Pond was characterized to SEA Inc. as a pond that wasdominated or choked by macrophytes.

Based on this characterization, we feelthat Braidwood Cooling Pond has undergone a transformation to a systemdominated by phytoplankton.

Although we were not prepared to sample thephytoplankton for densities and identification, it was very obvious that anB-I RS-14-138 Enclosure Page 54 of 322intensive phytoplankton bloom was in progress.

Secchi disc readings were only0.30 to 0.35 m throughout the pond. Although we were unable sample thephytoplankton, we would suspect it is dominated by Blue-Green algae(Cyanophyta),

based on the water temperatures, total phosphorous levels, highpH and apparent high densities.

Braidwood Cooling Pond appears to be a very dynamic system that receivesenergy subsidies in the form of heat, pumped circulation and make-up water fromthe Kankakee River. Several perched cooling ponds in the Midwest have hadhigh macrophyte densities in their earlier years but usually become dominated byphytoplankton if they have heavy thermal loading.

A switch to phytoplankton dominance is usually accompanied by a reduction in water transparency.

OurSecchi disc readings were about 0.3 m which is about one half of the 2 ft or0.6m)value listed in a privately produced fishing guide (Sportsman' Connection) published in 2000. Although we did not examine many of the isolated coves, wefound Milfoil ( Myriophyllum verticillatum) only in the last 1/3 of the cooling loop(Figure 1. sites7,8,9) and its abundance was spotty. The Sportsman' Connection fishing guide map had a much wider distribution of submerged, emergent andfloating vegetation and appeared to be more in line with earlier descriptions SEAInc. were given of Braidwood.

Nutrients that were previously tied up by themacrophytes are now likely being taken up by the phytoplankton.

The reducedwater transparency due to the phytoplankton bloom will limit light to thesubmerged macrophytes and likely cause further reductions.

The intensive phytoplankton bloom that Braidwood is currently experiencing mayhave more potential for adverse impacts to the biological community than on.operational impacts to the station.

The water seems to be fairly well buffered anddiurnal swings in pH were insignificant.

Analysis of the water for alkalinity couldconfirm the buffering capacity.

Blue-Green algae blooms may present problemswith D.O. levels and in some rare cases may release toxins with impact otheraquatic life.The light & dark bottle (Table 2.) and the pre-sunrise D. 0. levels (Table 4.)illustrated the intensity of the bloom. The light and dark bottles were at a 0.5 mdepth at end of the discharge canal for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Respiration in the dark bottleddepleted the initial D.O. from 10.8 mg/I (158% saturation) to 1.37 mg/I (20 %saturation).

The light bottle was supersaturated to the point the entire insidesurface was coated with oxygen bubbles and the D.O. was 11.8 (174%saturation).

The photosynthetic rate was much higher than could be measureddue to the extensive formation of oxygen bubbles in the light bottle. Thephotosynthetic rate was so high that the light bottle should have been limited to 6hours to obtain a better measurement of the gross plankton photosynthetic rate.The pre-sunrise D.O. measurements (Table 4.) also reflect the high respiration rate of the plankton community.

Most notable was Site #3 where D.O. levelsdropped to 4.1 mg/l. The midday sampling on the first day (Table 1.) wasconducted during bright and sunny conditions and D.O. levels at most sites werehigher than midday samples on the following day when it was overcast.

ThisB-2 RS-14-138 Enclosure Page 55 of 322plankton community is so productive that D.O. levels can be expected to swingrapidly.

During our survey, air temperatures were mild (high 65 F) and it waswindy both days. Under a scenario of several hot summer days, with little wind,full operation of the station, followed by a cloudy day, D.O. levels could drop tothe point that fish kills could occur. Some fish species will be already stressed byheat, saturation levels for D.O. will be lower, and high, predawn respiration ratescould create a significant problem.

Unfortunately, there are no operational changes the station can make to reduce this risk. The fish kill that did occur inlate August was apparently a result of depleted DO that most likely resulted fromthe phytoplankton bloom die off.Thermal refuges are critical to the survival of fish in heavily loaded cooling ponds.The deeper areas in the warmer end of the lake will not be refuges sinceadequate levels of oxygen are already absent from depths below 4 meters (Table2.). However, the flow and slightly cooler temperatures at site 7 (figurel.)

havemaintained oxygen levels down to nearly 10 meters. If these refuges are erodedaway during the summer, fishes will be stressed.

Of the three key species listedin the Sportsman's Connection for Braidwood, both the walleye and crappiewould be sensitive to D.O. at higher temperatures.

Two fish kills occurred inBraidwood this summer, the first in late July was likely related to temperature, thesecond in lake August resulted from DO depletion.

Although our expertise is not in water chemistry, Braidwood Cooling Pond maybe facing some water quality issues. One of the objectives of the survey was todetermine if macrophytes were contributing to the increasing pH. A chart of pHvalues from 1989 to 1998 provided by the Braidwood Station indicated theincreasing trend in pH has become more pronounced since 1997. Since thissurvey indicated macrophytes abundance was in a sharp decline, it is clear theyare not contributing to the elevated pH of 9.1 to 9.2 (Table 1). The intensive phytoplankton boom present during the survey could have contributed to theelevated pH. The phytoplankton bloom had crashed by August 27 and 28 (fish killinvestigation) and the pH had dropped to 8.6. It was not possible from this limiteddata to determine to what extent several factors may be contributing to theelevated pH. The cooling pond's buffering

capacity, photosynthetic

activity, blowndown rate, and plant operations are all potential factors to be investigated.

The Test America analytical results from three sites on 5/18/01 and 6/14/01provides some information on water quality (Table 5). Orthro phosphate is areadily available form for plants and is quickly taken up. The detection limit listedby the lab was 0.06 ppm, which was too high to show any differences betweensites or sample dates. Orthro phosphate levels in many Illinois lakes would bebelow 0.025 ppm. Total phosphate at the plant discharge on 5/18/01 was 5.5ppm, which is very high. The Illinois General Use Water Quality standard is not toexceed 0.05 ppm in lakes or reservoirs over 20 acres. The plant appears to bethe phosphate source and one possible explanation may be scale inhibitors commonly used by power plants. Scale inhibitors are typically high in phosphates but it is generally in a form not available to aquatic plants. Total phosphate levelson 6/14/01 were lower (0.18 to 0.28 ppm) but still elevated relative to other lakes.B-3 RS-14-138 Enclosure Page 56 of 322Phosphates are a major concern as elevated levels can contribute to nuisancephytoplankton blooms.Total Suspended Solids (TSS) on 5/18/01 were high (164 ppm) at the discharge and generally higher than expected throughout the pond. It is suspected that theplankton bloom may have been responsible for much of that elevation.

This couldhave been confirmed by comparing the volatile to the non-volatile portion of theTSS.Total Dissolved Substances (TDS), total hardness,

calcium, sulfates and specificconductance are all correlated and generally exhibited increases from 5/18/01 to6114/01.

The high evaporation rates in the cooling pond during the summerprobably contributed to this increase.

These parameters are of concern sincethey are indicators of potential scaling in heat exchangers.

Lowering these levelswould require an increase in make-up and blow-down rates. However it isrecognized there are restrictions on make up withdraws and blow-down concentrations are regulated.

SummaryIt appears that the Braidwood Cooling Pond plant community is changing fromone dominated by macrophytes to phytoplankton.

The phytoplankton bloom inMay was very rich and has the potential to deplete D.O. to the point that fish killscould occur. There are few operational changes that the plant can take to preventthese potential events. Monitoring the cooling pond and preparing regulatory agencies for these potential changes may be a way to help manage these risks.Unfortunately the fish kill in late August confirmed the potential for these kills.The phytoplankton bloom may a contributor to the increasing pH. The high totalphosphate level that appears to be coming from the plant may be fueling thephytoplankton bloom. Further investigation of the factors that may be contributing B-4 RS-14-283 Enclosure Page 3 of 9APPENDIX REPORT B-2.DRAFTInvestigation of Fish Kill on Braidwood Cooling PondAugust 27-28, 2001Executive Summary:Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of anon-going fish kill on Braidwood Cooling Pond on August 27 & 28, 2001. Theinvestigation consisted of surveying the shoreline to determine the extent of thekill and the species involved, and water quality analyses for pH, temperature, anddissolved oxygen.Most of the fish appeared to have been dead for about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than95% were gizzard shad. The other species involved in descending order ofrelative abundance were freshwater drum, quillback, carp, largemouth bass,channel catfish,

redhorse, smallmouth bass and bluegill.

Other than gizzard shadmost of the dead fish were located between the mid -point in the cooling loop tothe intake. Throughout most of the cooling pond, dissolved oxygen levels were ator below the minimum levels necessary to support most fish and was the mostlikely cause of the kill. Water clarity was very high and suggested a recent die offof much of the phytoplankton, which is usually followed by oxygen depletion.

Thisis a natural phenomenon that can occur in highly productive lakes during summermonths. Temperatures throughout most of the lake were within the tolerance limits of the species involved in the kill. It does not appear that operations of thepower station had a direct impact on the fish kill.Methods Overview and Results Presentation:

SEA Inc. arrived at 5:00 PM on August 27 and conducted an initial survey of themain portion of the cooling loop and checked temperature, dissolved oxygen(DO), and pH at two locations.

The investigation continued at sunrise on August28, and included investigation of many of the coves on the lake and water qualityanalyses at sixteen sites. Water quality analysis was conducted with a HydrolabSurveyor Ill. Measurements were for depth, temperature, DO, pH, specificconductance, and redox potential at the surface (0.5 Meters) and then at one-meter intervals to the bottom.The water quality sampling locations are shown on Figure 1. Dissolved oxygenprofiles from selected sites are illustrated in Figure 2. Figure 3 illustrates DOconcentrations at one-meter depth at all sites. The results of the water qualityanalyses are presented in Table 1. The station hourly inlet and outlet watertemperatures for August 24 through August 27 are listed in Table 2.B-5 RS-14-138 Enclosure Page 58 of 322Discussion of Results and Observations:

Upon arrival the investigation began at the south access boat ramp near Site 3(Figure 1.) and proceeded around the cooling loop toward the plant intake. NearSite 3 several gizzard shad in the 170 to 220'mm were observed.

They appearedto have been dead for 12 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In the portion of the pond between sites5.5 and 5.75 there were greater numbers of gizzard shad along the shoreline anda few largemouth bass. The largemouth bass appeared to have been dead formore than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The number of fish appeared to increase as theinvestigation progressed around the cooling loop. The largest concentrations ofdead fish were in several coves on the East side of the lake near Site 8. Theback 20 to 35 ft. of the cover were covered solid with dead fish. Gizzard shadcomprised more than 95% of the fish in these coves and were represented bythree size classes.

The other species involved in descending order of relativeabundance were freshwater drum, quillback, carp, largemouth bass, channelcatfish,

redhorse, smallmouth bass and bluegill.

There are two factors that may have influenced the distribution of dead fish. First,the temperature gradient becomes more favorable for fish toward the intake endof the cooling loop. Second, the circulation of water around the cooping loopwould tend to concentrate dead fish in the intake area of the cooling pond. Theconcentration of fish in coves at Sites 8 and 8.5 was most likely an accumulation resulting the above mention factors and wind direction.

However DO levels atSite 8.5 were only 2 ppm (Table 1, page 3) at a time of day when they shouldhave been much higher. This level of DO is not adequate to support most fishes.Several YOY freshwater drum were observed at the surface which had recentlydied or were about to. This kill did involve many fish, but during this survey manylive fish were observed on sonar in the cooler end on the lake. Bluegills exhibiting normal behaviors were observed in the cove just East of Site 2.5.Dissolved oxygen levels at the plant intake were 3.5 ppm at the surface and 1.2ppm at 3 meters (Table 3) during the evening of August 27. Percent DOsaturation was 49% and 17% respectively.

Surface DO level taken on May 29 bySEA Inc. at this same location, at the same time of day was 9.3 ppm and 117%saturation.

The DO levels at Site 3 were 3.8 ppm on August 27 which was muchlower than the 8.0 ppm taken at sunset on May 29. On August 28 just prior tosunrise the DO at Site 3 was 3.2 ppm only slightly lower than the previousevening indicating little diurnal variation.

On May 29 the overnight drop in DO atSite 3 was 50%.The surface DO level at Site 4 on August 28 was 2.9 ppm and dropped to 0.7ppm at 4 meters. Surface DO levels Sites 4.5, 5, 5.5, and 5.7 were even lowerB-6 RS-14-138 Enclosure Page 59 of 322ranging from 2.4 to 2.1 ppm. Site 6 had one of the higher DO levels at 4.4 ppm.Site 8 and 9 had the highest surface DO levels at 4.8-ppm (Table 1).Temperatures throughout most of the cooling pond were within the tolerance limits of most fish species and there had been no major temperature changes inthe last few days (Table 2). The oxygen levels throughout most of the lakesuggest that depleted oxygen levels were the most likely cause for the fish kill.Such kills can naturally occur in highly productive lakes or ponds that may exhibitlarge diurnal swings in DO levels due to high daytime photosynthetic rates andhigh respiration during the night. The survey SEA Inc. conducted on May 28 and29 suggested Braidwood Cooling Pond was a very productive and the potential existed for an oxygen depletion fish kill. This survey noted several changes in thecooling pond that suggested such a kill had occurred.

There was no indication that the fish kill was directly related to the operation of the power station.SEA Inc.'s initial investigation in May was to assess if the historically highabundance of macrophytes (rooted aquatic vegetation) was contributing anincreasing trend in pH. What was observed was an intensive phytoplankton bloom that limited light penetration and almost no healthy macrophytes remained.

Water transparency measured with a Secchi Disc was only 0.3meters. Diurnal swings in DO levels were very pronounced and at some locations dropped to 4 ppm just prior to sunrise and reached supersaturation levels by midday. Under these conditions any major change in nutrients, reduced lightintensity, increase in biological oxygen demand, or other factors could result in.,oxygen depletion.

Braidwood Cooling Pond appeared to be undergoing atransition from a system dominated by macrophytes to one dominated byphytoplankton.

One of the most notable changes during this investigation was the dramaticchange in water transparency.

There was no phytoplankton bloom and SecchiDisc readings had increased up to 2.7 meters. Plankton samples indicated verylow levels of phytoplankton but high abundance of zooplanktors (primarily.

Rotifers and Cladocera).

Oxygen levels were typically from 29% to 66% ofsaturation as opposed to May when most midday levels were at or abovesaturation.

As discussed

earlier, there were only minor differences in diurnaloxygen levels. All the above factors suggest the phytoplankton bloom hadrecently crashed.

There were no remaining macrophytes to fill the niche asprimary producers.

Not only was there a reduction in photosynthetic activity toproduce oxygen, there was an increased oxygen demand from decomposition and respiration of the abundant consumers.

It is suspected that oxygen levels aday or two prior to this investigation may have been even lower than observed.

The one-meter DO levels were lowest toward the center portion of the coolingloop (Figure 2). From Site 3 to Site 6.5 (with the exception of Site 6) DO levelswere 3.1ppm or less. A similar pattern of low DO was noted at Sites 3 and 4 inearly morning samples taken in the May survey, Factors contributing to lower DOB-7 RS-14-138 Enclosure Page 60 of 322levels were not clear, but it suggest this may be one of the most sensitive areasof the cooling pond to oxygen depletion.

Additional sampling would be required toattempt to identify the cause and to eliminate any data bias associated with thetime of day samples were taken.The unique changes in water depths and flow velocities in Braidwood CoolingPond have a major influence on DO levels and temperature stratification.

Areasof the cooling pond which were deep and not in a high velocity areas exhibited amore normal DO curve from top to bottom (Figure 3). At Site 2.5, DO declinedquickly between 6 and 8 meters and coincided with thermal stratification.

At Site4, the DO declined rapidly between 2 and 3 meters where thermal stratification was apparent (Table 1). In contrast, Sites 5.5 and 7 were located in areas withhigh velocities and had fairly consistent DO levels and temperatures from top tobottom (Figure 3). This is quite different from the DO and temperature profiles inmore typical perched cooling ponds and better utilizes the entire volume forcooling and may also provide for better thermal refuges for fish. During this lastincident it is unlikely Site 5.5 was an effective refuge for DO since levels werebelow 2.5 ppm. These DO levels were however due to lower DO levelsthroughout the cooling pond rather than depletion at this site.Braidwood Cooling Pond appears to be undergoing a transition from a ponddominated by marcophytes to one dominated by phytoplankton.

During such atransition major swings may be expected as different components of thisecosystem adapt to this change. Over time one would expect the amplitude ofthese changes to moderate.

During the May survey the intense phytoplankton bloom appeared to eliminate the macrophytes.

There were major differences indiumal DO levels suggesting a very productive system with heavy respiration anddecomposition demands at night and supersaturation from photosynthesis duringthe day. This survey indicated a major loss of the phytoplankton, no remaining macrophytes to carry on primary production and enough respiration anddecomposition to reduce oxygen below the levels to maintain many fishes.Additional studies on nutrients and the dynamics of the plankton would beneeded to better identify the changes that may be taking place in this coolingpond. Decisions on the operational management of this cooling pond as well asthe fishery management need to consider that this pond may be going throughtransitional changes.B-8 RS-14-138 Enclosure Page 61 of 322APPENDIX REPORT B-3.Results of Braidwood Cooling Pond Water QualityAnalysis from August 27 & 28, 2002SEA Inc. was asked to sample Braidwood Cooling Pond for a number of waterquality parameters on August 27, 2002. This sampling effort was to provide datato address operational concerns related to a trend toward an increasing pH andincreased scaling at the plant intake. This report provides the results of theAugust 27and 28, 2002 sampling and makes comparisons with data fromprevious sampling efforts by SEA Inc. and with other data provided by theBraidwood Station to SEA Inc.Executive Summary:Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with cooling pond blow down limits, and maintaining arecreational fishery.

Several of these parameters had significant increases in thepast year and could lead to greater operational costs and problems in the nearfuture.The excess of nutrients in the water has contributed to plankton blooms that haveeliminated the submerged aquatic plants, contributed to diurnal increases in pH,and lowered dissolved oxygen levels. Swings in the dissolved oxygen levelassociated with the plankton blooms could lead to fish kills.The plan to increase the blow down rate from the cooling pond is a good long-term solution to the continued viability of the cooling pond. Continued monitoring of the cooling lake water quality would be important in evaluating theeffectiveness of the increased blown down rate, the impacts of H2SO4 additions, and other water treatment changes.Overview of Methods and Scope of the Sampling Effort.The investigation on August 27 and 28 of 2002 consisted of collection of watersamples from various depths at six sites around Braidwood Cooling Pond (BCP),as well as in-situ profile measurements for temperature, conductivity, pH, anddissolved oxygen. A contract laboratory analyzed the water samples for theeleven chemical parameters as listed in Table 1. In addition to chemical samples,the primary production rate of the phytoplankton community was determined attwo sites by the light/dark bottle method, and plankton samples were taken forB-9 RS-14-138 Enclosure Page 62 of 322qualitative analysis.

Water transparency was measured with a Secchi disc ateach site. The sampling sites used in this investigation are identified on Figure 1.Additional investigations by SEA Inc. referenced in this report include June 28,2002, April 29,2002, March 6, 2002, January 10, 2002, August 28, 2001 and May29, 2001. The purpose and scope of each of these investigations varied but nonewere as extensive for water quality as the August 2002 investigation.

In severalcases SEA Inc. collected the water samples for Betz and the results were notmade available to SEA Inc. Data from the above referenced studies is included tohelp identify trends and provide a single summary of data for ongoinginvestigations.

The discussion of results is based on and limited to the studiesreferenced in this report and those provided to SEA Inc.Presentation of Results and Related Discussion:

The analytical results of the water quality analysis are presented in Table 1. Theeleven parameters were selected to provide input to the water quality issues thatwere described to SEA Inc. These issues include increasing trends for rising pH,scaling, algal blooms, and recent fish kills.Table 1 indicates abnormally high levels for TDS, alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus throughout the cooling pond. Thesevalues were not unexpected and support the ongoing program to increase theblow down rate from the cooling pond. These values can be put into perspective by comparing the cooling lake sites to the same values for the make -up waterpond (Site 7P in Table 1), which is the source water. The cooling pond values forthe above mentioned parameters ranged from 2X to nearly 9X higher than themake-up water.The alkalinity is a measure of water's capacity to neutralize acids and is a resultof the quantity of compounds in the water that shift the pH to the alkaline side.Bicarbonate and carbonate ions normally make up most of the alkalinity.

However in waters with a pH of greater than 8.3, carbonate alkalinity is theprimary form. Alkalinity is very high throughout the cooling pond and ranged from340 to 360 mg/I in the upper water layers (Table 1). In contrast, the make-upwater pond alkalinity was 150mg/I.

Other comparisons include a 14-year averagefor Clinton Lake of 168 mg/I and an IEPA survey of 63 lakes around the statewith alkalinity ranging from 20 to 270 mg/I. The high alkalinity gives Braidwood Cooling Pond has a great capacity to neutralize acids.Hardness is a measure of the divalent metallic cations present in water(such as calcium, magnesium, ferrous iron, and manganous manganese).

Calcium reacts with bicarbonate ions in water to form calcium carbonate B-10 RS-14-138 Enclosure Page 63 of 322scale. Magnesium typically reacts with sulfate; the ferrous ion withnitrate; and the manganous ion with silicates.

Hardness and alkalinity in water are related.

Carbonate hardness is the part oftotal hardness that is chemically equivalent to the bicarbonate plus carbonate alkalinities present in the water. If alkalinity is greater than total hardness thentotal hardness is equal to the carbonate hardness.

In cases such as in BCPwhere alkalinity is less than the total hardness then alkalinity equals carbonate hardness (as CaCO3) and the remaining part of hardness is the noncarbonate compounds such as magnesium sulfate.The total hardness in the upper layers of August 2002 samples ranged from 680to 720 mg/I (nearly twice the alkalinity level) so other ions are contributing significantly to the hardness.

The total hardness levels in 2002 were significantly higher than the 435 to 531mg/I range reported for two dates in 2001 by TestAmerica (Table 2). This increase in hardness is a reason for concern.Sulfate levels in the August 2002 samples ranged from 330 to 390 mg/I (Table 1).These levels are much higher than the make up water (58 mg/I) and to someextent may reflect the history of portions of the cooling pond as strip mine lakesthat are characteristically high in sulfates.

However there seems to be asignificant increase in sulfates in the past year. In the Test America data from twodates in 2001, sulfates ranged from 230 to 270 mg/I (Table 2). Sulfate levels insamples collected by SEA Inc. on April 29, 2002 were 250 mg/I (Table 3).Samples collected by SEA Inc. on June 28,2002 had levels ranging from 320 to340 mg/I (Table 4). The sulfate increase noted in the summer of 2002 may reflectthe use of H2SO4 to reduce pH levels in the cooling pond. This level of sulfatesmay be a concern since it significantly contributes to the non-carbonate hardnessand can be a factor in scaling.Calcium levels in the August 2002 samples were about twice the levels in2001and ranged from 130 to 140 mg/I (Table 1). The 2001 Test America dataranged from 41 to 58 mg/I (Table 2) and the make-up water in August 2002 was57 mg/l. The increase in calcium may be a major concern since with the highcarbonate alkalinity there is a high potential for scaling.Magnesium levels in the August 2002 sampling ranged from 84 to 93 mg/l. Theselevels were essentially the same as the 81 to 91 mg/I reported by Test America in2001. Magnesium levels are however elevated compared to the make-up waterthat had only 20mg/I or when compared to the 14-year average for Clinton Lakeof 32.2 mg/l. Magnesium levels are also a concern due to their potential forscaling.Total dissolved solids include all of the above parameters and other dissolved solids in the water. As would be expected, the August 2002 samples are elevatedand are higher than the previous year. The August 2002 TDS ranged from 930 toB-1 I RS-14-138 Enclosure Page 64 of 3221100 mg/I (Table 1) compared to a range of 684 to 788 in the 2001 Test Americadata (Table 2). The make-up water was 280 mg/I in the August 2002 sample.Sodium levels in the August 2002 samples ranged from 60 to 64 mg/I in theupper water layers. Comparable data from 2001 was not available, but thesodium levels in the make-up water was 9.1 mg/I in the August 2002 sample(Table 1).There were only minor variations in the concentrations of the above parameters from site to site in the upper water layers. Sulfates and TDS were slightly higherat the discharge (Site 2) end of the cooling pond. Levels for alkalinity,

sulfates, TDS, and total hardness were slightly lower near the bottom at the 10 and 11-meter depths at Site 4 and Site 7 respectively.

Phosphorus and nitrogen are essential nutrients for aquatic plants.Concentrations in the water are typically low since phytoplankton or macrophytes quickly assimilate these nutrients.

Total phosphate levels in the August 2002samples were at 1.5 mg/I throughout the cooling pond (Tablel).

Samplescollected on April 2002 ranged from 1.3 to 1.6 mg/I (Table 3). Total phosphates at two sites in the June 2002 samples were 1.8 mg/I (Table 4) in the upper waterlayers and 4.9 mg/I at a well stratified, 10-meter depth at Site 4. The TestAmerica data for 2001 had total phosphate levels from 0.16 to 5.5 mg/I (Table 2).The 5.5 mg/I occurred at the discharge on May 18 of 2001 and levels dropped to0.77mg/l at the plant intake on the same date. This suggests the Station was thesource of the phosphate.

Although the levels were slightly lower in 2002, theywere consistent throughout the cooling pond suggesting that phosphates are inexcess and not a limiting factor for phytoplankton.

The total phosphate levels inthe make- up water were 0.12 mg/I and 0.19mg/I in June (Table 4) and August of2002 respectively.

Relative to most lakes the phosphate level in BCP is quite high. Since BCP is acooling pond and not a lake, it is not subject to the Section 302.205 regulation that limits phosphorus in a lake of 20 acres or more to < 0.05mg/l.

The highphosphate level is of concern since these levels support phytoplankton bloomsand the breakdown of the phosphorus compounds can also contribute toincreased pH.Ortho-phosphate is the form that is most readily available to aquatic plants.These levels are usually very low in lakes since plants normally take it up withinminutes.

Ortho-phosphate levels were consistent throughout the lake in theAugust 2002 samples and ranged from 0.38 to 0.44mg/I.

Like the total phosphate levels, the ortho-phosphate levels are consistently high suggesting it is in excessof the needs of the phytoplankton.

The August 2002 levels were significantly higher than the <0.06mg/I reported by Test America in 2001 (Table 2). Ortho-phosphate level in the make-up water was 0.19 and although lower than the lakelevels is relatively high.B-12 RS-14-138 Enclosure Page 65 of 322Nitrate-nitrites are the other essential or potentially limiting nutrient forphytoplankton.

The August 2002 nitrate-nitrate levels were rather low in most ofBCP with the highest level of 0.1 mg/I at the discharge.

The rest of the coolingpond ranged for <0.01mg/I (below detection limit) to 0.08 mg/l in the upperwaters. Unlike most other parameters, the nitrate-nitrite level in the make-upwater was significantly higher at 2 mg/I (Table 1). Nitrate-nitrite data could not becompared to the 2001 Test America data because the detection limit of 1.0 mg/Iwas too high for a meaningful assessment.

The ratios of phosphates to nitrates-nitrites suggest BCP would be described asa nitrate-nitrites limited water rather than phosphate limited with respect tophytoplankton growth. However the limited phytoplankton data that SEA Inc. hascollected on BCP suggests that bluegreen algae dominate BCP for much of thesummer. Bluegreen algae have the unique ability to utilize atmospheric nitrogenand are not as limited by low nitrate-nitrite levels. Bluegreen algae made up 88.5% and 76.4% of the algae at Sites 3 and 7 respectively in the August 2002sample. The dominant bluegreen algae were Lynabya and Oscillatoria.

Bluegreen algae are the least desirable algae and are favored by high pH andwarmer temperatures.

Bluegreen blooms can impart a smell or taste to water,deplete dissolved oxygen, and in some cases generate toxins that may impactaquatic life.The ammonia levels appear reasonable relative to the high productivity in BCP.As productivity increases and oxygen is reduced at deeper depths there may beincreases in ammonia.

The abnormally high level at 5 meters at Site .9 (Table 1may have resulted from the water sampler disturbing the bottom sediments where ammonia is likely to be higher.The aquatic plant community in BCP appears to have undergone a change in thelast two years. SEA Inc.'s first investigation of BCP on May 29, 2001 was toassess the impact of the extensive growth of macrophytes (rooted aquatic plants)on the pond's increasing pH. That investigation found an extensive phytoplankton bloom and the few macrophytes that remained were being shaded out by thephytoplankton bloom. SEA Inc. projected that BCP was changing from amacrophyte dominated water to a phytoplankton-dominated water and that wouldsee more plankton blooms. The phosphate levels from the 2001 Test Americadata suggested there was an excess of phosphorus to support those blooms.Based upon SEA Inc.'s 2002 observations, BCP has transformed into aphytoplankton dominated water and is experiencing regular plankton blooms.This change not only reflects an increasing load of nutrients in BCP but alsocreates a higher risk to the fishery.

As plankton blooms come and go they cancreate oxygen depletion problems that impact fishes and other aquatic life.SEA Inc. has measured the primary production rates as an index to the activity ofthe plankton community.

The rate of oxygen production by the planktonB-13 RS-14-138 Enclosure Page 66 of 322community is measured in a light (clear) bottle and the plankton respiration (oxygen depletion) is measured in a dark bottle. In the first measurement in Mayof 2001, there was so much oxygen production in the normal 24 hr measurement period that the oxygen was super saturated and only a portion could bemeasured (Table 5). Subsequent measurements were limited to shorter timeperiods and provided a more useful index. The highest primary production ratewas 1.525 mg/I of 02/hr at Site 9 (Intake) on June 28, 2002. This correlated wellwith the highest chlorophyll a level provided by the Braidwood Station (Figure 2).In the August 2002 measurement, the rate at Site 9 had dropped to 0.653 mg/I of02/hr. This rate correlated with lower chlorophyll levels that occurred throughout most of August. Temperatures during the August 28,2002 measurements werehigh enough at the discharge (Site 2) to suppress photosynthetic activity.

Thetemperature at the discharge was 115.10 F (Table 5) and the intake (Site 9)temperature was 92.2°F and the corresponding production rates were 0.142 and0.653 mg/I of 02/hr respectively.

The temperature suppression of photosynthesis and an apparent die off of a phytoplankton bloom may account for the lowdissolved oxygen levels observed during the August 2002 sampling.

All of sampling by SEA Inc. has involved in-situ sampling with a HydroLab fortemperature, dissolved oxygen, pH, and specific conductivity.

The data from all2002 HydroLab sampling is presented in Tables 1,3,4,6, and 7.The dissolved oxygen (DO) levels on August 28 of 2002 were notably lower thanthe same date in 2001 (Table 6). As lakes undergo eutrophication andproductivity increases, the DO level can exhibit wide diurnal changes that maystress aquatic life. Afternoon DO levels may rise to supersaturated levels, butduring the night and early morning hours respiration demands may nearlydeplete the DO and can result in fish kills. There also becomes a morepronounced difference in DO levels between the upper and lower layers of thewater column due to increased oxygen demand from decomposition.

Dissolved oxygen levels at the same four sites in August 2001 and 2002 arecompared in Figure 3. These comparisons indicate that the DO levels weregenerally lower at the same sites in 2002, were slower to rise during the day, andthere was a greater differences between depths. Site 2 and Site 2.5 illustrate thelower DO levels in 2002 even later in the day when it should rise. Oxygen levelswere less than 1 ppm at 2 meters and below. Site 4, 2002 levels reflect theincrease in DO later in the day compared to earlier in the day in 2001. Theconsistent drop in DO at 4 meters is typical of a stratified site. At Site 7 the higherDO in 2002 reflect the later time of day than the 2001 sample. However the moresignificant difference is the drop in DO with increasing depth in 2002. This dropsuggests a more productive system that has a higher demand for oxygen in2002. Site 7 has good flow and in 2001 had a nearly constant DO level down tothe bottom and provided a good thermal refuge for fish. In 2002 the area below 6meters would be stressful for most fish. The Site 9 AM chart again demonstrates the 2002 DO level was lower even when taken later in the morning than the 2001I B-14 RS-14-138 Enclosure Page 67 of 322sample. The Site 9 PM chart shows some recovery of DO level in the midafternoon but levels are still below 4ppm. The more rapid drop in deeper samplesfrom the 2001 most likely reflects the loss of late afternoon light to the deeperdepths.The 2002 DO curves appear to reflect a more eutrophic environment that mayplace additional oxygen stress on the fishery.

During the August 2002 samplingthere were dead and dying gizzard shad from Site 2 to Site 4. The combinations of stress from the low DO and warmer temperatures were the most likelyexplanation for the loss of these fish. This loss was not extensive enough to havea significant impact on the fishery.

No other species were involved in the kill butsmall bluegills were exhibiting some signs of DO stress. As BCP continues tobecome more eutrophic the DO stress may be a greater problem for the fishery.The increasing pH levels have been a concern in BCP. Comparison of HydroLabdata from August 28 in 2001 (Table 6) and 2002 (Table 1) indicated only a littlevariation in pH. During the summer of 2002 the Station was adding H2SO4 intothe circulating water. The impact was only apparent at Site 2 (discharge canal)and Site 3. The 2002 samples collected in the morning hours at Site 2 rangedfrom 8.34 to 8.38 compared to 8.5 in 2001 (Table 2). At Site 3 the 2002 levelsranged from 8.35 in the morning to 8.54 at midday compared to a range of 8.4 to8.6 in 2001. The pH levels at Sites 4,7 and 9 had slight variations depending upon time of day but had similar ranges in 2001 and 2002. With the highalkalinity levels in BCP, it is not surprising that the addition of H2SO4 did notresult in larger changes.

This assessment is also based on only a few datapoints. Correlating H2SO4 feed rates with continuous pH monitoring at the intakewould provide more reliable information on the effects of the acid additions.

Questions have been raised on the impact of the phytoplankton on the increasing pH levels. As phytoplankton carries on photosynthesis and extract C02 from thewater it increases the pH. This however may not be as apparent in BCP due tothe high buffering capacity (alkalinity).

In general the higher pH levels in theafternoon reflect the photosynthetic activity.

Conversely the lower pH levels in theearly morning samples reflect the increase in C02 resulting from respiration during the night. The role of phytoplankton in increasing pH is quantified in themeasurement of primary productivity.

A comparison of the starting pH with theending pH in the light bottles illustrates the change due to photosynthesis.

ThepH during the 24-hour measurement on May 29, 2001 at Site 2 went from 9.22 to9.52 (Table 5).Summary and

Conclusions:

Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with blow down limits, and maintaining a recreational B-1 5 RS-14-138 Enclosure Page 68 of 322fishery.

The additional of treatment chemicals and evaporative loss of therecycled cooling water with limited blown down rates are most likely the primaryfactor in the increased levels of these parameters.

The make-up water does nothave elevated levels of the above-mentioned parameters.

With increasing capacity factors and increasing concentrations for these parameters in thecooling water, water treatment costs and operational concerns are likely toincrease.

Baseline water quality data is important in evaluating options and solutions toaddress water quality in the cooling pond. The comparison of the August 2002sampling to the 2001 Test America data indicated significant increases in totalhardness,

sulfates, and calcium in the past year. Increases of this magnitude canbe important predictors of future problems.

Critical assessments of the impact ofH2SO4 additions and other treatment changes are dependent upon havingpretreatment and post treatment data. The plan to increase the blow down ratefrom BCP is a good long-term solution to the continued viability of the coolingpond. The effectiveness of increasing the blown down rate from BCP can bequantified by continued monitoring of the cooling lake concentrations.

The high nutrient levels in BCP will continue to cause plankton blooms. Unlikemany waters, phosphates appear to be in excess and nitrates are more of alimiting factor. However, bluegreen algae appear to be the dominant summerform and are not as limited by low nitrates as other algae. The primary production measurements did correlate fairly well with chlorophyll a levels and were a goodindex to the productivity of BCP. The primary production measurements alsoillustrated how much of an influence phytoplankton have on diurnal increases inpH.Algal blooms are occurring in the pond and based on two comparable samplings, appear to be influencing the DO levels. The DO levels in the early hours weregenerally lower in 2002 than in 2001 and the DO at a deep site experienced adecline with depth that did not occur in 2001. These changes suggest a trendtoward an increasing rate of eutrophication.

If nutrient levels continue to increasethe potential for fish kills associated with oxygen depletion resulting from theblooms would also increase.

Jim SmithsonSEA Inc.11/04/02B-16 nsli &111 Keports (joing Back to 2UUJPage I of 2APPENDIX REPORT B-4.RS-14-138 Enclosure Fish Kill Reports Going Back to 2003 Page 69 of 322john.petro@exeloncorp.com

[john.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:42 PMTo: Jeremiah.Haas@exeloncorp.com 2003There were no fish kills in Braidwood Lake in 2003.u'iU30. 2004Investigated a fish mortality on July 30. 2004. Most fish were in the advanced state o decay_ by the timethe kill was investigated, Gizzard shad were the dominant species involved although cha~nn.el catfish we~reobserved as well. During..

ts.hs investigation, the shallow water near shore was teaming with planitonlwich under magnification proved to be dap hnia as well as Cypris, which is an Ostacod resembling a small clam.Temperature/dissolved oxy en profiles were conducted in earry October.

Water temperature just north ofthe south boat access was 29,2 C/84.50F at a depth of one foot with a dissolved oxygen reading of 3.8ppm. a pH of 8.03 and asecchi disk reading.

of 2.1 fe4t.

were somewhat improved in the area nearthe rearing cove. In a location several hundred .eet fromp.th lake make-up, more favorable dissolved oxygen levels were found. At one foot,_a water temnperature of 26.5 -C/79.7 OF with a dissolve~d oxygenreading of 7.6 and a pH of 8.47 were observed.

Water te~mperature showed minimal decrease to. 40 feetwhile the dissolved oxyqgendeclined to 5.3 Rpm.June 28, 2005 Fish KillAn on the water inspection of a thermal fish kill was conducted on June 28, 2005. No formal counts weremade however field assessments indicate a fairly significant kill that involved a variety of species including (in no specific order) gizzard shad, threadfin shad, common carp, channel catfish, quillback carpsucker, lJ black bass. Gizzard shad were the most numerous species effected by this kill and fish carcases wereobserved at most all areas of the lake that were checked.August 27-28, 2007 Fish KillRob Miller, IDNR investigated a thermal kill on August 27 and 28, 2007 and conducted temperature/dissolved oxygen evaluations.

The majority of the dead fish which were observed were largegizzard shad and threadfin shad up to 5 inches in length. Channel catfish were also prevalent.

Only a fewcommon carp and black bass were observed and no bluegills were noted. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in close proximity of the boat ramp and thebank fishing area. The number of dead fish observed decreased towards the south (hot) side of the lake.At a point several hundred yards from the south ramp surface water temperature was 35.3 C/95.9 F anddissolved oxygen was near 3ppm.The following are data which were collected at the north ramp at the time the fish kill was beingB-17https://hdrwebmail.hdrinc.com/owa/?ae=Item&t-=IPM.Note&id=RgAAAACNOxuwhEe8R...

12/8/2009 Fish Kill Reports Goinig Back to 2003 4%j 2 of 2Enclosure Page 70 of 322investigated:

Time Temperature

(°C) bissolved Oxygen (ppm) 712:10 30.3 3.114:25 33.1 5.415:30 33.5 6.7 C16:58 33.9 5.9Investigation of Fish Kill on Braidwood Cooling Pond (August 27-28. 2007)Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of an on-going fish kill onBraidwood Cooling Pond on August 27 & 28, 2007. The investigation consisted of surveying the shoreline todetermine the extent of the kill and the species involved, and water quality analyses for pH, temperature, and dissolved oxygen.Most of the fish appeared to have been dead for about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than 95% were gizzardshad. The other species involved in descending order of relative abundance were freshwater drum,quillback, carp, largemouth bass, channel catfish,

redhorse, smalimouth bass and bluegill.

Other thangizzard shad most of the dead fish were located between the mid -point in the cooling loop to the intake.Throughout most of the cooling pond, dissolved oxygen levels were at or below the minimum levelsnecessary to support most fish and was the most likely cause of the kill. Water clarity was very high andsuggested a recent die off of much of the phytoplankton, which is usually followed by oxygen depletion.

This is a natural phenomenon that can occur in highly productive lakes during summer months.Temperatures throughout most of the lake were within the tolerance limits of the species involved in thekill. It does not appear that operations of the power station had a direct impact on the fish kill.B-18https://hdrwebmail.hdrinc.com/owa/?ae=ltem&t=lPM.Note&id=RgAAAACNOxuLI whFegR...

1 000 r ; w:rdIiuwoo0i Lf.e risfl i&1niPage I of 2RS-14-138 APPENDIX REPORT B-5. Enclosure FW: Braidwood Lake Fish Kill Page 71 of 322john.petro@exeloncorp.com

[ohn.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:31 PMTo: Jeremiah.Haas@exeloncorp.com

---

Original Message----

From: ROB MILLER [1]

Sent: Tuesday, August 21, 2007 8:26 PMTo: JOE FERENCAK; STEVE PALLOCc: Petro, John R.; CHRIS MCCLOUD; LARRY DUNHAM; MIKE CONLIN

Subject:

Re: Braidwood Lake Fish KillI was contacted by John Petro and Tim Meents (Braidwood Station) thismorning at 11:20 but due to bad accident on 1-55 was somewhat delayed inarriving at the lake. When I got there (3:00) 1 met with Exelonbiologist Jeremiah Haas. Jeremiah had arrived earlier and had takendissolved oxygen/temperature readings.

He and I toured the lake via hisboat to assess the extent of the kill. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in closeproximity of the boat ramp and the bank fishing area. The number of deadfish we observed decreased as we traveled towards the south (hot) sideof the lake. At a point several hundred yards from the south ramp, wetook a reading and returned to the north ramp to meet up with JohnPetro. At this location water temperature was 35.3C and dissolved oxygenwas near 3ppm. The following are data which were collected at the northramp:Time Temp. (C) Dissolved Oxygen (ppm)12:10 30.3 3.114:25 33.1 5.415:30 33.5 6.716:58 33.9 5.9Based on the declining trend in d.o., it is possible that more fishcould succumb throughout the night.The majority of the dead fish which were observed were large gizzardshad and threadfin shad up to 5 inches. Channel catfish were alsoprevalent.

Only a few common carp and black bass were observed and nobluegills were noted. SET Environmental had arrived at the north rampand were conducting clean-up operations at 5:00. 1 will be attended theAFS Continuing Education course in Monticello tomorrow and thursday.

Ifyou need any further information, or if there are any furtherdevelopments, please contact me at 815/409-2426.

Thanks.RobRob MillerB-19https://hdrwebmail.hdrinc.com/owa/?ae=ltem&t=IPM.Note&id=RggAAAACNO0xuwh beC8 R... 1 2!8,'2009 FW: Braidwood Lake Fish Kill Page 2 of 2RS-14-138 Enclosure Page 72 of 322District Fisheries Biologist Illinois Department of Natural Resources 13608 Fox RoadYorkville, Illinois 60560630/553-6680 rob.miller@illinois.gov

>>> STEVE PALLO 08/21/07 12:10 PM >>> FJust got off phone with John Petro, Environmental Manager for Exelon.John wanted to report a moderate gizzard shad kill at Braidwood CoolingLake, and a minor kill of catfish.

Rob Miller, District Fisheries Manager was already notified.

Water temps in the lake had dropped some12F recently, there are no obvious power plant operational changes orpermit exceedances.

Exelon is arranging to have the fish picked up.B-20https://hdrwebmail.hdrinc

.com/owa/?ae~ltem&t=IPM.Note&id=RgAAAACNOxuwhEe8R...

1 2/8/2009 FW: Braidwood Fish Kill 8-21-07Page I of IAPPENDIX REPORT B-6. RS-14-138 Enclosure FW: Braidwood Fish Kill 8-21-07 Page 73 of 322john.petro@exeloncorp.com Uohn.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:28 PMTo: Jeremiah.H aas@exeloncorp.com

--Original Message--

From: Haas, Jeremiah 1.Sent: Tuesday, August 21, 2007 9:02 PMTo; Petro, John R.; Tidmore, Joseph W.; Meents, Timothy P.Cc: Hebeler, Ronald L.; Neels, Vicki J.; Steve Pailo (E-mail);

Haas, Jeremiah J.

Subject:

Braidwood Fish Kill 8-21-07All,Here's the quick and dirty of the incident.

I'll right something more formal in the morning.I arrived at Braidwood Lake at 12:00 and took a dissolved oxygen (DO) reading from the ramp dock which extendsabout 30 feet into the lake. The DO was 3.1 ppm w/ a temp of 30.3 C. Several thousand gizzard and threadfin shadwere floating across most all visible areas of the lake. The currents within the lake were visible with the dead fishmovement Also seen were dozens of channel catfish, most of which were adults from 3-15 lbs. Shad ranged from 4 -13 inches with the shorter fish being predominately threadfin and the larger ones being gizzard.

At this time I informedJohn P. of the DO situation and began setting up the boat for additional surveys.

During the entire day, no otherspecies was observed that counted more than 2 individuals.

I took several water readings throughout the afternoon before Rob Miller (IDNR biologist responsible for Braidwood Lake) arrived.

We did a quick boat survey throughout the lake, including the pockets that are not part of the coolingloop. These areas showed the same readings as the rest of the lake. During this time we had a few hours of directsunshine and DO reading rose as high as 6.7 ppm @ 15:30.Rob and I determined that the DO crash was a result of the past several days cloud cover and subsequent die-off ofphytoplankton.

The decay of the phytoplankton would have been sufficient to lower the DO available to the fish duringthe overnight hours. We also observed the DO beginning to lower @ 16:58 (5.9 ppm) and believe that there is anopportunity to see similar results tomorrow and possibly a few more days depending on the weather conditions.

A local newspaper reporter did arrive on site, took photos, and asked questions.

She was familiar with Braidwood Station's Site Communicator and said she would be in contact with them. Rob explained the cycle that was occurring in the lake several times to the reporter.

All in all, I believe that Rob and I are both comfortable with the explanation for the action that occurred to cause thefish kill. This is similar to the "annual" fish kill seen at Braidwood, but the densities were higher than the past fewyears. There is a survey of the lake scheduled for October and, if possible, I will be at the site for that.ExelonJeremiah J HaasPrincipal Aquatic Biologist Quad Cities Nuclear Station309.227.2867 jeremiah.haas@exeloncorp.com B-21https:/Ihdrwebmail.hdrinc.com/owal?ae=ltem&t=IPM.Note&id=RgAAAACN OxuwhEe 8R...12/8/2009 RS-14-138 Enclosure Page 74 of 322APPENDIX REPORT B-7. Lt.Braidwood Fish Kill Clean up8122&23107 I worked with SET Environmental to clean up a fish kill.This was a major kill and our clean up efforts were confined to the area nearNorth boat ramp on the intake end of the lake. SET had been working on the killfor one or two days when I was called to provide assistance.

A total of about 24cubic yards of fish were removed in this clean up. The species involved indecreasing order of abundance were: gizzard shad (large fish), channel catfish,bluegill, green sunfish, flathead

catfish, bigmouth

buffalo, quillback andlargemouth bass. LI went up in the restricted arm toward the intake and found huge masses of fishin the back of several coves. There were areas 50 to 75 ft by 100 ft of solidfloating mats of fish in these coves. We picked up 12 flathead catfish that wouldhave averaged near 50 lb. each. On the second day when we returned to thesecoves we counted as many large flathead catfish that we had picked up theprevious day. They were in a state of decomposition that prevented up frompicking them up.We did not take any water quality measurements or examine other parts of thelake in this clean up effort. From my past work on this cooling pond, I would -suspect a combination of DO depletion and high water temperatures caused thisfish kill. The plant did not report any abnormal operation conditions prior to thekill. Since 2001 when we first worked on this cooling pond we have seen a switchfrom macrophytes to phytoplankton with blue green dominating.

We havemeasured wide diurnal swings in DO levels even in the upper part of the watercolumn in late summers.

Even with the strong circulation from the circulating water pumps there is mid summer stratification and DO depletion in the deeperareas.Jim SmithsonSEA Inc.L_B-22 RS-14-138 Enclosure Page 75 of 322Attachment

1. 2 to Response

-- RAI # AQ-12a RS-14-138 Enclosure Page 76 of 322BRAIDWOOD STATIONBRAIDWOOD LAKE ADDITIONAL BIOLOGICAL SAMPLINGPROGRAM, 2010Prepared forEXELON NUCLEARWarrenville, IllinoisFebruary 2011.IDR Engineering, Inc.Environmental Science & Engineering Consultants 10207 Lucas RoadWoodstock, Illinois 60098 RS-14-138 Enclosure Page 77 of 322ACKNOWLEDGMENTS The field work and data analysis for this project was conducted by HDR Engineering, Inc.(HDR). Particular appreciation is extended to Rob Miller of the Illinois Department of NaturalResources (IDNR), Jim Smithson of Strategic Environmental

Actions, Inc. (SEA), and John Petroof Exelon Nuclear for providing historical fisheries and water quality data.This report was prepared by HDR and reviewed by Exelon Nuclear.

A special debt of gratitude is owed to the environmental staff at Braidwood Station and in particular Mr. Jeremiah Haas ofExelon Nuclear for his technical assistance, cooperation, and guidance during the preparation ofthis document and the study plan. Mr. Haas's experience and insight has been invaluable and isgreatly appreciated by the authors.HDR Engineering, Inc.

RS-14-138 Enclosure Page 78 of 322ABSTRACTHDR Engineering, Inc. (HDR) was contacted on March 12, 2009 by Braidwood NuclearGenerating

Station, requesting HDR to design and conduct a fish sampling program at Braidwood Lake. The information gathered during that study was to be used by Exelon to develop aneffective sampling program and set of procedures that could potentially predict fish die-offs in thecooling lake. That same sampling program was conducted again in 2010 with only minor changesto the original program design.Large die-offs of fish at Braidwood Lake could potentially challenge the integrity of the traveling screens at the Station.

With advanced

warning, the Station could be informed of a potential reportable event; regulatory agencies could be notified in advance; and crews responsible for fishcleanup and disposal could be put on alert to help manage the risk associated with a substantial fish die-off.

Currently, there are no practical or simple methods that can be used to predict orprevent the occurrence of fish die-offs at Braidwood Lake.Sampling has been conducted at Braidwood Lake by the IDNR since 1980. From 1980 through2007 IDNR (Illinois Department of Natural Resources) had collected 47 taxa of fish. In 2009,twenty-six taxa representing seven families were included among the 2143 fish collected by HDR(HDR 2010) by electrofishing, trap netting, and gill netting at Braidwood Lake during the Julyand August sampling periods.

Several taxa listed as collected by IDNR from 1980 to 2007 werenot captured by HDR in 2009. Many of the species listed by IDNR were only rarely captured, have not been captured during recent years, or represent taxa that were stocked.

However, fivespecies were captured in 2009 that were not listed as collected during IDNR sampling efforts.They included shortnose gar, blue catfish, bigmouth

buffalo, fathead minnow, and rosyfaceshiner. A single specimen of each species was collected.

In 2010, similar results were noted when 25 taxa of fish representing eight families were includedamong the 2432 fish captured by electrofishing, hoop netting, gill netting, and trap netting.

Threespecies that were not listed as being collected by IDNR were captured in 2010. Two of thesespecies, blue catfish and rosyface shiner, were collected by HDR during the 2009 samplingiiHDR Engineering, Inc.

RS-14-138 Enclosure Page 79 of 322program.

The third species, smallmouth

buffalo, had not been captured during any of theprevious studies prior to 2010. Thirty-nine blue catfish were collected by gill and hoop nets, 20rosyface shiner were collected by electrofishing, and one smallmouth buffalo was taken by trapnet. No threatened or endangered species were collected in either 2009 or 2010.The most abundant species collected in 2009 and 2010 were similar to those reported by IDNR inrecent years. Braidwood Lake is currently dominated by warmwater species including gizzardshad, threadfin shad, carp, channel catfish, flathead

catfish, largemouth bass, bluegill, and spotfinshiner.Water quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection.

Water temperature

("C), dissolved oxygen (ppm), pH, andconductivity (pymhos/cm) measurements were taken 0.5 m below the water surface at eachsampling location.

In addition, water quality was also measured approximately 0.5 m off thebottom at all three of the deep water collection sites (Location GN-1, HN-1, and HN-2). Watertemperatures during the July sampling period were slightly warmer (33.6 to 38.2 'C) than thoseobserved during August (29.6 to 33.9"C) in 2010 because both units at Braidwood Station wereoffline during the August sampling period. Diurnal swings in dissolved oxygen (DO) wereobserved at the lake with DO ranging from 4.7 to 12.2 ppm in July and 1.4 to 9.6 ppm in August.Dissolved oxygen readings were generally slightly lower during the August sampling period in2010. Cursory observations by the field crew indicated that the water appeared much clearerduring the August sampling dates. This suggests that a decline in the phytoplankton population within the lake had occurred between the first and second sampling period, which could explainthe decline in the oxygen levels noted in Braidwood Lake during August.Examination of pH data collected during these studies show pH ranged from 8.3 to 8.5 in Julyand from 8.3 to 8.7 in August. Conductivity ranged from 770 to 823 psmhos/cm in July and from832 to 862 pmnhos/cm in August.Review of historical water quality data reported in 2002 by Strategic Environmental

Actions, Inc.(SEA Inc.) at Braidwood Lake indicates that abnormally high levels of total dissolved solids(TDS), alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus exist throughout iiiHDR Engineering, Inc.

RS-14-138 Enclosure Page 80 of 322the cooling loop. This is not unexpected based upon the evaporation that takes place within thecooling loop coupled with the relatively low make-up and blow-down rates associated with theoperation of Braidwood Station.

These elevated levels within the lake were measured at two tonearly eight times higher than those of the make-up water from the Kankakee River. Elevatedlevels of water hardness are of concern to the Station because high levels have the potential toincrease problems associated with scaling at the Station.Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Studies conducted by SEA in 2002 indicated that nutrients within the cooling lake were at levels sufficiently high tocause problems associated with phytoplankton blooms. These blooms result in oxygen production via photosynthesis during daylight hours and oxygen depletion through respiration duringdarkness.

When algal populations crash and decompose they can produce severe oxygendepletion within the water column. Diurnal swings in oxygen readings have been routinely observed at Braidwood Lake during the past several years. In addition, DO levels of less than 3ppm have been recorded at the lake immediately following fish die-offs.

Deeper portions of thelake were also reported to stratify in 2002. In the deeper zones of the lake, DO levelsapproaching 0 ppm and reduced water temperatures have been measured below the thermocline.

This is noteworthy because dissolved oxygen levels of 3 ppm and less cannot be tolerated over anextended period of time by most fish species.

Piper et al. (1983) states that dissolved oxygenlevels below 5 ppm will reduce growth and survival for most species of fish cultured in racewaysor ponds. Dissolved oxygen requirements are dependent on species and other factors including water temperature and acclimation period.Review of historical fisheries information that was provided to HDR indicated that five separatefish kills were reported from 2001 to 2007. Numerically, the majority of fish observed duringthese events were either gizzard shad or threadfin shad. These two species have typically comprised over 90% to 95% of all fish observed.

Remaining species included carp, freshwater drum, bluegill, channel catfish, flathead

catfish, quillback and largemouth bass. Each of thereported fish die-offs was attributed to oxygen depletion at the lake and not the result of specificStation operations.

ivHDR Engineering, Inc.

RS-14-138 Enclosure TABLE OF CONTENTS Page 81 of 322Page No.ACKNOWLEDGEMENTS iABSTRACT iiTABLE OF CONTENTS vLIST OF TABLES viLIST OF FIGURES vii1.0 Introduction 1-12.0 Methods 2-12.1 Electrofishing 2-12.2 Trap Netting 2-32.3 Gill Netting 2-32.4 Hoop Netting 2-42.5 Sample Processing 2-52.6 Water Quality Measurements 2-53.0 Results and Discussion 3-13.1 Species Occurrence 3-13.2 Relative Abundance and CPE 3-13.2.1 Electrofishing 3-43.2.2 Trap Netting 3-93.2.3 Gill Netting 3-113.2.4 Hoop Netting 3-113.3 Length-Frequency Distributions 3-133.4 Physicochemical Data 3-193.5 Historical Information 3-213.5.1 Water Quality 3-213.5.2 Fish Kills 3-224.0 Summary and Recommendations 4-14.1 Summary 4-14.2 Recommendations 4-35.0 References Cited 5-16.0 Addendum 6-1vHDR Engineering, Inc.

RS-14-138 Enclosure Page 82 of 322LIST OF TABLESTable No. Title Page No.3-1 Species Occurrence of Fish Collected by the Illinois Department of Natural Resources at Braidwood Lake from 1980 through2007. 3-23-2 Total Number, Weight (g) and Percent Contribution of FishCollected by all Sampling Gears from Braidwood StationCooling Lake, 2009 and 2010. 3-53-3 Total Catch by Method for Fish Species Collected from theBraidwood Station Cooling Lake, 2010. 3-73-4 Number of Fish Captured by Electrofishing at Each SamplingLocation in Braidwood Lake, 2010. 3-83-5 Number of Fish Captured by Trap Netting at Each SamplingLocation in Braidwood Lake, 2010. 3-103-6 Number of Fish Captured by Deep (GN-1) and Shallow Water(GN-2) Gill Nets in Braidwood Lake, 2010. 3-123-7 Number of Fish Captured by Baited and Unbaited Deep andShallow Water Hoop Nets in Braidwood Lake, 2010. 3-14viHDR Engineering, Inc.

RS-14-138 Enclosure Page 83 of 322LIST OF FIGURESFigure No.CaptionPage No.2-23-13-2Sampling Locations at Braidwood Lake during July andAugust, 2010.Length-Frequency Distribution of Bluegill Collected fromBraidwood Lake During July and August, 2010.Length-Frequency Distribution of Largemouth BassCollected from Braidwood Lake During July and August,2010.Length-Frequency Distribution of Blue Catfish Collected from Braidwood Lake During July and August, 2010.2-23-153-163-173-3viiHDR Engineering, Inc.

RS-14-138 Enclosure Page 84 of 32

21.0 INTRODUCTION

The Braidwood Lake Fish and Wildlife Areas are comprised of approximately 2640 acres ofterrestrial and aquatic habitat that is located in Will County, Illinois.

Braidwood Lake is ownedby Exelon and is a partially

perched, cooling lake that was constructed in the late 1970s. The lakewas filled during 1980 and 1981 with water pumped from the Kankakee River. Several surfacemined pits existed at the site prior to the filling of the impoundment.

Fisheries management activities began in those surface mine pits in 1978, prior to the creation of Braidwood CoolingLake. Originally the lake was considered a semi-private area used by employees ofCommonwealth Edison Company until the end of 1981 when the Department of Conservation (now the Illinois Department of Natural Resources) acquired a long-term lease agreement fromthe company, which allowed for general public access to the area. Braidwood Lake is currently used for fishing, waterfowl

hunting, and fossil hunting.

From the late 1970's to the present time,Braidwood Lake has been stocked with a variety of warm- and coolwater fish species.

Thesestockings include largemouth and smallmouth bass, blue catfish, striped bass, crappie, walleye,and tiger muskie. Monitoring programs have documented the failure of the coolwater stockings to create a meaningful fishery.

This is attributed to the extreme water temperatures that occurwithin the cooling lake during the warm summer months.Construction of the Braidwood Nuclear Generating Station and its associated riverside intake anddischarge structures provided an opportunity to gather fisheries information from the KankakeeRiver and Braidwood Lake. These studies were initiated to determine the effects of construction and plant operation on the river and the lake. Units I and H began commercial operation on 29July and 17 October, 1988, respectively.

Fisheries surveys at Braidwood Lake were conducted annually by the Illinois Department of Natural Resources (IDNR) from 1980 through 1992. Since1992, fishery surveys have been conducted by IDNR every other year except 1995 and 1996.Fishery surveys on the Kankakee River near the Station's intake have also been conducted annually since the late 1970's by the Illinois Natural History Survey (1977-1979 and 1981-1990),

LMS Engineers (1991-1992 and 1994-2004),

Environmental Research and Technology (1993),HDR/LMS (2005-2007),

and HDR (2008-2010).

1-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 85 of 322The objectives of the 2010 Braidwood Lake Additional Sampling Program were to:1. Conduct fish surveys at Braidwood Lake for comparison with historical data thathas been collected by IDNR and HDR Engineering, Inc.2. Summarize any existing data related to fish kills that have occurred at Braidwood Lake.3. Develop a sampling procedure or protocol that will help anticipate fish die-offs inthe cooling lake that could potentially effect Station operations.

1-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 86 of 3222.0 METHODS2.1 Electrofishing Electrofishing was conducted using a boat-mounted boom-type electrofisher utilizing a 5000 watt,230 volt AC, 10 amp, three-phase Model GDP-5000 Multiquip generator equipped with volt/ampmeters and a safety-mat cutoff switch. The electrode array consisted of three pairs of stainless steel cables (1.5 m long, 6.5 mm in diameter) arranged 1.5 m apart and suspended perpendicular to the longitudinal axis of the boat 1.5 m off the bow. Each of the three electrodes was poweredby one of the phases, Electrofishing samples were collected on 21 and 22 July during the firstsampling effort and on 19 August during the final survey period (Appendix Table A-I).Eight locations around the dike and islands at Braidwood Lake were electrofished during both thefirst and second sampling periods (Figure 2-1). Electrofishing was conducted near the shoreline at each location to collect fish utilizing shallow water zones. Each electrofishing area wassampled for 30 minutes.

Voltage and amperage of the electrofishing unit was recorded at eachlocation at the beginning and end of each sampling effort. Sampling was restricted to the periodof time ranging from one-half hour after sunrise to one-half hour before sunset.The electrofishing crew consisted of two people. One crew member operated the boat while thesecond crew member dipped fish from the bow of the boat. The boat operator also dipped fishwhenever necessary.

When fish surfaced behind the boat the boat operator backed up to retrieveall stunned fish. All stunned fish were collected without bias of size or species.Fish at each location were put into barrels of water in the front of the boat for analysis at the endof each 30 minute collection period. All fish were processed in the field immediately following collection at each location.

Special emphasis was placed on the return of all collected game fishspecies to the water as quickly as possible following field analysis.

Catches were standardized tocatch-per-effort (CPE) from actual fishing time (30 min) to numbers caught per hour by dividingthe total numbers of fish collected by the actual fishing time in hours.2-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 87 of 322FIGURE 2-1. SAMPLING LOCATIONS AT BRAIDWOOD LAKE DURING JULY ANDAUGUST, 2010.2-2 RS-14-138 Enclosure Page 88 of 3222.2 Trap NettingTrap nets were set at eight separate locations in Braidwood Lake (Figure 2-1). Each trap netconsisted of a 25-ft. lead that was 4-ft. deep and attached to a series of rectangular frames. Thelast rectangular frame was attached to a hoop net constructed of 1.5-in. (bar) mesh nylon webbingon hoops 3.5 ft in diameter.

Two separate throats were contained within each trap net. One waslocated in the series of rectangular frames at the front end of the net, while the second throat waslocated toward the back of the net inside the 3.5 ft diameter hoop net. Trap nets were set duringlate afternoon or early evening and were allowed to fish overnight for approximately 12 hrsbefore being retrieved the following morning.

Trap nets were set on 20 July and retrieved on 21July during the first sampling period and set on 17 August and retrieved on 18 August during thesecond sampling period (Appendix Table A-2).Fish at each location were put into barrels of water in the front of the boat for analysis at the endof each collection period. All fish were processed in the field immediately following removalfrom the net. Special emphasis was placed on the return of all collected game fish species to thewater as quickly as possible following field analysis.

Catches were standardized to catch-per-effort by dividing the total number of fish caught by the total number of hours the nets wereallowed to fish (fish/ 12-hr set).2.3 Gill NettingTwo 125-ft. long and 6-ft. deep monofilament experimental gill nets were used to collect fishfrom two locations in Braidwood Lake (Figure 2-1). Each net consisted of five separate panelsthat were 25-ft long by 6-ft deep. Bar mesh sizes of each panel were 0.5, 0.75, 1.0, 2.0, and 3.0inches, respectively.

One of the two gill nets (GN-1) was set in deep water at a depth ofapproximately 7-8 m, while the second gill net was set in shallow water (GN-2) at a depth ofapproximately 1-2 m. During the first sampling period, the deep water gill net sample (GN-1)was collected during the late afternoon of 21 July, while the shallow water set (GN-2) wascollected during the morning of 22 July. During the second sampling period, both the deep and2-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 89 of 322shallow water gill net sets were collected during the late afternoon of 17 August (Appendix TableA-3).Gill nets were set for one hour at each location during both sampling dates. Elevated watertemperatures in the cooling lake prohibited longer set times due to the high mortality that occurredshortly after the fish became entangled in the monofilament netting.

All fish were processed inthe field as they were removed from the net. Special emphasis was placed on the return of gamefish species to the water as quickly as possible.

Catches were standardized to catch-per-effort (CPE) from actual fishing time the nets were in the water to numbers caught per hour by dividingthe total numbers of fish collected by the actual fishing time in hours.2.4 Hoop NettingHoop nets used to collect fish at Braidwood Lake were constructed of 1.25-in.

(bar) mesh nylonwebbing on hoops 3.5 ft in diameter.

Four separate nets were sampled during each samplingperiod (Figure 2-1). Two of the four nets were set in deep water (7.5 m), while the remaining two nets were set in shallow water (2.0 m). In addition, one of the deep (HN-1) and shallowwater (HN-3) hoop nets were baited with dead gizzard shad, while the remaining deep (HN-2)and shallow water (HN-4) nets were allowed to fish without bait. All four nets were set duringthe late afternoon of 20 July and retrieved during the morning of 21 July during the first samplingperiod. During the second sampling period the hoop nets were set during the late afternoon of 17August and retrieved during the morning of 18 August (Appendix Table A-4).Captured fish from each net were put into a barrel of water in the front of the boat for analysis atthe end of each collection period. All fish were processed in the field immediately following removal from the net. Special emphasis was placed on the return of all collected game fishspecies to the water as quickly as possible following field analysis.

Catches were standardized tocatch-per-effort by dividing the total number of fish caught by the total number of overnight setsconducted (fish/overnight set). Hoop nets were set and retrieved over a 16 to 18 hour2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> period oftime during both the July and August sampling periods.2-4HDR Engineering, Inc.

RS-14-138 Enclosure Page 90 of 3222.5 Sample Processing All fish were identified to the lowest positive taxonomic level and enumerated.

For each geartype, up to 25 individuals of a species were measured for total length (num) and weight (g) at eachlocation.

Any remaining individuals of that species were counted and weighed en masse.Minnow species (excluding carp) were counted and weighed en masse. Specimens that could notbe positively identified in the field were either photographed in the field or returned to thelaboratory for identification.

References used to facilitate identification included Pflieger (1975),Smith (1979), and Trautman (1981).2.6 Water Quality Measurements Four physicochemical parameters (temperature, dissolved oxygen [DO], pH, and conductivity) were measured in conjunction with the sampling program.

These data were collected at eachstation prior to each sampling effort. Physicochemical measurements were taken a half meterbelow the water surface at all locations prior to sample collection.

At deeper locations, temperature, conductivity, and DO were measured 0.5 m below the surface and 0.5 m off thebottom. Temperature

(°C), dissolved oxygen (ppm), and conductivity (pmnhos) were measuredusing an YSI Model 85 handheld oxygen, conductivity,

salinity, and temperature meter. A Cole-Parner pH Testeri was used to determine pH. All instruments were calibrated prior to eachmonthly sampling event.2-5HDR Engineering, Inc.

RS-14-138 Enclosure Page 91 of 3223.0 RESULTS AND DISCUSSION 3.1 Species occurrence.

Fish surveys have been conducted at Braidwood Lake by the Illinois Department of NaturalResources (IDNR) since 1980 when the cooling lake was first impounded with water pumpedfrom the Kankakee River. Sampling was conducted annually from 1980-1992, again in 1994, andevery other year from 1997-2007 (Table 3-1). During these 20 years of sampling, 47 taxa of fishhave been collected including 45 species and two hybrids (hybrid sunfish and tiger muskie).Gizzard shad, carp, channel catfish,

bluegill, and largemouth bass have been the dominate speciescollected during these surveys.

The total number of taxa collected by the IDNR has ranged from12 in 1980 to 27 in 1989. Several species have been rarely collected or only occasionally observed during this 30 year period. These include yellow bass, rock bass, redear sunfish,orangespotted

sunfish, tiger muskie, grass pickerel, longnose gar, goldfish, highfin carpsucker, silver redhorse, river redhorse, blackstripe topminnow, emerald shiner, common shiner, stripedshiner, redfin shiner, slenderhead darter, johnny darter, and bullhead minnow, which have beencollected in five or fewer of the 20 years of sampling conducted by the IDNR from 1980 through2007. The only protected species (one fish collected in 1999) collected during these surveys hasbeen river redhorse (Moxostoma carinatum),

which is currently listed as threatened in Illinois(Illinois Endangered Species Protection Board 2009). River redhorse have been collected fromthe Kankakee River during several years during past sampling programs (HDR 2009). Eighteenof the taxa identified by the IDR have not been captured since 1999.Braidwood Lake has been stocked with a variety of warmwater and coolwater fish species sincethe late 1970's. Some of these species, such as striped bass, tiger muskie, and walleye, have notbeen collected in recent years following the discontinuance of those stocking programs.

Currently, the fish community is dominated by warmwater species that are more tolerant of theelevated water temperatures that exist in the cooling lake during summer months.3.2 Relative Abundance and CPE.In 2009, 26 taxa representing seven families were included among the 2143 fish collected byelectrofishing, trap netting, and gill netting.

Similar results were recorded in 2010 when 25 taxa3-1HDR Engineering, Inc.

-EM nm now ova -W= mm no MW no =aTABLE 3-1SPECIES OCCURRENCE OF FISH COLLECTED BY THE ILLINOIS DEPARTMENT OF NATURAL RESOURCES2 AT BRAIDWOOD LAKE FROM 1980 THROUGH 2007.SAMPLING YEARTaxa 80 81 82 83 84 85 86 87 88 89 90 91 92 94 97 99 01 03 05 07Longnose garThreadfin shadGizzard shadGrass pickerelTiger muskieGoldfishCarpGolden shinerEmerald shinerCommon shinerStriped shinerSpotfin shinerSand shinerRedfin shinerBluntnose minnowBullhead minnowQuillback Highfin carpsucker Silver redhorseGolden redhorseShorthead redhorseRiver redhorseBlack bullheadYellow bullheadChannel catfishFlathead catfishBlackstripe topminnow Brook silverside Yellow bassStriped bass356427 2545 972 143 143 182 1412 5 24 7 18 3275 365 414 616 785 532 6664 82 I !1311413II 230 1227 1020 4248 1296 1382 3018 412 925 925 786 1031 872 1955122 3 1 1675 511 1915 626 108 227 285 853 385 929 620 204 4051 I I I I2 1 1 482 2I1419 3 37 75 5 41 1 26 I1 2 1I I198 3 27 2495 751 45 6 35 326 33 135 3I 61126 39 6 42 37 39 292153 39 20 42 26 66 20 3721I1 24 10I12 25 334 3118 102 1673 119 225836612118 713 73391 1 2 I 1 I 3 3 I I16 79 177 362 357 463 136 364 866 384 129 228I 2 10 164 1451I4 171 17 8 9 13 6 12 50 3 5-I(0M -K'3@ 00

--MM -Sq 11w,1 11. Box -----avw HW =1111-o m e sa w x -TABLE 3-1 (Continued).

SAMPLING YEAR80 81 82 83 84 85 86 87 88 89 90 91 92 94 97 99 01 03 05 07TaxaRock bassGreen sunfishOrangespotted sunfishBluegillLongear sunfishRedear sunfishHybrid sunfishSmallmouth bassLargemouth bassWhite crappieBlack crappieJohnny darterYellow perchLogperchSlenderhead darterWalleyeFreshwater drumII I24 57 163 125 16 7113 458 620 191 69 8113 13 2 7 1 10 8 23 13 37 139 26 10 771 1 121 9 31 277 121 698 247 252 241 998 1754 1393 1369 275825 I 7 3 I1 31 16 12 6 20 11 6 I 2 I 4 9 13 8 5 71 3 42 24 17 42 17 9 3 523 473 385 390 298 265 241 150 142 142 192 175 91 337 202 711 351 334 88 26341 19 30 17 6 5 4 6 3 10 2 32 36 4 2 7 6 3 I 4 3 11 6 1 20 2 2 122 66 42 20 35 69 93 74 61 10 312 71 472 211 727 88 156 71 36 213 7113 21 24 53 30 62 38 3711 7 14 12 II 61 1514 14 34 9Total fishTotal taxaTotal species400 5044 2840 1629 1489 1351 1305 1099 1942 7008 2730 2882 4165 1875 2536 3521 5193 3862 2957 440312 23 19 18 20 18 14 21 25 27 24 26 23 23 20 21 20 17 16 2012 22 18 16 18 17 13 20 25 26 24 25 21 22 19 20 19 16 15 19'Information provided by Rob Miller, District Fisheries Biologist with the Illinois Department of Natural Resources.

0 0.N) Wa RS-14-138 Enclosure Page 94 of 322representing eight families were included among the 2432 fish collected by electrofishing, trapnetting, gill netting, and hoop netting (Table 3-2). Several species that were listed as beingcollected by the IDNR during surveys conducted between 1980 and 2007 were not captured byHDR in either 2009 or 2010. Each of these taxa were either rarely captured during previousyears, represent taxa that were stocked, or have not been captured during recent years. However,five species were captured during 2009 that were not collected during earlier sampling efforts.They included shortnose gar, blue catfish, bigmnouth

buffalo, fathead minnow, and rosyfaceshiner. A single specimen of each of these species was collected (HDR 2010). In 2010, threespecies that have not been collected by IDNR were captured.

Two of these species, blue catfishand rosyface shiner, were also collected in 2009, while the third species, smallmouth

buffalo, hadnot been captured during any of the previous studies.

A single specimen of smallmouth buffalowas collected by trap netting, while 39 blue catfish were taken by gill netting and hoop netting,and 20 rosyface shiner were collected by electrofishing.

No threatened or endangered specieswere collected in 2010.Species that numerically dominated the catch in 2010 (all sampling methods combined) includedbluegill at 31.3%, channel catfish at 19.3%, spotfim shiner at 10.3%, carp at 9.7%, threadfin shadat 6.0%, gizzard shad at 5.9%, bluntnose minnow at 4.0%, and largemouth bass at 2.7% (Table3-3). All of these species were included in the catch during the surveys conducted by IDNR in2007 (Table 3-1). Biomass of fish captured by electrofishing, trap netting, gill netting, and hoopnetting was dominated by carp (51.1%),

channel catfish (27.0%),

bluegill (6.1 %), gizzard shad(4.8%), and largemouth bass (3.1%). These results are similar to data collected during previousyears and indicate that Braidwood Lake is best suited to support warmwater species.3.2.1 Electrofishing In 2010, electrofishing resulted in the collection of 1341 individuals representing 21 taxa (Table 3-3). The catch was dominated numerically by bluegill, which comprised 37.7% of all fishcaptured.

Spotfin shiner (18.7%),

threadfin shad (7.7 %), bluntnose minnow (7.2%), largemouth bass (4.5%), longear sunfish (4.3%), bullhead minnow (3.4%), and channel catfish (3.2%) werethe only other species to individually comprise greater than 3 % of the total catch by number. Thetotal number of fish collected by location ranged from 367 at Location E-5 to 77 at Location E-1(Table 3-4). The total number of taxa collected ranged from six at Location E-1 to 15 at Location3-4HDR Engineering, Inc.

TABLE 3-2TOTAL NUMBER, WEIGHT (g) AND PERCENT CONTRIBUTION OF FISH COLLECTED BY ALL SAMPLING GEARSFROM BRAIDWOOD STATION COOLING LAKE, 2009 AND 2010.2009a 2010bNUMBER WEIGHT NUMBER WEIGHTTAXON No. % (g) % No. % (g)Threadfin shad 250 11.7 2486 0.5 147 6.0 2033 0.3Gizzard shad 144 6.7 14,410 3.1 144 5.9 32,837 4.8Shormnose gar 1 <0.1 1750 0.4Longnose gar 4 0.2 9900 2.1 5 0.2 17,000 2.5Carp 145 6.8 222,327 47.5 236 9.7 353,432 51.1Common shiner 1 <0.1 17 <0.1Striped shiner 34 1.6 59 <0.1Rosyface shiner 1 <0.1 3 <0.1 20 0.8 48 <0.1Spotfin shiner 176 8.2 475 0.1 251 10.3 503 0.1Sand shiner 27 1.3 41 <0.1 14 0.6 27 <0.1Fathead minnow 1 <0.1 2 <0.1Blunmose minnow 164 7.7 332 0.1 97 4.0 203 <0.1Bullhead minnow 153 7.1 335 0.1 46 1.9 103 <0.1Smallmouth buffalo 1 <0.1 3350 0.5Bigmouth buffalo 1 <0.1 2550 0.5Yellow bullhead 2 0.1 77 <0.1Blue catfish 1 <0.1 1000 0.2 39 1.6 11,736 1.7Channel catfish 239 11.2 99,638 21.3 469 19.3 186,789 27.0Flathead catfish 3 0.1 38,750 8.3 1 <0. 1 14,000 2.0Brook silverside 1 <0.1 2 <0.1 23 0.9 25 <0.1Sunfish spp. 1 <0.1 1 <0.1Green sunfish 20 0.9 857 0.2 37 1.5 919 0.1Orangespotted sunfish 3 0.1 29 <0.1Redear sunfish 16 0.7 518 0.1 2 0.1 83 <0.1 (1)Bluegill 649 30.3 48,014 10.3 761 31.3 42,403 6.1 0 0K. 00 TABLE 3-2 (Continued).

2009' 2010'NUMBER WEIGHT NUMBER WEIGHTTAXON No. % (g) % No. % (g) %Longear sunfish 16 0.7 373 0.1 57 2.3 959 0.1Hybrid sunfish 10 0.5 162 < 0.1 4 0.2 75 < 0.1Smallmouth bass 2 0.1 1793 0.4 3 0.1 1534 0.2Largemouth bass 83 3.9 23,569 5.0 65 2.7 21,757 3.1Black crappie I < 0.1 147 < 0.1Freshwater drum 4 0.2 1073 0.2Totals 2143 468,247 2432 691,006Total taxa 26 25Total species 24 24'Sampling methods included electrofishing, trap netting and gill netting.bSampling methods included electrofishing, trap netting, gill netting and hoop netting.0) :3210U)r' M, TABLE 3-3TOTAL CATCH BY METHOD FOR FISH SPECIES COLLECTED FROM THE BRAIDWOOD STATION COOLING LAKE, 2010.ELECTROFISHING TRAP NETTING GILL NETTING HOOP NETTINGTAXON NUMBER WEIGHT NUMBER WEIGHT NUMBER WEIGHT NUMBER WEIGHTNo. % (g) % No. % (g) % No. % (g) % No. % (g) %Threadlin shadGizzard shadLongnose garCarpCommon shinerRosyface shinerSpotfin shinerSand shinerBluntnose minnow.Bullhead minnow-Smallmouth buffaloYellow bullheadBlue catfishChannel catfishFlathead catfishBrook silverside Hybrid sunfishGreen sunfishOrangespotted sunfishRedear sunfishBluegillLongear sunfishSmallmouth bassLargemouth bassFreshwater drumTotalsTotal taxaTotal species103 7.7 1309 1.036 2.7 6938 5.4 102 15.6 24,212 5.25 0.8 17,000 3.631 2.3 55,422 42.8 203 31.1 295,310 63.31 0.1 17 < 0.120 1.5 48 < 0.1251 18.7 503 0.414 1.0 27 < 0.197 7.2 203 0.246 3.4 103 0.11 0.2 3350 0.744 15.0 724 2.76 2.0 1687 6.2I 0.3 1200 4.41 0.7 1500 2.22 0.177 0.134 11.6 10,790 39.7 5 3.4 946 1.443 3.2 23,853 18.4 107 16.4 101,196 21.7 208 70.7 12,694 46.7 ill 76.6 49,040 72.61 0.7 14,000 20.723 1.7 25 < 0.14 0.3 75 0.137 2.8 919 0.73 0.2 29 < 0.12 0.1 83 0.1506 37.7 16,866 13.0 229 35.1 23,903 5.157 4.3 959 0.73 0.2 1534 1.261 4.5 20,381 15.7 3 0.5 1265 0.31 0.1 258 0.2 2 0.3 415 0.126 17.9 1634 2.41 0.3 III 0.4-00.7 400 0.6 0)CD67,520 !ý3-., ,r., D 0513412120129,62965288466,6512946627,20614566

--ml caaa 01zo -M2 -am, W o = = Lw M W O w WI E = 9 MTABLE 3-4NUMBERS OF FISH CAPTURED BY ELECTROFISHING AT EACH SAMPLING LOCATION IN BRAIDWOOD LAKE, 2010.SAMPLING LOCATIONS TAXON E- 1 E-2 E-3 E-4 E-5 E-6 E-7 E8 TOTAL % %Threadfin shadGizzard shadCarpCommon shinerRosyface shinerSpotfin shinerSand shinerBluntnose minnowe Bullhead minnow0i Yellow bullheadChannel catfishBrook silverside Green sunfishOrangespotted sunfishRedear sunfishBluegillLongear sunfishHybrid sunfishSmallmouth bassLargemouth bassFreshwater drum55231826118321353211421533324154712781211152711639693372243731518231120118513664452 1031 366 3112070 2512 1427 9712 4621 431 23373250 5067 57432 6117.72.72.30.11.518.71.07.23.40.13.21.72.80.20.137.74.30.30.24.50.13 323154 258111 12 13 21I9135361617Total fishTotal TaxaCPE (fishlhr) 77677.0'941094.0'20715207.0'12913129.0'36714367.0'15114151.0'13514135.0'18112181.0'134121167.6h_0.NiCDIbBased on 1.00 hrs electrofishing effort.Based on 8.00 hrs electrofisliing effort.

RS-14-138 Enclosure Page 99 of 322E-3. Fewer fish and taxa were collected at Locations E-1 and E-2 located closest to theBraidwood Station discharge.

In general, more fish and greater numbers of taxa were collected at locations located toward the cooler end of the Braidwood Lake cooling loop (Locations E-3, E-5, E-6, and E-10). Electrofishing biomass was dominated by carp, which constituted 47.5% ofthe 468.2 kg collected (Table 3-3). Other species that individually contributed more than 5% ofthe total biomass included channel catfish (21.3 %), bluegill (10.3%),

flathead catfish (8.3 %), andlargemouth bass (5.0%).The mean electrofishing catch-per-effort (CPE) for all locations combined was 167.6 fish/hr(Table 3-4). This value is similar to the mean electrofishing CPE of 177.5 fish/hr for all locations combined that was reported in 2009 (HDR 2010). In 2010, CPE ranged from 77.0 fish/hr atLocation E-1 to 367.0 fish/hr at Location E-5. Location E-5 also exhibited the highest catch ratein 2009. This site includes the area around the make-up water discharge into the lake from theKankakee River. Five species, gizzard shad, carp, channel catfish,

bluegill, and largemouth bass,were collected at each of the eight electrofishing locations.

3.2.2 Trap NettingA total of 652 fish including eight species was collected by trap net (Table 3-3). Bluegill was thedominant species captured, comprising 35.1 % of all fish taken. The second most abundantspecies collected was carp (31.1%),

followed by channel catfish (16.4%),

and gizzard shad(15.6%).

The total number of fish collected by location ranged from 41 at Location TN-8 to 190at Locations TN-2 (Table 3-5). The total number of species collected by location ranged fromfour at Locations TN-1, TN-3, TN-4, and TN-8 to six at Location TN-5. Total biomass of fishcaptured by trap net was 466.7 kg (Table 3-3). Species collected by trap netting that comprised greater than 5% of the catch by weight included carp (63.3%),

channel catfish (21.7%),

gizzardshad (5.2%), and bluegill (5.1%).During the July and August sampling

periods, mean trap netting CPE for all locations combinedwas 40.8 fish/net (overnight sets of approximately 12-hrs),

which is slightly higher than the 28.5fish/net reported in 2009 (HDR 2010). CPE by location ranged from 20.5 fish/net at LocationTN-8 to 95.0 fish/net at Locations TN-2. Carp, channel catfish, and bluegill were the only threespecies collected at each of the eight sampling locations.

3-9HDR Engineering, Inc.

l_,, ww. Em I E P -Em. m W E M 0 aTABLE 3-5NUMBER OF FISH CAPTURED BY TRAP NETTING AT EACH SAMPLING LOCATION IN BRAIDWOOD LAKE, 2010.0SAMPLING LOCATIONS TAXON TN- I a TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-8 TOTAL %Gizzard shad 28 27 17 13 10 4 3 102 15.6Longnose gar 3 2 5 0.8Carp 7 88 34 6 8 13 29 18 203 31.1Smallmouth buffalo 1 1 0.2Channel catfish 7 43 13 9 15 7 11 2 107 16.4Bluegill 2 30 51 44 45 17 20 20 229 35.1Largemouth bass 1 2 3 0.5Freshwater drum 1 1 2 0.3Total fish 44 190 115 72 83 42 65 41 652Total Taxa 4 6 4 4 6 5 5 4 8CPE (fish/trap net set) 22.0" 95.0' 57.5" 36.0' 41.5" 21.0" 32.56 20.5" 40.8The webbing of trap. net TN-I was severely damage.4 during the second.sampling period on August 17-18 due to vandalism or either by a muskrat or beaver. It is assumed that an unknown number of fish were lostbecause of te rela ively large hole that was found in the net upon retrieval.

'based on two over night sets of approximately 12 hr duration.

cBased on 16 over nig t sets of approximately 12 hr duration.

"uCD0 -'0)co RS-14-138 Enclosure Page 101 of 3223.2.3 Gill NettingGill netting resulted in the collection of 294 individuals representing six species (Table 3-3).Channel catfish dominated the catch by comprising 208 (70.7%) of the 294 total fish collected.

Threadf'm shad was the second most abundant species collected (15.0%).

The only other speciesto individually contribute more than 5% of the total catch was blue catfish (11.6%).

Channelcatfish comprised 12.7 kg (46.7%) of the 27.2 kg of fish collected by gill netting (Table 3-3),followed by blue catfish at 10.8 kg (39.7%),

and gizzard shad at 1.7 kg (6.2%).A total of 175 fish representing four species was collected from the two deep water sets conducted at Location GN-1 (Table 3-6). Gill nets at this location were set in a deep hole at a depth ofapproximately 7-8 m. At the shallow water sampling Location GN-2 the gill nets were set at adepth of approximately 1-2 m. One hundred nineteen fish and six species were collected fromthis sampling location during July and August. Similar results were noted between the deep andshallow water sets, with the exception of blue catfish, which were collected in greater numbers(32 individuals) in the deep water sets compared to the shallow water sets (two individuals).

Gill net CPE at the deep water Location GN-1 was 87.5 fish/hr based on 175 fish collected duringtwo hours of sampling time during the July and August sampling efforts.

CPE at the shallowwater Location GN-2 was slightly lower at 59.5 fish/hr based upon the 119 fish collected duringtwo hours of sampling effort in July and August. Mean CPE for the two sampling locations was73.5 fish/hr, which is higher than the 53.4 fish/hr reported in 2009 (HDR 2010). Gizzard shad,threadfin shad, channel catfish, and bluegill were the only species collected at both samplinglocations.

3.2.4 Hoop NettingA total of 145 fish including six species was collected by hoop nets (Table 3-3). Channel catfishwas the most abundant species captured, comprising 76.6% of all fish taken. The second andthird most abundant species captured were bluegill (17.9%) and blue catfish (3.4%). The onlyother species collected included one individual each of common carp, flathead

catfish, andfreshwater drum. A total of 67.5 kg of fish was collected by hoop net (Table 3-3). Channel3-11HDR Engineering, Inc.

RS-14-138 Enclosure Page 102 of 322TABLE 3-6NUMBERS OF FISH CAPTURED BY DEEP (GN-1) AND SHALLOW WATER (GN-2)GILL NETS IN BRAIDWOOD LAKE, 2010.SAMPLING LOCATIONTAXA GN-1a GN-2b TOTAL %Threadfim shad 29 15 44 15.0Gizzard shad 2 4 6 2.0Carp 1 1 0.3Blue catfish 32 2 34 11.6Channel catfish 112 96 208 70.7Largemouth bass 1 1 0.3Total fish 175 119 294Total taxa 4 6 6CPE (fish/hr) 87.5 59.5 73.5'GN-l was a deep water set in approximately 7-8 meters of water.bGN-2 was a shallow water set in approximately 1-2 meters of water.3-12 RS-14-138 Enclosure Page 103 of 322catfish (72.6%) and flathead catfish (20.7%) were the only two species that individually comprised greater than 5 % of the total hoop net catch by weight.The greatest number of fish (76 individuals) was collected at Location HN-1, which was a deepwater set baited with dead gizzard shad (Table 3-7). Only one flathead catfish was collected atLocation HN-2, which was also a deep water set, but the net was not baited. Similar numbers offish were collected at the two shallow water locations.

The hoop net at shallow water LocationHN-3 (33 individuals) was baited with dead gizzard shad, while the shallow water hoop net atLocation HN-4 (35 individuals) was not baited. The total number of species collected by locationranged from one at Locations HN-2 to three at Location HN-1 and HN-3. A total of 109 fish wascollected from the two baited net locations in July and August as compared to the 36 total fishcaptured from the two nets that were not baited at Braidwood Lake.Hoop netting CPE ranged from 38.0 fish/overnight set at Location HN-1 (deep water with bait) to0.5 fish/overnight set at Location HN-2 (deep water no bait). CPE for the two deep water sets(HN-1 and HN-2) averaged 19.2 fish/overnight set compared to 17.0 fish/overnight set at theshallow water locations (HN-3 and HN-4). The two baited net sets (HN-1 and HN-3) had anaverage CPE of 27.2 fish/overnight set compared 9.0 fish/overnight set for the two nets (HN-2and HN-4) that were not baited. Hoop nets were not used to collect fish in 2009. Mean CPE forall nets combined was 18.1 fish/overnight set.3.3 Length-Frequecy Distributions Length-frequency distributions of three selected species (bluegill, largemouth bass, and bluecatfish) captured by all sampling gears in 2010 were compiled and are presented graphically (Figures 3-1, 3-2, and 3-3). With the exception of electrofishing, the sampling gears used in thesestudies are biased toward larger fish. Therefore, smaller fish, especially young-of-year andyearlings, were not collected in numbers that would most accurately represent their trueabundance in Braidwood Lake. Although not presented graphically in this text, species such ascarp and channel catfish were also collected in large numbers with no obviously missing or weakage-classes included in their length-frequency analysis.

Two other common species, threadfin andgizzard shad, were also analyzed.

All of the threadfin shad collected during the current study3-13HDR Engineering, Inc.

TABLE 3-7NUMBERS OF FISH CAPTURED IN BAITED AND UNBAITED DEEP AND SHALLOW WATER HOOP NETSIN BRAIDWOOD LAKE, 2010.SAMPLING LOCATIONDEEP WATER3 SHALLOW WATERbTAXA BAIT) N-2 HN- HN-4TAX (BAHITD)

( AITED) (B A ITED) (UNBAITED)

TOTALCarp 1 1 0.7Blue catfish 5 5 3.4Channel catfish 70 26 15 111 76.6Flathead catfish 1 0.7Bluegill 6 20 26 17.9Freshwater drum 1 1 0.7Total fish 76 1 33 35 145Total taxa 3 1 3 2 6CPE (fish/overnight set)c 38.0f 0.5C 16.5c 17.5c 18.1d'Deep water hoop nets HN-I and HN-2 were set in 7.5 meters of water.bShallow water hoop nets HN-3 and HN-4 were set in approximately 2.0 meters of water.1CPE was based on two overnight sets of approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> duration.

dCPE was based on eight overnight sets of approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> duration.

CD0.21 0K) CD 0

-,- Em w cm m n mmimmm mM OEM10080CL0I 60-0N,Li2IM 402Oz200TOTAL LENGTH (mm):03.U,'FIGURE 3-1. LENGTH-FREQUENCY DISTRIBUTION OF BLUEGILL COLLECTED FROMBRAIDWOOD LAKE DURING JULY AND AUGUST, 2010.

-- an Em ow m m m I Em w m m m m m m m m0-0wNCl)zIAILmI I I I I I I I I I I I I I I I I I I Ia C a ~ a a a a a a a a a a a aN N N N Co C') CO CONNNNNNNNNN~nCOnA "0TOTAL LENGTH (mm) CD0) 0FIGURE 3-2. LENGTH-FREQUENCY DISTRIBUTION OF LARGEMOUTH BASS COLLECTED FROM BRAIDWOOD t Z 'LAKE DURING JULY AND AUGUST, 2010.

E m -aa Im )06- N=39wtCI,S4-2 -"- 743 mm0 -0 00 0 o 000~~~ N 80 c. cý c 0 0 8S6 6 6 6 c 6 6 6 ,--m N N N N N R- a 40 0TOTAL LENGTH (mm)0 0FIGURE 3-3. LENGTH-FREQUENCY DISTRIBUTION OF BLUE CATFISH COLLECTED FROM BRAIDWOOD N cLAKE DURING JULY AND AUGUST, 2010.

RS-14-138 Enclosure Page 108 of 322measured from 70 to 123 mm in total length, while 125 (88.7%) of the 141 gizzard shad capturedexceeded 250 mm in total length.Bluegill is one of the most abundant species found in Braidwood Lake. Four hundred fifty-eight individuals measuring from 65 to 200 mm in total length are included in the length-frequency histogram of bluegill that were captured in 2010 (Figure 3-1). Two major peaks in the length-frequency distribution representing at least two different age classes were noted. The first majorgroup of fish includes bluegill measuring from 90 to 140 mm, while the second major groupincludes fish measuring from 160 to 190 mm. The age of these fish, as well as other species, inthermally enhanced bodies of water, such as Braidwood Lake, is impossible to determine withouthard-part (scales, spines, and otoliths) analysis because the growing season extends throughout thewinter months. Regardless of age, Braidwood Lake supports a large population of bluegill thatare large enough to support a quality sport fishery.The length-frequency distribution of 65 largemouth bass measuring from 93 to 454 mm in totallength were collected from Braidwood Lake during 2010 (Figure 3-2). The length-frequency distribution indicates that several age classes of fish were included among the catch. The largestpeak in the length-frequency histogram occurs at 120 mm and likely represents either YOY orAge 1 fish. Sixteen (24.6%) of the 65 fish collected exceeded 350 mm (14 in.). The largestindividual that measured 454 mm was likely older than Age 5 or 6. Again, the age of fish incooling lakes is difficult to ascertain based on length-frequency analysis because of the extendedgrowing season that exist in these thermally enhanced bodies of water.Braidwood Lake has been stocked with a variety of warm- and coolwater fish specie since the1970's to the present time. Those efforts have included the introduction of blue catfish to thecooling lake. Because of those stocking

efforts, and because of the relatively large number ofblue catfish that were collected in 2010, a length-frequency histogram was also created for thisspecies (Figure 3-3). The length-frequency distribution of 39 fish measuring from 158 to 743 mmindicates that as many as five year classes of blue catfish were included in the catch at Braidwood Lake during 2010. Thirty-two (82.1%) of the 39 fish collected measured less than 270 mm intotal length, while the remaining seven (17.9%) individuals ranged from 360 to 743 mm in totallength. The authors of this report are uncertain of the recent stocking

history, if any, of blue3-18HDR Engineering, Inc.

RS-14-138 Enclosure Page 109 of 322catfish in Braidwood Lake. The relatively large number of smaller blue catfish collected in 2010may indicate that natural reproduction has taken place within Braidwood Lake (See Addendum).

3.4 Physicochemical DataWater quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection (Appendix Tables A-1 to A-4). During July 20-22, water temperature at Braidwood Lake ranged from 33.6 'C at Location TN-7 on 20 July to 38.2 'C at Location E- 1(the most southern location located closes to Braidwood Station discharge) on 21 July. Make-upwater from the Kankakee River was being pumped into the lake at Location E-5 during the timewater quality parameters were being measured.

Water temperatures during the second samplingperiod (August 17-19) were cooler than those measured in July because both Unit I and Unit IIwere off line. Temperatures during this period ranged from 29.6 'C at Location E-1 (closest tothe Braidwood Station discharge) on 19 August to 33.9 'C at Location E-1 on 17 August. Watertemperature decreased during the three day sampling period in August as the cooling loop cooleddue to the outage. As expected, the temperature gradient during the July sampling periodgenerally declined as the cooling water in the lake moved from the Station's discharge toward theBraidwood Station intake. However, during the second sampling period, temperature generally cooled more quickly near the discharge end of the lake once the units went off line.Dissolved oxygen (DO) ranged from 4.7 ppm at Locations TN-i and TN-2 to 12.2 ppm atLocation GN-1 during the July sampling period. Oxygen levels were lower during the Augustsampling period when DO ranged from 1.4 to 9.6 ppm at Locations TN-2 and E7, respectively.

Qualitative observations by the field crew indicated that the water appeared much clearer duringthe August sampling dates. This suggests that a decline in the phytoplankton population may haveoccurred between the first and second sampling period, which may explain the moderate declinein oxygen levels noted in Braidwood Lake during August.As was also observed in 2009 (HDR 2010), diurnal variations in the lake led to increased dissolved oxygen reading from early morning to late afternoon during July and August, 2010.These variations can be attributed to the phytoplankton within the lake that produces oxygenthroughout the daylight hours.3-19HDR Engineering, Inc.

RS-14-138 Enclosure Page 110 of 322Surface and bottom water temperature, DO, and conductivity readings were taken at deep watergill net set Location GN-land the deep water hoop net set Locations HN-1 and HN-2. Similarsurface and bottom readings were recorded at the deep water Locations HN-1 and HN-2. AtLocation GN-1, the bottom temperatures were slightly cooler (0.2 to 1.0 'C) than the surfacereading, while the DO levels measured near the bottom were more variable ranging from 0.6 to4.6 ppm less than the surface readings during the July and August sampling periods.Braidwood Lake is a very productive system with heavy oxygen demand (respiration anddecomposition) occurring during the night and intense oxygen production (photosynthesis) occurring during clear sunny days. Currently, the majority of the photosynthetic activity withinBraidwood Lake is attributable to phytoplankton, which has decreased the water clarity andreplaced aquatic macrophtyes as the primary producer.

In a report submitted to Exelon by SEAin 2001 (Appendix Report B-i); it states that "Several perched cooling ponds in the Midwest havehad high macrophyte densities in their earlier years but usually become dominated byphytoplankton if they have heavy thermal loading.

A switch to phytoplankton dominance isusually accompanied by a reduction in water transparency."

Braidwood Lake appears to be relatively well buffered with only minor diurnal variation in pHreadings.

Examination of pH data collected during the present surveys show that pH ranged from8.3 to 8.5 during the July sampling period and from 8.3 to 8.7 during the August samplingperiod. The pH of water typically increases with increased photosynthetic activity and theresulting oxygen production can explain upward shifts in pH during the course of bright sunnydays.During the July sampling period, conductivity ranged from 770 pmhos at Location TN-2 on 20July to 823 prnhos at Location TN-2 on 21 July. Conductivity during the August sampling periodranged from 832 /.mhos at Location TN-8 on 17 August to 862 Mmhos at Location TN-2 on 18August. Conductivity and pH readings were relatively similar throughout the entire length ofBraidwood Lake. Surface to bottom readings were also similar, suggesting that the waterthroughout the cooling loop was well mixed during the July and August sampling dates.Make-up water was being pumped into Braidwood Lake from the Kankakee River during the Julysampling period. As a result, water quality parameters can be expected to be generally more3-20HDR Engineering, Inc.

RS-14-138 Enclosure Page 111 of 322favorable near the make-up water discharge (Location E-5) compared to the remainder of thesampling locations.

However, the affects of the make-up water discharge is quickly dissipated because of the relatively low volume of make-up flow being pumped into the lake. Make-upwater was not being pumped into Braidwood Lake during the time of sample collection in August.During the July sampling period, water quality parameters were within the range of valuesacceptable for warmwater fish species.

During the August sampling period, pH and conductivity were measurements were relatively similar to the values recorded during July. However,temperature and dissolved oxygen readings in August were lower than those observed in July.The cooler water temperatures can be explained by the plant outage that occurred during theAugust sampling period. There was also a decline in DO readings that ranged from 1.4 ppm onthe morning of 18 August to 9.6 ppm during the afternoon of 19 August. The early morningdissolved oxygen readings that were measured during the August sampling dates wereapproaching values that adversely affect most fish species.

As previously noted, these diurnaloxygen fluctuations can be attributed to oxygen depletion (respiration and decomposition) duringthe night and oxygen production (photosynthesis) during the day. On cloudy calm days,photosynthesis and oxygen production can be slowed to levels that cannot compensate for oxygendepletion that occurs throughout the night. When this occurs over an extended period of time(days), an oxygen deficit can develop and cause substantial fish die-offs if suitable refuges withinthe system are not available.

3.5 Historical Information 3.5.1 Water QualityWater quality parameters were measured on seven separate occasions at Braidwood Lake fromMay 29, 2001 through August 27-28, 2002 (Appendix Reports B-1 through B-7). The purposeand scope of these investigations varied, but the most intensive sampling was conducted duringthe August 27-28, 2002 sampling event. Results of these investigations indicated that abnormally high levels of total dissolved solids (TDS), alkalinity,

hardness, sulfates, magnesium, calcium,and total phosphorus existed throughout the cooling loop. This data was not unexpected based onthe evaporation that occurs within the cooling loop coupled with the relative low make-up andblow-down flows associated with the operation of the Station.

The cooling lake exhibited elevated3-21HDR Engineering, Inc.

RS-14-138 Enclosure Page 112 of 322values for these parameters at levels of two to nearly eight times higher than those of the make-upwater from the Kankakee River. These elevated levels of water hardness can be of concern tothe Station because they have the potential to intensify problems associated with scaling.Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Concentrations ofthese nutrients are typically low in water because phytoplankton and aquatic macrophytes quicklyassimilate and utilize these nutrients for growth and reproduction.

The studies conducted by SEAin 2002 indicated that the high levels of these nutrients within the cooling lake would continue tocause problems associated with phytoplankton blooms. Unlike most water bodies, phosphorus levels within Braidwood Lake were in excess and nitrates were the limiting factor. Bluegreen algae appeared to be the dominant summer form of algae within Braidwood Lake because they arenot as limited by low nitrate levels as other algal species.Water quality analysis has indicated that dissolved oxygen levels within the cooling lake canexhibit large diurnal variation in response to algal blooms that are most problematic during thesummer months (June through August).

The nutrient rich water of Braidwood Lake is ideal forthe development of algal blooms that produce large amounts of oxygen during the day(photosynthesis) and oxygen depletion in the dark (respiration and decomposition).

As oxygen isproduced through photosynthesis, pH tends to increase if the water is not well buffered.

Dissolved oxygen levels of 4-5 ppm (levels that most fish species become stressed) and lowerhave been recorded throughout the cooling loop 0.5 m below the waters surface.

The lowest DOreadings occur during the early morning period and they typically increase throughout the day.Increases in DO of 4 to 5 ppm or more have been observed from morning to late afternoon atBraidwood Lake. In addition, stratification of the water column has also been reported during thesame period of time when DO readings are measured at less than 3 ppm. During these events,DO readings in the hypolimnion (the zone below the thermocline to the bottom of the lake) canapproach zero. When this occurs, it further limits the refuge available for fish and other aquaticorganisms.

3.5.2 Fish KillsHistorical fisheries data summarizing fish kills that have occurred at Braidwood Lake wasprovided to HDR by Exelon Nuclear, IDNR, and SEA (Appendix Reports B-2 through B-7). Five3-22HDR Engineering, Inc.

RS-14-138 Enclosure Page 113 of 322fish kills that occurred from 2001 through 2007 were identified in the information provided toHDR. Each of these events occurred during June, July, or August. Two of the kills occurred in2001. The first took place in late July and the second on August 27-28. A third kill was reportedon July 30, 2004, the fourth on June 28, 2005, and the fifth occurred over an extended period oftime during August 21-28, 2007. No additional information regarding fish kills has beenprovided to HDR since 2009. Therefore, it is assumed that no reportable fish kills have beenobserved at Braidwood Lake since August, 2007.Little information was provided for the fish kills that occurred in late July and August, 2001. Thespecies involved and the extent of dead fish observed during the first event in July were notincluded in the information received by HDR. The second fish die-off in late August wasdominated primarily by gizzard shad that comprised more than 95 % of all fish observed.

Theremaining species involved in the die-off in decreasing order of relative abundance

included, freshwater drum, quillback, carp, largemouth bass, channel catfish, redhorse spp., smallmouth bass, and bluegill.

With the exception of gizzard shad, the majority of the fish were located fromthe mid-point of the cooling loop to the intake. A report submitted by SEA indicated that warmwater temperatures and/or low dissolved oxygen levels were the most likely factors thatcontributed to the fish die-off in July. SEA also indicated that the die-off in late August was mostlikely the result of depleted dissolved oxygen levels that occurred in the lake following anextensive phytoplankton bloom collapse, which is a natural phenomenon that can occur in highlyproductive waters during summer months. Dissolved oxygen measurements throughout themajority of the lake were at or below minimum levels necessary to support most fish species.A third fish die-off at Braidwood Lake was investigated on July 30, 2004. Gizzard shad was thedominant species involved, although channel catfish were also observed.

The gizzard shadappeared to be in an advanced state of decay suggesting that the actual die-off occurred earlier inthe week. Water quality parameters at the time of the incident were not included in the briefsummary report provided to HDR, which suggest they were not measured concurrent with thefish die-off.

Water quality measurements were taken in early October following the fish die-off.During this period of time, DO levels of 3.8 ppm and a water temperature of 29.2 'C wererecorded at a depth of one foot below the surface, just north of the south boat ramp. At a locationseveral hundred feet from the lake make-up discharge from the Kankakee River, more favorable 3-23HDR Engineering, Inc.

RS-14-138 Enclosure Page 114 of 322dissolved oxygen (7.6 ppm) and water temperatures (26.5 'C) were measured.

DO readings atthis location were stratified exhibiting a decline to 5.3 ppm at 40 feet, while water temperature showed minimal decrease with water depth.In 2005, an inspection of a fish die-off was conducted on 28 June. Formal counts of fish were notconducted at this time, but field assessments indicated that a fairly substantial die-off involving several species had occurred.

Gizzard shad was again the most numerous species affected andfish carcasses were observed throughout the majority of the lake. Additional species observedincluded threadfin shad, quillback, largemouth and smallmouth bass, carp, and channel catfish.Water quality measurements during this event were not provided to HDR and are assumed to beunavailable.

Rob Miller of IDNR and Jeremiah Haas of Exelon Nuclear investigated another fish die-off thatwas first reported at Braidwood Lake on August 21, 2007. The majority of the dead fishobserved were either large gizzard shad or threadfin shad up to five inches in length. Channelcatfish were also prevalent, with only a few carp, largemouth bass, and flathead catfish beingobserved.

Most of the fish were distributed in close proximity to the north boat ramp due toprevailing south winds. The number of dead fish observed decreased towards the south (hot) endof the cooling loop. During the afternoon of 21 August, surface water temperature was 35.3 0Cand DO was near 3 ppm at a sampling point several hundred yards from the south ramp. Fourseparate water temperature and DO readings were also conducted at the north ramp between 1210hrs and 1658 hrs. Water temperature increased from 30.3 to 33.9 'C over the course of that timeinterval.

Dissolved oxygen was measured at 3.1 ppm at 1210 hrs and increased to 6.7 ppmduring the third reading at 1530 hrs. DO levels decreased during the last reading at 1658 hrs to5.9 ppm. Oxygen depletion appeared to be the factor responsible for the August fish kill thatoccurred at Braidwood Lake in 2007.3-24HDR Engineering, Inc.

RS-14-138 Enclosure Page 115 of 3224.0 SUMMARY AND RECOMMENDATIONS 4.1 Summary.

Braidwood Lake is a 2640 acre, partially perched cooling lake that was firstimpounded in 1980-1981 after several old strip-mine pits were inundated with water from theKankakee River. The lake has received supplemental stockings of both warmwater and coolwater fish species since the late 1970's. However, stocking efforts of species including

walleye, tigermuskie, smallmouth bass, and hybrid striped bass have not produced a sustainable quality fishery,which is most likely due to warm water temperatures that are currently common in the coolinglake throughout the summer months. Water quality, particularly water temperature, improves asthe water moves from the southern (hot) end of the cooling loop toward the northern (cool) end ofthe lake.Fisheries surveys have been conducted by IDNR at Braidwood Lake annually from 1980 through1992, in 1994, and at two year intervals from 1997 through 2007. Forty-five species of fish andtwo hybrid taxa (tiger muskie and hybrid sunfish) have been included among the 12 families offish collected.

River redhorse (one individual captured in 1999) is the only species that has beencollected which is currently listed as protected in Illinois.

Several of these species were rarelycollected, were the result of supplemental stocking

efforts, or have not been collected during thepast ten years of sampling.

In 2009, HDR collected 24 species and two taxa (hybrid sunfish andsmall unidentified young-of-year sunfish species) among the 2143 fish collected.

Similar resultswere observed in 2010 when 25 taxa representing eight families were included among the 2432fish collected by electrofishing, trap netting, gill netting, and hoop netting.

Several taxa that werecollected by IDNR during previous surveys conducted from 1980 to 2007 were not collected ineither 2009 or 2010. However, five species (shortnose gar, blue catfish, bigmouth buffalo,fathead minnow, and rosyface shiner) were captured in 2009 that had not been captured duringprevious sampling efforts (HDR 2010). In 2010, three species that had not been collected by theILDR were captured.

Two of these species, blue catfish and rosyface shiner, were also collected in 2009, while a third species, smallmouth

buffalo, had not been captured during any of theprevious studies.

In 2010, 39 blue catfish were collected by gill nets and hoop nets, 20 rosyfaceshiner were collected by electrofishing, and a single smallmouth buffalo was collected by one ofthe trap nets. No threatened or endangered species were encountered in either the 2009 or 20104-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 116 of 322lake surveys.

Since 1980, 51 species of fish and two hybrids (tiger muskie and hybrid sunfish)have been collected at Braidwood Lake by the IDNR and HDR.The Braidwood Lake Fish and Wildlife Area has evolved through three distinct phases since itsinception prior to the 1980's. Originally, several surface mined pits existed at the site until thelake was impounded with water from the Kankakee River during 1980 and 1981. The lakecontinued to function in this capacity until July 29 and November 17, 1988 when Braidwood Station began commercial operation of Units I and Unit II, respectively.

From 1980 through July1988, Braidwood Lake did not receive any thermal loading from Braidwood Station.

Since 1988,the lake has functioned as a cooling loop for the operation of the Station.

Currently, the lake isbest suited to support a warmwater fishery due to the warm temperatures prevalent in the lakeduring summer months. Dominant species currently found in Braidwood Lake include gizzardshad, threadfin shad, bluegill, channel catfish, and carp. Additional species such as largemouth bass, green sunfish, flathead

catfish, spotfin shiner, bluntnose minnow, and sand shiner are alsocommonly encountered.

Excluding several of the stocked taxa that have been introduced into thelake, the taxa encountered have also been collected from the Kankakee River, which is the sourceof make-up water for the lake. With the possible exception of common carp and channel catfish,these species are better suited to conditions that exist within the river. Survival of individuals thatmay be introduced into the lake with the make-up water is limited by the elevated watertemperatures that exist within the cooling loop during summer months.Braidwood Lake can be currently described as a well buffered body of water with elevated watertemperatures, high levels of total dissolved solids (TDS), phosphates, and nitrates.

Primaryproductivity in the lake can be very high in conjunction with algal blooms that occur throughout the lake, especially during the June through August period. These blooms are driven by the highnutrient levels that occur within the lake. In recent years, phytoplankton has replaced aquaticmacrophytes as the principal source of primary production.

The lake can also display relatively large diurnal fluctuations in dissolved oxygen measurements, particularly during the summerwhen oxygen is produced in large quantities by photosynthesis during the day and used in largequantities by respiration and decomposition during the night. In addition, Braidwood Lake canstratify during certain portions of the year, which has led to anoxic (oxygen depletion) or nearanoxic conditions throughout the hypolimnion (stratified bottom layer of water below the4-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 117 of 322thermocline) as a result of respiration and decomposition from a collapsing algal bloom. Even inthe surface waters of the epilimnion, dissolved oxygen readings of less than 4 ppm have beenreported following an extensive and rapid die-off of an existing phytoplankton bloom. It is duringthese periods when water temperatures are elevated and dissolved oxygen levels are low that fishdie-offs occur within lake. The conditions described in this paragraph should not be expected tochange at Braidwood Lake in the foreseeable future.4.2 Recommedations.

Five separate fish die-offs attributed to low DO levels were observed atBraidwood Lake between 2001 and 2007. It is expected that the conditions which led to thosefive events will not change or improve in the foreseeable future. Therefore, it should be assumedthat fish die-offs will continue to occur when algal blooms crash and oxygen depletion occurs.Substantial fish die-offs within the cooling loop could adversely affect both the operation andmaintenance of Braidwood Nuclear Station.Currently, there are no practical or simple solutions that could prevent the occurrence of fish die-offs at Braidwood Lake. It should be anticipated that fish die-offs will continue to occur at thelake on a fairly regular basis. Therefore, it would be advantageous if a reliable sampling protocolor set of procedures were developed that would reasonably predict fish die-offs which mayadversely affect the operation and/or maintenance of the Station.

With advanced warning theStation would be informed of a potential reportable

incident, regulatory agencies could benotified, and crews responsible for fish disposal could be put on alert to help manage the riskassociated with a substantial fish die-off.

HDR believes this can be accomplished by conducting routine visual inspections of the lake, monitoring dissolved oxygen levels, and by having a basicunderstanding of environmental conditions that may trigger these events, especially weatherconditions.

HDR recommends a two tier sampling procedure that may be utilized to help predict the onset ofa possible reportable fish die-off.

We recommend that visual inspections of the lake and waterquality measurements be conducted routinely throughout the year, particularly during the warmweather months, if budget allows and staff is available to monitor the lake. The frequency ofobservations and the intensity of the water quality measurements should be discussed by themanagement who would analyze risk management at Braidwood Station.

Historically, all the fish4-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 118 of 322die-offs at Braidwood Lake have occurred during the warm weather period of June throughAugust. This is the period of time when water in the cooling loop is the warmest and dissolved oxygen levels can fall substantially following die-offs of extensive phytoplankton booms.Therefore, this is the most critical period of time to monitor existing conditions that could result ina potential problem (May through September).

Sampling on a less frequent basis throughout theremainder of the year may provide additional information that could be useful to the Station andpossibly alert the Station of an impending problem which may not have been identified in the past.Water quality measurements should include dissolved oxygen readings at a minimum becausefisheries biologists that have investigated these events in the past have concluded that the mortality of fish was the result of oxygen depletion.

The most effective way to monitor dissolved oxygenlevels within the lake would be through the use of a permanently fixed continuous water qualitysamplers and data loggers installed at several depths that could be programmed to takemeasurements at predetermined time intervals.

The number of water quality samplers purchased or the type of sampler utilized would be dependent upon the desired results and cost of theequipment.

Ideally, the best system would allow the sampling unit to take measurements atprogrammed time interval (perhaps every 15 minutes to daily), would measure at least DO, watertemperature, and pH, could provide instantaneous readouts to Braidwood staff without having tomanually go into the field to download data, and would require minimal maintenance orcalibration to operate.

The price range of this type of equipment is highly variable depending onthe unit selected, the anchoring mechanism for the unit if required, battery life, the number ofparameters

measured, etc. An alternative to this approach would be to utilize a technician tomanually take these measurements.

The disadvantage of this approach is the number of readingsthat could be taken on a daily basis and the time involved to conduct the water quality analysis inthe field.Water quality at Braidwood Lake should be monitored on some predetermined routine basis. Thatcould be at least weekly throughout the year or perhaps only through the more critical time periodof approximately June through August. The two tiered sampling approach would be initiated when dissolved oxygen readings hit a pre-determined trigger point (perhaps 5 to 6 ppm). OnceDO readings decrease to the trigger point, sampling frequency should be increased to at leasthourly. If automatic samplers are not used, field technicians should be in the field by sunrisewhen DO readings are typically the lowest. If automatic samplers were utilized, dissolved 4-4HDR Engineering, Inc.

RS-14-138 Enclosure Page 119 of 322oxygen, temperature and other water quality parameters could be tracked throughout the day.This would become important if DO readings ranged from 4 or 5 ppm in the morning to 7 or 8ppm in the afternoon.

This information would indicate that photosynthesis is still occurring during the daylight period, which would replenish DO levels in the water and reduce the risk of afish die-off.

However, if DO levels were 4 or 5 ppm in the morning and only increased slightlythroughout the day, this would indicate very little oxygen production due to photosynthesis.

Thiscondition would lead to a greater oxygen deficit during the evening, and could indicate the onsetof a phytoplankton bloom die-off that could trigger a fish kill. Once DO levels approach 3 ppm,Station management could be notified of a potential

problem, increased visual inspections of thelake could be conducted, and fish cleanup and disposal crews could be notified and put on standbystatus.Additionally, Braidwood staff should be aware of weather patterns that can influence these events.When phytoplankton blooms are prevalent and several cloudy days with little or no wind areforecast, massive dies offs of the bloom and subsequent oxygen depletion throughout the watercolumn should be anticipated.

Increased sampling of DO during these weather patterns isadvisable in conjunction with an increase in the frequency of visual inspections at the lake formoribund or dead fish. An increase in water clarity or transparency within the lake would also beexpected to occur as the phytoplankton population crash is in progress.

Visual inspections for fish die-offs should be conducted around the entire cooling loop asprevailing winds may push most of the fish toward one end of the lake. HDR recommends waterquality measurements be conducted at a depth of approximately one meter, if multiple depths arenot sampled.

If only one sampling location is selected, that location should be located near theapproximate mid-point of the cooling loop. The number of water quality stations sampled shouldbe determined by Exelon management or an advisory staff. It is further recommended that anadvisory team should be formed to devise an effective sampling program and set of procedures that can effectively monitor conditions within the lake. HDR is willing to participate and interactwith the advisory team to provide expertise in the development of an effective sampling program.4-5HDR Engineering, Inc.

RS-14-138

5.0 REFERENCES

CITED Enclosure Page 120 of 322Becker, G.C. 1983. Fishes of Wisconsin.

The University of Wisconsin Press. Madison, Wisconsin.

Environmental Science & Engineering.

1993. Kankakee River Fish Monitoring Program Braidwood Station 1993. Report to Commonwealth Edison Company,

Chicago, Illinois.

HDR Engineering, Inc. 2009. Braidwood Station Kankakee River Fish Monitoring

Program, 2008.Prepared for Exelon Nuclear, Warrenville, Illinois.

HDR Engineering, Inc. 2010. Braidwood Lake Additional Biological Sampling

Program, 2009.Prepared for Exelon Nuclear, Warrenville, Illinois.

HDR/LMS 2006. Braidwood Station Kankakee River Fish Monitoring

Program, 2005. Prepared forExelon Nuclear, Warrenville, Illinois.

HDR/LMS 2007. Braidwood Station Kankakee River Fish Monitoring

Program, 2006. Prepared forExelon Nuclear, Warrenville, Illinois.

HDR/LMS 2008. Braidwood Station Kankakee River Fish Monitoring

Program, 2007. Prepared forExelon Nuclear, Warrenville, Illinois.

Illinois Endangered Species Protection Board. 2009. Checklist of Endangered and Threatened Animals and Plants of Illinois.

Illinois Department of Natural Resources, Springfield, Illinois 18 pp.Lawler, Matusky and Skelly Engineers (LMS). 1992. Braidwood Station Kankakee River FishMonitoring

Program, 1991. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1996. Braidwood Station Kankakee River FishMonitoring

Program, 1995. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1999. Braidwood Station Kankakee River FishMonitoring

Program, 1998. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2001. Braidwood Station Kankakee River FishMonitoring

Program, 2000. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2005. Braidwood Station Kankakee River FishMonitoring

Program, 2004. Report to Commonwealth Edison Company,

Chicago, Illinois.

Piper, R.G. et al. 1983. Fish Hatchery Management.

United States Department of the Interior Fishand Wildlife Service.

Second Printing.

Washington, D.C. 517 pp.Pflieger, W.L. 1975. The Fishes of Missouri.

Missouri Department of Conservation.

Jefferson City, Missouri.

Smith, P.W. 1979. The Fishes of Illinois.

University of Illinois Press, Urbana, Illinois.

314 pp.Trautman, M.B. 1981. The Fishes of Ohio. Ohio State Press in Collaboration with the Ohio SeaGrant Program Center for Lake Erie Area Research.

782 pp.5-1HDR Engineering, Inc.

RS-14-138 Enclosure 6.0 ADDENDUM Page 121 of 322The following information was provided to the authors of this document after the report hadbeen finalized and prepared for publication.

The information received was titled "Braidwood Lake 2010 Fisheries Field Activities Summary".

This information is pertinent to Section 3.3(Length-Frequency Distributions) pages 3-19 and 3-20 that refers to the relatively largepercentage of small blue catfish that were captured in 2010. The authors were uncertain of anyrecent stocking

history, if any, of blue catfish in Braidwood Lake. The information that wasprovided below indicates that the smaller fish that were observed in 2010 were the result of thestocking activities that took place in 2010 by IDNR and not the result of natural reproduction.

Fish Stocking Activity in 2010* 46,160 4-inch largemouth bass fingerlings equivalent to 20.6 fish/acre.

• 9,812 5.3-inch blue catfish fingerlings equivalent to 4.3 fish/acre.

Field Activities in 2010For the fourth consecutive year, MEHS fish habitat units were purchased by Exelon'sBraidwood Generating Station.

A total of 80 units were placed in groups positioned atpreviously selected locations throughout the lake in early April. This activity is acooperative effort between Exelon, IDNR, and local bass fishing clubs.In early June the DC electrofishing unit was utilized at settings which have been showneffective for the collection of blue and flathead catfish.

The following settings wereused to obtain an amperage of close to one (1): pps -7.5, "high" setting @ roughly15-20%. Approximately two hours of effort were expended with no blue or flatheadcatfish collected.

The unit did succeed in bringing small channel catfish skittering along the surface.

Water temperature ranged from 88 to 95 'F. Skies were mostlysunny with air temperatures in the upper 80's. Areas selected for sampling included thechannel leading towards the lake intake, obvious current breaks in the cooler portion ofthe lake, the "Arrowhead" area, and the lake make-up, which was receiving water.The poor results are felt to be a function of the high water temperatures.

No major fish kills were reported in 2010.6-1 RS-14-138 Enclosure Page 122 of 322APPENDIX APHYSICOCHEMICAL DATA RS-14-138 Enclosure Page 123 of 322LIST OF TABLESTable No.A-1A-2A-3TitlePhysicochemical Measurements Recorded Concurrently withElectrofishing Samples Collected from Braidwood Lake, 2010.Physicochemical Measurements Recorded Concurrently withTrap Netting Samples Collected from Braidwood Lake, 2010.Physicochemical Measurements Recorded Concurrently withGill Netting Samples Collected from Braidwood Lake, 2010.Physicochemical Measurements Recorded Concurrently withHoop Netting Samples Collected from Braidwood Lake, 2010.Page No.A-IA-2A-3A-4A-40iHDR Engineering, Inc.

n mm u EM -0 1 a ETABLE A- IPHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH ELECTROFISHING SAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2010PARAMETER E-1 E-2 E-3 E-4 E-5 E-6 E-7 E-8Date (First Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (munhos/cm)

JUL 21123038.27.88.5774JUL 21133036.47.98.5813JUL 21143035.410.38.5804JUL 21151535.810.28.5807JUL 22070533.87.08.4794JUL 22081034.07.28.4805JUL 22090533.76.98.3801JUL 21163035.610.48.5809Date (Second Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (pmhos/cm)

AUG 19073029.63.48.5850AUG 19081530.24.88.6850AUG 19092030.27.78.6844AUG 19101530.57.18.6842AUG 19110031.07.98.6840AUG 19130031.46.88.6837AUG 19134532.09.68.6838AUG 19120031.08.68.6cD840:030 a-TABLE A-2PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH TRAP NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2010PARAMETER TN-1 TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-8Date (First Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (W-nhos/cm)

Date (Second Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (piihos/crn)

JUL 20-21 JUL 20-21 JUL 20-21JUL 20-21 JUL 20-21 JUL 20-21 JUL 20-21JUL 20-21173080750b36.735.78.14.78.58.4.8108221737070036.835.78.24.78.58.47708231749063535.534.38.75.88.58.48098171753062035.534.38.75.18.58.48098181716081034.433.07.66.58.58.48108121803083734.733.88.46.88.58.48088141844090633.633.07.36.88.58.47998011635090033.833.08.46.88.58.4799801AUG 17-18 AUG 17-18 AUG 17-18 AUG 17-18 AUG 17-18 AUG 17-18 AUG 17-18 AUG 17-181822070033.930.86.21.98.68.38608561818071533.931.46.21.48.68.38568621810073532.730.87.43.08.68.48608531805074532. I30.87.72.78.68.48568511757080031.730.09.44.58.78.68518461750081532.330.99.43.68.78.58568511615083031.830.88.24.78.68.68508361610084531.830.28.15.18.7 -u8.7 'C847832 o,Pc¢aTop number represents subsurface readings taken 0.5 meter below the surface when the nets were set in the evening on July 20.bBottom number represent subsurface readings taken 0. 5 meter below the surface when the nets were retrieved the next morning approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> later on July 21.Lýý L7 =- aj L- 'J 1-2 r1=11-E-M C--r-1 .6 V. K-;-717Z4 amNonoý m E- mi MaTABLE A-3PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH GILL NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2010GN-1 in Deep water GN-2 in shallow water(7-8 m) (1-2 m)PARAMETER Surface Bottom Surface BottomDate (First Sample Period) JUL 21 JUL 22Time 1615 1615 0900 aTemperature (OC) 34.7 33.7 33.7 aDissolved oxygen (ppm) 12.2 7.6 7.0 apH 8.5 a 8.3 aConductivity (pmhos/cm) 804 801 800 aDate (Second Sample Period) AUG 17 AUG 17Time 1530 1530 1630 aTemperature

(°C) 31.8 31.6 31.7 aDissolved oxygen (ppm) 6.2 5.6 6.5 apH 8.5 a 8.5 aConductivity (umhos/cm) 842 846 845 aM0) = ý0 -0rs ,a Water quality measurement not taken.

TABLE A-4PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH TRAP NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2010HN-I HN-2 HN-3 HN-4DEEP WATER BAITED DEEP WATER UNBAITED SHALLOW WATER SHALLOW WATERPARAMETER (7.5 m) (7.5 m) BAITED (2.0 m) UNBAITED (2.0 m)Date (First Sample Period)JUL 20(SET)JUL 21(LIFT)JUL 20(SET)JUL 21(LIFT)JUL 20(SET)JUL 21(LIFT)JUL 20(SET)JUL 21(LIFT)Time1652>Temperature (0 C)Dissolved oxygen (ppm)pHConductivity (punhos/cm)

Date (Second Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (pmhos/cm) 33.5a33.5b6.86.88.5093533.133.26.86.58.5170133.533.56.87.08.5094533.133.26.86.48.4170833.67.18.5100033.36.78.4171033.67.08.5101533.36.78.4798798AUG 17(SET)154532.032.07.77.78.6845843820AUG 18(LIFT)092430.830.84.84.78.7840843797775AUG 17(SET)154032.032.07.77.78.6848851819AUG 18(LIFT)092030.830.84.84.78.7840843799AUG 17(SET)155532.0808AUG 18(LIFT)095030.8799AUG 17(SET)155032.0812AUG 18(LIFT)094030.87.78.68415.18.78387.78.68405.1-u8.7 i ,..0 -838 K) 3co'Top number represents subsurface readings taken 0.5 meter below the surface.Bottom number represent deep water readings taken 0.5 meter off the bottom.

RS-14-138 Enclosure Page 128 of 322APPENDIX BHISTORICAL WATER QUALITY AND FISHERIES DATA RS-14-138 Enclosure Page 129 of 322LIST OF TABLESReport No. Title Page No.B-1 Results of Initial Braidwood Cooling Pond Survey by SEA Inc.,2001. B-1B-2 Investigation of Fish Kill on Braidwood Cooling Pond August27-28, 2001. B-5B-3 Results of Braidwood Cooling Pond Water Quality Analysisfrom August 27 and 28, 2002. B-9B-4 Fish Kill Reports going back to 2003. B-17B-5 Braidwood Lake Fish Kill, August 21, 2007. B-19B-6 Braidwood Fish Kill August 21, 2007. B-21B-7 Braidwood Fish Kill Clean-up August 21, 2007. B-22HDR Engineering, Inc.

RS-14-283 Enclosure Page 4 of 9APPENDIX REPORT B-I.Results of Initial Braidwood Cooling Pond Survey by SEA Inc.SEA Inc. was asked to conduct an initial water quality and ecological assessment of Braidwood Cooling Pond. The objective was to determine if the densemacrophytes were contributing to an increasing trend toward a higher pH in thepond. The results and discussion presented in this report are primarily basedupon the samples taken and observations made on May 29 and 30, 2001, and ona preliminary review of water quality data from three sites taken on May 18, andJune 14, 2001. SEA Inc. was also asked to investigate a fish kill on Braidwood Cooling Pond on August 27 and 28. The results of that investigation are in aseparate report but some of that information is referenced in this report.Overview of Methods and Results Presentation.

SEA's initial survey (May 29-30) consisted of:" water quality parameters at several key sites with a Hydrolab Surveyor III,during both daylight and night conditions,

• measuring phytoplankton community respiration (light & dark bottle method)," identification of macrophytes and observations on their distribution andabundance, and" monitoring temperatures throughout the cooling loop.The survey results are summarized in Tables 1,2, 3, and 4. Table 1 provides theresults from key sampling sites that were selected to characterize the coolingpond. These sites were sampled three to four times over a 36-hour period.Parameters sampled with the Hydrolab included:

Depth, Temperature, Dissolved Oxygen (D.O.), pH, Specific Conductance, and Redox Potential.

Sample timesincluded midday, just before sunset, and prior to sunrise.Table 2. includes results from two sites for depth profiles, 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration light& dark bottles, and the SX discharge.

Table 3. provides D.O. and temperatures sequentially around the cooling loop at midday. Table 4. lists the D.O. levels and% saturation at four sites prior to sunrise.

Table 5 list the water quality analysispreformed by Test America at three locations on two dates. Figure 1. is a mapidentifying the sample locations listed in the tables.Discussion of Results and Observations:

Braidwood Cooling Pond was characterized to SEA Inc. as a pond that wasdominated or choked by macrophytes.

Based on this characterization, we feelthat Braidwood Cooling Pond has undergone a transformation to a systemdominated by phytoplankton.

Although we were not prepared to sample thephytoplankton for densities and identification, it was very obvious that anB-1 RS-14-138 Enclosure Page 131 of 322intensive phytoplankton bloom was in progress.

Secchi disc readings were only0.30 to 0.35 m throughout the pond. Although we were unable sample thephytoplankton, we would suspect it is dominated by Blue-Green algae(Cyanophyta),

based on the water temperatures, total phosphorous levels, highpH and apparent high densities.

Braidwood Cooling Pond appears to be a very dynamic system that receivesenergy subsidies in the form of heat, pumped circulation and make-up water fromthe Kankakee River. Several perched cooling ponds in the Midwest have hadhigh macrophyte densities in their earlier years but usually become dominated byphytoplankton if they have heavy thermal loading.

A switch to phytoplankton dominance is usually accompanied by a reduction in water transparency.

OurSecchi disc readings were about 0.3 m which is about one half of the 2 ft or0.6m)value listed in a privately produced fishing guide (Sportsman' Connection) published in 2000. Although we did not examine many of the isolated coves, wefound Milfoil ( Myriophyllum verticillatum) only in the last 1/3 of the cooling loop(Figure 1. sites7,8,9) and its abundance was spotty. The Sportsman' Connection fishing guide map had a much wider distribution of submerged, emergent andfloating vegetation and appeared to be more in line with earlier descriptions SEAInc. were given of Braidwood.

Nutrients that were previously tied up by themacrophytes are now likely being taken up by the phytoplankton.

The reducedwater transparency due to the phytoplankton bloom will limit light to thesubmerged macrophytes and likely cause further reductions.

The intensive phytoplankton bloom that Braidwood is currently experiencing mayhave more potential for adverse impacts to the biological community than onoperational impacts to the station.

The water seems to be fairly well buffered anddiurnal swings in pH were insignificant.

Analysis of the water for alkalinity couldconfirm the buffering capacity.

Blue-Green algae blooms may present problemswith D.O. levels and in some rare cases may release toxins with impact otheraquatic life.The light & dark bottle (Table 2.) and the pre-sunrise D. 0. levels (Table 4.)illustrated the intensity of the bloom. The light and dark bottles were at a 0.5 mdepth at end of the discharge canal for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Respiration in the dark bottleddepleted the initial D.O. from 10.8 mg/I (158% saturation) to 1.37 mg/I (20 %saturation).

The light bottle was supersaturated to the point the entire insidesurface was coated with oxygen bubbles and the D.O. was 11.8 (174%saturation).

The photosynthetic rate was much higher than could be measureddue to the extensive formation of oxygen bubbles in the light bottle. Thephotosynthetic rate was so high that the light bottle should have been limited to 6hours to obtain a better measurement of the gross plankton photosynthetic rate.The pre-sunrise D.O. measurements (Table 4.) also reflect the high respiration j:]rate of the plankton community.

Most notable was Site #3 where D.O. levelsdropped to 4.1 mg/I. The midday sampling on the first day (Table 1.) wasconducted during bright and sunny conditions and D.O. levels at most sites werehigher than midday samples on the following day when it was overcast.

ThisB-2 RS-14-138 Enclosure Page 132 of 322plankton community is so productive that D.O. levels can be expected to swingrapidly.

During our survey, air temperatures were mild (high 65 F) and it waswindy both days. Under a scenario of several hot summer days, with little wind,full operation of the station, followed by a cloudy day, D.O. levels could drop tothe point that fish kills could occur. Some fish species will be already stressed byheat, saturation levels for D.O. will be lower, and high, predawn respiration ratescould create a significant problem.

Unfortunately, there are no operational changes the station can make to reduce this risk. The fish kill that did occur inlate August was apparently a result of depleted DO that most likely resulted fromthe phytoplankton bloom die off.Thermal refuges are critical to the survival of fish in heavily loaded cooling ponds.The deeper areas in the warmer end of the lake will not be refuges sinceadequate levels of oxygen are already absent from depths below 4 meters (Table2.). However, the flow and slightly cooler temperatures at site 7 (figurel.)

havemaintained oxygen levels down to nearly 10 meters. If these refuges are erodedaway during the summer, fishes will be stressed.

Of the three key species listedin the Sportsman's Connection for Braidwood, both the walleye and crappiewould be sensitive to D.O. at higher temperatures.

Two fish kills occurred inBraidwood this summer, the first in late July was likely related to temperature, thesecond in lake August resulted from DO depletion.

Although our expertise is not in water chemistry, Braidwood Cooling Pond maybe facing some water quality issues. One of the objectives of the survey was todetermine if macrophytes were contributing to the increasing pH. A chart of pHvalues from 1989 to 1998 provided by the Braidwood Station indicated theincreasing trend in pH has become more pronounced since 1997. Since thissurvey indicated macrophytes abundance was in a sharp decline, it is clear theyare not contributing to the elevated pH of 9.1 to 9.2 (Table 1). The intensive phytoplankton boom present during the survey could have contributed to theelevated pH. The phytoplankton bloom had crashed by August 27 and 28 (fish killinvestigation) and the pH had dropped to 8.6. It was not possible from this limiteddata to determine to what extent several factors may be contributing to theelevated pH. The cooling pond's buffering

capacity, photosynthetic

activity, blowndown rate, and plant operations are all potential factors to be investigated.

The Test America analytical results from three sites on 5/18/01 and 6/14/01provides some information on water quality (Table 5). Orthro phosphate is areadily available form for plants and is quickly taken up. The detection limit listedby the lab was 0.06 ppm, which was too high to show any differences betweensites or sample dates. Orthro phosphate levels in many Illinois lakes would bebelow 0.025 ppm. Total phosphate at the plant discharge on 5/18/01 was 5.5ppm, which is very high. The Illinois General Use Water Quality standard is not toexceed 0.05 ppm in lakes or reservoirs over 20 acres. The plant appears to bethe phosphate source and one possible explanation may be scale inhibitors commonly used by power plants. Scale inhibitors are typically high in phosphates but it is generally in a form not available to aquatic plants. Total phosphate levelson 6/14/01 were lower (0.18 to 0.28 ppm) but still elevated relative to other lakes.B-3 RS-14-138 Enclosure Page 133 of 322Phosphates are a major concern as elevated levels can contribute to nuisancephytoplankton blooms.Total Suspended Solids (TSS) on 5/18/01 were high (164 ppm) at the discharge and generally higher than expected throughout the pond. It is suspected that theplankton bloom may have been responsible for much of that elevation.

This couldhave been confirmed by comparing the volatile to the non-volatile portion of theTSS.Total Dissolved Substances (TDS), total hardness,

calcium, sulfates and specificconductance are all correlated and generally exhibited increases from 5/18/01 to6/14/01.

The high evaporation rates in the cooling pond during the summerprobably contributed to this increase.

These parameters are of concern sincethey are indicators of potential scaling in heat exchangers.

Lowering these levelswould require an increase in make-up and blow-down rates. However it isrecognized there are restrictions on make up withdraws and blow-down concentrations are regulated.

SummaryIt appears that the Braidwood Cooling Pond plant community is changing fromone dominated by macrophytes to phytoplankton.

The phytoplankton bloom inMay was very rich and has the potential to deplete D.O. to the point that fish killscould occur. There are few operational changes that the plant can take to preventthese potential events. Monitoring the cooling pond and preparing regulatory agencies for these potential changes may be a way to help manage these risks.Unfortunately the fish kill in late August confirmed the potential for these kills.The phytoplankton bloom may a contributor to the increasing pH. The high totalphosphate level that appears to be coming from the plant may be fueling thephytoplankton bloom. Further investigation of the factors that may be contributing B-4 RS-14-283 Enclosure Page 5 of 9APPENDIX REPORT B-2.DRAFTInvestigation of Fish Kill on Braidwood Cooling PondAugust 27-28, 2001Executive Summary:Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of anon-going fish kill on Braidwood Cooling Pond on August 27 & 28, 2001. Theinvestigation consisted of surveying the shoreline to determine the extent of thekill and the species involved, and water quality analyses for pH, temperature, anddissolved oxygen.Most of the fish appeared to have been dead for about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than95% were gizzard shad. The other species involved in descending order ofrelative abundance were freshwater drum, quillback, carp, largemouth bass,channel catfish,

redhorse, smallmouth bass and bluegill.

Other than gizzard shadmost of the dead fish were located between the mid -point in the cooling loop tothe intake. Throughout most of the cooling pond, dissolved oxygen levels were ator below the minimum levels necessary to support most fish and was the mostlikely cause of the kill. Water clarity was very high and suggested a recent die offof much of the phytoplankton, which is usually followed by oxygen depletion.

Thisis a natural phenomenon that can occur in highly productive lakes during summermonths. Temperatures throughout most of the lake were within the tolerance limits of the species involved in the kill. It does not appear that operations of thepower station had a direct impact on the fish kill.Methods Overview and Results Presentation:

SEA Inc. arrived at 5:00 PM on August 27 and conducted an initial survey of themain portion of the cooling loop and checked temperature, dissolved oxygen(DO), and pH at two locations.

The investigation continued at sunrise on August28, and included investigation of many of the coves on the lake and water qualityanalyses at sixteen sites. Water quality analysis was conducted with a HydrolabSurveyor Ill. Measurements were for depth, temperature, DO, pH, specificconductance, and redox potential at the surface (0.5 Meters) and then at one-meter intervals to the bottom.The water quality sampling locations are shown on Figure 1. Dissolved oxygenprofiles from selected sites are illustrated in Figure 2. Figure 3 illustrates DOconcentrations at one-meter depth at all sites. The results of the water qualityanalyses are presented in Table 1. The station hourly inlet and outlet watertemperatures for August 24 through August 27 are listed in Table 2.B-5 RS-14-138 Enclosure Page 135 of 322Discussion of Results and Observations:

Upon arrival the investigation began at the south access boat ramp near Site 3(Figure 1.) and proceeded around the cooling loop toward the plant intake. NearSite 3 several gizzard shad in the 170 to 220 mm were observed.

They appearedto have been dead for 12 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In the portion of the pond between sites5.5 and 5.75 there were greater numbers of gizzard shad along the shoreline anda few largemouth bass. The largemouth bass appeared to have been dead formore than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The number of fish appeared to increase as theinvestigation progressed around the cooling loop. The largest concentrations ofdead fish were in several coves on the East side of the lake near Site 8. Theback 20 to 35 ft. of the cover were covered solid with dead fish. Gizzard shadcomprised more than 95% of the fish in these coves and were represented bythree size classes.

The other species involved in descending order of relative dabundance were freshwater drum, quillback, carp, largemouth bass, channelcatfish,

redhorse, smallmouth bass and bluegill.

There are two factors that may have influenced the distribution of dead fish. First,the temperature gradient becomes more favorable for fish toward the intake endof the cooling loop. Second, the circulation of water around the cooping loopwould tend to concentrate dead fish in the intake area of the cooling pond. Theconcentration of fish in coves at Sites 8 and 8.5 was most likely an accumulation resulting the above mention factors and wind direction.

However DO levels atSite 8.5 were only 2 ppm (Table 1, page 3) at a time of day when they shouldhave been much higher. This level of DO is not adequate to support most fishes.Several YOY freshwater drum were observed at the surface which had recentlydied or were about to. This kill did involve many fish, but during this survey manylive fish were observed on sonar in the cooler end on the lake. Bluegills exhibiting normal behaviors were observed in the cove just East of Site 2.5.Dissolved oxygen levels at the plant intake were 3.5 ppm at the surface and 1.2ppm at 3 meters (Table 3) during the evening of August 27. Percent DOsaturation was 49% and 17% respectively.

Surface DO level taken on May 29 bySEA Inc. at this same location, at the same time of day was 9.3 ppm and 117%saturation.

The DO levels at Site 3 were 3.8 ppm on August 27 which was muchlower than the 8.0 ppm taken at sunset on May 29. On August 28 just prior tosunrise the DO at Site 3 was 3.2 ppm only slightly lower than the previousevening indicating little diurnal variation.

On May 29 the overnight drop in DO atSite 3 was 50%.The surface DO level at Site 4 on August 28 was 2.9 ppm and dropped to 0.7ppm at 4 meters. Surface DO levels Sites 4.5, 5, 5.5, and 5.7 were even lowerB-6 RS-14-138 Enclosure Page 136 of 322ranging from 2.4 to 2.1 ppm. Site 6 had one of the higher DO levels at 4.4 ppm.Site 8 and 9 had the highest surface DO levels at 4.8-ppm (Table 1).Temperatures throughout most of the cooling pond were within the tolerance limits of most fish species and there had been no major temperature changes inthe last few days (Table 2). The oxygen levels throughout most of the lakesuggest that depleted oxygen levels were the most likely cause for the fish kill.Such kills can naturally occur in highly productive lakes or ponds that may exhibitlarge diurnal swings in DO levels due to high daytime photosynthetic rates andhigh respiration during the night. The survey SEA Inc. conducted on May 28 and29 suggested Braidwood Cooling Pond was a very productive and the potential existed for an oxygen depletion fish kill. This survey noted several changes in thecooling pond that suggested such a kill had occurred.

There was no indication that the fish kill was directly related to the operation of the power station.SEA Inc.'s initial investigation in May was to assess if the historically highabundance of macrophytes (rooted aquatic vegetation) was contributing anincreasing trend in pH. What was observed was an intensive phytoplankton bloom that limited light penetration and almost no healthy macrophytes remained.

Water transparency measured with a Secchi Disc was only 0.3meters. Diurnal swings in DO levels were very pronounced and at some locations dropped to 4 ppm just prior to sunrise and reached supersaturation levels by midday. Under these conditions any major change in nutrients, reduced lightintensity, increase in biological oxygen demand, or other factors could result inoxygen depletion.

Braidwood Cooling Pond appeared to be undergoing atransition from a system dominated by macrophytes to one dominated byphytoplankton.

One of the most notable changes during this investigation was the dramaticchange in water transparency.

There was no phytoplankton bloom and SecchiDisc readings had increased up to 2.7 meters. Plankton samples indicated verylow levels of phytoplankton but high abundance of zooplanktors (primarily Rotifers and Cladocera).

Oxygen levels were typically from 29% to 66% ofsaturation as opposed to May when most midday levels were at or abovesaturation.

As discussed

earlier, there were only minor differences in diurnaloxygen levels. All the above factors suggest the phytoplankton bloom hadrecently crashed.

There were no remaining macrophytes to fill the niche asprimary producers.

Not only was there a reduction in photosynthetic activity toproduce oxygen, there was an increased oxygen demand from decomposition and respiration of the abundant consumers.

It is suspected that oxygen levels aday or two prior to this investigation may have been even lower than observed.

The one-meter DO levels were lowest toward the center portion of the coolingloop (Figure 2). From Site 3 to Site 6.5 (with the exception of Site 6) DO levelswere 3.1ppm or less. A similar pattern of low DO was noted at Sites 3 and 4 inearly morning samples taken in the May survey. Factors contributing to lower DOB-7 RS-14-138 Enclosure Page 137 of 322levels were not clear, but it suggest this may be one of the most sensitive areasof the cooling pond to oxygen depletion.

Additional sampling would be required toattempt to identify the cause and to eliminate any data bias associated with thetime of day samples were taken.The unique changes in water depths and flow velocities in Braidwood CoolingPond have a major influence on DO levels and temperature stratification.

Areasof the cooling pond which were deep and not in a high velocity areas exhibited amore normal DO curve from top to bottom (Figure 3). At Site 2.5, DO declinedquickly between 6 and 8 meters and coincided with thermal stratification.

At Site4, the DO declined rapidly between 2 and 3 meters where thermal stratification was apparent (Table 1). In contrast, Sites 5.5 and 7 were located in areas withhigh velocities and had fairly consistent DO levels and temperatures from top tobottom (Figure 3). This is quite different from the DO and temperature profiles inmore typical perched cooling ponds and better utilizes the entire volume forcooling and may also provide for better thermal refuges for fish. During this lastincident it is unlikely Site 5.5 was an effective refuge for DO since levels werebelow 2.5 ppm. These DO levels were however due to lower DO levelsthroughout the cooling pond rather than depletion at this site.Braidwood Cooling Pond appears to be undergoing a transition from a ponddominated by marcophytes to one dominated by phytoplankton.

During such atransition major swings may be expected as different components of thisecosystem adapt to this change. Over time one would expect the amplitude ofthese changes to moderate.

During the May survey the intense phytoplankton bloom appeared to eliminate the macrophytes.

There were major differences indiurnal DO levels suggesting a very productive system with heavy respiration anddecomposition demands at night and supersaturation from photosynthesis duringthe day. This survey indicated a major loss of the phytoplankton, no remaining macrophytes to carry on primary production and enough respiration anddecomposition to reduce oxygen below the levels to maintain many fishes. LJAdditional studies on nutrients and the dynamics of the plankton would beneeded to better identify the changes that may be taking place in this coolingpond. Decisions on the operational management of this cooling pond as well asthe fishery management need to consider that this pond may be going throughtransitional changes.:.3!B-8 RS-14-138 Enclosure Page 138 of 322APPENDIX REPORT B-3.Results of Braidwood Cooling Pond Water QualityAnalysis from August 27 & 28, 2002SEA Inc. was asked to sample Braidwood Cooling Pond for a number of waterquality parameters on August 27, 2002. This sampling effort was to provide datato address operational concerns related to a trend toward an increasing pH andincreased scaling at the plant intake. This report provides the results of theAugust 27and 28, 2002 sampling and makes comparisons with data fromprevious sampling efforts by SEA Inc. and with other data provided by theBraidwood Station to SEA Inc.Executive Summary:Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with cooling pond blow down limits, and maintaining arecreational fishery.

Several of these parameters had significant increases in thepast year and could lead to greater operational costs and problems in the nearfuture.The excess of nutrients in the water has contributed to plankton blooms that haveeliminated the submerged aquatic plants, contributed to diurnal increases in pH,and lowered dissolved oxygen levels. Swings in the dissolved oxygen levelassociated with the plankton blooms could lead to fish kills.The plan to increase the blow down rate from the cooling pond is a good long-term solution to the continued viability of the cooling pond. Continued monitoring of the cooling lake water quality would be important in evaluating theeffectiveness of the increased blown down rate, the impacts of H2SO4 additions, and other water treatment changes.Overview of Methods and Scope of the Sampling Effort.The investigation on August 27 and 28 of 2002 consisted of collection of watersamples from various depths at six sites around Braidwood Cooling Pond (BCP),as well as in-situ profile measurements for temperature, conductivity, pH, anddissolved oxygen. A contract laboratory analyzed the water samples for theeleven chemical parameters as listed in Table 1. In addition to chemical samples,the primary production rate of the phytoplankton community was determined attwo sites by the light/dark bottle method, and plankton samples were taken forB-9 RS-14-138 Enclosure Page 139 of 322qualitative analysis.

Water transparency was measured with a Secchi disc ateach site. The sampling sites used in this investigation are identified on Figure 1.Additional investigations by SEA Inc. referenced in this report include June 28,2002, April 29,2002, March 6, 2002, January 10, 2002, August 28, 2001 and May29, 2001. The purpose and scope of each of these investigations varied but nonewere as extensive for water quality as the August 2002 investigation.

In severalcases SEA Inc. collected the water samples for Betz and the results were notmade available to SEA Inc. Data from the above referenced studies is included tohelp identify trends and provide a single summary of data for ongoinginvestigations.

The discussion of results is based on and limited to the studiesreferenced in this report and those provided to SEA Inc.Presentation of Results and Related Discussion:

The analytical results of the water quality analysis are presented in Table 1. Theeleven parameters were selected to provide input to the water quality issues thatwere described to SEA Inc. These issues include increasing trends for rising pH,scaling, algal blooms, and recent fish kills.Table 1 indicates abnormally high levels for TDS, alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus throughout the cooling pond. Thesevalues were not unexpected and support the ongoing program to increase theblow down rate from the cooling pond. These values can be put into perspective by comparing the cooling lake sites to the same values for the make -up waterpond (Site 7P in Table 1), which is the source water. The cooling pond values forthe above mentioned parameters ranged from 2X to nearly 9X higher than themake-up water.The alkalinity is a measure of water's capacity to neutralize acids and is a resultof the quantity of compounds in the water that shift the pH to the alkaline side.Bicarbonate and carbonate ions normally make up most of the alkalinity.

However in waters with a pH of greater than 8.3, carbonate alkalinity is theprimary form. Alkalinity is very high throughout the cooling pond and ranged from340 to 360 mg/I in the upper water layers (Table 1). In contrast, the make-up Awater pond alkalinity was 150mg/I.

Other comparisons include a 14-year averagefor Clinton Lake of 168 mg/I and an IEPA survey of 63 lakes around the statewith alkalinity ranging from 20 to 270 mg/I. The high alkalinity gives Braidwood Cooling Pond has a great capacity to neutralize acids.Hardness is a measure of the divalent metallic cations present in water(such as calcium, magnesium, ferrous iron, and manganous manganese).

Calcium reacts with bicarbonate ions in water to form calcium carbonate B-10 RS-14-138 Enclosure Page 140 of 322scale. Magnesium typically reacts with sulfate; the ferrous ion withnitrate; and the manganous ion with silicates.

Hardness and alkalinity in water are related.

Carbonate hardness is the part oftotal hardness that is chemically equivalent to the bicarbonate plus carbonate alkalinities present in the water. If alkalinity is greater than total hardness thentotal hardness is equal to the carbonate hardness.

In cases such as in BCPwhere alkalinity is less than the total hardness then alkalinity equals carbonate hardness (as CaCO3) and the remaining part of hardness is the noncarbonate compounds such as magnesium sulfate.The total hardness in the upper layers of August 2002 samples ranged from 680to 720 mg/I (nearly twice the alkalinity level) so other ions are contributing significantly to the hardness.

The total hardness levels in 2002 were significantly higher than the 435 to 531mg/I range reported for two dates in 2001 by TestAmerica (Table 2). This increase in hardness is a reason for concern.Sulfate levels in the August 2002 samples ranged from 330 to 390 mg/I (Table 1).These levels are much higher than the make up water (58 mg/I) and to someextent may reflect the history of portions of the cooling pond as strip mine lakesthat are characteristically high in sulfates.

However there seems to be asignificant increase in sulfates in the past year. In the Test America data from twodates in 2001, sulfates ranged from 230 to 270 mg/I (Table 2). Sulfate levels insamples collected by SEA Inc. on April 29, 2002 were 250 mg/I (Table 3).Samples collected by SEA Inc. on June 28,2002 had levels ranging from 320 to340 mg/I (Table 4). The sulfate increase noted in the summer of 2002 may reflectthe use of H2SO4 to reduce pH levels in the cooling pond. This level of sulfatesmay be a concern since it significantly contributes to the non-carbonate hardnessand can be a factor in scaling.Calcium levels in the August 2002 samples were about twice the levels in2001and ranged from 130 to 140 mg/I (Table 1). The 2001 Test America dataranged from 41 to 58 mg/I (Table 2) and the make-up water in August 2002 was57 mg/l. The increase in calcium may be a major concern since with the highcarbonate alkalinity there is a high potential for scaling.Magnesium levels in the August 2002 sampling ranged from 84 to 93 mg/I. Theselevels were essentially the same as the 81 to 91 mg/I reported by Test America in2001. Magnesium levels are however elevated compared to the make-up waterthat had only 20mg/I or when compared to the 14-year average for Clinton Lakeof 32.2 mg/I. Magnesium levels are also a concern due to their potential forscaling.Total dissolved solids include all of the above parameters and other dissolved solids in the water. As would be expected, the August 2002 samples are elevatedand are higher than the previous year. The August 2002 TDS ranged from 930 toB-1 I RS-14-138 Enclosure Page 141 of 3221100 mg/I (Table 1) compared to a range of 684 to 788 in the 2001 Test Americadata (Table 2). The make-up water was 280 mg/I in the August 2002 sample.Sodium levels in the August 2002 samples ranged from 60 to 64 mg/I in theupper water layers. Comparable data from 2001 was not available, but thesodium levels in the make-up water was 9.1 mg/I in the August 2002 sample(Table 1).There were only minor variations in the concentrations of the above parameters from site to site in the upper water layers. Sulfates and TDS were slightly higherat the discharge (Site 2) end of the cooling pond. Levels for alkalinity,

sulfates, TDS, and total hardness were slightly lower near the bottom at the 10 and 11-meter depths at Site 4 and Site 7 respectively.

Phosphorus and nitrogen are essential nutrients for aquatic plants.Concentrations in the water are typically low since phytoplankton or macrophytes quickly assimilate these nutrients.

Total phosphate levels in the August 2002samples were at 1.5 mg/I throughout the cooling pond (Tablel).

Samplescollected on April 2002 ranged from 1.3 to 1.6 mg/I (Table 3). Total phosphates at two sites in the June 2002 samples were 1.8 mg/I (Table 4) in the upper waterlayers and 4.9 mg/I at a well stratified, 10-meter depth at Site 4. The TestAmerica data for 2001 had total phosphate levels from 0.16 to 5.5 mg/I (Table 2).The 5.5 mg/I occurred at the discharge on May 18 of 2001 and levels dropped to0.77mg/I at the plant intake on the same date. This suggests the Station was thesource of the phosphate.

Although the levels were slightly lower in 2002, theywere consistent throughout the cooling pond suggesting that phosphates are inexcess and not a limiting factor for phytoplankton.

The total phosphate levels in Uthe make- up water were 0.12 mg/I and 0.19mg/I in June (Table 4) and August of2002 respectively.

Relative to most lakes the phosphate level in BCP is quite high. Since BCP is acooling pond and not a lake, it is not subject to the Section 302.205 regulation that limits phosphorus in a lake of 20 acres or more to < 0.05mg/I.

The highphosphate level is of concern since these levels support phytoplankton bloomsand the breakdown of the phosphorus compounds can also contribute toincreased pH.Ortho-phosphate is the form that is most readily available to aquatic plants.These levels are usually very low in lakes since plants normally take it up withinminutes.

Ortho-phosphate levels were consistent throughout the lake in theAugust 2002 samples and ranged from 0.38 to 0.44mg/l.

Like the total phosphate levels, the ortho-phosphate levels are consistently high suggesting it is in excess of the needs of the phytoplankton.

The August 2002 levels were significantly higher than the <0.06mg/I reported by Test America in 2001 (Table 2). Ortho-phosphate level in the make-up water was 0.19 and although lower than the lakelevels is relatively high.B- 12 RS-14-138 Enclosure Page 142 of 322Nitrate-nitrites are the other essential or potentially limiting nutrient forphytoplankton.

The August 2002 nitrate-nitrate levels were rather low in most ofBCP with the highest level of 0.1mg/I at the discharge.

The rest of the coolingpond ranged for <0.01mg/I (below detection limit) to 0.08 mg/I in the upperwaters. Unlike most other parameters, the nitrate-nitrite level in the make-upwater was significantly higher at 2 mg/I (Table 1). Nitrate-nitrite data could not becompared to the 2001 Test America data because the detection limit of 1.0 mg/Iwas too high for a meaningful assessment.

The ratios of phosphates to nitrates-nitrites suggest BCP would be described asa nitrate-nitrites limited water rather than phosphate limited with respect tophytoplankton growth. However the limited phytoplankton data that SEA Inc. hascollected on BCP suggests that bluegreen algae dominate BCP for much of thesummer. Bluegreen algae have the unique ability to utilize atmospheric nitrogenand are not as limited by low nitrate-nitrite levels. Bluegreen algae made up 88.5% and 76.4% of the algae at Sites 3 and 7 respectively in the August 2002sample. The dominant bluegreen algae were Lynabya and Oscillatoria.

Bluegreen algae are the least desirable algae and are favored by high pH andwarmer temperatures.

Bluegreen blooms can impart a smell or taste to water,deplete dissolved oxygen, and in some cases generate toxins that may impactaquatic life.The ammonia levels appear reasonable relative to the high productivity in BCP.As productivity increases and oxygen is reduced at deeper depths there may beincreases in ammonia.

The abnormally high level at 5 meters at Site 9 (Table 1may have resulted from the water sampler disturbing the bottom sediments where ammonia is likely to be higher.The aquatic plant community in BCP appears to have undergone a change in thelast two years. SEA Inc.'s first investigation of BCP on May 29, 2001 was toassess the impact of the extensive growth of macrophytes (rooted aquatic plants)on the pond's increasing pH. That investigation found an extensive phytoplankton bloom and the few macrophytes that remained were being shaded out by thephytoplankton bloom. SEA Inc. projected that BCP was changing from amacrophyte dominated water to a phytoplankton-dominated water and that wouldsee more plankton blooms. The phosphate levels from the 2001 Test Americadata suggested there was an excess of phosphorus to support those blooms.Based upon SEA Inc.'s 2002 observations, BCP has transformed into aphytoplankton dominated water and is experiencing regular plankton blooms.This change not only reflects an increasing load of nutrients in BCP but alsocreates a higher risk to the fishery.

As plankton blooms come and go they cancreate oxygen depletion problems that impact fishes and other aquatic life.SEA Inc. has measured the primary production rates as an index to the activity ofthe plankton community.

The rate of oxygen production by the planktonB-13 RS-14-138 Enclosure Page 143 of 322community is measured in a light (clear) bottle and the plankton respiration (oxygen depletion) is measured in a dark bottle. In the first measurement in Mayof 2001, there was so much oxygen production in the normal 24 hr measurement period that the oxygen was super saturated and only a portion could bemeasured (Table 5). Subsequent measurements were limited to shorter timeperiods and provided a more useful index. The highest primary production ratewas 1.525 mg/I of 02/hr at Site 9 (Intake) on June 28, 2002. This correlated wellwith the highest chlorophyll a level provided by the Braidwood Station (Figure 2).In the August 2002 measurement, the rate at Site 9 had dropped to 0.653 mg/I of02/hr. This rate correlated with lower chlorophyll levels that occurred throughout most of August. Temperatures during the August 28,2002 measurements werehigh enough at the discharge (Site 2) to suppress photosynthetic activity.

Thetemperature at the discharge was 115.10 F (Table 5) and the intake (Site 9)temperature was 92.20F and the corresponding production rates were 0.142 and0.653 mg/I of 02/hr respectively.

The temperature suppression of photosynthesis and an apparent die off of a phytoplankton bloom may account for the lowdissolved oxygen levels observed during the August 2002 sampling.

All of sampling by SEA Inc. has involved in-situ sampling with a HydroLab fortemperature, dissolved oxygen, pH, and specific conductivity.

The data from all2002 HydroLab sampling is presented in Tables 1,3,4,6, and 7.The dissolved oxygen (DO) levels on August 28 of 2002 were notably lower thanthe same date in 2001 (Table 6). As lakes undergo eutrophication andproductivity increases, the DO level can exhibit wide diurnal changes that maystress aquatic life. Afternoon DO levels may rise to supersaturated levels, butduring the night and early morning hours respiration demands may nearlydeplete the DO and can result in fish kills. There also becomes a morepronounced difference in DO levels between the upper and lower layers of thewater column due to increased oxygen demand from decomposition.

Dissolved oxygen levels at the same four sites in August 2001 and 2002 arecompared in Figure 3. These comparisons indicate that the DO levels were ]generally lower at the same sites in 2002, were slower to rise during the day, andthere was a greater differences between depths. Site 2 and Site 2.5 illustrate thelower DO levels in 2002 even later in the day when it should rise. Oxygen levels ]were less than 1 ppm at 2 meters and below. Site 4, 2002 levels reflect theincrease in DO later in the day compared to earlier in the day in 2001. Theconsistent drop in DO at 4 meters is typical of a stratified site. At Site 7 the higherDO in 2002 reflect the later time of day than the 2001 sample. However the moresignificant difference is the drop in DO with increasing depth in 2002. This dropsuggests a more productive system that has a higher demand for oxygen in2002. Site 7 has good flow and in 2001 had a nearly constant DO level down tothe bottom and provided a good thermal refuge for fish. In 2002 the area below 6meters would be stressful for most fish. The Site 9 AM chart again demonstrates 3the 2002 DO level was lower even when taken later in the morning than the 2001B-14 RS-14-138 Enclosure Page 144 of 322sample. The Site 9 PM chart shows some recovery of DO level in the midafternoon but levels are still below 4ppm. The more rapid drop in deeper samplesfrom the 2001 most likely reflects the loss of late afternoon light to the deeperdepths.The 2002 DO curves appear to reflect a more eutrophic environment that mayplace additional oxygen stress on the fishery.

During the August 2002 samplingthere were dead and dying gizzard shad from Site 2 to Site 4. The combinations of stress from the low DO and warmer temperatures were the most likelyexplanation for the loss of these fish. This loss was not extensive enough to havea significant impact on the fishery.

No other species were involved in the kill butsmall bluegills were exhibiting some signs of DO stress. As BCP continues tobecome more eutrophic the DO stress may be a greater problem for the fishery.The increasing pH levels have been a concern in BCP. Comparison of HydroLabdata from August 28 in 2001 (Table 6) and 2002 (Table 1) indicated only a littlevariation in pH. During the summer of 2002 the Station was adding H2SO4 intothe circulating water. The impact was only apparent at Site 2 (discharge canal)and Site 3. The 2002 samples collected in the morning hours at Site 2 rangedfrom 8.34 to 8.38 compared to 8.5 in 2001 (Table 2). At Site 3 the 2002 levelsranged from 8.35 in the morning to 8.54 at midday compared to a range of 8.4 to8.6 in 2001. The pH levels at Sites 4,7 and 9 had slight variations depending upon time of day but had similar ranges in 2001 and 2002. With the highalkalinity levels in BCP, it is not surprising that the addition of H2SO4 did notresult in larger changes.

This assessment is also based on only a few datapoints. Correlating H2SO4 feed rates with continuous pH monitoring at the intakewould provide more reliable information on the effects of the acid additions.

Questions have been raised on the impact of the phytoplankton on the increasing pH levels. As phytoplankton carries on photosynthesis and extract C02 from thewater it increases the pH. This however may not be as apparent in BCP due tothe high buffering capacity (alkalinity).

In general the higher pH levels in theafternoon reflect the photosynthetic activity.

Conversely the lower pH levels in theearly morning samples reflect the increase in C02 resulting from respiration during the night. The role of phytoplankton in increasing pH is quantified in themeasurement of primary productivity.

A comparison of the starting pH with theending pH in the light bottles illustrates the change due to photosynthesis.

ThepH during the 24-hour measurement on May 29, 2001at Site 2 went from 9.22 to9.52 (Table 5).Summary and

Conclusions:

Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with blow down limits, and maintaining a recreational B-15 RS-14-138 Enclosure Page 145 of 322fishery.

The additional of treatment chemicals and evaporative loss of therecycled cooling water with limited blown down rates are most likely the primaryfactor in the increased levels of these parameters.

The make-up water does nothave elevated levels of the above-mentioned parameters.

With increasing capacity factors and increasing concentrations for these parameters in thecooling water, water treatment costs and operational concerns are likely toincrease.

Baseline water quality data is important in evaluating options and solutions toaddress water quality in the cooling pond. The comparison of the August 2002sampling to the 2001 Test America data indicated significant increases in totalhardness,

sulfates, and calcium in the past year. Increases of this magnitude canbe important predictors of future problems.

Critical assessments of the impact ofH2SO4 additions and other treatment changes are dependent upon havingpretreatment and post treatment data. The plan to increase the blow down ratefrom BCP is a good long-term solution to the continued viability of the coolingpond. The effectiveness of increasing the blown down rate from BCP can bequantified by continued monitoring of the cooling lake concentrations.

UThe high nutrient levels in BCP will continue to cause plankton blooms. Unlikemany waters, phosphates appear to be in excess and nitrates are more of alimiting factor. However, bluegreen algae appear to be the dominant summer tiform and are not as limited by low nitrates as other algae. The primary production measurements did correlate fairly well with chlorophyll a levels and were a goodindex to the productivity of BCP. The primary production measurements alsoillustrated how much of an influence phytoplankton have on diurnal increases inpH.Algal blooms are occurring in the pond and based on two comparable samplings, appear to be influencing the DO levels. The DO levels in the early hours weregenerally lower in 2002 than in 2001 and the DO at a deep site experienced adecline with depth that did not occur in 2001. These changes suggest a trendtoward an increasing rate of eutrophication.

If nutrient levels continue to increasethe potential for fish kills associated with oxygen depletion resulting from theblooms would also increase.

Jim SmithsonSEA Inc.11/04/02BB- 16]

Fish Kill Reports Going Back to 2003 Page 1 of 2APPENDIX REPORT B-4. RS-14-138 Enclosure Page 146 of 322Fish Kill Reports Going Back to 2003john.petro@exeloncorp.com

[john.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:42 PMTo: Jeremiah.Haas@exeloncorp.com 2003There were no fish kills in Braidwood Lake in 2003.&3-. 004Investigated a fish mortality on July 30, 2094. Most fish were in the advancedstate 0f clecay by the timthe kill was investigated.

Gizzard shad were the dominant species involved although channel catfish wereobseryed_

as well. D uri-ng this investigation, the shallow water near shore was teaming with plankton whichunder magnif icatioon-proved to be daphnia as well as Cypris, which is an Ostacod resembling a small clam.Temperature/dissolved oxygen profi!es were conducted in early October.

Water temperature just north ofthe south boat access was 29.2--9c/84.5--F at a of one foot with a dissolved oxygenl.lreglqan.,'of-3.8 pprnla.pH of 8.03 and a secchi disk readingolf 2? feet. Readings were somewhat improved in the area nearthe rearing cove. In a location several hundred feet..from the lake make-up, more favorable dissolved oMegln levels were found. At one foota waterltelmprature of 26.5 0C/79.7 OF with a dissolved oxygenreading o_ 7.6 anld a_..H.-f 1847 were observed.

Water temperature showed minimal decrease to 40 feetwhile the dissolved o x;ygen decllined to 5.3.ppm.June 28. 2005 Fish KillAn on the water inspection of a thermal fish kill was conducted on June 28, 2005. No formal counts weremade however field assessments indicate a fairly significant kill that involved a variety of species including (in no specific order) gizzard shad, threadfin shad, common carp, channel catfish, quillback carpsucker, black bass. Gizzard shad were the most numerous species effected by this kill and fish carcases wereobserved at most all areas of the lake that were checked.August 27--282007.Fish KillRob Miller, IDNR investigated a thermal kill on August 27 and 28, 2007 and conducted temperature/dissolved oxygen evaluations.

The majority of the dead fish which were observed were largegizzard shad and threadf in shad up to 5 inches in length. Channel catfish were also prevalent.

Only a fewcommon carp and black bass were observed and no bluegills were noted. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in close proximity of the boat ramp and thebank fishing area. The number of dead fish observed decreased towards the south (hot) side of the lake.At a point several hundred yards from the south ramp surface water temperature was 35.3 C/95.9 F anddissolved oxygen was near 3ppm.The following are data which were collected at the north ramp at the time the fish kill was beingB-17https://hdrwebmail.hdrinc.com/owa/?ae=Item&t=IPM.Note&id=RgAAAACN0xuwhEe8R...

12/8/2009

.,,, tb uoing 13ack to 2003 s_ ge 2 of 2Enclosure Page 147 of 322investigated:

Time Temperature (0C) Dissolved Oxygen (ppm)12:10 30.3 3.114:25 33.1 5.415:30 33.5 6.716:58 33.9 5.9Investigation of Fish Kill on Braidwood Po l(ugulSt.2_7-8...l 2007)Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of an on-going fish kill onBraidwood Cooling Pond on August 27 & 28, 2007. The investigation consisted of surveying the shoreline todetermine the extent of the kill and the species involved, and water quality analyses for pH, temperature, and dissolved oxygen.Most of the fish appeared to have been dead for about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than 95% were gizzardshad. The other species involved in descending order of relative abundance were freshwater drum,quillback, carp, largemouth bass, channel catfish,

redhorse, smallmouth bass and bluegill.

Other thangizzard shad most of the dead fish were located between the mid -point in the cooling loop to the intake.Throughout most of the cooling pond, dissolved oxygen levels were at or below the minimum levelsnecessary to support most fish and was the most likely cause of the kill. Water clarity was very high andsuggested a recent die off of much of the phytoplankton, which is usually followed by oxygen depletion.

This is a natural phenomenon that can occur in highly productive lakes during summer months.Temperatures throughout most of the lake were within the tolerance limits of the species involved in thekill. It does not appear that operations of the power station had a direct impact on the fish kill.BB-18https://hdrwebmail

.hdrinc .com/owai"'ae=ltem&t1l PM .Note&id=RgAAA ACNOX. LIN\ 1 FefR P I~I/(I~I -) /0 /-) nnn FW: Braidwood Lake Fish Kill Page 1 of 2RS-14-138 Enclosure APPENDIX REPORT B-5. Page 148 of 322FW: Braidwood Lake Fish Killjohn.petro@exeloncorp.com

[john.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:31 PMTo: Jeremiah.Haas@exeloncorp.com

---

Original Message -----From: ROB MILLER [mLailto:ROB.MILLER(_IIlingis.oyv]

Sent: Tuesday, August 21,2007 8:26 PMTo: JOE FERENCAK; STEVE PALLOCc: Petro, John R.; CHRIS MCCLOUD; LARRY DUNHAM; MIKE CONLIN

Subject:

Re: Braidwood Lake Fish KillI was contacted by John Petro and Tim Meents (Braidwood Station) thismorning at 11:20 but due to bad accident on 1-55 was somewhat delayed inarriving at the lake. When I got there (3:00) 1 met with Exelonbiologist Jeremiah Haas. Jeremiah had arrived earlier and had takendissolved oxygen/temperature readings.

He and I toured the lake via hisboat to assess the extent of the kill. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in closeproximity of the boat ramp and the bank fishing area. The number of deadfish we observed decreased as we traveled towards the south (hot) sideof the lake. At a point several hundred yards from the south ramp, wetook a reading and returned to the north ramp to meet up with JohnPetro. At this location water temperature was 35.3C and dissolved oxygenwas near 3ppm. The following are data which were collected at the northramp:Time Temp. (C) Dissolved Oxygen (ppm)12:10 30.3 3.114:25 33.1 5.415:30 33.5 6.716:58 33.9 5.9Based on the declining trend in d.o., it is possible that more fishcould succumb throughout the night.The majority of the dead fish which were observed were large gizzardshad and threadfin shad up to 5 inches. Channel catfish were alsoprevalent.

Only a few common carp and black bass were observed and nobluegills were noted. SET Environmental had arrived at the north rampand were conducting clean-up operations at 5:00. 1 will be attended theAFS Continuing Education course in Monticello tomorrow and thursday.

Ifyou need any further information, or if there are any furtherdevelopments, please contact me at 815/409-2426.

Thanks.RobRob MillerB-19https://hdrwebmail.hdrinc.com/owa/?ae=Item&t=lPM.Note&id=RgAAAACNoOxuLI

ý h l.-c8R...

I " /2009 FW: Braidwood Lake Fish Kill Page 2 of 2RS-14-138 Enclosure Page 149 of 322District Fisheries Biologist Illinois Department of Natural Resources 13608 Fox RoadYorkville, Illinois 60560630/553-6680 rob.miller@illinois.gov

>>> STEVE PALLO 08/21/07 12:10 PM >>>Just got off phone with John Petro, Environmental Manager for Exelon.John wanted to report a moderate gizzard shad kill at Braidwood CoolingLake, and a minor kill of catfish.

Rob Miller, District Fisheries Manager was already notified.

Water temps in the lake had dropped some12F recently, there are no obvious power plant operational changes orpermit exceedances.

Exelon is arranging to have the fish picked up.B-20https://hdrwebmail.hdrinc.coi-/owa/?ae=ltem&t=]PM.Note&id=RgAAAACN~x uwhEe8 R... 12/8/2009 FW: Braidwood Fish Kill 8-21-07Page I of']APPENDIX REPORT B-6. RS-14-138 Enclosure Page 150 of 322FW: Braidwood Fish Kill 8-21-07john.petro@exeloncorp.com

[john.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:28 PMTo: Jeremiah.Haas@exeloncorp.com

---

Original Message----

From: Haas, Jeremiah J.Sent: Tuesday, August 21, 2007 9:02 PMTo: Petro, John R.; Tidmore, Joseph W.; Meents, Timothy P.Cc: Hebeler, Ronald L.; Neels, Vicki I.; Steve Pallo (E-mail);

Haas, Jeremiah J.

Subject:

Braidwood Fish Kill 8-21-07All,Here's the quick and dirty of the incident.

I'll right something more formal in the morning.I arrived at Braidwood Lake at 12:00 and took a dissolved oxygen (DO) reading from the ramp dock which extendsabout 30 feet into the lake. The DO was 3.1 ppm w/ a temp of 30.3 C. Several thousand gizzard and threadfin shadwere floating across most all visible areas of the lake. The currents within the lake were visible with the dead fishmovement.

Also seen were dozens of channel catfish, most of which were adults from 3-15 lbs. Shad ranged from 4 -13 inches with the shorter fish being predominately threadfin and the larger ones being gizzard.

At this time I informedJohn P. of the DO situation and began setting up the boat for additional surveys.

During the entire day, no otherspecies was observed that counted more than 2 individuals.

I took several water readings throughout the afternoon before Rob Miller (IDNR biologist responsible for Braidwood Lake) arrived.

We did a quick boat survey throughout the lake, including the pockets that are not part of the coolingloop. These areas showed the same readings as the rest of the lake. During this time we had a few hours of directsunshine and DO reading rose as high as 6.7 ppm @ 15:30.Rob and I determined that the DO crash was a result of the past several days cloud cover and subsequent die-off ofphytoplankton.

The decay of the phytoplankton would have been sufficient to lower the DO available to the fish duringthe overnight hours. We also observed the DO beginning to lower @ 16:58 (5.9 ppm) and believe that there is anopportunity to see similar results tomorrow and possibly a few more days depending on the weather conditions.

A local newspaper reporter did arrive on site, took photos, and asked questions.

She was familiar with Braidwood Station's Site Communicator and said she would be in contact with them. Rob explained the cycle that was occurring in the lake several times to the reporter.

All in all, I believe that Rob and I are both comfortable with the explanation for the action that occurred to cause thefish kill. This is similar to the "annual" fish kill seen at Braidwood, but the densities were higher than the past fewyears. There is a survey of the lake scheduled for October and, if possible, I will be at the site for that.ExelonJeremiah J HaasPrincipal Aquatic Biologist Quad Cities Nuclear Station309.227.2867 jeremiah.haas@exeloncorp.com B-21https://hdrwebmail.hdrinc.com/owa/?ae=Item&t=IPM.Note&id=RgAAAACNOxuwhEe8R...

12/8/2009 RS-14-138 Enclosure Page 151 of 322APPENDIX REPORT B-7.Braidwood Fish Kill Clean up8122&23107 I worked with SET Environmental to clean up a fish kill.This was a major kill and our clean up efforts were confined to the area nearNorth boat ramp on the intake end of the lake. SET had been working on the killfor one or two days when I was called to provide assistance.

A total of about 24cubic yards of fish were removed in this clean up. The species involved indecreasing order of abundance were: gizzard shad (large fish), channel catfish,bluegill, green sunfish, flathead

catfish, bigmouth

buffalo, quillback andlargemouth bass.I went up in the restricted arm toward the intake and found huge masses of fishin the back of several coves. There were areas 50 to 75 ft by 100 ft of solidfloating mats of fish in these coves. We picked up 12 flathead catfish that wouldhave averaged near 50 lb. each. On the second day when we returned to thesecoves we counted as many large flathead catfish that we had picked up theprevious day. They were in a state of decomposition that prevented up frompicking them up.We did not take any water quality measurements or examine other parts of thelake in this clean up effort. From my past work on this cooling pond, I wouldsuspect a combination of DO depletion and high water temperatures caused thisfish kill. The plant did not report any abnormal operation conditions prior to thekill. Since 2001 when we first worked on this cooling pond we have seen a switchfrom macrophytes to phytoplankton with blue green dominating.

We havemeasured wide diurnal swings in DO levels even in the upper part of the watercolumn in late summers.

Even with the strong circulation from the circulating water pumps there is mid summer stratification and DO depletion in the deeperareas.Jim SmithsonSEA Inc.B-22 RS-14-138 Enclosure Page 152 of 322RAI #: AQ-12b Category:

Aquatic Resources Statement of Question:

Section 2.2.5, Page 2-16 of the ER states that "HDR [HDR Engineering]

assessed water qualityand fish populations in the cooling pond in late summer 2009 and 2010 to develop a betterunderstanding of the factors contributing to fish kills and design a water quality or fishmonitoring program that could be used to predict (and conceivably mitigate) fish kills in thepond."b. Has Exelon designed a water quality or fish monitoring program for the cooling pond, asmentioned in the ER? If so, provide a brief description of the program and anyassociated monitoring reports for available data years.Response:

Summer monitoring of fish populations and water quality in the Braidwood cooling pond for thepurpose of developing a better understanding of the factors contributing to fish kills has beenongoing since 2009. Monitoring reports for 2009 and 2010 are attached to the response forRAI # AQ-12a, above. Monitoring reports for 2011 and 2012 are attached to this response.

Based on the annual summer aquatic sampling results since 2009, HDR Engineering has notbeen able identify a practical way to prevent fish kills or reduce their effects in the Braidwood cooling pond. In fact, each annual summer sampling report notes that fish die-offs should beanticipated to occur on a fairly regular basis. Accordingly, HDR has recommended that routinesampling of dissolved oxygen levels be implemented as an indicator of conditions that couldcause fish kills so that plant personnel can better prepare for fish kill events.Consistent with HDR's recommendation, Braidwood has incorporated weekly sampling forchlorophyll a and dissolved oxygen into a plan for managing macrobiological challenges in thecooling pond. The sampling data are reviewed against established criteria to identify abnormalresults at the time of collection.

If chlorophyll a, an indicator of the water's oxygen-producing

capacity, is showing a decreasing trend, the dissolved oxygen sampling frequency may beincreased.

If dissolved oxygen trends indicate potential for a large fish loss to exist (i.e.,dissolved oxygen concentrations are trending below three parts per million),

then plantpersonnel are placed on standby to initiate actions that would mitigate potential adverseoperational effects of a fish kill, should one occur. Such actions could include increasing thespeed of the Lake Screen House traveling screens and/or the frequency with which the trashbasket is dumped to deal with higher numbers of accumulating dead fish.No monitoring reports containing sampling results for chlorophyll a and dissolved oxygen arecreated.

RS-14-138 Enclosure Page 153 of 322List of Attachments Provided:

1. (Exelon Nuclear 2012) Exelon Nuclear.

2012. Braidwood Station -Braidwood LakeAdditional Biological Sampling

Program, 2011. Prepared by HDR Engineering, Inc.Copyright by Exelon Corporation.

2. (Exelon Nuclear 2013) Exelon Nuclear, 2013. Braidwood Station -Braidwood LakeAdditional Biological Sampling

Program, 2012. Prepared by HDR Engineering, Inc.Copyright by Exelon Corporation.

RS-14-138 Enclosure Page 154 of 322Attachment

1. 1 to Response

-- RAI # AQ-12b RS-14-138 Enclosure Page 155 of 322BRAIDWOOD STATIONBRAIDWOOD LAKE ADDITIONAL BIOLOGICAL SAMPLINGPROGRAM, 2011Prepared forEXELON NUCLEARFebruary 2012HDR Engineering, Inc.Environmental Science & Engineering Consultants 10207 Lucas RoadWoodstock, Illinois 60098 RS-14-138 Enclosure Page 156 of 322BRAIDWOOD STATIONBRAIDWOOD LAKE ADDITIONAL BIOLOGICAL SAMPLINGPROGRAM, 2011Prepared forEXELON NUCLEARWarrenville, IllinoisHDR Engineering, Inc.Environmental Science & Engineering Consultants 10207 Lucas RoadWoodstock, Illinois 60098 RS-14-138 Enclosure Page 157 of 322ACKNOWLEDGMENTS The field work and data analysis for this project was conducted by HDR Engineering, Inc.(HDR). Particular appreciation is extended to Rob Miller of the Illinois Department of NaturalResources (IDNR), Jim Smithson of Strategic Environmental

Actions, Inc. (SEA), and John Petroof Exelon Nuclear for providing historical fisheries and water quality data.This report was prepared by HDR and reviewed by Exelon Nuclear.

A special debt of gratitude is owed to the environmental staff at Braidwood Station and in particular Mr. Jeremiah Haas ofExelon Nuclear for his technical assistance, cooperation, and guidance during the preparation ofthis document and the study plan. Mr. Haas's experience and insight has been invaluable and isgreatly appreciated by the authors.icHDR Engineering, Inc.

RS-14-138 Enclosure Page 158 of 322ABSTRACTHDR Engineering, Inc. (HDR) was contacted on March 12, 2009 by Braidwood NuclearGenerating

Station, requesting HDR to design and conduct a fish sampling program at Braidwood Lake. The information gathered during that study was to be used by Exelon to develop aneffective sampling program and set of procedures that could potentially predict fish die-offs in thecooling lake. That same sampling program was conducted again in 2010 and 2011 with onlyminor changes to the original program design.Large die-offs of fish at Braidwood Lake could potentially challenge the integrity of the traveling screens at the Station.

With advanced

warning, the Station could be informed of a potential reportable event; regulatory agencies could be notified in advance; and crews responsible for fishcleanup and disposal could be put on alert to help manage the risk associated with a substantial fish die-off.

Currently, there are no practical or simple methods that can be used to predict orprevent the occurrence of fish die-offs at Braidwood Lake.Sampling has been conducted at Braidwood Lake by the IDNR since 1980. From 1980 through2009 IDNR (Illinois Department of Natural Resources) collected 49 taxa of fish. In comparison, thirty-one taxa representing eight families have been included among the 6873 fish collected byHDR since 2009. Several taxa listed as collected by IDNR from 1980 to 2009 have not beencaptured by HDR. Many of the species listed by IDNR were only rarely captured, have not beencaptured during recent years, or represent taxa that were stocked.

However, five species havebeen captured by HDR that have not been collected during IDNR sampling efforts.

Theyincluded shormose gar, smallmouth

buffalo, bigmouth

buffalo, fathead minnow, and rosyfaceshiner.In 2011, 18 taxa of fish representing six families were included among the 2298 fish captured byelectrofishing, hoop netting, gill netting, and trap netting.,

The relative abundance of speciescollected during the course of these studies is similar to those reported by IDNR in recent years.Braidwood Lake is dominated by warmwater species including gizzard shad, threadfin shad, carp,ii.eHDR Engineering, Inc.

RS-14-138 Enclosure Page 159 of 322channel catfish, flathead

catfish, largemouth bass, bluegill, and spotfin shiner. No threatened orendangered species have been collected by HDR since these studies were initiated in 2009.Water quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection.

Water temperature (0C), dissolved oxygen (ppm), pH, andconductivity (pnihos/cm) measurements were taken 0.5 m below the water surface at eachsampling location.

In addition, water quality was also measured approximately 0.5 m off thebottom at all three of the deep water collection sites (Location GN-I, HN-1, and HN-2).Water temperatures during the early August sampling period were warmer (34.8 to 41.0 QC) thanthose observed during the late August sampling period (30.1 to 35.3QC) in 2011 because of theunusually hot and humid conditions that existed throughout the Midwest during late July and earlyAugust. Diurnal swings in dissolved oxygen (DO) were observed at the lake with DO rangingfrom 3.1 to 13.5 ppm in early August and from 5.6 to 14.0 ppm in late August. Dissolved oxygen readings were typically slightly higher during the second sampling effort in late August.Cursory observations by the field crew indicated that the water color appeared greener during thelate August sampling dates. This suggests that an increase in the phytoplankton population occurred within the lake between the first and second sampling period, which would explain(coupled with slightly cooler water temperatures) the slight increase in oxygen levels noted inBraidwood Lake during late August.Examination of pH data collected during these studies show pH ranged from 8.3 to 8.7 during thefirst sampling effort and from 8.5 to 8.6 during the second sampling effort. Conductivity rangedfrom 928 to 993 anhos/cm in early August and from 988 to 1036/zmhos/cm in late August.Review of historical water quality data reported in 2002 by Strategic Environmental

Actions, Inc.(SEA Inc.) at Braidwood Lake indicates that abnormally high levels of total dissolved solids(TDS), alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus exist throughout the entire cooling loop. This is not unexpected based upon the evaporation that takes place withinthe cooling loop coupled with the relatively low make-up and blow-down flows associated withthe operation of Braidwood Station.

These elevated levels within the lake were measured at twoto nearly eight times higher than those of the make-up water from the Kankakee River. ElevatedfiiiHDR Engineering, Inc.

RS-14-138 Enclosure Page 160 of 322levels of water hardness are of concern to the Station because high levels have the potential toincrease problems associated with scaling at the Station.Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Studies conducted by SEA in 2002 indicated that nutrients within the cooling lake were at levels sufficiently high tocause problems associated with phytoplankton blooms. These blooms result in oxygen production via photosynthesis during daylight and oxygen depletion through respiration during darkness.

When algal populations crash and decompose they can produce severe oxygen depletion withinthe water column. Diurnal swings in oxygen readings have been routinely observed at Braidwood Lake during the past several years. In addition, DO levels of less than 3 ppm have been recordedat the lake immediately following fish die-offs.

Deeper portions of the lake were also reported tostratify in 2002. In the deeper zones of the lake, DO levels approaching 0 ppm and reducedwater temperatures have been measured below the thermocline.

This is noteworthy becausedissolved oxygen levels of 3 ppm and less cannot be tolerated over an extended period of time bymost fish species.

Piper et al. (1983) states that dissolved oxygen levels below 5 ppm will reducegrowth and survival for most species of fish cultured in raceways or ponds. Dissolved oxygenrequirements are dependent upon species and other factors including water temperature andacclimation period.Review of historical fisheries information that was provided to HDR indicated that five separatefish kills were reported from 2001 to 2007. Numerically, the majority of fish observed duringthese events were either gizzard shad or threadfin shad. These two species have typically comprised over 90% to 95% of all fish observed.

Remaining species included carp, freshwater drum, bluegill, channel catfish, flathead

catfish, quillback and largemouth bass. Each of thereported fish die-offs was attributed to oxygen depletion at the lake and not the result of specificStation operations.

HDR Engineering, Inc.

RS-14-138 Enclosure Page 161 of 322TABLE OF CONTENTSPage No.ACKNOWLEDGEMENTS iABSTRACT iiTABLE OF CONTENTS vLIST OF TABLES viLIST OF FIGURES vii1.0 Introduction 1-I2.0 Methods 2-12.1 Electrofishing 2-12.2 Trap Netting 2-32.3 Gill Netting 2-42.4 Hoop Netting 2-42.5 Sample Processing 2-52.6 Water Quality Measurements 2-53.0 Results and Discussion 3-13.1 Species Occurrence 3-13.2 Relative Abundance and CPE 3-43.2.1 Electrofishing 3-43.2.2 Trap Netting 3-93.2.3 Gill Netting 3-113.2.4 Hoop Netting 3-133.3 Length-Frequency Distributions 3-133.4 Physicochemical Data 3-223.5 Historical Information 3-243.5. 1 Water Quality 3-243.5.2 Fish Kills 3-254.0 Summary and Recommendations 4-14.1 Summary 4-14.2 Recommendations 4-35.0 References Cited 5-IVHDR Engineering, Inc.

RS-14-138 Enclosure Page 162 of 322LIST OF TABLESTable No. Title Page No.3.1 Species Occurrence of Fish Collected by the Illinois Department of Natural Resources at Braidwood Lake from 1980 through2009. 3-23-2. Total Number, Weight (g) and Percent Contribution of FishCollected by all Sampling Gears from Braidwood StationCooling Lake During 2011 and 2009 Through 2011. 3-5ý:3-3 Total Catch by Method for Fish Species Collected from theBraidwood Station Cooling Lake, 2011. 3-73-4 Numbers of Fish Captured by Electrofishing at Each SamplingLocation in Braidwood Lake, 2011. 3-83-5 Number of Fish Captured by Trap Netting at Each SamplingLocation in Braidwood Lake, 2011. 3-103-6 Number of Fish Captured by Deep (GN-l) and Shallow Water(GN-2) Gill Nets in Braidwood Lake, 2011. 3-123-7 Number of Fish Captured by Baited and Unbaited Deep andShallow Water Hoop Nets in Braidwood Lake, 2011. 3-14,iHDR Engineering, Inc.

RS-14-138 Enclosure Page 163 of 322LIST OF FIGURESFigure No.CaptionPage No.2-13-13-23-33-43-5Sampling Locations at Braidwood Lake.Length-Frequency Distribution of Bluegill Collected fromBraidwood Lake During August, 2011.Length-Frequency Distribution of Largemouth BassCollected from Braidwood Lake During August, 2011.Length-Frequency Distribution of Channel Catfish Collected from Braidwood Lake During August, 2011.Length-Frequency Distribution of Blue Catfish Collected from Braidwood Lake During August, 2011.Length-Frequency Distribution of Threadfin and GizzardShad Collected from Braidwood Lake During August, 2011.2-23-153-163-173-183-19Vii.HDR Engineering, Inc.

RS-14-138 Enclosure Page 164 of 32

21.0 INTRODUCTION

The Braidwood Lake Fish and Wildlife Areas are comprised of approximately 2640 acres ofterrestrial and aquatic habitat that is located in Will County, Illinois.

Braidwood Lake is ownedby Exelon and is a partially

perched, cooling lake that was constructed in the late 1970s. The lakewas filled during 1980 and 1981 with water pumped from the Kankakee River. Several surfacemined pits existed at the site prior to the filling of the impoundment.

Fisheries management activities began in those surface mine pits in 1978, prior to the creation of Braidwood CoolingLake. Originally the lake was considered a semi-private area used by employees ofCommonwealth Edison Company until the end of 1981 when the Department of Conservation (now the Illinois Department of Natural Resources) acquired a long-term lease agreement fromthe company, which allowed for general public access to the area. Braidwood Lake is currently used for fishing, waterfowl

hunting, and fossil hunting.

From the late 1970's to the present time,Braidwood Lake has been stocked with a variety of warm- and coolwater fish species.

Thesestockings include largemouth and smallmouth bass, blue catfish, striped bass, crappie, walleye,and tiger muskie. Monitoring programs have documented the failure of the coolwater stockings to create a meaningful fishery.

This is attributed to the extreme water temperatures that occurwithin the cooling lake during the warm summer months.Construction of the Braidwood Nuclear Generating Station and its associated riverside intake anddischarge structures provided an opportunity to gather fisheries information from the KankakeeRiver and Braidwood Lake. These studies were initiated to determine the effects of construction and plant operation on the river and the lake. Units I and II began commercial operation on 29July and 17 October, 1988, respectively.

Fisheries surveys at Braidwood Lake were conducted annually by the Illinois Department of Natural Resources (IDNR) from 1980 through 1992. Since1992, fishery surveys have been conducted by IDNR every other year except 1995 and 1996.Fishery surveys on the Kankakee River near the Station's intake have also been conducted annually since the late 1970's by the Illinois Natural History Survey (1977-1979 and 1981-1990),

LMS Engineers (1991-1992 and 1994-2004),

Environmental Research and Technology (1993),HDR/LMS (2005-2007),

and HDR (2008-2011).

1-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 165 of 322The objectives of the 2011 Braidwood Lake Additional Sampling Program were to:I. Conduct fish surveys at Braidwood Lake for comparison with historical data thathas been collected by IDNR and HDR Engineering, Inc.2. Summarize any existing data related to fish kills that have occurred at Braidwood Lake.3. Develop a sampling procedure or protocol that will help anticipate fish die-offs inthe cooling lake that could potentially effect Station operations.

14eKDR Engineering, Inc.

RS-14-138 Enclosure Page 166 of 3222.0 METHODS2.1 Electrofishing Electrofishing was conducted using a boat-mounted boom-type electrofisher utilizing a 5000 watt,230 volt AC, 10 amp, three-phase Model GDP-5000 Multiquip generator equipped with volt/ampmeters and a safety-mat cutoff switch. The electrode array consisted of three pairs of stainless steel cables (1.5 m long, 6.5 mm in diameter) arranged 1.5 m apart and suspended perpendicular to the longitudinal axis of the boat 1.5 m off the bow. Each of the three electrodes was poweredby one of the phases. Electrofishing samples were collected on 4 August during the first samplingeffort and on 31 August and I September during the final survey period (Appendix Table A-1).The first sampling event that was scheduled for late July was rescheduled for the first week ofAugust due to extremely warm air and water temperatures that existed throughout the Midwest.Heat indexes of 110 to 120 'F were recorded during late July. Therefore, sampling was delayeduntil the first week of August to avoid unnecessary stress to the fish, field equipment, and thesampling crew.Eight locations around the dike and islands at Braidwood Lake were electrofished during both thefirst and second sampling periods (Figure 2-1). Electrofishing was conducted near the shoreline at each location to collect fish utilizing shallow water habitats.

Voltage and amperage of theelectrofishing unit was recorded at each location at the beginning and end of each sampling effort,Sampling was restricted to the period of time ranging from one-half hour after sunrise to one-halfhour before sunset. Each electrofishing location was sampled for 20 minutes.

Electrofishing effort was reduced from 30 minutes per sample in 2009 and 2010 to 20 minutes per sample in2011. This reduced the stress and handling mortality of fish associated with the field collection process with minimal impact on the data that was used to evaluate the fish assemblage atBraidwood Lake.The electrofishing crew consisted of two people. One crew member operated the boat while thesecond crew member dipped fish from the bow of the boat. The boat operator also dipped fish2-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 167 of 322FIGURE 2-1. SAMPLING LOCATIONS AT BRAIDWOOD LAKE.2-2 RS-14-138 Enclosure Page 168 of 322whenever necessary.

When fish surfaced behind the boat the boat operator backed up to retrieveall stunned fish. All stunned fish were collected without bias of size or species.Fish at each location were put into barrels of water in the front of the boat for analysis at the endof each 20 minute collection period. All fish were processed in the field immediately following collection at each location.

Special emphasis was placed on the return of all game fish species tothe water as quickly as possible following field analysis.

Catches were standardized to catch-per-effort (CPE) from actual fishing time (20 min/sample) to numbers caught per hour by dividing thetotal numbers of fish collected by the actual fishing time in hours.2.2 Trap NettingTrap nets were set at eight separate locations in Braidwood Lake (Figure 2-1). Each trap netconsisted of a 25-ft. lead that was 4-ft. deep and attached to a series of rectangular frames. Thelast rectangular frame was attached to a hoop net constructed of 1.5-in. (bar) mesh nylon webbingon hoops 3.5 ft in diameter.

Two separate throats were contained within each net. One waslocated in the series of rectangular frames at the front of the net, while the second throat waslocated toward the back of the net inside the 3.5 ft diameter hoop net. Trap nets were set duringlate afternoon or early evening and were allowed to fish overnight for approximately 12 hrsbefore being retrieved the following morning.

Trap nets were set on 1 August and retrieved on 2August during the first sampling period and set on 30 August and retrieved on 31 August duringthe second sampling period (Appendix Table A-2).Fish at each location were put into barrels of water in the front of the boat for analysis at the endof each collection period. All fish were processed in the field immediately following removalfrom the net. Special emphasis was placed on the return of all game fish species to the water asquickly as possible following field analysis.

Catches were standardized to catch-per-effort bydividing the total number of fish caught by the total number of hours the nets were allowed to fish(fish/l 2-hr set).2-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 169 of 3222.3 Gill NettingTwo 125-ft. long and 6-ft. deep monofilament experimental gill nets were used to collect fishfrom two locations in Braidwood Lake (Figure 2-1). Each net consisted of five separate panelsthat were 25-ft long by 6-ft deep. Bar mesh sizes of each panel were 0.5, 0.75, 1.0, 2.0, and 3.0inches, respectively.

One of the two gill nets (GN-1) was set in deep water at a depth ofapproximately 10-13 m, while the second gill net was set in shallow water (GN-2) at a depth ofapproximately 2-3 m. During the first sampling period, the deep water gill net sample (GN-1)and the shallow water gill net sample (GN-2) were set and retrieved during the late afternoon of IAugust. Both nets were allowed to fish for 0.5 hrs before they were retrieved.

During thesecond sampling period, both the deep and shallow water gill net were set and retrieved 15minutes later during the late afternoon of 30 August (Appendix Table A-3). Gill net set timeswere reduced from previous years based on the number of fish that were being captured coupledwith concerns expressed by Illinois Department of Natural Resources.

Elevated watertemperatures in the cooling lake prohibited longer set times due to the high mortality that occurredshortly after the fish became entangled in the monofilament netting.All fish were processed in the field as they were removed from the net. Special emphasis wasplaced on the return of game fish species to the water as quickly as possible.

Catches werestandardized to catch-per-effort (CPE) from actual fishing time the nets were in the water tonumbers caught per hour by dividing the total numbers of fish collected by the actual fishing timein hours.2.4 Hoop NettingHoop nets used to collect fish at Braidwood Lake were constructed of 1.25-in.

(bar) mesh nylonwebbing on hoops 3.5 ft in diameter.

Four separate nets were sampled during each samplingperiod (Figure 2-1). Two of the four nets were set in deep water (7.5 m), while the remaining two nets were set in shallow water (2.0 m). In addition, one of the deep (HN-1) and shallowwater (HN-3) hoop nets were baited with dead gizzard shad, while the remaining deep (HN-2)and shallow water (HN-4) nets were allowed to fish without bait. All four nets during the first2-4HDR Engineering, Inc.

RS-14-138 Enclosure Page 170 of 322sampling period in early August were set during the late afternoon of 1 August and retrieved thefollowing morning on 2 August. During the second sampling period in late August the hoop netswere set during the late afternoon of 30 August and retrieved the following morning on 31 August(Appendix Table A-.4).Captured fish from each net were put into a barrel of water in the front of the boat for analysis atthe end of each collection period. All fish were processed in the field immediately following removal from the net. Special emphasis was placed on the return of all game fish species to thewater as quickly as possible following field analysis.

Catches were standardized to catch-per-effort by dividing the total number of fish caught by the total number of overnight sets conducted (fish/overnight set). Hoop nets were set and retrieved over a 16 to 18 hour2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> period of time duringboth the first and second sampling periods.2.5 Sample Processing All fish were identified to the lowest positive taxonomic level and enumerated.

For each geartype, up to 25 individuals of a species were measured for total length (mm) and weight (g) at eachlocation.

Any remaining individuals of that species were counted and weighed en masse.Minnow species (excluding carp) were counted and weighed en masse. Specimens that could notbe positively identified in the field were either photographed in the field or returned to thelaboratory for identification.

References used to facilitate identification included Pflieger (1975),Smith (1979), and Trautman (1981).2.6 Water Quality Measurements Four physicochemical parameters (temperature, dissolved oxygen [DO], pH, and conductivity) were measured in conjunction with the sampling program.

These data were collected at eachstation prior to each sampling effort. Physicochemical measurements were taken a half meterbelow the water surface at all locations prior to sample collection.

At deeper locations, temperature, conductivity, and DO were measured 0.5 m below the surface and 0.5 m off thebottom. Temperature

('C), dissolved oxygen (ppm), and conductivity were measured2-5HDR Engineering, Inc.

RS-14-138 Enclosure Page 171 of 322using an YSI Model 85 handheld oxygen, conductivity,

salinity, and temperature meter. A Cole-Parmer pH Testerl was used to determine pH. All instruments were calibrated prior to eachmonthly sampling event.2-6HDR Engineering, Inc.

RS-14-138 Enclosure Page 172 of 3223.0 RESULTS AND DISCUSSION 3.1 Species occurrence.

Fish surveys have been conducted at Braidwood Lake by the Illinois Department of NaturalResources (IDNR) since 1980 when the cooling lake was first impounded with water pumpedfrom the Kankakee River. Sampling was conducted annually from 1980-1992, again in 1994, andevery other year from 1997-2011 (Table 3-1). During these 22 years of sampling, 49 taxa of fishhave been collected including 47 species and two hybrids (hybrid sunfish and tiger muskie).Gizzard shad (32.6%),

bluegill (21.7), common carp (18.5%),

largemouth bass (8.7%), andchannel catfish (5.8%) have been the dominate species collected during these surveys.

The totalnumber of taxa collected by the IDNR has ranged from 12 in 1980 to 27 in 1989. Several specieshave been rarely collected or only occasionally observed during this 32 year period. Theseinclude yellow bass, rock bass, redear sunfish, orangespotted

sunfish, tiger muskie, grasspickerel, longnose gar, goldfish, highfin carpsucker, silver redhorse, river redhorse, blackstripe topminnow, emerald shiner, common shiner, striped shiner, redfin shiner, slenderhead darter,johnny darter, bullhead minnow, blue catfish and mosquito fish that were captured for the firsttime in 2009. All of these taxa have been collected in five or fewer of the 22 years of samplingconducted by the IDNR from 1980 through 2009. Sampling was collected by the IDNR in 2011;however, the data had not been tabulated in time for inclusion in this report.The only protected species (one fish collected in 1999) collected during these surveys has beenriver redhorse (Moxostomna carinatuni),

which is currently listed as threatened in Illinois (Illinois Endangered Species Protection Board 2009). River redhorse have been collected from theKankakee River during several years during past sampling programs (HDR 2011). Eighteen ofthe taxa identified by the IDNR have not been captured since 1999.Braidwood Lake has been stocked with a variety of warmwater and coolwater fish species sincethe late 1970's. Some of these species, such as striped bass, tiger muskie, and walleye, have notbeen collected in recent years following the discontinuance of those stocking programs.

Currently, the fish community is dominated by warmwater species that are more tolerant of theelevated water temperatures that exist in the cooling lake during summer months.3-1HDR Engineering, Inc.

TABLE 3-1SPECIES OCCURRENCE OF FISH COLLECTED BY THE ILLINOIS DEPARTMENT OF NATURAL RESOURCES' AT BRAIDWOOD LAKE FROM 1980 THROUGH 20090.SAMPLING YEARSTaxa 80-85 86-90 91 92 94 97 99 01 03 05 07 09 1I b TOTAL %Longnose garThreadfin shadGizzard shadGrass pickerelTiger muskieGoldfishCarpGolden shinerEmerald shinerCommon shinerStriped shinerSpotfin shinerSand shinerRedfin shinerBlunnose minnowBullhead minnowQuillback Highfin carpsucker Silver redhorseGolden redhorseShorthead redhorseRiver redhorseBlack bullheadYellow bullheadBlue catfishChannel catfishFlathead catfish3 135644012 6712 1382 3018 412 925 925 78639II 5 122 3 I I2987 4393 108 227 285 853 385 92988 I I II 3 I 4831 4II 230 122 7701031 872 195 543620 204 405 403II 214I 1245 396 785241I I198 33 1327 249 95975 1016 0. 11697 2.720.813 32.639 0.128 <0 17 <0 I11.799 18.595 0.153 0.135 0114 <0.11572 2.5137 0,2I 165 0.316 :<0.1529 0.82 <0.13 <0. I10 <0.133 0.1I <0. i319 0.575 0.13 <0. 13736 5.818 <0.16 36 49II 5189 183 26 66 20 37257202334 3131946 14 1I3 3I339 318 362 357 463 136 364 866 384 129 228 901 2 10 I I 30=K.) 00-TABLE 3-1 (Continued).

SAMPLING YEARSTaxa 80-85 86-90 91 92 94 97 99 01 03 05 07 09 I lb TOTAL %Blackstripe topminnow MosquitoBrook silversidc Yellow bassStriped bassRock bassGreen sunfishOrangespotted sunfishBluegillLongear sunfishRedear sunfishIlybrid sunfishSmallmouth bassLargemouth bassWhite crappieBlack crappieJohnny darterYellow perchLogperchSlenderhead darterWalleyeFreshwater drum66 <0.123 5 I 12450<0 I0-7150 192I I8 9 13 6 12 509 4 I I 152 I436 36 10I28 23 13 37 139 26 10 77 492 <0.I30 <0. I5 <0. 1864 1-43 <0- I1432 459 698 247 252 241 998 1754 1393 1369 2758 228025 I 7 3 I 5I 3 1355 18 2 I 4 9 13 8 5 7 74 42 24 17 42 17 9 3 5 31834 867 175, 91 337 202 711 351 334 88 263 315107 24 10 2 357 22 6 I 20 2 2 I I2234 24113.8814217129166556814611221-70.1<0.10.20.38,70.20.22 <0.1475 0.7226 0.45 <,50.1130 II 724 16 71 36 2168 22019 1137 88 1i30725505.01414 14 349 I ITotal fishTotal taxaTotal species12.753 14,244 2882 4165 1875 2536 3521 5193 3862 2957 4404 551731 30 26 23 23 20 21 20 17 16 20 2229 28 25 21 22 19 20 19 16 Is 19 2163.909.49.47CDW ,)W.. 63-'Table was reformatted from data provided by: the Illinois Department of Natural Resources.

4Data was collected in 2011 but not tabulated prior to the preparation of this report.

RS-14-138 Enclosure Page 175 of 3223.2 Relative Abundance and CPE.In 2011, 18 taxa representing six families were included among the 2298 fish collected byelectrofishing, trap netting, hoop netting, and gill netting.

Thirty-one taxa representing eightfamilies have been included among the 6873 fish collected by HDR since 2009 (Table 3-2).Several species that were listed as collected by the IDNR during surveys conducted between 1980and 2009 have not been captured by HDR. Each of these taxa were either rarely encountered during previous years, represent taxa that were stocked, or have not been captured during recentyears. However, five species have been captured that have not been collected by IDNR. Theyincluded shortnose gar, bigmouth

buffalo, smallmouth

buffalo, fathead minnow, and rosyfaceshiner. No threatened or endangered species were collected in 2011.Species that numerically dominated the catch in 2011 (all sampling methods combined) includedthreadfin shad at 24.2%, bluegill at 23.5%, channel catfish at 17.8%, carp at 12.6%, spotfinshiner at 5.2%, largemouth bass at 4.6%, and gizzard shad at 4.1% (Table 3-2). All of thesespecies have been commonly collected by the IDNR during recent sampling efforts (Table 3-1).Biomass of fish captured by electrofishing, trap netting, gill netting, and hoop netting wasdominated by carp (56.5%),

channel catfish (28.3%),

flathead catfish (5.0%), largemouth bass(3.4%), bluegill (2.9%), and gizzard shad (1.6%). These results are similar to data collected during previous years and indicate that Braidwood Lake is best suited to support warmwater species.3.2.1 Electrofishing In 2011, electrofishing resulted in the collection of 1480 individuals representing 15 taxa (Table 3-3). The catch was dominated numerically by bluegill, which comprised 33.4% of all fishcaptured, Threadfin shad (29.0%),

spotfin shiner (8.0%), largemouth bass (6.4%), carp (5.4%),gizzard shad (4.5%), longear sunfish (3.6%), channel catfish (3.1%), and bullhead minnow(3.1 %) were the only other species to individually comprise greater than 3 % of the total catch bynumber. The total number of fish collected by location ranged from 407 at Location E-3 to 61 atLocation E- I (Table 3-4). The total number of taxa collected ranged from seven at Location E- 1to 11 at Locations E-3, E6, and E8. The fewest number fish and taxa were collected at LocationE-1 located closest to the Braidwood Station discharge.

In general, more fish and greater3-4HDR Engineering, Inc.

TABLE 3-2TOTAL NUMBER, WEIGHT (g) AND PERCENT CONTRIBUTION OF FISH COLLECTED BY ALL SAMPLING GEARSFROM BRAIDWOOD STATION COOLING LAKE DURING 2011 AND 2009 THROUGH 2011.2011 2009-2011 NUMBER WEIGH NUMBER WEIGHTTAXON No. % (g) % No. % (g) %Threadfin shadGizzard shadShormose garLongnose garCarpCommon shinerStriped shinert.n Rosyface shinerSpotfin shinerSand shinerFathead minnowBlunanose minnowBullhead minnowSmallmouth buffaloBigmouth buffaloYellow bullheadBlue catfishChannel catfishFlathead catfishBrook silverside Sunfish spp.Green sunfishOrangespotted sunfishRedear sunfishBluegill5569524.24.1516611.3470.71.6290 12.6 404.018 56.5119 5.2 336 <0.146 2.0 128 <0.12 0.1 3240 0.595338319671134215464112612453136611177242100321194913.95.6<0.10.19.8<0.10.50.37.90.6<0.13.83.6<0.1<0.I<0.11.00.10.3<0.11.5<0.10.328.4968558,594175026.900979,77717595113146825355666590255013715.830488.89988.750272279329832110.8690.53.10.11.452.2<0.1<0.1<0.10.1<0.1<0.1<0.1<0.10.40.1<0.10.826.14.7<0.1<0.10.1<0.1<0.15.912640931433539<0.11.117.80.1<0.11.90.12.3.5603094202.47236.000<0.10.428.35.0<0.10.1<0.12.91101723120,452CDC.) = -0C TABLE 3-2 (Continued).

2011 2009-2011 NUMBER WEIGHT WEIGHTTAXON No. % (g) % No. % (9) %Longear sunfish 53 2.3 975 0.1 126 1.8 2307 0.1lHybrid sunfish 3 0.1 88 < 0.1 17 0.2 325 < 0.1Smallmoudh bass 5 0.1 3327 0.2Largemoudi bass 105 4.6 24.025 3.4 253 3.7 69.351 3.7Black crappie I < 0.1 147 < 0.1Freshwater drum 4 0.2 -2357 0.3 8 0.1 3430 0.2Totals 2298 71M.007 6873 1.875.513 Total taxa 18 31Total species 16 29'Sampling methods included electrofishing, trap netting, gill netting and hoop netting.01%CD6)

TABLE 3-3TOTAL CATCH BY METHOD FOR FISH SPECIES COLLECTED FROM THE BRAIDWOOD STATION COOLING LAKE, 2011.ELECTROFISHING TRAP NETrING GILL NET1ING HOOP NETTINGTAXON NUMBER WEIGH NUMBER WEIGHT NUMBER WEIGHT NUMBER WEIGHTNo. % (g) % No. % (g) % No. % (g) % No.; % (g) %Threadfin shadGizzard shadCarpSpotfin shinerBullhead minnowSmallmouth buffaloYellow bullhead.-- Blue catfishChannel catfishFlathead catfishIlybrid sunfishSunfish spp..Green sunfishRedear sunfishBluegillLongear sunfishLargernouth bassFreshwater drum:TUotalsTotal laxaTotal species429 29.0 3990 2.066 4.5 3662 1.9 22 4.5 5586 1.280 5.4 123.713 63.4 207 42.0 274.765 57.9119 8.0 336 0.246 3.1 128 0.11 0.1 40 < 0.1 I 0.2 3200 0.71 0.1 60 < 0.11 0.2 663 0.146 3.1 26.084 13.4 227 46.0 158.551 33.42 0.4 21.500 4:5127 46.9 1176 10.96 2.2 1920 17.7"331.9 179 0.55.6 5480 15.625 9.2 2431 22.4113 4L-7 5308 49;023 42.6 12.529 36.51 1.9 14.500 42.23 0.2 88 <0. II 0.1 I <0.143 2.9 1017 0.53 0.2 231 0.1494 33.4 17.061 8.753 3.6 975 0.595 6.4 17.899 9.219 3.9 1730 0.410 2.0 6126 1.34 0.8 2357 0.526 48J.1 16614.814801513195.3454939474.478271A4.410.8355434.349(D0.N CD 0 TABLE 3-4NUMBERS OF FISH CAPTURED BY ELECTROFISHING AT EACH SAMPLING LOCATION IN BRAIDWOOD LAKE, 2011.SAMPLING LOCATIONS TAXON E-I E-2 E-3 E-4 E-5 E-6 E-7 E-8 TOTAL %%Threadfin shad II 22 224 I 7 40 105 19 429 29.0Gizzard shad 35 17 2 6 5 I 66 4.5Carp 7 8 16 11 6 5 10 17 80 5.4Spotfin shiner 2 2 52 6 13 II 8 25 119 8.0Bullhead minnow 25 8 8 5 46 3.1Smallmouth buffalo I I 0.1Yellow bullhead I I 0.1Channel catfish 2 16 6 2 2 8 10 46 3.1Leponis spp. I I 0.1Green sunfish I 5 27 3 6 I 43 2.9Redear sunfish 2 I 3 0.2Bluegill 2 55 55 85 214 16 35 32 494 33.4Longear sunfish 4 9 6 9 II 11 3 53 3.6Hybrid sunfish 3 3 0.2Largemouth bass 2 24 15 13 7 10 14 10 95 6.4Total fish 61 148 407 135 289 113 207 120 1480Total Taxa 7 8 II 8 10 Ii 10 II 15CPE (fish/hr) 91.0 220.9 607.5 201.5 431.3 168.7 309.0 179.1 277.7Based on 0.67 hrs clectrofshing effort.Based on 5.33 hrs electrofishing cffort.00T0CD4 , ;q-0 -fC,w CD RS-14-138 Enclosure Page 180 of 322numbers of taxa were collected at sampling areas located toward the middle and cooler end of theBraidwood Lake cooling loop (Locations E-3, E-5, and E-7). Electrofishing biomass wasdominated by carp, which constituted 63.4% of the 195.3 kg collected (Table 3-3). Other speciesthat individually contributed more than 5% of the total biomass included channel catfish (13.4%),largemouth bass (9.2%), and bluegill (8.7%).The mean electrofishing catch-per-effort (CPE) for all locations combined in 2011 was 277.7fish/hr (Table 3-4). This value is higher then the mean electrofishing CPE of 177.5 and 167.6fish/hr for all locations combined in 2009 and 2010, respectively (HDR 2010, 2011). Some ofthis increase may be the result of reducing the sampling effort from 30 minutes per location in2009 and 2010 to 20 minutes per location in 2011. This was done to minimize the stress on fishthat were being held in the holding tank before they could be processed in the field. Due to therelatively small size of the sampling areas that have been electrofished during each annual effort,the majority of the collected fish have been captured during the first 15 to 20 minutes of sampling.

Toward the end of each sampling run in 2009 and 2010 some of the areas had to be electrofished again in order to make the 30 minute sampling period. Fewer fish were collected during thesecond runs through each of these areas.In 2011, CPE ranged from 91.0 fish/hr at Location E-1 to 607.5 fish/hr at Location E-3. Thesecond highest CPE occurred at Location E-5 (431.3 fish/br).

Location E-5 exhibited the highestCPE's in 2009 and 2010. This site includes the area around the make-up water discharge into thelake from the Kankakee River. Five species, threadfin shad, common carp, spotfin shiner,bluegill, and largemouth bass, were collected at each of the eight electrofishing locations.

3.2.2 Trap NettingA total of 493 fish including nine species was collected by trap net (Table 3-5). Channel catfishwas the dominant species captured, comprising 46.0% of all fish taken. The second mostabundant species collected was carp (42.0%),

followed by gizzard shad (4.5%), bluegill (3.9%),and largemouth bass (2.0%). The total number of fish collected by location ranged from 27 atLocation TN-2 and TN-4 to 102 at Locations TN-8. The total number of species collected bylocation ranged from two at Location TN-2 to six at Locations TN-3, TN-5, and TN-6. The totalbiomass of fish captured by trap netting was 474.5 kg (Table 3-3). Carp (57.9%),

channel catfish3-9HDR Engineering, Inc.

TABLE 3-5NUMBER OF FISH CAPTURED BY TRAP NETTING AT EACH SAMPLING LOCATION IN BRAIDWOOD LAKE, 2011.SAMPLING LOCATIONS TAXON TN-I TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-8 TOTAL %Gizzard shad I 3 15 2 I 22 4.5Carp 5 8 9 6 10 75 44 50 207 42.0Smallmouth buffalo 1 1 0.2Blue catfish I I 0.2Channel catfish 36 19 56 17 43 14 5 37 227 46.0Flathead catfish I I 2 0.4Bluegill I I I I I 2 12 19 3.9Largemouth bass 2 5 2 I 10 2.0Freshwater drum I I 2 4 0.8Total fish 45 27 73 27 72 93 54 102 493Total Taxa 5 2 6 4 6 6 5 5 9CPE (fish/trap net set) 22.52 13.5* 36.51 13.5* 36.0' 46.54 27.03 51.03 30.8b,3ased on Iwo over night sets of approximately 12 hr duration.

Iased on 16 over nig t sets of approximately 12 hr duration, 40ccCD0.0r') OD RS-14-138 Enclosure Page 182 of 322(33.4%),

flathead catfish (4.5%), largemouth bass (1.3%), and gizzard shad (1.2%) were the onlyspecies to individually comprise more than 1 % of the total biomass collected.

During the two August sampling

periods, mean trap netting CPE for all locations combined was30.8 fish/net (overnight sets of approximately 12-hrs),

which is similar to the 28.5 fish/netreported in 2009 (HDR 2010) and the 40.8 fish/net reported in 2010 (HDR 2011). CPE bylocation ranged from 13.5 fish/net at Locations TN-2 and TN-4 to 51.0 fish/net at Location TN-8.Carp and channel catfish were the only species collected at each of the eight sampling locations.

3.2.3 Gill NettingGill netting resulted in the collection of 271 individuals representing four species (Table 3-6).Threadfin shad dominated the catch by comprising 127 (46.9%) of the 271 total fish collected.

Channel catfish was the second most abundant species collected (41.7%).

The only other speciesto individually contribute more than 5% of the total catch was blue catfish (9.2%). Channelcatfish comprised 5.3 kg (49.0%) of the 10.8 kg of fish collected by gill netting (Table 3-3),followed by blue catfish at 2.4 kg (22.4%),

gizzard shad at 1.9 kg (17.7%),

and threadfin shad1.2 kg (10.9%).A total of 252 fish representing four species was collected from the two deep water sets conducted at Location GN-I (Table 3-6). Gill nets at this location were set in a deep hole at a depth ofapproximately 10-13 m. At the shallow water sampling Location GN-2 the gill nets were set at adepth of approximately 2 m. Nineteen fish and two species were collected from this samplinglocation during the two combined August sampling dates.Gill net CPE at the deep water Location GN-1 was 336.0 fish/hr based on 252 fish collected during 0.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> of sampling effort during the two combined August sampling efforts.

CPE atthe shallow water Location GN-2 was substantially lower at 25.3 fish/hr based upon the 19 fishcollected during 0.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> of total sampling effort in August. Mean CPE for the two samplinglocations was 180.7 fish/hr, which is higher than 73.5 fish/hr in 2010 (HDR 2011) and the 53.4fish/hr reported in 2009 (HDR 2010). Threadfin shad and channel catfish were the only speciescollected at both sampling locations.

3-11HDR Engineering, Inc.

RS-14-138 Enclosure Page 183 of 322TABLE 3-6NUMBERS OF FISH CAPTURED BY DEEP (GN-1) AND SHALLOW WATER (GN-2)GILL NETS IN BRAIDWOOD LAKE, 2011.SAMPLING LOCATIONTAXA GN-12 GN-2h TOTAL %Threadfin shad 122 5 127 46.9Gizzard shad 6 6 2.2Blue catfish 25 25 9.2Channel catfish 99 14 113 41.7Total fish 252 19 271Total taxa 4 2 4CPE (fish/hr) 336.0V 25.k' 180.7dIGN4 I was a deep water set in approximately 10-13 meters of water.'GN-2 was a shallow water set in approximately 2 meters of water.'Based on 0.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> of total effort.dBased on 1.50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> of total effort.3-12 RS-14-138 Enclosure Page 184 of 3223.2.4 Hoop NettingA total of 54 fish including five species was collected by hoop nets (Table 3-7). Bluegill was themost abundant species captured, comprising 48.1 % of all fish taken. The second and third mostabundant species captured were channel catfish (42.6%) and carp (5.6%). The only other speciescollected included one individual each of gizzard shad and flathead catfish.

A total of 34.3 kg offish was collected by hoop net (Table 3-3). Flathead catfish (42.2%),

channel catfish (36.5%),and carp (15.6%) were the only species that individually comprised greater than 5% of the totalhoop net catch by weight.The greatest number of fish (23 individuals) was collected at Location HN-3, which was a shallowwater set baited with dead gizzard shad (Table 3-7). Twenty fish were collected at Location HN-4, which was also a shallow water set, but the net was not baited. Similar numbers of fish werecollected at the two shallow water locations.

Only three individuals were collected in the deepwater baited net at Location HN-I, while eight fish were collected in the deep water net withoutbait at Location HN-2. The total number of species collected by location ranged from two atLocations HN-3 and HN-4 to four at Location HN-2. A total of 26 fish was collected from thetwo baited net locations compared to 28 fish captured from the two nets that were not baited atBraidwood Lake in 2011.Hoop netting CPE ranged from 1.5 fish/overnight set at Location HN-1 (deep water with bait) to11.5 fish/overnight set at Location HN-3 (deep water with bait). CPE for the two deep water sets(HN-1 and HN-2) averaged 2.8 fish/overnight set compared to 10.8 fish/overnight set at theshallow water locations (HN-3 and HN-4). The two baited net sets (HN-1 and HN-3) had anaverage CPE of 6.5 fish/overnight set compared to 7.0 fish/overnight set for the two nets (HN-2and HN-4) that were not baited. Mean CPE for all nets combined was 6.8 fish/overnight set.3.3 Length-Frequecy Distributions Length-frequency distributions of six selected species (bluegill, largemouth bass, channel catfish,blue catfish, threadfin shad, and gizzard shad) captured by all sampling gears in 2011 werecompiled and are presented graphically (Figure 3-1 through Figure 3-5). With the exception ofelectrofishing, the sampling gears used in these studies are biased toward larger fish. Therefore, 3-13HDR Engineering, Inc.

TABLE 3-7NUMBERS OF FISH CAPTURED IN BAITED AND UNBAITED DEEP AND SHALLOW WATER HOOP NETSIN BRAIDWOOD LAKE, 2011.SAMPLING LOCATIONDEEP WATERW SHALLOW WATERb(BNTED HN-3 TOTATAXA ( D) UN(NAITED)(BAITED)

(UNANTED)

TOTALGizzard shad 1 1 1.9Carp 1 2 3 5.6Channel catfish 1 4 17 1 23 42.6Flathead catfish 1 1 1.9Bluegill 1 6 19 26 48.1Total fish 3 8 23 20 54Total taxa 3 4 2 2 5CPE (fish/overnight set) 1.5c 4.0c 11.5c 10.0c 6.8d'Deep water hoop nets HN-1 and HN-2 were set in 7.5 meters of water.'Shallow water hoop nets HN-3 and HN-4 were set in approximately 2.0 meters of water.1CPE was based on two overnight sets of approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> duration.

'CPE was based on eight overnight sets of approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> duration.

"02, 6'C3R) @c (.

'7560(L0o 45LuNU)wm 30zLA15ý0TOTAL LENGTH (mm)(D03) 00 -2C 05FIGURE 3-1.LENGTH-FREQUENCY DISTRIBUTION OF BLUEGILL COLLECTED FROMBRAIDWOOD LAKE DURING AUGUST, 2011.

CLD00IL"P0 a 0 v s CC a0 am a a a a a a m 1, a1 a1. a ý a a a *a. a m m v0 W 0C3CTOTAL LENGTH (mm) CDFIGURE 3-2. LENGTH-FREQUENCY DISTRIBUTION OF LARGEMOUTH BASS COLLECTED FROM BRAIDWOOD LAKE DURING AUGUST, 2011.

C-00LuNLUzI I I I ***I I I I I I I I I I N IN I I I u I I I I.VL ~ qu u u- i I I I -1 I1:o m o 0ma, aj mc ma b D( a) o a, mc m~a a, a, (D a) 0) 1, a, Im C) a, a, C) C) W , C) I ,D m m mm m)0m mm ( a, 0) mm'mmc- maca- u'0 -wm Q&cm )V n-O caa aol- &, wac .- wmm a -C m a ca CDf. ct a, 40 N e c.) V arýc , m"-,C4F-C?

CC?'?C?'-IT

'T4co a, o 6 66 C5 6 6 6 6 (6 6 6 c6 6 6 6 6 6 6 6 a 6 6 A a a C) a 6 a a a a a a c'a;- " vL w -w m_ n -c C _lJc)'TOTAL LENGTH (mm)FIGURE 3-3. LENGTH-FREQUENCY DISTRIBUTION OF CHANNEL CATFISH COLLECTED FROM BRAIDWOOD LAKE DURING AUGUST, 2011._0CDa, m0~.wU).OD a 10-,8-CL0S6-luNU)lzBLUE CATFISHN = 26002-....* Iif3-LAI-jJAI,m'o CD m a 'oD ""o C, C 'T-"r D o o a o7 CD C CD C' C CD C CD CD C 0D a) ) " I 0 .C N a) 0 G) CD I M 0) 0 m CD.to C GO M Go 0) ' ') C)U -C ) 0 -N c')v 6 6 66 ' C6 6 C?' CoCD a~ 0D 0 a- a C') 0 U) (0 0- CD, ') ' ) C--- N N N r4 4 N N N Nm N4 N- m' c') 0' C') ) C') V) V') V') V) ITTOTAL LENGTH (mm)FIGURE 3-4. LENGTH-FREQUENCY DISTRIBUTION OF BLUE CATFISH COLLECTED FROM BRAIDWOOD LAKE DURING AUGUST, 2011.-ozo,aD 0Z:JC (a

0. 4U-o O THREADFIN SHAD = 179N .... ._ _ _ _S30-U)LuZ 20- .., 0 c I w m--D000 a) -n -r a) a) CD Ny N) a) N) M N) N)C )a )a C) )Ca ) a~) a~C~) 0) a) m~ Im M C Q0~LN M-N t f .~ 1 D 0 40 M V C Lo ~tI 0 1,- M M 0 4 -V----------------------

N 3 N N 7 Ný Ny Ny ? C?2 I? C? T~ V2 M6 60 cc? cc? M62 ol Iwm0 5-i10).FIGURE 3-5. LENGTH-FREQUENCY DISTRIBUTION OF THREADFIN AND GIZZARD SHAD COLLECTED FROM P IBRAIDWOOD LAKE DURING AUGUST, 2011.

RS-14-138 Enclosure Page 191 of 322smaller fish, especially young-of-year and yearlings, were not collected in numbers that wouldmost accurately represent their true abundance in Braidwood Lake.Bluegill is one of the most abundant species found in Braidwood Lake. Two hundred ninety-seven individuals measuring from 80 to 194 mm in total length are included in the length-frequency histogram of bluegill that were captured in 2011 (Figure 3-1). Two major peaks in thelength-frequency distribution representing at least two different age classes were noted. The firstmajor group of fish includes bluegill measuring from 80 to 130 mrm, while the second majorgroup includes fish measuring from 130 to 180 mm. The age of these fish, as well as otherspecies, in thermally enhanced bodies of water, such as Braidwood Lake, is impossible todetermine without hard-part (scales, spines, and otoliths) analysis because the growing seasonextends throughout the winter months. Regardless of age, Braidwood Lake supports a largepopulation of bluegill that is large enough to support a quality sport fishery.The length-frequency distribution of 105 largemouth bass measuring from 70 to 453 mm in totallength were collected from Braidwood Lake during 2011 (Figure 3-2). The length-frequency distribution indicates that several age classes of fish were included among the catch. The largestpeak in the length-frequency histogram occurs from 100 to 120 mm and likely represents eitherYOY or Age I fish. Thirteen (12.4%) of the 105 fish collected exceeded 350 mm (14 in.). Thelargest individual that measured 454 mm was likely Age 4 or 5. Again, the age of fish in coolinglakes is difficult to ascertain based on length-frequency analysis because of the extended growingseason that exist in these thermally enhanced bodies of water. Only three fish were collected thatmeasured between 150 and 250 mm in TL. This may represent a weak or missing year class inthe length-frequency histogram for largemouth bass as illustrated in Figure 3-2. It should also benoted that the IDNR stocked 46,160 four inch fingerlings into Braidwood Lake in 2010. This wasequivalent to 20.6 fish/acre (HDR 2011). The authors of this report are uncertain if anyadditional stocking activities were conducted for this or any other species in 2011.Channel catfish is an abundant species that is targeted by recreational anglers at Braidwood Lake.A total of 281 fish measuring from 84 to 686 mm are included in the length frequency analysis forchannel catfish captured in 2011 (Figure 3-3). Several age classes of channel catfish are includedamong the 281 fish observed in the length-frequency analysis.

Recruitment of this species appears3-20HDR Engineering, Inc.

RS-14-138 Enclosure Page 192 of 322to be very good based on Figure 3-3, which illustrates that there are not any missing or obviousweak year classes in the catch.Braidwood Lake has been stocked with a variety of warm- and coolwater fish specie since the1970's to the present time. Those efforts have included the introduction of blue catfish to thecooling lake. Because of those stocking

efforts, and because of the number of blue catfish thatwere collected in 2011, a length-frequency histogram was also created for this species (Figure 3-4). The length-frequency distribution of 26 fish measuring from 164 to 423 mm indicates that asmany as four or perhaps five year classes of blue catfish were included in the catch at Braidwood Lake during 2011. Twenty (76.9%) of the 26 fish collected measured less than 270 mm in totallength, while the remaining six (23.1 %) individuals ranged from 277 to 423 mm in total length.Blue catfish were stocked in Braidwood Lake by IDNR in 2010. This stocking effort included9,812 blue catfish fingerlings (5.3 inches) equivalent to 4.3 fish/acre (HDR 2011). The authors ofthis report are uncertain if any of these species were stocked again in 2011.Two additional

species, threadfin shad and gizzard shad, were also analyzed (Figure 3-5). Bothof these abundant forage species reside in Braidwood Lake. They are important to the ecology ofthe system because they have the potential to pose a treat to the operation and maintenance ofBraidwood Nuclear Station when fish kills occur at the cooling lake. Large numbers of deadgizzard and threadfin shad could accumulate on the bar grills, traveling water screens, and othersystems at the Stations intake, which could potentially interfere with water flow used to cool thereactors and other support systems.A total of 85 gizzard shad and 179 threadfin shad are included in the length-frequency histogram for these two species (Figure 3-5). All of the threadfin shad collected during the current studymeasured from 57 to 147 mm in total length, while 50 (58.8%) of the 85 gizzard shad capturedexceeded 150 mm in total length. Gizzard shad ranged in length from 92 to 426 mm. At leastthree or four year classes of gizzard shad were collected during 2011. In contrast, threadfin shadrarely exceed 150 mm in total length and individuals spawned early in the year commonly matureand spawn late in their first summer of life. Few threadfin shad live for more than two or threeyears.3-21HDR Engineering, Inc.

RS-14-138 Enclosure Page 193 of 3223.4 Physicochemical DataWater quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection (Appendix Tables A-I to A-4). During August 1-4, water temperature at Braidwood Lake ranged from 34.8 TC at Location E-3 on 4 August to 41.0 'C at Location TN-2 on 1 August. Water temperatures during the second sampling period (30 August through ISeptember) were cooler than those measured in early August. Temperatures during this periodranged from 30.1 'C at Location TN-5 (where make-up water is pumped into the lake from theKankakee River) on 31 August to 35.3 TC at Location TN-2 on 30 August. As expected, thetemperature gradient generally declined as the cooling water in the lake moved from the Station's discharge toward the Braidwood Station intake.During the first sampling period (August 1-4), dissolved oxygen (DO) ranged from 3.1 ppm atLocations TN-2.during the early morning of 2 August to 13.5 ppm at Location TN-5 during thelate afternoon of 1 August. Oxygen levels were generally higher during the second samplingperiod in late August and early September.

Dissolved oxygen levels ranged from 5.6 ppm atLocation TN-3 during the morning of 31 August to 14.0 ppm at Location E-3 during theafternoon of 31 August.Dissolved oxygen measurements increased each day in the lake from early morning to lateafternoon during both the first and second sampling periods.

Similar conditions were alsoobserved in 2009 and 2010 (HDR 2010, 2011). The increase in dissolved oxygen measurements from early morning to late afternoon can be attributed to photosynthesis by the extensive phytoplankton population in the lake that produces oxygen throughout the daylight hours.Surface and bottom water temperature, DO, and conductivity readings were taken at deep watergill net set Location GN-land the deep water hoop net set Locations HN-1 and HN-2. Similarsurface and bottom readings were recorded at the deep water Locations HN-1 and HN-2. AtLocation GN-l, the bottom temperatures were slightly cooler (0.3 to 0.8 0C) than the surfacereading, while the DO levels measured near the bottom were more variable ranging from 1.4 to2.7 ppm less than the surface readings during the two August sampling periods.3-22HDR Engineering, Inc.

RS-14-138 Enclosure Page 194 of 322Braidwood Lake is a very productive system with heavy oxygen demand (respiration anddecomposition) occurring during the night and intense oxygen production (photosynthesis) occurring during clear sunny days. Currently, the majority of the photosynthetic activity withinBraidwood Lake is attributable to phytoplankton, which has decreased the water clarity andreplaced aquatic macrophtyes as the primary producer.

In a report submitted to Exelon by SEAin 2001 (Appendix Report B-i); it states that "Several perched cooling ponds in the Midwest havehad high macrophyte densities in their earlier years but usually become dominated byphytoplankton if they have heavy thermal loading.

A switch to phytoplankton dominance isusually accompanied by a reduction in water transparency."

Braidwood Lake appears to be relatively well buffered with only minor diurnal variation in pHreadings.

Examination of pH data collected during the present surveys show that pH ranged from8.3 to 8.7 during the first August sampling period and from 8.5 to 8.6 during the second Augustsampling period. The pH of water typically increases with increased photosynthetic activity andthe resulting oxygen production can explain upward shifts in pH during the course of bright sunnydays.During the early August sampling period, conductivity ranged from 928 /mhos at Location TN-Ion I August to 993 pmhos at Location E-3 on 4 August. Conductivity during the late Augustsampling period ranged from 988 pmhos at Location E-3 on 31 August to 1036 jarnhos atLocations TN-I and TN-2 on 31 August. Conductivity and pH readings were similar throughout the entire length of Braidwood Lake. Surface to bottom readings were also similar, suggesting that the water throughout the cooling loop was well mixed during early and late August.Make-up water is pumped into Braidwood Lake on an irregular basis from the Kankakee Riverthroughout most of the year. As a result, water quality parameters can be expected to begenerally more favorable near the make-up water discharge (Location E-5) compared to theremainder of the sampling locations.

However, the affects of the make-up water discharge isquickly dissipated because of the relatively low volume of make-up flow being pumped into thelake. Make-up water was pumped into Braidwood Lake during portions of the first samplingperiod in early August. Make-up flow was not observed being pumped into Braidwood Lakeduring the late August sampling dates.3-23HDR Engineering, Inc.

RS-14-138 Enclosure Page 195 of 322During the early August sampling period, water temperatures were at the upper limits of therange of values acceptable for some warmwater fish species.

Air temperatures during late Julyand early August were unusually high throughout the Midwest in 2011, which accounted for mostof the increase in the water temperatures at Braidwood Lake during early August. Conductivity and dissolved oxygen readings were slightly higher during the second sampling period, while pHmeasurements were similar during both sampling periods.

The early morning dissolved oxygenreadings that were measured on 2 August (3 ppm at Location TN-I and TN-2) were approaching values that adversely affect most fish species.

As previously noted, these diurnal oxygenfluctuations are common at Braidwood Lake during the summer months and can be attributed tooxygen depletion (respiration and decomposition) during the night and oxygen production (photosynthesis) during the day. On cloudy calm days, photosynthesis and oxygen production canbe slowed to levels that cannot compensate for oxygen depletion that occurs throughout the night.When this occurs over an extended period of time (days), an oxygen deficit can develop and causesubstantial fish die-offs if suitable refuges within the system are not available.

3.5 Historical Information 3.5.1 Water QualityWater quality parameters were measured on seven separate occasions at Braidwood Lake fromMay 29, 2001 through August 27-28, 2002 (Appendix Reports B-1 through B-7). The purposeand scope of these investigations varied, but the most intensive sampling was conducted duringthe August 27-28, 2002 sampling event. Results of these investigations indicated that abnormally high levels of total dissolved solids (TDS), alkalinity,

hardness, sulfates, magnesium, calcium,and total phosphorus existed throughout the cooling loop. This data was not unexpected based onthe evaporation that occurs within the cooling loop coupled with the relative low make-up andblow-down flows associated with the operation of the Station.

The cooling lake exhibited elevatedvalues for these parameters at levels of two to nearly eight times higher than those of the make-upwater from the Kankakee River. These elevated levels of water hardness can be of concern tothe Station because they have the potential to intensify problems associated with scaling.Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Concentrations ofthese nutrients are typically low in water because phytoplankton and aquatic macrophytes quickly3-24HDR Engineering, Inc.

RS-14-138 Enclosure Page 196 of 322assimilate and utilize these nutrients for growth and reproduction.

The studies conducted by SEAin 2002 indicated that the high levels of these nutrients within the cooling lake would continue tocause problems associated with phytoplankton blooms. Unlike most water bodies, phosphorus levels within Braidwood Lake were in excess and nitrates were the limiting factor. Bluegreen algae appeared to be the dominant summer form of algae within Braidwood Lake because they arenot as limited by low nitrate levels as other algal species.Water quality analysis has indicated that dissolved oxygen levels within the cooling lake canexhibit large diurnal variation in response to algal blooms that are most problematic during thesummer months (June through August).

The nutrient rich water of Braidwood Lake is ideal forthe development of algal blooms that produce large amounts of oxygen during the day(photosynthesis) and oxygen depletion in the dark (respiration and decomposition).

As oxygen isproduced through photosynthesis, pH tends to increase if the water is not well buffered.

Dissolved oxygen levels of 4-5 ppm (levels that most fish species become stressed) and lowerhave been recorded throughout the cooling loop 0.5 m below the waters surface.

The lowest DOreadings generally occur during the early morning period and typically increase throughout theday. Increases in DO of 4 to 5 ppm or more have been observed from morning to late afternoon at Braidwood Lake. In addition, stratification of the water column has also been reported duringthe same period of time when DO readings are measured at less than 3 ppm. During theseevents, DO readings in the hypolimnion (the zone below the thermocline to the bottom of thelake) can approach zero. When this occurs, it further limits the refuge available for fish and otheraquatic organisms.

3.5.2 Fish KillsHistorical fisheries data summarizing fish kills that have occurred at Braidwood Lake wasprovided to HDR by Exelon Nuclear, IDNR, and SEA (Appendix Reports B-2 through B-7). Fivefish kills that occurred from 2001 through 2007 were identified in the information provided toHDR. Each of these events occurred during June, July, or August. Two of the kills occurred in2001. The first took place in late July and the second on August 27-28. A third kill was reportedon July 30, 2004, the fourth on June 28, 2005, and the fifth occurred over an extended period oftime during August 21-28, 2007. No additional information regarding fish kills has been3-25HDR Engineering, Inc.

RS-14-138 Enclosure Page 197 of 322provided to HDR since 2009. Therefore, it is assumed that no reportable fish kills have beenobserved at Braidwood Lake since August, 2007.Little information was provided for the fish kills that occurred in late July and August, 2001. Thespecies involved and the extent of dead fish observed during the first event in July were notincluded in the information received by HDR. The second fish die-off in late August wasdominated primarily by gizzard shad that comprised more than 95% of all fish observed.

Theremaining species involved in the die-off in decreasing order of relative abundance

included, freshwater drum, quillback, carp, largemouth bass, channel catfish, redhorse spp., smalimouth bass, and bluegill.

With the exception of gizzard shad, the majority of the fish were located fromthe mid-point of the cooling loop to the intake. A report submitted by SEA indicated that warmwater temperatures and/or low dissolved oxygen levels were the most likely factors thatcontributed to the fish die-off in July. SEA also indicated that the die-off in late August was mostlikely the result of depleted dissolved oxygen levels that occurred in the lake following anextensive phytoplankton bloom collapse, which is a natural phenomenon that can occur in highlyproductive waters during summer months. Dissolved oxygen measurements throughout themajority of the lake were at or below minimum levels necessary to support most fish species.A third fish die-off at Braidwood Lake was investigated on July 30, 2004. Gizzard shad was thedominant species involved, although channel catfish were also observed.

The gizzard shadappeared to be in an advanced state of decay suggesting that the actual die-off occurred earlier inthe week. Water quality parameters at the time of the incident were not included in the briefsummary report provided to HDR, which suggests they were not measured concurrent with thefish die-off.

Water quality measurements were taken in early October following the fish die-off.During this period of time, DO levels of 3.8 ppm and a water temperature of 29.2 °C wererecorded at a depth of one foot below the surface, just north of the south boat ramp. At a locationseveral hundred feet from the take make-up discharge from the Kankakee River, more favorable dissolved oxygen (7.6 ppm) and water temperatures (26.5 'C) were measured.

DO readings atthis location were stratified exhibiting a decline to 5.3 ppm at 40 feet, while water temperature showed minimal decrease with water depth.In 2005, an inspection of a fish die-off was conducted on 28 June. Formal counts of fish were notconducted at this time, but field assessments indicated that a fairly substantial die-off involving 3-26HDR Engineering, Inc.

RS-14-138 Enclosure Page 198 of 322several species had occurred.

Gizzard shad was again the most numerous species affected andfish carcasses were observed throughout the majority of the lake. Additional species observedincluded threadfin shad, quillback, largemouth and smallmouth bass, carp, and channel catfish.Water quality measurements during this event were not provided to HDR and are assumed to beunavailable.

Rob Miller of IDNR and Jeremiah Haas of Exelon Nuclear investigated another fish die-off thatwas first reported at Braidwood Lake on August 21, 2007. The majority of the dead fishobserved were either large gizzard shad or threadfin shad up to five inches in length. Channelcatfish were also prevalent, with only a few carp, largemouth bass, and flathead catfish beingobserved.

Most of the fish were distributed in close proximity to the north boat ramp due toprevailing south winds. The number of dead fish observed decreased towards the south (hot) endof the cooling loop. During the afternoon of 21 August, surface water temperature was 35.3 "Cand DO was near 3 ppm at a sampling point several hundred yards from the south ramp. Fourseparate water temperature and DO readings were also conducted at the north ramp between 1210hrs and 1658 hrs. Water temperature increased from 30.3 to 33.9 'C over the course of that timeinterval.

Dissolved oxygen was measured at 3.1 ppm at 1210 hrs and increased to 6.7 ppmduring the third reading at 1530 hrs. DO levels decreased during the last reading at 1658 hrs to5.9 ppm. Oxygen depletion appeared to be the factor responsible for the August fish kill thatoccurred at Braidwood Lake in 2007.3-27HDR Engineering, Inc.

RS-14-138 Enclosure Page 199 of 3224.0 SUMMARY AND RECOMMENDATIONS 4.1 Summary.

Braidwood Lake is a 2640 acre, partially perched cooling lake that was firstimpounded in 1980-1981 after several old strip-mine pits were inundated with water from theKankakee River. The lake has received supplemental stockings of both warmwater and coolwater fish species since the late 1970's. However, stocking efforts of species including

walleye, tigermuskie, smallmouth bass, and hybrid striped bass have not produced a sustainable quality fishery,which is due to the warm temperatures that are currently common in the cooling lake throughout the summer months. Water quality, particularly water temperature, improves as the water movesfrom the southern (hot) end of the cooling loop toward the northern (cool) end of the lake.Fisheries surveys have been conducted by IDNR at Braidwood Lake annually from 1980 through1992, in 1994, and at two year intervals from 1997 through 2011. Forty-seven species of fish andtwo hybrid taxa (tiger muskie and hybrid sunfish) have been included among the 13 families offish collected.

Several of these species were rarely collected, were the result of supplemental stocking

efforts, or have not been collected during the past ten years of sampling.

Two species,mosquitofish and blue catfish, were collected for the first time in 2009 by the IDNR. Riverredhorse (one individual captured in 1999) is the only species that has been collected which iscurrently listed as protected in Illinois.

Fisheries surveys were again conducted by the IDNR in2011, but the data had not been compiled prior to the preparation of this report.In 2009, HDR collected 24 species and two taxa (hybrid sunfish and small unidentified young-of-year sunfish species) among the 2143 fish collected.

Similar results were observed in 2010 when25 taxa representing eight families were included among the 2432 fish collected by electrofishing, trap netting, gill netting, and hoop netting.

In 2011, 18 taxa representing 16 species wereincluded among the 2298 fish collected by HDR. Several taxa that were collected by IDNR from1980 to 2009 were not collected by HDR during 2009-2011.

However, five species (shortnose gar, smallmouth

buffalo, bigmouth

buffalo, fathead minnow, and rosyface shiner) that have beencaptured by HDR have not been captured by IDNR. No threatened or endangered species havebeen encountered by HDR during any of the three years of sampling.

Since 1980, 52 species of4-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 200 of 322fish and two hybrids (tiger muskie and hybrid sunfish) have been collected at Braidwood Lake bythe IDNR and HDR.The Braidwood Lake Fish and Wildlife Area evolved through three distinct phases since itsinception prior to the 1980's. Originally, several surface mined pits existed at the site until thelake was impounded with water from the Kankakee River during 1980 and 1981. The lakecontinued to function in this capacity until July 29 and November 17, 1988 when Braidwood Station began commercial operation of Units I and Unit II, respectively.

From 1980 through July1988, Braidwood Lake did not receive any thermal loading from Braidwood Station.

Since 1988,the lake has functioned as a cooling loop for the operation of the Station.

Currently, the lake isbest suited to support a warmwater fi.hery due to the warm temperatures prevalent in the lakethroughout the summer months. Dominant species currently found at Braidwood Lake includegizzard shad, threadfin shad, bluegill, channel catfish, and carp. Additional species such aslargemouth bass, green sunfish, flathead

catfish, spotfin shiner, bluntnose minnow, and sandshiner have also been commonly encountered.

Excluding the stocked fish that have beenintroduced into the Braidwood Lake, the taxa encountered have also been collected from theKankakee River, which is the source of make-up water for the lake. With the possible exception of common carp and channel catfish, these species are better suited to conditions that exist withinthe river. Survival of individuals that are introduced into the lake with the make-up water islimited by the elevated water temperatures that exist within the cooling loop during summermonths.Braidwood Lake can be currently described as a well buffered body of water with elevated watertemperatures, high levels of total dissolved solids (TDS), phosphates, and nitrates.

Primaryproductivity in the lake can be very high in conjunction with algal blooms that occur throughout the lake, especially during the June through August period. These blooms are driven by the highnutrient levels that exist within the lake. In recent years, phytoplankton has replaced aquaticmacrophytes as the principal source of primary production.

The lake can also display relatively large diurnal fluctuations in dissolved oxygen measurements, particularly during the summerwhen oxygen is produced in large quantities by photosynthesis during the day and used in largequantities by respiration and decomposition during the night. In addition, Braidwood Lake canstratify during certain portions of the year, which has led to anoxic (oxygen depletion) or near4-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 201 of 322anoxic conditions throughout the hypolimnion (stratified bottom layer of water below thethermocline) as a result of respiration and decomposition from a collapsing algal bloom. Even inthe surface waters of the epilimnion, dissolved oxygen readings of less than 4 ppm have beenreported following an extensive and rapid die-off of an existing phytoplankton bloom. It is duringthese periods of time when water temperatures are elevated and dissolved oxygen levels are lowthat the fish die-offs are observed at the lake. The conditions described in this paragraph shouldnot be expected to change at Braidwood Lake in the foreseeable future.4.2 Recommedations.

Five separate fish die-offs attributed to low DO levels were observed atBraidwood Lake between 2001 and 2007. It is expected that the conditions which led to thosefive events will not change or improve in the foreseeable future. Therefore, it should be assumedthat fish die-offs will continue to occur when algal blooms crash and oxygen depletion occurs.Substantial fish die-offs within the cooling loop could adversely affect both the operation andmaintenance of Braidwood Nuclear Station.Currently, there are no practical or simple solutions that could prevent the occurrence of fish die-offs at Braidwood Lake. It should be anticipated that fish die-offs will continue to occur at thelake on a fairly regular basis. Therefore, it would be advantageous if a reliable sampling protocolor set of procedures were developed that would reasonably predict fish die-offs that mayadversely affect the operation and/or maintenance of the Station.

With advanced warning theStation could be informed of a potential reportable

incident, regulatory agencies could be notified,..

and crews responsible for fish disposal could be put on alert to help manage the risk associated with a substantial fish die-off.

HDR believes this can be accomplished by conducting routinevisual inspections of the lake, monitoring dissolved oxygen levels, and by having a basicunderstanding of environmental conditions that may trigger these events, especially weatherconditions.

HDR recommends a two tier sampling procedure that may be utilized to help predict the onset ofa possible reportable fish die-off.

We recommend that visual inspections of the lake and waterquality measurements be conducted routinely throughout the year, particularly during the warmweather months, if budget and staff is available to monitor the lake. The frequency ofobservations and the intensity of the water quality measurements should be discussed by the4-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 202 of 322management who would analyze risk management at Braidwood Station.

Historically, all the fishdie-offs at Braidwood Lake have occurred during the warm weather period of June throughAugust. This is the period of time when water in the cooling loop is the warmest and dissolved oxygen levels can fall substantially following die-offs of extensive phytoplankton booms.Therefore, this is the most critical time to monitor existing conditions that could result in apotential problem (May through September).

Sampling on a less frequent basis throughout theremainder of the year may provide additional information that could be useful to the Station andpossibly alert the Station to an impending problem that may not have been identified in the past.Water quality measurements should include dissolved oxygen readings at a minimum becausefisheries biologists that have investigated these events in the past have concluded that the mortality of fish was the result of oxygen depletion.

The most effective way to monitor dissolved oxygenlevels within the lake would be through the use of permanently fixed continuous water qualitysamplers and data loggers installed at several depths that could be programmed to takemeasurements at predetermined time intervals.

The number of water quality samplers purchased or the type of sampler utilized would be dependent upon the desired results and cost of theequipment.

Ideally, the best system would allow the sampling unit to take measurements atprogrammed time interval (perhaps every 15 minutes to daily), would measure at least DO, watertemperature, and pH, could provide instantaneous readouts to Braidwood staff without having tomanually go into the field to download data, and would require minimal maintenance orcalibration to operate.

The price range of this type of equipment is highly variable depending onthe unit selected, the anchoring mechanism for the unit if required, battery life, the number ofparameters

measured, etc. An alternative to this approach would be to utilize a technician tomanually take these measurements.

The disadvantage of this approach is the number of readingsthat could be taken on a daily basis and the time involved to conduct the water quality analysis inthe field.Water quality at Braidwood Lake should be monitored on some predetermined routine basis. Thatcould be at least weekly throughout the year or perhaps only through the more critical time periodof approximately June through August. The two tiered sampling approach would be initiated when dissolved oxygen readings hit a pre-determined trigger point (perhaps 5 to 6 ppm). OnceDO readings decrease to the trigger point, sampling frequency should be increased.

If automatic 4-4HDR Engineering, Inc.

RS-14-138 Enclosure Page 203 of 322samplers are not used, field technicians should be in the field by sunrise when DO readings aretypically the lowest. If automatic samplers were utilized, dissolved oxygen, temperature andother water quality parameters could be tracked throughout the day. This would becomeimportant if DO readings ranged from 4 or 5 ppm in the morning to 7 or 8 ppm in the afternoon.

This information would indicate that photosynthesis is still occurring during the daylight period,which would replenish DO levels in the water and reduce the risk of a fish die-off.

However, ifDO levels were 4 or 5 ppm in the morning and only increased slightly throughout the day, thiswould indicate very little oxygen production due to photosynthesis.

This condition would lead toa greater oxygen deficit during the evening, and could indicate the onset of a phytoplankton bloom die-off that could trigger a fish kill. Once DO levels approach 3 ppm, Station management could be notified of a potential

problem, increased visual inspections of the lake could beconducted, and fish cleanup and disposal crews could be notified and put on standby status.Additionally, Braidwood staff should be aware of weather patterns that can influence these events.When phytoplankton blooms are prevalent and several cloudy days with little or no wind areforecast, massive dies offs of the bloom and subsequent oxygen depletion throughout the watercolumn should be anticipated.

Increased sampling of DO during these weather patterns isadvisable in conjunction with an increase in the frequency of visual inspections at the lake formoribund or dead fish. An increase in water clarity or transparency within the lake would also beexpected to occur as the phytoplankton population crash is in progress.

Visual inspections for fish die-offs should be conducted around the entire cooling loop asprevailing winds may push most of the fish toward one end of the lake. HDR recommends waterquality measurements be conducted at a depth of approximately one meter, if multiple depths arenot sampled.

If only one sampling location is selected, that location should be located near theapproximate mid-point of the cooling loop. The number of water quality stations sampled shouldbe determined by Exelon management or an advisory staff. It is further recommended that anadvisory team should be formed to devise an effective sampling program and set of procedures that can effectively monitor conditions within the lake. HDR is willing to participate and interactwith the advisory team to provide expertise in the development of an effective sampling program.4-5HDR Engineering, Inc.

RS-14-138 Enclosure Page 204 of 32

25.0 REFERENCES

CITEDBecker, G.C. 1983. Fishes of Wisconsin.

The University of Wisconsin Press. Madison, Wisconsin.

Environmental Science & Engineering.

1993. Kankakee River Fish Monitoring Program Braidwood Station 1993. Report to Commonwealth Edison Company,

Chicago, Illinois.

HDR Engineering, Inc. 2009. Braidwood Station Kankakee River Fish Monitoring

Program, 2008.Prepared for Exelon Nuclear, Warrenville, Illinois.

HDR Engineering, Inc. 2010. Braidwood Lake Additional Biological Sampling

Program, 2009.Prepared for Exelon Nuclear, Warrenville, Illinois.

HDR Engineering, Inc. 2011. Braidwood Lake Additional Biological Sampling

Program, 2010.Prepared for Exelon Nuclear, Warrenville, Illinois.

HDR/LMS 2006. Braidwood Station Kankakee River Fish Monitoring

Program, 2005. Prepared forExelon Nuclear, Warrenville, Illinois.

HDR/LMS 2007. Braidwood Station Kankakee River Fish Monitoring

Program, 2006. Prepared forExelon Nuclear, Warrenville, Illinois.

HDR/LMS 2008. Braidwood Station Kankakee River Fish Monitoring

Program, 2007. Prepared forExelon Nuclear, Warrenville, Illinois.

Illinois Endangered Species Protection Board. 2009. Checklist of Endangered and Threatened Animals and Plants of Illinois.

Illinois Department of Natural Resources, Springfield, Illinois 18 pp.Lawler, Matusky and Skelly Engineers (LMS). 1992. Braidwood Station Kankakee River FishMonitoring

Program, 1991. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1996. Braidwood Station Kankakee River FishMonitoring

Program, 1995. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1999. Braidwood Station Kankakee River FishMonitoring

Program, 1998. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2001. Braidwood Station Kankakee River FishMonitoring

Program, 2000. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2005. Braidwood Station Kankakee River FishMonitoring

Program, 2004. Report to Commonwealth Edison Company,

Chicago, Illinois.

Piper, R.G. et al. 1983. Fish Hatchery Management.

United States Department of the Interior Fishand Wildlife Service.

Second Printing.

Washington, D.C. 517 pp.HDR Engineering, Inc.

RS-14-138 Enclosure Page 205 of 322Pflieger, W.L. 1975. The Fishes of Missouri.

Missouri Department of Conservation.

Jefferson City, Missouri.

Smith, P.W. 1979. The Fishes of Illinois.

University of Illinois Press, Urbana, Illinois.

314 pp.Trautman, M.B. 1981. The Fishes of Ohio. Ohio State Press in Collaboration with the Ohio SeaGrant Program Center for Lake Erie Area Research.

782 pp.5-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 206 of 322APPENDIX APHYSICOCHEMICAL DATA RS-14-138 Enclosure Page 207 of 322LIST OF TABLESTable No.TitlePage No.A-1IA-2A-3A-40Physicochemnical Measurements Recorded Concurrently withElectrofishing Samples Collected from Braidwood Lake, 2011.Physicochemnical Measurements Recorded Concurrently withTrap Netting Samples Collected from Braidwood Lake, 2011.Physicochemical Measurements Recorded Concurrently withGill Netting Samples Collected from Braidwood Lake, 2011.Physicochemical Measurements Recorded Concurrently withHoop Netting Samples Collected from Braidwood Lake, 2011.A-]A-2A-3A-4HDR Engineering, Inc.

TABLE A- IPHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH ELECTROFISHING SAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2011PARAMETER E-1 E-2 E-3 E-4 E-5 E-6 E-7 E-8Date (First Sample Period) AUG 4 AUG 4 AUG 4 AUG 4 AUG 4 AUG 4 AUG 4 AUG 4Time 1120 1030 0925 0840 0710 1200 1245 0755Temperature

(°C) 39.0 36.6 34.8 35.5 35.5 35.4 35.0 35.0Dissolved oxygen (ppm) 5.15 6.34 6.31 4.90 4.42 7.14 10.6 4.65pH 8.4 8.5 8.6 8.5 8.6 8.5 8.7 8.4Conductivity (Mumhos/cm) 972 987 993 990 988 969 954 983Date (Second Sample Period) AUG 31 AUG 31 AUG 31 AUG 31 SEP 1 SEP 1 SEP 1 AUG 31Time 1300 1350 1440 1330 0740 0845 0915 1612Temperature

(°C) 34.1 33.6 32.1 33.1 32.8 32.4 31.8 32.8Dissolved oxygen (ppm) 12.2 13.4 14.0 12.4 7.27 8.44 7.56 9.74pH 8.6 8.6 8.6 8.6 8.6 8.5 8.6 8.6Conductivity (Amhos/cm) 1009 1001 988 1003 1031 1024 1015 1023 C*O00 ..0 "005- '

TABLE A-2PHYSICOCHLEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH TRAP NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2011PARAMETER TN-1 TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-8Date (First Sample Period) AUG 1-2 AUG 1-2 AUG 1-2 AUG 1-2 AUG 1-2 AUG 1-2 AUG 1-2 AUG 1-2Time 1910' 1902 1854 1751 1742 1736 1702 16500645" 0650 0658 0705 0715 0740 0805 082540.8 41.0 39.2 38.9 37.9 38.5 37. 1 37.0Temperature (0 C) 39.7 39.8 38.4 38.3 35.7 37.7 36.7 36.8Dissolved oxygen (ppm) 97,17 9.30 12.0 12.55 13.5 12.08 9.04 10.903.18 3.07 3.84 3.87 6.02 4.73 5.19 6.25pH 8.6 8.6 8.7 8.7 8.6 8.5 8.5 8.48.3 8.3 8.4 8.5 8.6 8.6 8.6 8.6Conductivity (pmhos/cm) 928 971 966 957 955 958 946 941991 993 989 988 983 986 974 969Date (Second Sample Period) AUG 30-31 AUG 30-31 AUG 30-31 AUG 30-31 AUG 30-31 AUG 30-31 AUG 30-31 AUG 30-31Time 1715 1710 1700 1650 1620 1610 1552 15480700 0725 0745 0800 0830 0845 0930 0910Temperature

(' C) 35.2 35.3 34.6 34.3 32.8 34.2 32.6 32.533.3 33.3 31.8 31.8 30.1 31.2 31.3 30.7Dissolved oxygen (ppm) 11.21 11.34 12.52 13.93 13.40 12.40 9.80 9.335.76 5.76 5.58 5.73 7.61 6.52 6.99 7.99pH 8.6 8.6 8.6 8.6 8.5 8.5 8.5 8.58.5 8.5 8.5 8.5 8.6 8.6 8.6 8.61013 1014 1010 1007 1009 1008 1004 10011036 1036 1030 1031 1024 1028 1020 1011 Co.900 X~,0 P0'Top number represents subsurface readings taken 0.5 meter belox% the surface when the nets were set in the evening.bBottom number represent subsurface readings taken 0.5 meter below the surface wvhen the nets were retrieved the next morning approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> later.IN TABLE A-3PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH GILL NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2011GN-I in Deep water GN-2 in shallow water(10-13 m) (2 m)PARAMETER Surface Bottom Surface BottomDate (First Sample Period) AUG I AUG ITime 1725 1725 1640 aTemperature

(" C) 37.9 37.1 37.0 aDissolved oxygen (ppm) 12.01209.3 10.9apH 8.5 a 8.4 aConductivity (ptmhos/cm) 955 957 941 aDate (Second Sample Period) AUG 30 AUG 30Time 1610 1610 1540 aTemperature (Q C) 33. I 32.9 32.5 aDissolved oxygen (ppm) 12.7 11.3 9.33 apH 8.6 a 8.6 accConductivity (pmhos/cm) 1005 1009 1001 a .oN,-Water quality measurement not taken.

TABLE A-4PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH TRAP NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2011HN-I HN-2 HN-3 HN-4DEEP WATER BAITED DEEP WATER UNBAITED SHALLOW WATER SHALLOW WATERPARAMETER (7.5 m) (7.5 m) BAITED (2.0 m) UNBAITED (2.0 m)Date (First Sample Period)AUG I(SET)Time>.LTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (pimhos/cm)

Date (Second Sample Period)TimeTemperature (o C)Dissolved oxygen (ppm)pHConductivity (itmhos/cm) 162337.1137.lb9.048.448.5946945AUG 30(SET)152532.632.59.89.08.510041002AUG 2(LIFT)084536.836.25.395.348.6976975AUG 31(LIFT)093731.331.36.996.898.610201020AUG I(SET)163837.137.19.048.448.5946945AUG 30(SET)153032.632.59.89.08.610041002AUG 2(LIFT)090036.836.55.445.338.6976975AUG 31(LIFT)100231.331.36.996.898.610201020AUG I(SET)AUG 2(LIFT)164037.19.048.5090536.95.888.6164237. I9.048.5AUG I(SET)AUG 2(LIFT)091036.95.888.6946AUG 30(SET)153532.69.808.51004970AUG 31(LIFT)100731.36.998.61020946AUG 30(SET)153832.69.808.51004970AUG 31(LIFT)101231.36.998.6(D1020 RcoaTop number represents subsurface rcadings taken 0.5 meter below-the surface.bBottom number represent deep water readings taken 0.5 meter off the bottom.

RS-14-138 Enclosure Page 212 of 322APPENDIX BHISTORICAL WATER QUALITY AND FISHERIES DATA RS-14-138 Enclosure Page 213 of 322LIST OF TABLESReport No. Title Page No.B-I Results of Initial Braidwood Cooling Pond Survey by SEA Inc.,2001. B-iB-2 Investigation of Fish Kill on Braidwood Cooling Pond August27-28, 2001. B-5B-3 Results of Braidwood Cooling Pond Water Quality Analysisfrom August 27 and 28, 2002. B-9B-4 Fish Kill Reports going back to 2003. B- 17B-5 Braidwood Lake Fish Kill, August 21, 2007. B-19B-6 Braidwood Fish Kill August 21, 2007. B-21B-7 Braidwood Fish Kill Clean-up August 21, 2007. B-22HDR Engineering, Inc.

RS-14-283 Enclosure Page 6 of 9APPENDIX REPORT B-I.Results of Initial Braidwood Cooling Pond Survey by SEA Inc.SEA Inc. was asked to conduct an initial water quality and ecological assessment of Braidwood Cooling Pond. The objective was to determine if the densemacrophytes were contributing to an increasing trend toward a higher pH in thepond. The results and discussion presented in this report are primarily basedupon the samples taken and observations made on May 29 and 30, 2001, and ona preliminary review of water quality data from three sites taken on May 18, andJune 14, 2001. SEA Inc. was also asked to investigate a fish kill on Braidwood Cooling Pond on August 27 and 28. The results of that investigation are in aseparate report but some of that information is referenced in this report.Overview of Methods and Results Presentation.

SEA's initial survey (May 29-30) consisted of:" water quality parameters at several key sites with a Hydrolab Surveyor Ill,during both daylight and night conditions,

" measuring phytoplankton community respiration (light & dark bottle method)," identification of macrophytes and observations on their distribution andabundance, and" monitoring temperatures throughout the cooling loop.The survey results are summarized in Tables 1,2, 3, and 4. Table 1 provides theresults from key sampling sites that were selected to characterize the coolingpond. These sites were sampled three to four times over a 36-hour period.Parameters sampled with the Hydrolab included:

Depth, Temperature, Dissolved Oxygen (D.O.), pH, Specific Conductance, and Redox Potential.

Sample timesincluded midday, just before sunset, and prior to sunrise.Table 2. includes results from two sites for depth profiles, 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration light&:dark bottles, and the SX discharge.

Table 3. provides D.O. and temperatures sequentially around the cooling loop at midday. Table 4. lists the D.O. levels and% saturation at four sites prior to sunrise.

Table 5 list the water quality analysispreformed by Test America at three locations on two dates. Figure 1. is a mapidentifying the sample locations listed in the tables.Discussion of Results and Observations:

Braidwood Cooling Pond was characterized to SEA Inc. as a pond that wasdominated or choked by macrophytes.

Based on this characterization, we feelthat Braidwood Cooling Pond has undergone a transformation to a systemdominated by phytoplankton.

Although we were not prepared to sample thephytoplankton for densities and identification, it was very obvious that anB-I RS-14-138 Enclosure Page 215 of 322intensive phytoplankton bloom was in progress.

Secchi disc readings were only0.30 to 0.35 m throughout the pond. Although we were unable sample thephytoplankton, we would suspect it is dominated by Blue-Green algae(Cyanophyta),

based on the water temperatures, total phosphorous levels, highpH and apparent high densities.

Braidwood Cooling Pond appears to be a very dynamic system that receivesenergy subsidies in the form of heat, pumped circulation and make-up water fromthe Kankakee River. Several perched cooling ponds in the Midwest have hadhigh macrophyte densities in their earlier years but usually become dominated byphytoplankton if they have heavy thermal loading.

A switch to phytoplankton dominance is usually accompanied by a reduction in water transparency.

OurSecchi disc readings were about 0.3 m which is about one half of the 2 ft or0.6m)value listed in a privately produced fishing guide (Sportsman' Connection) published in 2000. Although we did not examine many of the isolated coves, wefound Milfoil ( Myriophyllum verticillatum) only in the last 1/3 of the cooling loop(Figure 1. sites7,8,9) and its abundance was spotty. The Sportsman' Connection fishing guide map had a much wider distribution of submerged, emergent andfloating vegetation and appeared to be more in line with earlier descriptions SEAInc. were given of Braidwood.

Nutrients that were previously tied up by themacrophytes are now likely being taken up by the phytoplankton.

The reducedwater transparency due to the phytoplankton bloom will limit light to thesubmerged macrophytes and likely cause further reductions.

The intensive phytoplankton bloom that Braidwood is currently experiencing mayhave more potential for adverse impacts to the biological community than onoperational impacts to the station.

The water seems to be fairly well buffered anddiurnal swings in pH were insignificant.

Analysis of the water for alkalinity couldconfirm the buffering capacity.

Blue-Green algae blooms may present problemswith D.O. levels and in some rare cases may release toxins with impact otheraquatic life.The light & dark bottle (Table 2.) and the pre-sunrise D. 0. levels (Table 4.)illustrated the intensity of the bloom. The light and dark bottles were at a 0.5 mdepth at end of the discharge canal for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Respiration in the dark bottleddepleted the initial D.O. from 10.8 mg/I (158% saturation) to 1.37 mg/I (20 %saturation).

The light bottle was supersaturated to the point the entire insidesurface was coated with oxygen bubbles and the D.O. was 11.8 (174%saturation).

The photosynthetic rate was much higher than could be measureddue to the extensive formation of oxygen bubbles in the light bottle. Thephotosynthetic rate was so high that the light bottle should have been limited to 6hours to obtain a better measurement of the gross plankton photosynthetic rate.The pre-sunrise D.O. measurements (Table 4.) also reflect the high respiration rate of the plankton community.

Most notable was Site #3 where D.O. levelsdropped to 4.1 mg/l. The midday sampling on the first day (Table 1.) wasconducted during bright and sunny conditions and D.O. levels at most sites werehigher than midday samples on the following day when it was overcast.

ThisB-2 RS-14-138 Enclosure Page 216 of 322plankton community is so productive that D.O. levels can be expected to swingrapidly.

During our survey, air temperatures were mild (high 65 F) and it waswindy both days. Under a scenario of several hot summer days, with little wind,full operation of the station, followed by a cloudy day, D.O. levels could drop tothe point that fish kills could occur. Some fish species will be already stressed byheat, saturation levels for D.O. will be lower, and high, predawn respiration ratescould create a significant problem.

Unfortunately, there are no operational changes the station can make to reduce this risk. The fish kill that did occur inlate August was apparently a result of depleted DO that most likely resulted fromthe phytoplankton bloom die off.Thermal refuges are critical to the survival of fish in heavily loaded cooling ponds.The deeper areas in the warmer end of the lake will not be refuges sinceadequate levels of oxygen are already absent from depths below 4 meters (Table2.). However, the flow and slightly cooler temperatures at site 7 (figurel.)

havemaintained oxygen levels down to nearly 10 meters. If these refuges are erodedaway during the summer, fishes will be stressed.

Of the three key species listedin the Sportsman's Connection for Braidwood, both the walleye and crappiewould be sensitive to D.O. at higher temperatures.

Two fish kills occurred inBraidwood this summer, the first in late July was likely related to temperature, thesecond in lake August resulted from DO depletion.

Although our expertise is not in water chemistry, Braidwood Cooling Pond maybe facing some water quality issues. One of the objectives of the survey was todetermine if macrophytes were contributing to the increasing pH. A chart of pHvalues from 1989 to 1998 provided by the Braidwood Station indicated theincreasing trend in pH has become more pronounced since 1997. Since thissurvey indicated macrophytes abundance was in a sharp decline, it is clear theyare not contributing to the elevated pH of 9.1 to 9.2 (Table 1). The intensive phytoplankton boom present during the survey could have contributed to theelevated pH. The phytoplankton bloom had crashed by August 27 and 28 (fish killinvestigation) and the pH had dropped to 8.6. It was not possible from this limiteddata to determine to what extent several factors may be contributing to theelevated pH. The cooling pond's buffering

capacity, photosynthetic

activity, blowndown rate, and plant operations are all potential factors to be investigated.

The Test America analytical results from three sites on 5/18/01 and 6/14/01provides some information on water quality (Table 5). Orthro phosphate is areadily available form for plants and is quickly taken up. The detection limit listedby the lab was 0.06 ppm, which was too high to show any differences betweensites or sample dates. Orthro phosphate levels in many Illinois lakes would bebelow 0.025 ppm. Total phosphate at the plant discharge on 5/18/01 was 5.5ppm, which is very high. The Illinois General Use Water Quality standard is not toexceed 0.05 ppm in lakes or reservoirs over 20 acres. The plant appears to bethe phosphate source and one possible explanation may be scale inhibitors commonly used by power plants. Scale inhibitors are typically high in phosphates but it is generally in a form not available to aquatic plants. Total phosphate levelson 6/14/01 were lower (0.18 to 0.28 ppm) but still elevated relative to other lakes.B-3 RS-14-138 Enclosure Page 217 of 322Phosphates are a major concern as elevated levels can contribute to nuisancephytoplankton blooms.Total Suspended Solids (TSS) on 5/18/01 were high (164 ppm) at the discharge and generally higher than expected throughout the pond. It is suspected that theplankton bloom may have been responsible for much of that elevation.

This couldhave been confirmed by comparing the volatile to the non-volatile portion of theTSS.Total Dissolved Substances (TDS), total hardness,

calcium, sulfates and specificconductance are all correlated and generally exhibited increases from 5/18/01 to6/14/01.

The high evaporation rates in the cooling pond during the summerprobably contributed to this increase.

These parameters are of concern sincethey are indicators of potential scaling in heat exchangers.

Lowering these levelswould require an increase in make-up and blow-down rates. However it isrecognized there are restrictions on make up withdraws and blow-down concentrations are regulated.

SummaryIt appears that the Braidwood Cooling Pond plant community is changing fromone dominated by macrophytes to phytoplankton.

The phytoplankton bloom inMay was very rich and has the potential to deplete D.O. to the point that fish killscould occur. There are few operational changes that the plant can take to preventthese potential events. Monitoring the cooling pond and preparing regulatory agencies for these potential changes may be a way to help manage these risks.Unfortunately the fish kill in late August confirmed the potential for these kills.The phytoplankton bloom may a contributor to the increasing pH. The high totalphosphate level that appears to be coming from the plant may be fueling thephytoplankton bloom. Further investigation of the factors that may be contributing B-4 RS-14-283 Enclosure Page 7 of 9APPENDIX REPORT B-2.DRAFTInvestigation of Fish Kill on Braidwood Cooling PondAugust 27-28, 2001Executive Summary:Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of anon-going fish kill on Braidwood Cooling Pond on August 27 & 28, 2001. Theinvestigation consisted of surveying the shoreline to determine the extent of thekill and the species involved, and water quality analyses for pH, temperature, anddissolved oxygen.Most of the fish appeared to have been dead for about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than95% were gizzard shad. The other species involved in descending order ofrelative abundance were freshwater drum, quillback, carp, largemouth bass,channel catfish,

redhorse, smallmouth bass and bluegill.

Other than gizzard shadmost of the dead fish were located between the mid -point in the cooling loop tothe intake. Throughout most of the cooling pond, dissolved oxygen levels were ator below the minimum levels necessary to support most fish and was the mostlikely cause of the kill. Water clarity was very high and suggested a recent die offof much of the phytoplankton, which is usually followed by oxygen depletion.

Thisis a natural phenomenon that can occur in highly productive lakes during summermonths. Temperatures throughout most of the lake were within the tolerance limits of the species involved in the kill. It does not appear that operations of thepower station had a direct impact on the fish kill.Methods Overview and Results Presentation:

SEA Inc. arrived at 5:00 PM on August 27 and conducted an initial survey of themain portion of the cooling loop and checked temperature, dissolved oxygen(DO), and pH at two locations.

The investigation continued at sunrise on August28, and included investigation of many of the coves on the lake and water qualityanalyses at sixteen sites. Water quality analysis was conducted with a HydrolabSurveyor Ill. Measurements were for depth, temperature.

DO, pH, specificconductance, and redox potential at the surface (0.5 Meters) and then at one-meter intervals to the bottom.The water quality sampling locations are shown on Figure 1. Dissolved oxygenprofiles from selected sites are illustrated in Figure 2. Figure 3 illustrates DOconcentrations at one-meter depth at all sites. The results of the water qualityanalyses are presented in Table 1. The station hourly inlet and outlet watertemperatures for August 24 through August 27 are listed in Table 2.B-5 RS-14-138 Enclosure Page 219 of 322Discussion of Results and Observations:

Upon arrival the investigation began at the south access boat ramp near Site 3(Figure 1.) and proceeded around the cooling loop toward the plant intake. NearSite 3 several gizzard shad in the 170 to 220 mm were observed.

They appearedto have been dead for 12 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In the portion of the pond between sites5.5 and 5.75 there were greater numbers of gizzard shad along the shoreline anda few largemouth bass. The largemouth bass appeared to have been dead formore than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The number of fish appeared to increase as theinvestigation progressed around the cooling loop. The largest concentrations ofdead fish were in several coves on the East side of the lake near Site 8. Theback 20 to 35 ft. of the cover were covered solid with dead fish. Gizzard shadcomprised more than 95% of the fish in these coves and were represented bythree size classes.

The other species involved in descending order of relativeabundance were freshwater drum, quillback, carp, largemouth bass, channelcatfish,

redhorse, smallmouth bass and bluegill.

There are two factors that may have influenced the distribution of dead fish. First,the temperature gradient becomes more favorable for fish toward the intake endof the cooling loop. Second, the circulation of water around the cooping loopwould tend to concentrate dead fish in the intake area of the cooling pond. Theconcentration of fish in coves at Sites 8 and 8.5 was most likely an accumulation resulting the above mention factors and wind direction.

However DO levels atSite 8.5 were only 2 ppm (Table 1, page 3) at a time of day when they shouldhave been much higher. This level of DO is not adequate to support most fishes.Several YOY freshwater drum were observed at the surface which had recentlydied or were about to. This kill did involve many fish, but during this survey manylive fish were observed on sonar in the cooler end on the lake. Bluegills exhibiting normal behaviors were observed in the cove just East of Site 2.5.Dissolved oxygen levels at the plant intake were 3.5 ppm at the surface and 1.2ppm at 3 meters (Table 3) during the evening of August 27. Percent DOsaturation was 49% and 17% respectively.

Surface DO level taken on May 29 bySEA Inc. at this same location, at the same time of day was 9.3 ppm and 117%saturation.

The DO levels at Site 3 were 3.8 ppm on August 27 which was muchlower than the 8.0 ppm taken at sunset on May 29. On August 28 just prior tosunrise the DO at Site 3 was 3.2 ppm only slightly lower than the previousevening indicating little diurnal variation.

On May 29 the overnight drop in DO atSite 3 was 50%.The surface DO level at Site 4 on August 28 was 2.9 ppm and dropped to 0.7ppm at 4 meters. Surface DO levels Sites 4.5, 5,5.5, and 5.7 were even lowerB-6 RS-14-138 Enclosure Page 220 of 322ranging from 2.4 to 2.1 ppm. Site 6 had one of the higher DO levels at 4.4 ppm.Site 8 and 9 had the highest surface DO levels at 4.8-ppm (Table 1).Temperatures throughout most of the cooling pond were within the tolerance limits of most fish species and there had been no major temperature changes inthe last few days (Table 2). The oxygen levels throughout most of the lakesuggest that depleted oxygen levels were the most likely cause for the fish kill.Such kills can naturally occur in highly productive lakes or ponds that may exhibitlarge diurnal swings in DO levels due to high daytime photosynthetic rates andhigh respiration during the night. The survey SEA Inc. conducted on May 28 and29 suggested Braidwood Cooling Pond was a very productive and the potential existed for an oxygen depletion fish kill. This survey noted several changes in thecooling pond that suggested such a kill had occurred.

There was no indication that the fish kill was directly related to the operation of the power station.SEA Inc.'s initial investigation in May was to assess if the historically highabundance of macrophytes (rooted aquatic vegetation) was contributing anincreasing trend in pH. What was observed was an intensive phytoplankton bloom that limited light penetration and almost no healthy macrophytes remained.

Water transparency measured with a Secchi Disc was only 0.3meters. Diurnal swings in DO levels were very pronounced and at some locations dropped to 4 ppm just prior to sunrise and reached supersaturation levels by midday. Under these conditions any major change in nutrients, reduced lightintensity, increase in biological oxygen demand, or other factors could result inoxygen depletion.

Braidwood Cooling Pond appeared to be undergoing atransition from a system dominated by macrophytes to one dominated byphytoplankton.

One of the most notable changes during this investigation was the dramaticchange in water transparency.

There was no phytoplankton bloom and SecchiDisc readings had increased up to 2.7 meters. Plankton samples indicated verylow levels of phytoplankton but high abundance of zooplanktors (primarily Rotifers and Cladocera).

Oxygen levels were typically from 29% to 66% ofsaturation as opposed to May when most midday levels were at or abovesaturation.

As discussed

earlier, there were only minor differences in diurnaloxygen levels. All the above factors suggest the phytoplankton bloom hadrecently crashed.

There were no remaining macrophytes to fill the niche asprimary producers.

Not only was there a reduction in photosynthetic activity toproduce oxygen, there was an increased oxygen demand from decomposition and respiration of the abundant consumers.

It is suspected that oxygen levels aday or two prior to this investigation may have been even lower than observed.

The one-meter DO levels were lowest toward the center portion of the coolingloop (Figure 2). From Site 3 to Site 6.5 (with the exception of Site 6) DO levelswere 3. lppm or less. A similar pattern of low DO was noted at Sites 3 and 4 inearly morning samples taken in the May survey. Factors contributing to lower DOB-7 RS-14-138 Enclosure Page 221 of 322levels were not clear, but it suggest this may be one of the most sensitive areasof the cooling pond to oxygen depletion.

Additional sampling would be required toattempt to identify the cause and to eliminate any data bias associated with thetime of day samples were taken.The unique changes in water depths and flow velocities in Braidwood CoolingPond have a major influence on DO levels and temperature stratification.

Areasof the cooling pond which were deep and not in a high velocity areas exhibited amore normal DO curve from top to bottom (Figure 3). At Site 2.5, DO declinedquickly between 6 and 8 meters and coincided with thermal stratification.

At Site4, the DO declined rapidly between 2 and 3 meters where thermal stratification was apparent (Table 1). In contrast, Sites 5.5 and 7 were located in areas withhigh velocities and had fairly consistent DO levels and temperatures from top tobottom (Figure 3). This is quite different from the DO and temperature profiles inmore typical perched cooling ponds and better utilizes the entire volume forcooling and may also provide for better thermal refuges for fish. During this lastincident it is unlikely Site 5.5 was an effective refuge for DO since levels werebelow 2.5 ppm. These DO levels were however due to lower DO levelsthroughout the cooling pond irather than depletion at this site.Braidwood Cooling Pond appears to be undergoing a transition from a ponddominated by marcophytes to one dominated by phytoplankton.

During such atransition major swings may be expected as different components of thisecosystem adapt to this change. Over time one would expect the amplitude ofthese changes to moderate.

During the May survey the intense phytoplankton bloom appeared to eliminate the macrophytes.

There were major differences indiurnal DO levels suggesting a very productive system with heavy respiration anddecomposition demands at night and supersaturation from photosynthesis duringthe day. This survey indicated a major loss of the phytoplankton, no remaining macrophytes to carry on primary production and enough respiration anddecomposition to reduce oxygen below the levels to maintain many fishes.Additional studies on nutrients and the dynamics of the plankton would beneeded to better identify the changes that may be taking place in this coolingpond. Decisions on the operational management of this cooling pond as well asthe fishery management need to consider that this pond may be going throughtransitional changes.B-8 RS-14-138 Enclosure Page 222 of 322APPENDIX REPORT B-3.Results of Braidwood Cooling Pond Water QualityAnalysis from August 27 & 28, 2002SEA Inc. was asked to sample Braidwood Cooling Pond for a number of waterquality parameters on August 27, 2002. This sampling effort was to provide datato address operational concerns related to a trend toward an increasing pH andincreased scaling at the plant intake. This report provides the results of theAugust 27and 28, 2002 sampling and makes comparisons with data fromprevious sampling efforts by SEA Inc. and with other data provided by theBraidwood Station to SEA Inc.Executive Summary:Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with cooling pond blow down limits, and maintaining arecreational fishery.

Several of these parameters had significant increases in thepast year and could lead to greater operational costs and problems in the nearfuture.The excess of nutrients in the water has contributed to plankton blooms that haveeliminated the submerged aquatic plants, contributed to diurnal increases in pH,and lowered dissolved oxygen levels. Swings in the dissolved oxygen levelassociated with the plankton blooms could lead to fish kills.The plan to increase the blow down rate from the cooling pond is a good long-term solution to the continued viability of the cooling pond. Continued monitoring of the cooling lake water quality would be important in evaluating theeffectiveness of the increased blown down rate, the impacts of H2SO4 additions, and other water treatment changes.Overview of Methods and Scope of the Sampling Effort.The investigation on August 27 and 28 of 2002 consisted of collection of watersamples from various depths at six sites around Braidwood Cooling Pond (BCP),as well as in-situ profile measurements for temperature, conductivity, pH, anddissolved oxygen. A contract laboratory analyzed the water samples for theeleven chemical parameters as listed in Table 1. In addition to chemical samples,the primary production rate of the phytoplankton community was determined attwo sites by the light/dark bottle method, and plankton samples were taken forB-9 RS-14-138 Enclosure Page 223 of 322qualitative analysis.

Water transparency was measured with a Secchi disc ateach site. The sampling sites used in this investigation are identified on Figure 1.Additional investigations by SEA Inc. referenced in this report include June 28,2002, April 29,2002, March 6, 2002, January 10, 2002, August 28, 2001 and May29, 2001. The purpose and scope of each of these investigations varied but nonewere as extensive for water quality as the August 2002 investigation.

In severalcases SEA Inc. collected the water samples for Betz and the results were notmade available to SEA Inc. Data from the above referenced studies is included tohelp identify trends and provide a single summary of data for ongoinginvestigations.

The discussion of results is based on and limited to the studiesreferenced in this report and those provided to SEA Inc.Presentation of Results and Related Discussion:

The analytical results of the water quality analysis are presented in Table 1. Theeleven parameters were selected to provide input to the water quality issues thatwere described to SEA Inc. These issues include increasing trends for rising pH,scaling, algal blooms, and recent fish kills.Table 1 indicates abnormally high levels for TDS, alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus throughout the cooling pond. Thesevalues were not unexpected and support the ongoing program to increase theblow down rate from the cooling pond. These values can be put into perspective by comparing the cooling lake sites to the same values for the make -up waterpond (Site 7P in Table 1), which is the source water. The cooling pond values forthe above mentioned parameters ranged from 2X to nearly 9X higher than themake-up water.The alkalinity is a measure of water's capacity to neutralize acids and is a resultof the quantity of compounds in the water that shift the pH to the alkaline side.Bicarbonate and carbonate ions normally make up most of the alkalinity.

However in waters with a pH of greater than 8.3, carbonate alkalinity is theprimary form. Alkalinity is very high throughout the cooling pond and ranged from340 to 360 mg/I in the upper water layers (Table 1). In contrast, the make-upwater pond alkalinity was 150mg/l.

Other comparisons include a 14-year averagefor Clinton Lake of 168 mg/I and an IEPA survey of 63 lakes around the statewith alkalinity ranging from 20 to 270 mg/I. The high alkalinity gives Braidwood Cooling Pond has a great capacity to neutralize acids.Hardness is a measure of the divalent metallic cations present in water(such as calcium, magnesium, ferrous iron, and manganous manganese).

Calcium reacts with bicarbonate ions in water to form calcium carbonate B-10 RS-14-138 Enclosure Page 224 of 322scale. Magnesium typically reacts with sulfate; the ferrous ion withnitrate; and the manganous ion with silicates.

Hardness and alkalinity in water are related.

Carbonate hardness is the part oftotal hardness that is chemically equivalent to the bicarbonate plus carbonate alkalinities present in the water. If alkalinity is greater than total hardness thentotal hardness is equal to the carbonate hardness.

In cases such as in BCPwhere alkalinity is less than the total hardness then alkalinity equals carbonate hardness (as CaCO3) and the remaining part of hardness is the noncarbonate compounds such as magnesium sulfate.The total hardness in the upper layers of August 2002 samples ranged from 680to 720 mg/I (nearly twice the alkalinity level) so other ions are contributing significantly to the hardness.

The total hardness levels in 2002 were significantly higher than the 435 to 531mg/I range reported for two dates in 2001 by TestAmerica (Table 2). This increase in hardness is a reason for concern.Sulfate levels in the August 2002 samples ranged from 330 to 390 mg/I (Table 1).These levels are much higher than the make up water (58 mg/I) and to someextent may reflect the history of portions of the cooling pond as strip mine lakesthat are characteristically high in sulfates.

However there seems to be asignificant increase in sulfates in the past year. In the Test America data from twodates in 2001, sulfates ranged from 230 to 270 mg/I (Table 2). Sulfate levels insamples collected by SEA Inc. on April 29, 2002 were 250 mg/I (Table 3).Samples collected by SEA Inc. on June 28,2002 had levels ranging from 320 to340 mg/I (Table 4). The sulfate increase noted in the summer of 2002 may reflectthe use of H2SO4 to reduce pH levels in the cooling pond. This level of sulfatesmay be a concern since it significantly contributes to the non-carbonate hardnessand can be a factor in scaling.Calcium levels in the August 2002 samples were about twice the levels in2001 and ranged from 130 to 140 mg/I (Table 1). The 2001 Test America dataranged from 41 to 58 mg/I (Table 2) and the make-up water in August 2002 was57 mg/l. The increase in calcium may be a major concern since with the highcarbonate alkalinity there is a high potential for scaling.Magnesium levels in the August 2002 sampling ranged from 84 to 93 mg/I. Theselevels were essentially the same as the 81 to 91 mg/I reported by Test America in2001. Magnesium levels are however elevated compared to the make-up waterthat had only 20mg/I or when compared to the 14-year average for Clinton Lakeof 32.2 mg/l. Magnesium levels are also a concern due to their potential forscaling.Total dissolved solids include all of the above parameters and other dissolved solids in the water. As would be expected, the August 2002 samples are elevatedand are higher than the previous year. The August 2002 TDS ranged from 930 toB-1 I RS-14-138 Enclosure Page 225 of 3221100 mg/I (Table 1) compared to a range of 684 to 788 in the 2001 Test Americadata (Table 2). The make-up water was 280 mg/I in the August 2002 sample.Sodium levels in the August 2002 samples ranged from 60 to 64 mg/I in theupper water layers. Comparable data from 2001 was not available, but thesodium levels in the make-up water was 9.1 mg/I in the August 2002 sample(Table 1).There were only minor variations in the concentrations of the above parameters from site to site in the upper water layers. Sulfates and TDS were slightly higherat the discharge (Site 2) end of the cooling pond. Levels for alkalinity,

sulfates, TDS, and total hardness were slightly lower near the bottom at the 10 and 11-meter depths at Site 4 and Site 7 respectively.

Phosphorus and nitrogen are essential nutrients for aquatic plants.Concentrations in the water are typically low since phytoplankton or macrophytes quickly assimilate these nutrients.

Total phosphate levels in the August 2002samples were at 1.5 mg/I throughout the cooling pond (Tablel).

Samplescollected on April 2002 ranged from 1.3 to 1.6 mg/I (Table 3). Total phosphates at two sites in the June 2002 samples were 1.8 mg/I (Table 4) in the upper waterlayers and 4.9 mg/I at a well stratified, 10-meter depth at Site 4. The TestAmerica data for 2001 had total phosphate levels from 0.16 to 5.5 mg/I (Table 2).The 5.5 mg/I occurred at the discharge on May 18 of 2001 and levels dropped to0.77mg/I at the plant intake on the same date. This suggests the Station was thesource of the phosphate.

Although the levels were slightly lower in 2002, theywere consistent throughout the cooling pond suggesting that phosphates are inexcess and not a limiting factor for phytoplankton.

The total phosphate levels inthe make- up water were 0.12 mg/I and 0.19mg/I in June (Table 4) and August of2002 respectively.

Relative to most lakes the phosphate level in BCP is quite high. Since BCP is acooling pond and not a lake, it is not subject to the Section 302.205 regulation that limits phosphorus in a lake of 20 acres or more to < 0.05mg/l.

The highphosphate level is of concern since these levels support phytoplankton bloomsand the breakdown of the phosphorus compounds can also contribute toincreased pH.Ortho-phosphate is the form that is most readily available to aquatic plants.These levels are usually very low in lakes since plants normally take it up withinminutes.

Ortho-phosphate levels were consistent throughout the lake in theAugust 2002 samples and ranged from 0.38 to 0.44mg/I.

Like the total phosphate levels, the ortho-phosphate levels are consistently high suggesting it is in excessof the needs of the phytoplankton.

The August 2002 levels were significantly higher than the <0.06mg/I reported by Test America in 2001 (Table 2). Ortho-phosphate level in the make-up water was 0.19 and although lower than the lakelevels is relatively high.B-12 RS-14-138 Enclosure Page 226 of 322Nitrate-nitrites are the other essential or potentially limiting nutrient forphytoplankton.

The August 2002 nitrate-nitrate levels were rather low in most ofBCP with the highest level of 0.1mg/I at the discharge.

The rest of the coolingpond ranged for <0.01mg/I (below detection limit) to 0.08 mg/I in the upperwaters. Unlike most other parameters, the nitrate-nitrite level in the make-upwater was significantly higher at 2 mg/I (Table 1). Nitrate-nitrite data could not becompared to the 2001 Test America data because the detection limit of 1.0 mg/Iwas too high for a meaningful assessment.

The ratios of phosphates to nitrates-nitrites suggest BCP would be described asa nitrate-nitrites limited water rather than phosphate limited with respect tophytoplankton growth. However the limited phytoplankton data that SEA Inc. hascollected on BCP suggests that bluegreen algae dominate BCP for much of thesummer. Bluegreen algae have the unique ability to utilize atmospheric nitrogenand are not as limited by low nitrate-nitrite levels. Bluegreen algae made up 88.5% and 76.4% of the algae at Sites 3 and 7 respectively in the August 2002sample. The dominant bluegreen algae were Lynabya and Oscillatoria.

Bluegreen algae are the least desirable algae and are favored by high pH andwarmer temperatures.

Bluegreen blooms can impart a smell or taste to water,deplete dissolved oxygen, and in some cases generate toxins that may impactaquatic life.The ammonia levels appear reasonable relative to the high productivity in BCP.As productivity increases and oxygen is reduced at deeper depths there may beincreases in ammonia.

The abnormally high level at 5 meters at Site 9 (Table 1may have resulted from the water sampler disturbing the bottom sediments where ammonia is likely to be higher.The aquatic plant community in BCP appears to have undergone a change in thelast two years. SEA Inc.'s first investigation of BCP on May 29, 2001 was toassess the impact of the extensive growth of macrophytes (rooted aquatic plants)on the pond's increasing pH. That investigation found an extensive phytoplankton bloom and the few macrophytes that remained were being shaded out by thephytoplankton bloom. SEA Inc. projected that BCP was changing from amacrophyte dominated water to a phytoplankton-dominated water and that wouldsee more plankton blooms. The phosphate levels from the 2001 Test Americadata suggested there was an excess of phosphorus to support those blooms.Based upon SEA Inc.'s 2002 observations, BCP has transformed into aphytoplankton dominated water and is experiencing regular plankton blooms.This change not only reflects an increasing load of nutrients in BCP but alsocreates a higher risk to the fishery.

As plankton blooms come and go they cancreate oxygen depletion problems that impact fishes and other aquatic life.SEA Inc. has measured the primary production rates as an index to the activity ofthe plankton community.

The rate of oxygen production by the planktonB-13 RS-14-138 Enclosure Page 227 of 322community is measured in a light (clear) bottle and the plankton respiration (oxygen depletion) is measured in a dark bottle. In the first measurement in Mayof 2001, there was so much oxygen production in the normal 24 hr measurement period that the oxygen was super saturated and only a portion could bemeasured (Table 5). Subsequent measurements were limited to shorter timeperiods and provided a more useful index. The highest primary production ratewas 1.525 mg/I of 02/hr at Site 9 (Intake) on June 28, 2002. This correlated wellwith the highest chlorophyll a level provided by the Braidwood Station (Figure 2).In the August 2002 measurement, the rate at Site 9 had dropped to 0.653 mg/I of02/hr. This rate correlated with lower chlorophyll levels that occurred throughout most of August. Temperatures during the August 28,2002 measurements werehigh enough at the discharge (Site 2) to suppress photosynthetic activity.

Thetemperature at the discharge was 115.10 F (Table 5) and the intake (Site 9)temperature was 92.20F and the corresponding production rates were 0.142 and0.653 mg/I of 021hr respectively.

The temperature suppression of photosynthesis and an apparent die off of a phytoplankton bloom may account for the lowdissolved oxygen levels observed during the August 2002 sampling.

All of sampling by SEA Inc. has involved in-situ sampling with a HydroLab fortemperature, dissolved oxygen, pH, and specific conductivity.

The data from all2002 HydroLab sampling is presented in Tables 1,3,4,6, and 7.The dissolved oxygen (DO) levels on August 28 of 2002 were notably lower thanthe same date in 2001 (Table 6). As lakes undergo eutrophication andproductivity increases, the DO level can exhibit wide diurnal changes that maystress aquatic life. Afternoon DO levels may rise to supersaturated levels, butduring the night and early morning hours respiration demands may nearlydeplete the DO and can result in fish kills. There also becomes a morepronounced difference in DO levels between the upper and lower layers of thewater column due to increased oxygen demand from decomposition.

Dissolved oxygen levels at the same four sites in August 2001 and 2002 arecompared in Figure 3. These comparisons indicate that the DO levels weregenerally lower at the same sites in 2002, were slower to rise during the day, andthere was a greater differences between depths. Site 2 and Site 2.5 illustrate thelower DO levels in 2002 even later in the day when it should rise, Oxygen levelswere less than lppm at 2 meters and below. Site 4, 2002 levels reflect theincrease in DO later in the day compared to earlier in the day in 2001.. Theconsistent drop in DO at 4 meters is typical of a stratified site. At Site 7 the higherDO in 2002 reflect the later time of day than the 2001 sample. However the moresignificant difference is the drop in DO with increasing depth in 2002. This dropsuggests a more productive system that has a higher demand for oxygen in2002. Site 7 has good flow and in 2001 had a nearly constant DO level down tothe bottom and provided a good thermal refuge for fish. In 2002 the area below 6meters would be stressful for most fish. The Site 9 AM chart again demonstrates the 2002 DO level was lower even when taken later in the morning than the 2001B-14 RS-14-138 Enclosure Page 228 of 322sample. The Site 9 PM chart shows some recovery of DO level in the midafternoon but levels are still below 4ppm. The more rapid drop in deeper samplesfrom the 2001 most likely reflects the loss of late afternoon light to the deeperdepths.The 2002 DO curves appear to reflect a more eutrophic environment that mayplace additional oxygen stress on the fishery.

During the August 2002 samplingthere were dead and dying gizzard shad from Site 2 to Site 4. The combinations of stress from the low DO and warmer temperatures were the most likelyexplanation for the loss of these fish. This loss was not extensive enough to havea significant impact on the fishery.

No other species were involved in the kill butsmall bluegills were exhibiting some signs of DO stress. As BCP continues tobecome more eutrophic the DO stress may be a greater problem for the fishery.The increasing pH levels have been a concern in BCP. Comparison of HydroLabdata from August 28 in 2001 (Table 6) and 2002 (Table 1) indicated only a littlevariation in pH. During the summer of 2002 the Station was adding H2SO4 intothe circulating water. The impact was only apparent at Site 2 (discharge canal)and Site 3. The 2002 samples collected in the morning hours at Site 2 rangedfrom 8.34 to 8.38 compared to 8.5 in 2001 (Table 2). At Site 3 the 2002 levelsranged from 8.35 in the morning to 8.54 at midday compared to a range of 8.'4 to8.6 in 2001. The pH levels at Sites 4,7 and 9 had slight variations depending upon time of day but had similar ranges in 2001 and 2002. With the highalkalinity levels in BCP, it is not surprising that the addition of H2SO4 did notresult in larger changes.

This assessment is also based on only a few datapoints. Correlating H2SO4 feed rates with continuous pH monitoring at the intakewould provide more reliable information on the effects of the acid additions.

Questions have been raised on the impact of the phytoplankton on the increasing pH levels. As phytoplankton carries on photosynthesis and extract C02 from thewater it increases the pH. This however may not be as apparent in BCP due tothe high buffering capacity (alkalinity).

In general the higher pH levels in theafternoon reflect the photosynthetic activity.

Conversely the lower pH levels in theearly morning samples reflect the increase in C02 resulting from respiration during the night. The role of phytoplankton in increasing pH is quantified in themeasurement of primary productivity.

A comparison of the starting pH with theending pH in the light bottles illustrates the change due to photosynthesis.

ThepH during the 24-hour measurement on May 29, 2001at Site 2 went from 9.22 to9.52 (Table 5).Summary and

Conclusions:

Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with blow down limits, and maintaining a recreational B-15 RS-14-138 Enclosure Page 229 of 322fishery.

The additional of treatment chemicals and evaporative loss of therecycled cooling water with limited blown down rates are most likely the primaryfactor in the increased levels of these parameters.

The make-up water does nothave elevated levels of the above-mentioned parameters.

With increasing capacity factors and increasing concentrations for these parameters in thecooling water, water treatment costs and operational concerns are likely toincrease.

Baseline water quality data is important in evaluating options and solutions toaddress water quality in the cooling pond. The comparison of the August 2002sampling to the 2001 Test America data indicated significant increases in totalhardness,

sulfates, and calcium in the past year. Increases of this magnitude canbe important predictors of future problems.

Critical assessments of the impact ofH2SO4 additions and other treatment changes are dependent upon havingpretreatment and post treatment data. The plan to increase the blow down ratefrom BCP is a good long-term solution to the continued viability of the coolingpond. The effectiveness of increasing the blown down rate from BCP can bequantified by continued monitoring of the cooling lake concentrations.

The high nutrient levels in BCP will continue to cause plankton blooms. Unlikemany waters, phosphates appear to be in excess and nitrates are more of alimiting factor. However, bluegreen algae appear to be the dominant summerform and are not as limited by low nitrates as other algae. The primary production measurements did correlate fairly well with chlorophyll a levels and were a goodindex to the productivity of BCP. The primary production measurements alsoillustrated how much of an influence phytoplankton have on diurnal increases inpH.Algal blooms are occurring in the pond and based on two comparable samplings, appear to be influencing the DO levels. The DO levels in the early hours weregenerally lower in 2002 than in 2001 and the DO at a deep site experienced adecline with depth that did not occur in 2001. These changes suggest a trendtoward an increasing rate of eutrophication.

If nutrient levels continue to increasethe potential for fish kills associated with oxygen depletion resulting from theblooms would also increase.

Jim SmithsonSEA Inc.11/04/02B-16 Fish Kill Reports Going Back to 2003 Page I of 2RS-1-4-138 APPENDIX REPORT B-4. Enclosure Page 230 of 322Fish Kill Reports Going Back to 2003john.petro@exeloncorp.com

[john.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:42 PMTo: leremlah.Haas@exeloncorp.com 2003There were no fish kills in Braidwood Lake in 2003.Jet30 2_00P4Investigated a fish -mortality lnJuly 3_0 2001 Ost fish were in the advanced state of decay by the timethe kill was investigated..Gi.ZZard shad were the dominantspechies involved although channel catfish wereogbservedas well.lDuring this investigation, thelshallow water near shore was teaming with whichunderl m agnlfilclation.proved to be d aphnia as well as Cypris, which is an Ostacod resembling a small clam.Temnperature/dissolved oxygenprofi~les were conducted in early October.

Water temperature just north ofthe south boat access was 29.2-°C/84.5° 0F at a depth of one foot with a dissolved oxygrenreading.l9fl3.8 pplm, a pHof 8l.03 and a secchi disk-reading of 2.1 feet., Readings were somewhat improved in the area nearthe realngqclVlelll..In a location several _hun'dred feet from the lake mak -up, more favorable_dissoLved oxygen levels were found. At one foot, a water temperature of 26.5 9C/79.7 OF with a dlissolved&

oxygenreading of 7.6 and aopH of 847 were observed.

Waterl temperature showed minimal decrease to 40_feetwhile the dissolved oxgen declined to 5.3 pp~m.June 28, 2005 Fish KillAn on the water inspection of a thermal fish kill was conducted on June 28, 2005. No formal counts weremade however field assessments indicate a fairly significant kill that involved a variety of species including (in no specific order) gizzard shad, threadfin shad, common carp, channel catfish, quillback carpsucker, black bass. Gizzard shad were the most numerous species effected by this kill and fish carcases wereobserved at most all areas of the lake that were checked.August ..27-.28, 2007 Fish KillRob Miller, IDNR investigated a thermal kill on August 27 and 28, 2007 and conducted temperature/dissolved oxygen evaluations.

The majority of the dead fish which were observed were largegizzard shad and threadfin shad up to 5 inches in length. Channel catfish were also prevalent.

Only a fewcommon carp and black bass were observed and no bluegills were noted. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in close proximity of the boat ramp and thebank fishing area. The number of dead fish observed decreased towards the south (hot) side of the lake.At a point several hundred yards from the south ramp surface water temperature was 35.3 C/95.9 F anddissolved oxygen was near 3ppm.The following are data which were collected at the north ramp at the time the fish kill was beingB-17https://hdrwebmail.hdrinc.com/owa/?ae=Item&t=IPM.Note&id=RgAAAACNOxuwhEe8R...

12/8/2009 Fish Kill Reports Going Back to 2003 Page 2 of 2RS-14-138 Enclosure Page 231 of 322investigated:

Time Temperature (0C) Dissolved Oxygen (ppm)12:10 30.3 3.114:25 33.1 5.415"30 33.5 6.716:58 33.9 5.9Investigationolf Fish Kill onBraidwood Cooling Pond_(August 27-28. 2007)Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of an on-going fish kill onBraidwood Cooling Pond on August 27 A 28, 2007. The investigation consisted of surveying the shoreline todetermine the extent of the kill and the species involved, and water quality analyses for pH, temperature, and dissolved oxygen.Most of the fish appeared to hove been dead for about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than 95% were gizzardshad. The other species involved in descending order of relative abundance were freshwater drum,quiliback, carp, largemouth bass, channel catfish,

redhorse, smallmouth bass and bluegill.

Other thangizzard shad most of the dead fish were located between the mid -point in the cooling loop to the intake.Throughout most of the cooling pond, dissolved oxygen levels were at or below the minimum levelsnecessary to support most fish and was the most likely cause of the kill. Water clarity was very high andsuggested a recent die off of much of the phytoplankton, which :is usually followed by oxygen depletion.

This is a natural phenomenon that can occur in highly productive lakes during summer months.Temperatures throughout most of the lake were within the tolerance limits of the species involved in thekill. It does not appear that operations of the power station had a direct impact on the fish kill.B-18https://hdrwebmail.hdrinc.com!owa/?ae~ltem&t~lPM.Note&id=RgAAAACNOx\uwhrc8R...

12/8/2009 FW: Braidwood Lake Fish Kill Page 1 of 2RS-14-138 Enclosure APPENDIX REPORT B-5. Page 232 of 322FW: Braidwood Lake Fish Killjohn.petro@exeloncorp.com

[John.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:31 PMTo: Jeremlah.Haas@exeloncorp.com

---

Original Message -----From: ROB MILLER [mailto;ROB.M.ILLERf.

i ilinois.gov]

Sent: Tuesday, August 21, 2007 8:26 PMTo: JOE FERENCAK; STEVE PALLOCc: Petro, John R.; CHRIS MCCLOUD; LARRY DUNHAM; MIKE CONLIN

Subject:

Re: Braidwood Lake Fish KillI was contacted by John Petro and Tim Meents (Braidwood Station) thismorning at 11:20 but due to bad accident on 1-55 was somewhat delayed inarriving at the lake. When I got there (3:00) 1 met with Exelonbiologist Jeremiah Haas. Jeremiah had arrived earlier and had takendissolved oxygen/temperature readings.

He and I toured the lake via hisboat to assess the extent of the kill. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in closeproximity of the boat ramp and the bank fishing area. The number of deadfish we observed decreased as we traveled towards the south (hot) sideof the lake. At a point several hundred yards from the south ramp, wetook a reading and returned to the north ramp to meet up with JohnPetro. At this location water temperature was 35.3C and dissolved oxygenwas near 3ppm. The following are data which were collected at the northramp:Time Temp. (C) Dissolved Oxygen (ppm)12:10 30.3 3.114:25 33.1 5.415:30 33.5 6.716:58 33.9 5.9Based on the declining trend in d.o., it is possible that more fishcould succumb throughout the night.The majority of the dead fish which were observed were large gizzardshad and threadfin shad up to 5 inches. Channel catfish were alsoprevalent.

Only a few common carp and black bass were observed and nobluegills were noted. SET Environmental had arrived at the north rampand were conducting clean-up operations at 5:00. I will be attended theAFS Continuing Education course in Monticello tomorrow and thursday.

Ifyou need any further information, or if there are any furtherdevelopments, please contact me at 815/409-2426.

Thanks.RobRob MillerB-19https://hdrwebmail.hdrinc.com/owa/?ae=Item&t=J PM.Note&id=Rg\AAAACNOx uw, hl t8R.... 12,:H;2009 FW: Braidwood Lake Fish Kill Page 2 of 2RS-14-138 Enclosure Page 233 of 322District Fisheries Biologist Illinois Department of Natural Resources 13608 Fox RoadYorkville, Illinois 60560630/553-6680 rob.miller@illinois.gov

>>> STEVE PALLO 08/21/07 12:10 PM >>>Just got off phone with John Petro, Environmental Manager for Exelon.John wanted to report a moderate gizzard shad kill at Braidwood CoolingLake, and a minor kill of catfish.

Rob Miller, District Fisheries Manager was already notified.

Water temps in the lake had dropped some12F recently, there are no obvious power plant operational changes orpermit exceedances.

Exelon is arranging to have the fish picked up.B-20https://hdrwebmail.hdrinc.com/owa/?ae=ltem&t=IPM.Note&id=RgAAAACNOxuwhEe8R...

12/8/2009 FW: Braidwood Fish Kill 8-21-07 Page I of* IAPPENDIX REPORT B-6. RS-14-138 Enclosure Page 234 of 322FW: Braidwood Fish Kill 8-21-07john .petro@exeloncorp.com

[Bohn.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:28 PMTo: Jeremiah.Haas@exeloncorp.com

---

Original Message----

From: Haas, Jeremiah 3.Sent: Tuesday, August 21, 2007 9:02 PMTo: Petro, John R.; Tidmore, Joseph W.; Meents, Timothy P.Cc: Hebeler, Ronald L,; Neels, Vicki J.; Steve Pallo (E-mail);

Haas, Jeremiah J.

Subject:

Braldwood Fish Kill 8-21-07All,Here's the quick and dirty of the incident.

I'll right something more formal in the morning.I arrived at Braidwood Lake at 12:00 and took a dissolved oxygen (DO) reading from the ramp dock which extendsabout 30 feet into the lake. The DO was 3.1 ppm w/ a temp of 30.3 C. Several thousand gizzard and threadfin shadwere floating across most all visible areas of the lake. The currents within the lake were visible with the dead fishmovement.

Also seen were dozens of channel catfish, most of which were adults from 3-15 lbs. Shad ranged from 4 -13 inches with the shorter fish being predominately threadfin and the larger ones being gizzard.

At this time I informedJohn P. of the DO situation and began setting up the boat for additional surveys.

During the entire day, no otherspecies was observed that counted more than 2 individuals.

I took several water readings throughout the afternoon before Rob Miller (IDNR biologist responsible for Braidwood Lake) arrived.

We did a quick boat survey throughout the lake, including the pockets that are not part of the coolingloop. These areas showed the same readings as the rest of the lake, During this time we had a few hours of directsunshine and DO reading rose as high as 6.7 ppm @ 15:30.Rob and I determined that the DO crash was a result of the past several days cloud cover and subsequent die-off ofphytoplankton.

The decay of the phytoplankton would have been sufficient to lower the DO available to the fish duringthe overnight hours. We also observed the DO beginning to lower @ 16:58 (5.9 ppm) and believe that there is anopportunity to see similar results tomorrow and possibly a few more days depending on the weather conditions.

A local newspaper reporter did arrive on site, took photos, and asked questions.

She was familiar with Braidwood Station's Site Communicator and said she would be in contact with them. Rob explained the cycle that was occurring in the lake several times to the reporter.

All in all, I believe that Rob and I are both comfortable with the explanation for the action that occurred to cause thefish kill. This is similar to the "annual" fish kill seen at Braidwood, but the densities were higher than the past fewyears. There is a survey of the lake scheduled for October and, if possible, I will be at the site for that.___. Exe-lonJeremiah J HaasPrincipal Aquatic Biologist Quad Cities Nuclear Station309.227.2867 jeremiah.haas@exeloncorp.com B-21https://hdrwebmail.hdrinc.com/owa/?ae=ltem&t=IPM.Note&id=RgAAAACNOxuwhEe8R...

12/8/2009 RS-14-138 Enclosure Page 235 of 322APPENDIX REPORT B-7.Braidwood Fish Kill Clean up8/22&23/07 I worked with SET Environmental to clean up a fish kill.This was a major kill and our clean up efforts were confined to the area nearNorth boat ramp on the intake end of the lake. SET had been working on the killfor one or two days when I was called to provide assistance.

A total of about 24cubic yards of fish were removed in this clean up. The species involved indecreasing order of abundance were: gizzard shad (large fish), channel catfish,bluegill, green sunfish, flathead

catfish, bigmouth

buffalo, quillback andlargemouth bass.I went up in the restricted arm toward the intake and found huge masses of fishin the back of several coves. There were areas 50 to 75 ft by 100 ft of solidfloating mats of fish in these coves. We picked up 12 flathead catfish that wouldhave averaged near 50 lb. each. On the second day when we returned to thesecoves we counted as many large flathead catfish that we had picked up theprevious day. They were in a state of decomposition that prevented up frompicking them up.We did not take any water quality measurements or examine other parts of thelake in this clean up effort. From my past work on this cooling pond, I wouldsuspect a combination of DO depletion and high water temperatures caused thisfish kill. The plant did not report any abnormal operation conditions prior to thekill. Since 2001 when we first worked on this cooling pond we have seen a switchfrom macrophytes to phytoplankton with blue green dominating.

We havemeasured wide diurnal swings in DO levels even in the upper part of the watercolumn in late summers.

Even with the strong circulation from the circulating water pumps there is mid summer stratification and DO depletion in the deeperareas.Jim SmithsonSEA Inc.B-22 RS-14-138 Enclosure Page 236 of 322Attachment

1. 2 to Response

-- RAI # AQ-12b RS-14-138 Enclosure Page 237 of 322BRAIDWOOD STATIONBRAIDWOOD LAKE ADDITIONAL BIOLOGICAL SAMPLINGPROGRAM, 2012Prepared forEXELON NUCLEARFebruary 2013HDR Engineering, Inc.Environmental Science & Engineering Consultants 10207 Lucas RoadWoodstock, Illinois 60098 RS-14-138 Enclosure Page 238 of 322BRAI WOOD STA.TIONBRAIDWOOD LAKE ADDITIONAL BIOLOGICAL SAMPLINGPROGRAM, 20121'4Prepared forEXE'LON !NUCLEARWýrenille, Illiniois HDR.Engineering, Inc,Environmental Sciifiec

&

Itants1.0207 Lucas RoadWoodstock,

llinois, 60098 RS-14-138 Enclosure Page 239 of 322ACKNOWLEDGMENTS The field work and data analysis for this project was conducted by HDR Engineering, Inc.(HDR). Particular appreciation is extended to Rob Miller of the Illinois Department of NaturalResources (IDNR), Jim Smithson of Strategic Environmental

Actions, Inc. (SEA), and John Petroof Exelon Nuclear for providing historical fisheries and water quality data.This report was prepared by HDR and reviewed by Exelon Nuclear.

A special debt of gratitude is owed to the environmental staff at Braidwood Station and in particular Mr. Jeremiah Haas ofExelon Nuclear for his technical assistance, cooperation, and guidance during the preparation ofthis document and the study plan. Mr. Haas's experience and insight has been invaluable and isgreatly appreciated by the authors.HDR Engineering, Inc.

RS-14-138 Enclosure Page 240 of 322ABSTRACTHDR Engineering, Inc. (HDR) was contacted on March 12, 2009 by Braidwood NuclearGenerating

Station, requesting HDR to design and conduct a fish sampling program at Braidwood Lake. The information gathered during that study was to be used by Exelon to develop aneffective sampling program and set of procedures that could potentially predict fish die-offs in thecooling lake. That same sampling program was conducted again in 2010, 2011, and 2012 withonly minor changes to the original program design.Large die-offs of fish at Braidwood Lake could potentially challenge the integrity of the traveling screens at the Station.

With advanced

warning, the Station could be informed of a potential reportable event; regulatory agencies could be notified in advance; and crews responsible for fishcleanup and disposal could be put on alert to manage the risk associated with a substantial fish die-off. Currently, there are no practical or simple methods that can be used to predict or prevent theoccurrence of fish die-offs at Braidwood Lake.Sampling has been conducted at Braidwood Lake by the IDNR since 1980. From 1980 through2009 IDNR (Illinois Department of Natural Resources) collected 49 taxa of fish. In comparison, thirty-four taxa representing ten families have been included among the 8787 fish collected byHDR since 2009. Several taxa listed as collected by IDNR from 1980 to 2009 have not beencaptured by HDR. Many of the species listed by IDNR were only rarely captured, have not beencaptured during recent years, or represent taxa that were stocked.

However, six species and onehybrid have been captured by HDR that have not been collected during IDNR sampling efforts.They included shortnose gar, smallmouth

buffalo, bigmouth

buffalo, fathead minnow, rosyfaceshiner, shovelnose tiger catfish, and hybrid striped bass.In 2012, 23 taxa of fish representing eight families were included among the 1914 fish capturedby electrofishing, hoop netting, gill netting, and trap netting.

The relative abundance of speciescollected during the course of these studies is similar to those reported by IDNR in recent years.Braidwood Lake is dominated by warmwater species including gizzard shad, threadfin shad, carp,HDR Engineering, Inc.

RS-14-138 Enclosure Page 241 of 322channel catfish, flathead

catfish, largemouth bass, bluegill, and spotfin shiner. No threatened orendangered species have been collected by HDR since these studies were initiated in 2009.Water quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection.

Water temperature (C), dissolved oxygen (ppm), pH, andconductivity

(/rnhos/cm) measurements were taken 0.5 m below the water surface at eachsampling location.

In addition, water quality was also measured approximately 0.5 m off thebottom at all three of the deep water collection sites (Location GN-1, HN-1, and HN-2).Water temperatures during the August sampling period were warmer (30.3 to 35.1 "(C) than thoseobserved during the September sampling period (27.4 to 33.60C) in 2012 because of the unusually hot and humid conditions that existed throughout the Midwest during July and early August.Diurnal swings in dissolved oxygen (DO) were observed at the lake with DO ranging from 4.6 to11.5 ppm in August and from 4.3 to 13.2 ppm in September.

Dissolved oxygen readings weregenerally slightly higher during the second sampling effort in September.

Cursory observations by the field crew indicated that the water color appeared greener during the September samplingdates. This suggests that an increase in the phytoplankton population occurred within the lakebetween the first and second sampling period, which would explain (coupled with cooler watertemperatures) the slight increase in oxygen levels noted in Braidwood Lake during September.

Examination of pH data collected during these studies show pH ranged from 8.5 to 8.8 during thefirst sampling effort and from 8.7 to 9.0 during the second sampling effort. Conductivity rangedfrom 1081 to 1114 jimhos/cm in August and from 1160 to 1275 armhos/cm in September.

Review of historical water quality data reported in 2002 by Strategic Environmental

Actions, Inc.(SEA Inc.) at Braidwood Lake indicates that abnormally high levels of total dissolved solids(TDS), alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus exist throughout the entire cooling loop. This is not unexpected based upon the evaporation that takes place withinthe cooling loop coupled with the relatively low make-up and blow-down flows associated withthe operation of Braidwood Station.

These elevated levels within the lake were measured at twoto nearly eight times higher than those of the make-up water from the Kankakee River. ElevatediiiHDR Engineering, Inc.

RS-14-138 Enclosure Page 242 of 322levels of water hardness are of concern to the Station because high levels have the potential toincrease problems associated with scaling at the Station.Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Studies conducted by SEA in 2002 indicated that nutrients within the cooling lake were at levels sufficiently high tocause problems associated with phytoplankton blooms. These blooms result in oxygen production 3via photosynthesis during daylight and oxygen depletion through respiration during darkness.

When algal populations crash and decompose they can produce severe oxygen depletion withinthe water column. Diurnal swings in oxygen readings have been routinely observed at Braidwood Lake during the past several years. In addition, DO levels of less than 3 ppm have been recordedat the lake immediately following fish die-offs.

Deeper portions of the lake were also reported tostratify in 2002. In the deeper zones of the lake, DO levels approaching 0 ppm and reducedwater temperatures have been measured below the thermocline.

This is noteworthy becausedissolved oxygen levels of 3 ppm and less cannot be tolerated over an extended period of time bymost fish species.

Piper et al. (1983) states that dissolved oxygen levels below 5 ppm will reducegrowth and survival for most species of fish cultured in raceways or ponds. Dissolved oxygenrequirements are dependent upon species and other factors including water temperature andacclimation period.Review of historical fisheries information that was provided to HDR indicated that five separatefish kills were reported from 2001 to 2007. Numerically, the majority of fish observed duringthese events were either gizzard shad or threadfin shad. These two species have typicallycomprised over 90% to 95% of all dead fish observed.

Remaining species included carp,freshwater drum, bluegill, channel catfish, flathead

catfish, quillback and largemouth bass. Eachof the reported fish die-offs was attributed to oxygen depletion at the lake and not the result ofspecific Station operations.

ivHDR Engineering, Inc.

RS-14-138 Enclosure Page 243 of 322TABLE OF CONTENTSPage No.ACKNOWLEDGEMENTS ABSTRACTTABLE OF CONTENTS vLIST OF TABLES viLIST OF FIGURES vii1.0 Introduction 1-12.0 Methods 2-12.1 Electrofishing 2-12.2 Trap Netting 2-32.3 Gill Netting 2-42.4 Hoop Netting 2-42.5 Sample Processing 2-52.6 Water Quality Measurements 2-53.0 Results and Discussion 3-13.1 Species Occurrence 3-13.2 Relative Abundance and CPE 3-43.2.1 Electrofishing 3-43.2.2 Trap Netting 3-103.2.3 Gill Netting 3-103.2.4 Hoop Netting 3-133.3 Length-Frequency Distributions 3-153.4 Physicochemical Data 3-223.5 Historical Information 3-243.5.1 Water Quality 3-243.5.2 Fish Kills 3-264.0 Summary and Recommendations 4-14.1 Summary 4-14.2 Recommendations 4-35.0 References Cited 5-1VHDR Engineering, Inc.

RS-14-138 Enclosure Page 244 of 322LIST OF TABLESTable No. Title Page No.3-1 Species Occurrence of Fish Collected by the Illinois Department of Natural Resources at Braidwood Lake from 1980 through2009. 3-23-2 Total Number, Weight (g) and Percent Contribution of FishCollected by all Sampling Gears from Braidwood StationCooling Lake During 2012 and 2009 Through 2012. 3-53-3 Total Catch by Method for Fish Species Collected from theBraidwood Station Cooling Lake, 2012. 3-73-4 Numbers of Fish Captured by Electrofishing at Each SamplingLocation in Braidwood Lake, 2012. 3-93-5 Number of Fish Captured by Trap Netting at Each SamplingLocation in Braidwood Lake, 2012. 3-113-6 Number of Fish Captured by Deep (GN-1) and Shallow Water(GN-2) Gill Nets in Braidwood Lake, 2012. 3-123-7 Number of Fish Captured by Baited and Unbaited Deep andShallow Water Hoop Nets in Braidwood Lake, 2012. 3-14viHDR Engineering, Inc.

RS-14-138 Enclosure Page 245 of 322LIST OF FIGURESFigure No.CaptionPage No.I)2-13-13-23-33-43-5Sampling Locations at Braidwood Lake.Length-Frequency Distribution of Bluegill Collected fromBraidwood Lake During August, 2012.Length-Frequency Distribution of Largemouth BassCollected from Braidwood Lake During August, 2012,Length-Frequency Distribution of Channel Catfish Collected from Braidwood Lake During August, 2012.Length-Frequency Distribution of Blue Catfish Collected from Braidwood Lake During August, 2012.Length-Frequency Distribution of Threadfin and GizzardShad Collected from Braidwood Lake During August, 2012.vii2-23-163-173-183-193-20HDR Engineering, Inc.

RS-14-138 Enclosure Page 246 of 32

21.0 INTRODUCTION

The Braidwood Lake Fish and Wildlife Areas are comprised of approximately 2640 acres ofterrestrial and aquatic habitat that is located in Will County, Illinois.

Braidwood Lake is ownedby Exelon and is a partially

perched, cooling lake that was constructed in the late 1970s. The lakewas filled during 1980 and 1981 with water pumped from the Kankakee River. Several surfacemined pits existed at the site prior to the filling of the impoundment.

Fisheries management activities began in those surface mine pits in 1978, prior to the creation of Braidwood CoolingLake. Originally the lake was considered a semi-private area used by employees ofCommonwealth Edison Company until the end of 1981 when the Department of Conservation (now the Illinois Department of Natural Resources) acquired a long-term lease agreement fromthe company, which allowed for general public access to the area. Braidwood Lake is currently used for fishing, waterfowl

hunting, and fossil hunting.

From the late 1970's to the present time,Braidwood Lake has been stocked with a variety of warm- and coolwater fish species.

Thesestockings include largemouth and smallmouth bass, blue catfish, striped bass, crappie, walleye,and tiger muskie. Monitoring programs have documented the failure of the coolwater stockings to create a meaningful fishery.

This is attributed to the extreme water temperatures that occurwithin the cooling lake during the warm summer months.Construction of the Braidwood Nuclear Generating Station and its associated riverside intake anddischarge structures provided an opportunity to gather fisheries information from the KankakeeRiver and Braidwood Lake. These studies were initiated to determine the effects of construction and plant operation on the river and the lake. Units I and II began commercial operation on 29July and 17 October, 1988, respectively.

Fisheries surveys at Braidwood Lake were conducted annually by the Illinois Department of Natural Resources (IDNR) from 1980 through 1992. Since1992, fishery surveys have been conducted by IDNR every other year except 1995 and 1996.Fishery surveys on the Kankakee River near the Station's intake have also been conducted annually since the late 1970's by the Illinois Natural History Survey (1977-1979 and 1981-1990),

LMS Engineers (1991-1992 and 1994-2004),

Environmental Research and Technology (1993),HDR/LMS (2005-2007),

and HDR (2008-2012).

1-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 247 of 322The objectives of the 2012 Braidwood Lake Additional Sampling Program were to:1. Conduct fish surveys at Braidwood Lake for comparison with historical data thathas been collected by IDNR and HDR Engineering, Inc.2. Summarize any existing data related to fish kills that have occurred at Braidwood Lake.3. Develop a sampling procedure or protocol that will help anticipate fish die-offs inthe cooling lake that could potentially effect Station operations.

1-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 248 of 3222.0 METHODS2.1 Electrofishing Electrofishing was conducted using a boat-mounted boom-type electrofisher utilizing a 5000 watt,230 volt AC, 10 amp, three-phase Model GDP-5000 Multiquip generator equipped with volt/ampmeters and a safety-mat cutoff switch. The electrode array consisted of three pairs of stainless steel cables (1.5 m long, 6.5 mm in diameter) arranged 1.5 m apart and suspended perpendicular to the longitudinal axis of the boat 1.5 m off the bow. Each of the three electrodes was poweredby one of the phases. Electrofishing samples were collected on 23 August during the firstsampling effort and on 11 and 12 September during the final survey period (Appendix Table A-i).The first sampling event that was scheduled for late July was rescheduled for September due toextremely warm air and water temperatures that existed throughout the Midwest in July.Therefore, the first sampling period was delayed until the third week of August to avoidunnecessary stress to the fish, field equipment, and the sampling crew. The second samplingperiod was then moved to the second week of September at the recommendation of the IllinoisDNR and Exelon.Eight locations around the dike and islands at Braidwood Lake were electrofished during both thefirst and second sampling periods (Figure 2-1). Electrofishing was conducted near the shoreline at each location to collect fish utilizing shallow water habitats.

Voltage and amperage of theelectrofishing unit was recorded at each location at the beginning and end of each sampling effort.Sampling was restricted to the period of time ranging from one-half hour after sunrise to one-halfhour before sunset. Each electrofishing location was sampled for 20 minutes.

Electrofishing effort was reduced from 30 minutes per sample in 2009 and 2010 to 20 minutes per sample in2011 and 2012. This reduced the stress and handling mortality of fish associated with the fieldcollection process with minimal impact on the data that was collected to evaluate the fishassemblage at Braidwood Lake.The electrofishing crew consisted of two people. One crew member operated the boat while thesecond crew member dipped fish from the bow of the boat. The boat operator also dipped fish2-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 249 of 3221FIGURE 2-1. SAMPLING LOCATIONS AT BRAIDWOOD LAKE DURING AUGUST ANDSEPTEMBER, 2012.2-2 RS-14-138 Enclosure Page 250 of 322whenever necessary.

When fish surfaced behind the boat the boat operator backed up to retrieveall stunned fish. All stunned fish were collected without bias of size or species.Fish at each location were put into large tubs of water in the front of the boat for analysis at theend of each 20 minute collection period. All fish were processed in the field immediately following collection at each location.

Special emphasis was placed on the return of all game fishspecies to the water as quickly as possible following field analysis.

Catches were standardized tocatch-per-effort (CPE) from actual fishing time (20 min/sample) to numbers caught per hour bydividing the total numbers of fish collected by the actual fishing time in hours.2.2 Trap NettingTrap nets were set at eight separate locations in Braidwood Lake (Figure 2-1). Each trap netconsisted of a 25-ft. lead that was 4-ft. deep and attached to a series of rectangular frames. Thelast rectangular frame was attached to a hoop net constructed of 1.5-in. (bar) mesh nylon webbingon hoops 3.5 ft in diameter.

Two separate throats were contained within each net. One waslocated in the series of rectangular frames at the front of the net, while the second throat waslocated toward the back of the net inside the 3.5 ft diameter hoop net. Trap nets were set duringlate afternoon or early evening and were allowed to fish overnight for approximately 12 hrsbefore being retrieved the following morning.

Trap nets were set on 20 August and retrieved on21 August during the first sampling period and set on 10 September and retrieved on 11September during the second sampling period (Appendix Table A-2).Fish at each location were put into large tubs of water in the front of the boat for analysis at theend of each collection period. All fish were processed in the field immediately following removalfrom the net. Special emphasis was placed on the return of all game fish species to the water asquickly as possible following field analysis.

Catches were standardized to catch-per-effort bydividing the total number of fish caught by the total number of hours the nets were allowed to fish(fish/12-hr set).2-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 251 of 3222.3 Gill NettingTwo 125-ft. long and 6-ft. deep monofilament experimental gill nets were used to collect fishfrom two locations in Braidwood Lake (Figure 2-1). Each net consisted of five separate panelsthat were 25-ft long by 6-ft deep. Bar mesh sizes of each panel were 0.5, 0.75, 1.0, 2.0, and 3.0inches, respectively.

One of the two gill nets (GN-1) was set in deep water at a depth ofapproximately 8-10 m, while the second gill net was set in shallow water (GN-2) at a depth ofapproximately 2-3 m. During the first sampling period, the shallow water gill net sample (GN-1)and the deep water gill net sample (GN-2) were set and retrieved during the late afternoon of 20August. Both nets were allowed to fish for 15 minutes before they were retrieved.

During thesecond sampling period, both the shallow and deep water gill net were set and retrieved duringthe late morning of 11 September.

The shallow water gill net was allowed to fish for 20 minutes,while the deep water gill net was allowed to fish for 15 minutes (Appendix Table A-3). Gill netset times were reduced from previous years based on the number of fish that were being capturedcoupled with concerns expressed by Illinois Department of Natural Resources.

Elevated watertemperatures in the cooling lake prohibited longer set times due to the high mortality that occurredshortly after the fish became entangled in the monofilament netting.All fish were processed in the field as they were removed from the net. Special emphasis wasplaced on the return of game fish species to the water as quickly as possible.

Catches werestandardized to catch-per-effort (CPE) from actual fishing time the nets were in the water tonumbers caught per hour by dividing the total numbers of fish collected by the actual fishing timein hours.2.4 Hoop NettingHoop nets used to collect fish at Braidwood Lake were constructed of 1:25-in.

(bar) mesh nylonwebbing on hoops 3.5 ft in diameter.

Four separate nets were sampled during each samplingperiod (Figure 2-1). Two of the four nets were set in deep water (8-10 m), while the remaining two nets were set in shallow water (1-2 m). In addition, one of the deep (HN-1) and shallowwater (HN-3) hoop nets were baited with dead gizzard shad, while the remaining deep (HN-2)2-4HDR Engineering, Inc.

RS-14-138 Enclosure Page 252 of 322and shallow water (HN-4) hoop nets were allowed to fish without bait. All four nets during thefirst sampling period in August were set during the late afternoon of 20 August and retrieved thefollowing morning on 21 August. During the second sampling period the hoop nets were setduring the late afternoon of 10 September and retrieved the following morning on 11 September (Appendix Table A-4).Captured fish from each net were put into large tubs of water in the front of the boat for analysisat the end of each collection period. All fish were processed in the field immediately following removal from the net. Special emphasis was placed on the return of all game fish species to thewater as quickly as possible following field analysis.

Catches were standardized to catch-per-effort by dividing the total number of fish caught by the total number of overnight sets conducted (fish/overnight set). Hoop nets were set and retrieved over a 16 to 18 hour2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> period of time duringboth the first and second sampling periods.2.5 Sample Processing All fish were identified to the lowest positive taxonomic level and enumerated.

For each geartype, up to 25 individuals of a species were measured for total length (mm) and weight (g) at eachlocation.

Any remaining individuals of that species were counted and weighed en masse.Minnow species (excluding carp) were counted and weighed en masse. Specimens that could notbe positively identified in the field were either photographed in the field or returned to thelaboratory for identification.

References used to facilitate identification included Pflieger (1975),Smith (1979), and Trautman (1981).2.6 Water Quality Measurements Four physicochemical parameters (temperature, dissolved oxygen [DO], pH, and conductivity) were measured in conjunction with the sampling program.

These data were collected at eachstation prior to each sampling effort. Physicochemical measurements were taken a half meterbelow the water surface at all locations prior to sample collection.

At deeper locations, temperature, conductivity, and DO were measured 0.5 m below the surface and 0.5 rn off the2-5HDR Engineering, Inc.

RS-14-138 Enclosure Page 253 of 3221 bottom. Temperature

(°C) and dissolved oxygen (ppm) were measured using a YSI Model 55handheld meter. Conductivity (4tmhos) was measured using an YSI Model 30 handheldconductivity,

salinity, and temperature meter. A Cole-Parmer pH Testerl was used to determine pH. All instruments were calibrated prior to each monthly sampling event.2-6HDR Engineering, Inc.

RS-14-138 Enclosure Page 254 of 3223.0 RESULTS AND DISCUSSION 3.1 Species occurrence.

Fish surveys have been conducted at Braidwood Lake by the Illinois Department of NaturalResources (IDNR) since 1980 when the cooling lake was first impounded with water pumpedfrom the Kankakee River. Sampling was conducted annually from 1980-1992, again in 1994, andevery other year from 1997-2011 (Table 3-1). During this 33 year period (21 years of actualsample collection),

49 taxa of fish including 47 species and two hybrids (hybrid sunfish and tigermuskie) were collected by IDNR. Gizzard shad (32.6%),

bluegill (21.7%),

common carp(18.5%),

largemouth bass (8.7%), and channel catfish (5.8%) have been the dominate speciescollected during these surveys.

The total number of taxa collected by the IDNR has ranged from12 in 1980 to 27 in 1989. Several species have been rarely collected or only occasionally observed during this 32 year period. These include yellow bass, rock bass, redear sunfish,orangespotted

sunfish, tiger muskie, grass pickerel, longnose gar, goldfish, highfin carpsucker, silver redhorse, river redhorse, blackstripe topminnow, emerald shiner, common shiner, stripedshiner, redfin shiner, slenderhead darter, johnny darter, bullhead minnow, blue catfish andmosquitofish.

All of these taxa have been collected in five or fewer of the 21 years of samplingconducted by the IDNR from 1980 through 2009. Sampling was conducted by the IDNR in2011; however, the data were not available to the authors at the time this report was prepared.

The only protected species (one fish collected in 1999) collected during these surveys has beenriver redhorse (Moxostoma carinctuin),

which is currently listed as threatened in Illinois (Illinois Endangered Species Protection Board 2009). River redhorse have been collected from theKankakee River during past sampling programs (HDR 2011 and 2012). Eighteen of the taxaidentified by the IDNR have not been captured since 1999.Braidwood Lake has been stocked with a variety of warmwater and co0lwater fish species sincethe late 1970's. Some of these species, such as striped bass, tiger muskie, and walleye, have notbeen collected in recent years following the discontinuance of those stocking programs.

Currently, the fish community is dominated by warmwater species that are more tolerant of theelevated water temperatures that exist in the cooling lake during summer months.3-1HDR Engineering, Inc.

TABLE 3-1SPECIES OCCURRENCE OF FISH COLLECTED BY THE ILLINOIS DEPARTMENT OF NATURAL RESOURCES, AT BRAIDWOOD LAKE FROM 1980 THROUGH 20092.SAMPLING YEARSTaxa 80-85 86-90 91 92 94 97 99 01 03 05 07 09 I P TOTAL %Loagnose garThreadfin shadGizzard shadGrass pickerelTiger muskieGoldlishCarpGolden shinerEmerald shinerCommon shinertri Striped shinerSpotfin shinerSand shinerRedlin shinerBluntnose minnowBulihead minnowQuiliback Highfin carpsucker Silver rcdhorseGolden redhorseShorihead redhorseRiver redhorseBlack bullheadYellow bullheadBlue catfishChannel callishFlathead catfish35644012 671239I12987 4393881 331 414I 1245 3913II 230 122 7701031 872 195 54316 <0.11697 2.720.813 32.639 0.11382 3018 412 925 925 7865 122 3 1 I108 227 285 853 385 929I 1 11 48620 204 405 4031 1 228711.7999553<0.1<0.118.50.10.135 0.114 <0.1524!I198 3 27 249 9595 75 1015721372.50.2I <0.16 786 33 135 3I 6 49II 5165165290.3<0.10.8189 183 26 66 20 3722 <0.I72031946 14II310<0.1<0.1234 313 3I 4333 0.11 <0. 1319 0.575 0.1 -u3 <0. n )3736 5.8 c_. 018 <0.1 NK) OCD39 318 362 357 463 136 364 866 384 129 2281 2 10 I I903 TABLE 3-1 (Continued).

LdaSAMPLING YEARSTaxa 80-85 86-90 91 92 94 97 99 01 03 05 07 09 11 b TOTAL %Blackstripe toplinnow 6 6 <0. IMosquito 2 2 <0. IBrook silverside ISA 192 8 9 13 6 12 50 3 5 I I 450 0.7Yellow bass I I 2 <0. IStriped boss 9 4 I I 15 30 <0. IRock bass 2 I 2 5 <0. IGreen sunfish 436 36 10 8 23 13 37 139 26 10 77 49 864 1.4Orangespoucd sunfish I 1 I 3 <0.IBluegill 1432 459 698 247 252 241 998 1754 1393 1369 2758 2280 13,881 21.7Longear sunfish 25 1 7 3 I 5 42 0.1Redear sunfish I 3 13 17 <0. IHybrid sunfish 55 18 2 I 4 9 13 8 5 7 7 129 0.2Smallmouth bass 4 42 24 17 42 17 9 3 5 3 166 0.3Largcroutll bass 1834 867 175 91 337 202 711 351 334 88 263 315 5568 8.7White crappic 107 24 10 2 3 146 0.2Black crappie 57 22 6 I 20 2 2 I I 112 0.2Johnny darter 2 2 <0.1Yellow perch 234 241 475 0.7Logpcrch 130 I1 72 6 7 226 0.4Slenderhead darter 4 1 5 <0. IWalleyc 68 220 7 8 I 3 307 0.5Freshwiler drum 19 113 8 1i 6 21 14 14 34 9 I I 255 0.4Total fish 12.753 14,244 2882 4165 1875 2536 3521 5193 3862 2957 4404 5517 63.909Total ta.xa 31 30 26 23 23 20 21 20 17 16 20 22 49Total species 29 28 25 21 22 19 20 19 16 15 19 21 47Coo)O=(00 03@_,,D'Table was reformatted firom data provided by the Illinois Department of Natural Resources.

bData was collected in 2011, but the data was not available to the authors prior to the preparation of this report.

RS-14-138 Enclosure Page 257 of 3223.2 Relative Abundance and CPE.In 2012, 23 taxa representing eight families were included among the 1914 fish collected byelectrofishing, trap netting, hoop netting, and gill netting.

Thirty-four taxa representing tenfamilies have been included among the 8787 fish collected by HDR since 2009 (Table 3-2).Several species that were listed as collected by the IDNR during surveys conducted between 1980and 2009 have not been captured by HDR. Each of these taxa were either rarely encountered during previous years, represent taxa that were stocked, or have not been captured during recentyears. However, six species have been captured by HDR that have not been collected by IDNR.They included shortnose gar, bigmouth

buffalo, smallmouth

buffalo, fathead minnow, rosyfaceshiner, and a shovelnose tiger catfish, which was collected for the first time in 2012. This exoticspecies was collected in a trap net and almost certainly was an unwanted aquarium fish that wasreleased into Braidwood Lake. The shovelnose tiger catfish measure 490 mm in total length andweighed 862 grams. In addition, a single hybrid striped bass was also collected for the first timein 2012. This fish was also captured in a trap net and measure 342 mm in total length andweighed 408 grams. It is assumed that this fish was the result of a recent stocking effort in 2011by IDNR. With the exception of these two fish, no threatened, endangered, or new species werecollected in 2012.Species that numerically dominated the catch in 2012 (all sampling methods combined) includedbluegill at 28.7%, bullhead minnow at 16.2%, channel catfish at 14.1%, threadfin shad at 9.2%,carp at 6.8%, spotfin shiner at 5.1%, bluntnose minnow at 5.0%, largemouth bass at 4.3%, andgizzard shad at 2.7% (Table 3-2). All of these species have been commonly collected by theIDNR during recent sampling efforts (Table 3-1). Biomass of fish captured by electrofishing, trapnetting, gill netting, and hoop netting was dominated by carp (40.6%),

channel catfish (34.3%),bluegill (10.3%),

largemouth bass (8.3%), flathead catfish (2.1%), and gizzard shad (1.9%).These results are similar to data collected during previous years and indicate that Braidwood Lakeis best suited to support warmwater species.3.2.1 Electrofishing In 2012, electrofishing resulted in the collection of 1271 individuals representing 18 taxa (Table 3-3). The catch was dominated numerically by bullhead minnow (310 individuals),

which3-4HDR Engineering, Inc.

TABLE 3-2TOTAL NUMBER, WEIGHT (g) AND PERCENT CONTRIBUTION OF FISH COLLECTED BY ALL SAMPLING GEARSFROM BRAIDWOOD STATION COOLING LAKE DURING 2012 AND 2009 THROUGH 2012.2012 2009-2012 NUMBER WEIGHT NUMBER WEIGHTTAXON No. % (g) % No. % (g)%Threadfin shadGizzard shadShortnose garLongenose garCarpCommon shinerStriped shinerRosyface shinerSpotfin shinerSand shinerFathead minnowBlunnose minnowBullhcad minnowSinallmouth buffaloBigniouth buffaloYellow bullheadBlue catfishChannel catfishFlathead catfishShovelnose tiger caifishMosquitofish Brook silverside Hybrid striped bassSunfish spp.Green sunfish177529.22.7122471060.31.9130 6.8 150,91840.698669631082702213455.10.30.35.016.20.414.10.10.10.10.10.10.22.42421018228746lo0S127,482780086255408311430.1<0.1< 0.10.10.21130435198011342164446735755531374138782226514512.95.0<0.10.19.1<0.10.40.27.30.50.14.16.3<0.1< 0.1< 0.10.815.80.1<0.1<0.10.3<0.10.11.710,90965,700175026,9001.130,695 1759511556782076313126590255013716.835616,38196,550862532408539360.52.90.11.250.3<0.1< 0.1< 0.10.1<0.1<0.1<0.10.10.30.1<0. 10.727.44.3<0.1<0.1<0.1<0.1<0.10.20.334.32.10.2< 0.1< 0.10. I<0.10.3c m0 0CA) ch-I. C-0 TABLE 3-2 (Continued).

2012 2009-2012 NUMBE WEIGHT NUMBER WEIGHTTAXON No. % (g) % No. % (g) %Orangespotted sunfish 3 < 0.1 29 < 0.1Rcdear sunfish 30 1.6 1815 0.5 51 0.6 2647 0.1Bluegill 550 28.7 38,160 10.3 2499 28.4 149.029 6.6Longear sunfish 39 2.0 936 0.3 165 1.9 3243 0.1Hybrid sunfish 17 0.2 325 < 0.1Smallnmouth bass 4 0.2 134 < 0.1 9 0. 1 3461 0.2Largemouth bass 83 4.3 30,988 8.3 336 3.8 100,339 4.5Black crappie I < 0.1 147 < 0.1Freshwater drum I 0. I 246 0. I 9 0. I 3676 0.2Totals 1914 371,484 8787 2,246,997 Total taxa 23 34Total species 21 31aSampling methods included electrofishing, trap netting, gill netting and hoop netting.LCCDCACS0 0K)D O TABLE 3-3TOTAL CATCH BY METHOD FOR FISH SPECIES COLLECTED FROM THE BRAIDWOOD STATION COOLING LAKE, 2012.ELECTROFISHING TRAP NETTING GILL NETTING HOOP NETTINGTAXON NUMBER WEIGHT NUMBE WEIGHT N[UMBER WEIGHT NUMBER WEIGHTNo. % (g) % No. % (g) % No. % (g) % No. (g)Thrcadlin shadGizzard shadCarpSpotlin shinerSand shinerFathead minnowBluntnose minnowBullhead minnowBlue catfishchaniliel catfish'-' Flathead catfishShovelnose tiger catfishMosquitofish Brook silverside Hybrid striped bassSunfish spp.Green sunfishRedear sunfishBILICgill Longear sunfishSmallitiouth bassLargensouath bassFreshwater drumTotalsTotal tuamTotal speciesIII46659856963108.7 627 0.33.6 5620 2.95.1 99,249 50.97.7 242 0.10.4 10 < 0.10.5 18 < 0.17.6 228 0.124.4 746 0.42 0.5 619 0.464 15. 1 51,591 35.81 0.2 518 0,472 16.9 45,954 31.8I 0.2 7800 5.4I 0.2 862 0.666 60.6 597 15.54 3.7 867 22.6I 0.9 78 2.07 6.4 487 12.731 28.4 1815 47.2 104 95.4 28,055 98.963 5.0 51.658 26.5220.20.2<0.15 <0.13452928039467127118171 0.2 408 0.30.2 3 < 0.13.5 1143 0.62.3 1673 0.9 1 0.2 142 0.122.0 12,362 6.3 265 62.4 25,488 17.73.1 936 0.50.3 134 0.15.3 20.310 10.4 16 3.8 10.678 7.41 0.2 246 0.25 4.6 310 1.1194,969425II10144,30610938441092228.365I0og WK3sOD RS-14-138 Enclosure Page 261 of 322comprised 24.4% of all fish captured.

Bluegill (22.0%),

threadfin shad (8.7%), spotfin shiner(7.7%), bluntnose minnow (7.6%), largemouth bass (5.3%), carp (5.1 %), channel catfish (5.0%),gizzard shad (3.6%), green sunfish (3.5%), longear sunfish (3.1%), and redear sunfish (2.3%)were the only other species to individually comprise greater than 2 % of the total catch by number.The total number of fish collected by location ranged from 69 at Location E-3 to 254 at LocationE-5 (Table 3-4). The total number of taxa collected ranged from nine at Location E-3 to 15 atLocations E-5 and E8. The fewest number fish and taxa were collected at Location E-1 locatedclosest to the Braidwood Station discharge.

In general, more fish and greater numbers of taxawere collected at sampling areas located toward the middle and cooler end of the Braidwood Lake*cooling loop (Locations E-4, E-5, E6, E7, and E-8). Electrofishing biomass was dominated bycarp, which constituted 50.9% of the 195.0 kg collected (Table 3-3). Other species thatindividually contributed more than 2% of the total biomass included channel catfish (26.5%),largemouth bass (10.4 %), bluegill (6.3 %), and gizzard shad (2.9 %).The mean electrofishing catch-per-effort (CPE) for all locations combined in 2012 was 238.3fish/hr (Table 3-4). This value is higher then the mean electrofishing CPE of 177.5 and 167.6fish/hr for all locations combined in 2009 and 2010, and slightly less than the 277.7 fish/hr thatwas reported in 2011 (HDR 2010, 2011, and 2012). Some of the increase in CPE during the lasttwo years is indirectly the result of reducing the sampling effort from 30 minutes per location in2009 and 2010 to 20 minutes per location in 2011 and 2012. This was done to minimize thestress on fish that were being held in the holding tank before they could be processed in the field.Due to the relatively small size of the sampling areas that have been electrofished during eachannual effort, the majority of the collected fish that were captured in 2009 and 2010 werecollected during the first 15 to 20 minutes of sampling.

Toward the end of each sampling effort in2009 and 2010 some of the areas had to be electrofished a second time in order to make the 30minute sampling period requirement.

Fewer fish and lower CPE's were observed during thesecond runs through each of these re-sampled areas.In 2012, CPE ranged from 103.5 fish/hr at Location E-3 to 381.0 fish/hr at Location E-5.Location E-5 also exhibited the highest CPE's in 2009 and 2010, and the second highest CPE in2011. This site includes the area around the make-up water discharge into the lake from theKankakee River. Four species, common carp, bullhead minnow, bluegill, and largemouth bass,were collected at each of the eight electrofishing locations.

3-8HDR Engineering, Inc.

TABLE 3-4I,.)NUMBERS OF FISH CAPTURED BY ELECTROFISHING AT EACH SAMPLING LOCATION IN BRAIDWOOD LAKE, 2012.SAMPLING LOCATIONS TAXON E- I E-2 E-3 E-4 E-5 E-6 E-7 E-8 TOTAL %%Threadfin shad I 1 I 98 9 I I11 8.7Gizzard shad 29 7 3 3 4 46 3.6Carp 16 11 7 6 4 2 8 11 65 5.1Spotfin shiner 30 4 7 8 27 5 17 98 7.7Sand shiner I 2 I I 5 0.4Fathead minnow 1 2 I 1 I 6 0.5Bhluntnose minnow 3 1 20 22 14 7 29 96 7.6Bullhead minnow 24 2 9 50 15 39 33 138 310 24.4Channel catfish 7 29 8 4 4 10 1 63 5.0Mosquitofish 2 2 0.2Brook silverside 2 2 0.2Lepomis spp. 3 3 0.2Green sunfish 1 1 27 6 10 45 3.5Redear sunfish 1 12 1 4 2 3 6 29 2.3Bluegill 1 40 20 33 53 21 59 53 280 22.0Longear sunfish 2 2 4 3 10 II 7 39 3.1Smallmouth bass 2 2 4 0.3Largemouth bass I 10 6 6 6 9 24 5 67 5.3Total fish 113 105 69 134 254 139 172 205 1271Total Taa 10 II 9 12 15 12 13 15 18CPE (fishlhr) 169.5' 157.5' 103.5a 201.0' 381.03 208.5' 258.5' 307.5' 238.3bBased on 0.67 lirs eleetrofishina, effort.Based on 5.33 hrs eleciro is iinz effort.CDN) -0N) 0 RS-14-138 Enclosure Page 263 of 3223.2.2 Trap NettingA total of 425 fish including ten species and one hybrid striped bass was collected by trap net(Table 3-5). Bluegill was the dominant species captured, comprising 62.4% of all fish taken. Thesecond most abundant species collected was channel catfish (16.9%),

followed by carp (15.1%),and largemouth bass (3.8%). The total number of fish collected by location ranged from one atLocation TN-7 to 99 at Locations TN-4. The trap net at Location TN-7 collapsed in the currentsometime during each of the two 12-hr sets during both sampling events in 2012, which did notallow the net to fish properly.

The total number of species collected by location ranged from oneat Location TN-7 to six at Locations TN-4 and TN-8. The total biomass of fish captured by trapnetting was 144.3 kg (Table 3-3). Carp (35.8%),

channel catfish (31.8%),

bluegill (17.7%),largemouth bass (7.4%), and flathead catfish (5.4%) were the only species to individually comprise more than 1 % of the total biomass collected.

During the August and September sampling

periods, mean trap netting CPE for all locations combined was 26.6 fish/net (overnight sets of approximately 12-hrs),

which is similar to, butslightly less than, the 28.5, 40.8, and 30.8 fish/net reported from 2009-2011 (HDR 2010, 2011,and 2012). CPE by location ranged from 0.5 fish/net at Locations TN-7 to 49.5 fish/net atLocation TN-4. Channel catfish was the only species collected at each of the eight samplinglocations.

3.2.3 Gill NettingGill netting resulted in the collection of 109 individuals representing five species (Table 3-6).Threadfin shad dominated the catch by comprising 66 (60.6%) of the 109 total fish collected.

Channel catfish was the second most abundant species collected (28.4 %). The only other speciesto individually contribute more than 5% of the total catch was blue catfish (6.4%). Channelcatfish comprised 1.8 kg (47.2%) of the 3.8 kg of fish collected by gill netting (Table 3-3),followed by gizzard shad at 0.9 kg (22.6%),

threadfin shad at 0.6 kg (15.5%),

and blue catfish at0.5 kg (12.7%).A total of 91 fish representing five species was collected from the two deep water sets conducted at Location GN-2 (Table 3-6). Gill nets at this location were set in a deep hole at a depth of3-10HDR Engineering, Inc.

TABLE 3-5NUMBER OF FISH CAPTURED BY TRAP NETTING AT EACH SAMPLING LOCATION IN BRAIDWOOD LAKE, 2012.SAMPLING LOCATIONS TAXON TN-I TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-8 TOTAL %Gizzard shad 1 I 2 0.5Carp 15 11 10 10 10 I 7 64 15.1Blue catfish 1 I 0.2Channel catfish 11 15 16 12 4 8 1 5 72 16.9Flathead catfish I I 0.2Shovelnose tiger catfish I I 0.2Hlybrid striped bass I I 0.2Redear sunfish 1 1 0.2Blucgill 24 8 39 72 15 82 25 265 62.4Largemouth bass 8 5 3 16 3.8Freshwater drum 1 1 0.2Total fish 59 34 70 99 31 91 I 40 425Total Taxa 5 3 4 6 5 3 I 6 1ICPE (fish/trap net set) 29.52 17.0' 35.0' 49.5' 15.53 45.5* 0.53 20.0' 26.6",,Based on two over niplit sets of aporoNirnactf1y 12 hr duration.

'Based on 16 over nig It sets of appi-oxirnlety 12 hr dUration.

CDCd)0 0~MCD 0 RS-14-138 Enclosure Page 265 of 322TABLE 3-6NUMBERS OF FISH CAPTURED BY DEEP (GN-1) AND SHALLOW WATER (GN-2)GILL NETS IN BRAIDWOOD LAKE, 2012.SAMPLING LOCATIONTAXA GN-1P GN-2h TOTAL %Threadfin shad 13 53 66 60.6Gizzard shad 2 2 4 3.7Carp 1 1 0.9Blue catfish 7 7 6.4Channel catfish 3 28 31 28.4Total fish 18 91 109Total taxa 3 5 5CPE (fish/hr) 31.0c 182.0d 100.9c'GN-I was a shallow water set in approximately 2-3 meters of water.'GN-2 was a deep water set in approximately 8-10 meters of water.'Based on 0.58 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br /> of total effort."Based on 0.50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> of total effort.'Based on 1.08 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of total effort.3-12 RS-14-138 Enclosure Page 266 of 322approximately 8-10 m. Gill nets at the shallow water sampling Location GN-1 were set at a depthof approximately 2-3 m. Eighteen fish and three species were collected from this samplinglocation during the August and September sampling dates.Gill net CPE at the deep water Location GN-2 was 182.0 fish/hr based on 91 fish collected during0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of sampling effort during the two combined sampling dates. CPE at the shallow waterLocation GN-1 was substantially lower at 31.0 fish/hr based upon the 18 fish collected during0.58 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br /> of total sampling effort in August and September.

Mean CPE for the two samplinglocations in 2012 was 100.9 fish/hr, which is higher than 73.5 fish/hr in 2010 (HDR 2011) andthe 53.4 fish/hr reported in 2009 (HDR 2010), but lower than the 180.7 fish/hr reported in 2011(HDR 2012). Threadfin shad, gizzard shad, and channel catfish were the only species collected atboth sampling locations.

3.2.4 Hoop NettingA total of 108 fish including two species was collected by hoop nets (Table 3-7). Channel catfishdominated the catch by comprising 95.4% of all fish taken. The only other species collected wasbluegill (4.6%), which was represented by five individuals.

A total of 28.4 kg of fish wascollected by hoop net (Table 3-3). Channel catfish comprised 98.9% of the catch by weight,while bluegill constituted the remaining 1.1 % of the biomass collected by hoop net.The greatest number of fish (58 individuals) was collected at Location I2N-2, which was a deepwater set that was not baited with dead gizzard shad (Table 3-7). Eighteen fish were collected atLocation HN-1, which was also a deep water set that was baited with dead gizzard shad. Twenty-five fish were captured at Location HN-3, which was a shallow water set baited with gizzardshad. Only three channel catfish were collected at Location HN-4, which was a shallow water setthat was not baited with dead gizzard shad. A total of 43 fish was collected from the two baitednet locations compared to 66 fish captured from the two nets that were not baited at Braidwood Lake in 2012. Baiting hoop nets with dead gizzard shad has provided inconsistent results duringthe course of this four year study period (2009-2012).

Hoop netting CPE ranged from 4.0 fish/overnight set at Location HN-4 (shallow water withoutbait) to 29.0 fish/overnight set at Location HN-2 (deep water without bait). CPE for the two deep3-13HIDR Engineering, Inc.

TABLE 3-7NUMBERS OF FISH CAPTURED IN BAITED AND UNBAITED DEEP AND SHALLOW WATER HOOP NETSIN BRAIDWOOD LAKE, 2012.SAMPLING LOCATIONDEEP WATER3 SHALLOW WATERbTAXA HN- HN-2 HN-3 HN-4(BATD) (UNBAITED)

(BAITED)

(UNBAITED)

Channel catfish 18 58 25 3 104 95.4Bluegill 5 5 4.6Total fish 18 58 25 8 108Total taxa I I 1 2 2CPE (fish/overnight set) 9.OC 29,0v IL.5C 4.0c 13.5dIr,"Deep waler hoop nets HN-t and HN-2 were set in 8.0 -10.0 meters of water.'Shallow water hoop nets HN-3 and HN-4 were set in approximately 1.0 -2.0 meters of water.1CPE was based on two overnight sets of approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> duration.

dCPE was based on eight overnight sets of approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> duration.

CD0 -.caC.r-~NM @. 60 RS-14-138 Enclosure Page 268 of 322water sets (HN-1 and HN-2) averaged 19.0 fish/overnight set compared to 7.8 fish/overnight setat the shallow water locations (HN-3 and HN-4). The two baited net sets (HN-1 and HN-3) hadan average CPE of 10.2 fish/overnight set compared to 16.5 fish/overnight set for the two nets(HN-2 and HN-4) that were not baited. Mean CPE for all nets combined was 13.5 fish/overnight set.3.3 Length-Frequecy Distributions Length-frequency distributions of six selected species (bluegill, largemouth bass, channel catfish,blue catfish, threadfin shad, and gizzard shad) captured by all sampling gears in 2012 werecompiled and are presented graphically (Figure 3-1 through Figure 3-5). With the exception ofelectrofishing, the sampling gears used in these studies are biased toward larger individuals.

Therefore, smaller fish, especially young-of-year and yearlings, were not collected in numbersthat would most accurately represent their true abundance in Braidwood Lake.Bluegill is one of the most abundant species found in Braidwood Lake. Four hundred forty-eight individuals measuring from 34 to 190 mm in total length are included in the length-frequency histogram of bluegill that were captured in 2012 (Figure 3-1). A major peak in the length-frequency distribution representing one or two age classes was observed from 140 to 180 mm intotal length. A second minor peak in the length-frequency histogram occurred at 80-90 nun intotal length. The age of these fish, as well as all other species, in thermally enhanced bodies ofwater like Braidwood Lake, is difficult to determine without hard-part (scales, spines, andotoliths) analysis because the growing season extends throughout the winter months. Regardless of age, Braidwood Lake supports a substantial population of bluegill that are large enough tosupport a quality sport fishery.The length-frequency distribution of 83 largemouth bass measuring from 98 to 495 mm in totallength were collected from Braidwood Lake during 2012 (Figure 3-2). The length-frequency distribution indicates that several age classes of fish were included among the catch. The largestpeak in the length-frequency histogram occurs from 120 to 170 mm and likely represents eitherYOY or Age 1 fish. Eighteen (21.7%) of the 83 fish collected exceeded 350 mm (14 in.). Thelargest individual that measured 495 nim was likely Age 4 or older. Again, the age of fish incooling lakes is difficult to ascertain based on length-frequency analysis because of the extended3-15HDR Engineering, Inc.

15012500wNzIrn1007550!250TOTAL LENGTH (mm)(0N) 0FIGURE 3-1.LENGTH-FREQUENCY DISTRIBUTION OF BLUEGILL COLLECTED FROMBRAIDWOOD LAKE DURING AUGUST AND SEPTEMBER, 2012.

11a.-uJ4-2-6 ? 6 :- 6 -.6 .- ...0 ' 01C7q T0 03 0 -N cq Vr ) 30 N 03 03 3' a 30 30 0 030 0 3 3 0 0 V 0 0 N 0------N N N -m3" A " m0TOTAL LENGTH (mm) (03FIGURE 3-2. LENGTH-FREQUENCY DISTRIBUTION OF LARGEMOUTH BASS COLLECTED FROM BRAIDWOOD KLAKE, DURING AUGUST AND SEPTEMBER, 2012.

0Nwzi011lItIINLIItI.IIIIII11II11II.Itui I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 -----v 06 6) 6 0) 0 0S 0) Q 0) 0S o) a a 0o 0) 0)0) 0 00 a) 0) a) 0) o) 0 0) 6 0) 6 0) 6) 0 0) a) a 0) 0 0) 0) a 6 0 6) C3 0) 0r- -)0 O'C3 rq :r 0 w N0 0mO 0(4 M) 10r C) (D '-CO0) C)0- N' c) 4 0r--0 )0 MC3 N 1)V O (0 r -00 a) 0C3 ('N N 4N0 MC40t e )C )nV rq lq t" ,ý oL f oL oUTOTAL LENGTH (mm)ccCD)0 -K) @ OFIGURE 3-3.LENGTH-FREQUENCY DISTRIBUTION OF CHANNEL CATFISH COLLECTED FROM BRAIDWOOD LAKE DURING AUGUST AND SEPTEMBER, 2012.

0NU)wmu=3N ý 2 ý2 LO CD I- ý cl Z; 0 10 'Q Cw r f -wD mNN N N N " N N N NTOTAL LENGTH (mm)K)CD OFIGURE 3-4.LENGTH-FREQUENCY DISTRIBUTION OF BLUE CATFISH COLLECTED FROM BRAIDWOOD LAKE DURING AUGUST AND SEPTEMBER, 2012.

30-25-a.0wNEnwwz20-15-10-E GIZZARD SHAD = 52ED THREADFIN SHAD = 79LO5-0o 0) 0m CD c CD m) T) 0 0) m 0D 0m 0m c 0m 0) 0) m) m 0) a) m) 0m CD 0) 0) 0) a) 03 03) a) a) 03oo U- a? I-- CV Uw mD a'. C ) 0 -N C) C D D 0 -N mO 0 tD C0f 0D 0 0o 0) a o o o o ~ o ~oo c!5 A3a a ( 56 a C 3cOý M N O~ 0 1, M- M) M) -" O Iq Co wD I- M) M 01 ;; " O n C W-~~ ~ --N N N N N N N N "O mO mO mO mO 0TOTAL LENGTH (mm)CD0.r') 00C.FIGURE 3-5. LENGTH-FREQUENCY DISTRIBUTION OF THREADFIN AND GIZZARD SHAD COLLECTED FROMBRAIDWOOD LAKE DURING AUGUST AND SEPTEMBER, 2012.

RS-14-138 Enclosure Page 274 of 322growing season that exist in these thermally enhanced bodies of water. Only eight fish were] collected that measured between 190 and 310 mm in TL. This may represent a weak year class inthe length-frequency histogram for largemouth bass as illustrated in Figure 3-2. It should also benoted that the IDNR stocked 46,160 four inch fingerlings into Braidwood Lake in 2010. This wasequivalent to 20.6 fish/acre (HDR 2011). Stocking activities conducted by IDNR at Braidwood Lake in 2012 were not available at the time this report was prepared.

Channel catfish is an abundant species that is targeted by recreational anglers at Braidwood Lake.A total of 252 fish measuring from 147 to 610 mm are included in the length frequency analysisfor channel catfish (Figure 3-3). Several age classes of channel catfish are included among the252 fish observed in the length-frequency analysis.

Recruitment of this species appears to be verygood based on Figure 3-3, which illustrates that there are not any missing or obvious weak yearclasses in the catch.Braidwood Lake has been stocked with a variety of warm- and coolwater fish species since the1970's to the present time. Those efforts have included the introduction of blue catfish to thecooling lake. Because of those stocking

efforts, and because of the number of blue catfish thatwere collected during recent years, a length-frequency histogram was also created for this species(Figure 3-4). The length-frequency distribution of eight fish measuring from 84 to 400 mmindicates that as many as three or perhaps four year classes of blue catfish were included in thecatch at Braidwood Lake during 2012. Six (75.0%) of the eight fish collected measured from 190to 260 mm in total length. Blue catfish were stocked in Braidwood Lake by IDNR in 2010. Thisstocking effort included 9,812 blue catfish fingerlings (5.3 inches) equivalent to 4.3 fish/acre (HDR 2011). The authors of this report do not know if any of these individuals were stocked inBraidwood Lake by IDNR in 2012.Two additional

species, threadfin shad and gizzard shad, were also analyzed (Figure 3-5). Bothof these abundant forage species reside in Braidwood Lake. They are important to the ecology ofthe system and they have the potential to pose a threat to the operation and maintenance ofBraidwood Nuclear Station when fish kills occur at the cooling lake. Large numbers of deadgizzard and threadfm shad could accumulate on the bar grills, traveling water screens, and othersystems at the Stations intake, which could potentially interfere with water flow used to cool thereactors and other support systems.3-21HDR Engineering, Inc.

RS-14-138 Enclosure Page 275 of 322A total of 52 gizzard shad and 79 threadfin shad are included in the length-frequency histogram for these two species (Figure 3-5). All of the threadfin shad collected during the current studymeasured from 52 to 130 mm in total length, while 50 (96.2%) of the 52 gizzard shad capturedexceeded 100 mm in total length. Gizzard shad ranged in length from 89 to 369 mm in totallength. At least three or four year classes of gizzard shad were collected during 2012. Incontrast, threadfin shad rarely exceed 150 mm in total length and individuals spawned early in theyear commonly mature and spawn late in their first summer of life. Few threadfin shad live formore than two or three years.3.4 Physicochemical DataWater quality data recorded in conjunction with fish sampling was measured at each location priorto every sample collection (Appendix Tables A-1 to A-4). During August 20-23, watertemperature at Braidwood Lake ranged from 30.3 'C at Location E-3 on 23 August to 35.1 °C atLocations TN-1 and TN-2 on 20 August. Water temperatures during the second sampling period(September 10-12) were slightly cooler than those measured in August. Temperatures during thisperiod ranged from 27.4 'C at Location TN-8 on 11 September to 33.6 'C at Locations TN-i andTN-2 on 10 September.

As expected, the temperature gradient generally declined as the coolingwater in the lake moved from the Station's discharge toward the Braidwood Station intake.During the first sampling period (August 20-23), dissolved oxygen (DO) ranged from 4.6 ppm atLocations E-1 during the early morning of 23 August to 11.5 ppm at Location TN-4 during thelate afternoon of 20 August. Oxygen levels were generally slightly higher during the secondsampling period in September.

Dissolved oxygen levels ranged from 4.3 ppm at Location TN-1during the morning of 11 September to 13.2 ppm at Location TN-5 during the afternoon of 10September.

Dissolved oxygen measurements increased each day in the lake from early morning to lateafternoon during both the first and second sampling periods.

Similar conditions were alsoobserved in previous years. The increase in dissolved oxygen measurements from early morningto late afternoon can be attributed to photosynthesis by the phytoplankton population in the lakethat produces oxygen throughout the daylight hours.3-22HDR Engineering, Inc.

RS-14-138 Enclosure Page 276 of 322Surface and bottom water temperature, DO, and conductivity readings were taken at deep watergill net set Location GN-1 and the two deep water hoop net set Locations HN-1 and HN-2(Appendix Tables A-3 and A-4). At all three of these locations, slightly cooler watertemperatures (0.1 to 0.3 0C) and slightly lower DO readings (0.19 to 1.38 ppm) were measured0.5 meters off the bottom when compared to the surface readings.

Conductivity measurements atthe surface and bottom in Braidwood Lake were very similar (1-11 pinhos/cm) at all three of thesesampling locations.

Braidwood Lake is a very productive system with heavy oxygen demand (respiration anddecomposition) occurring during the night and intense oxygen production (photosynthesis) occurring during clear sunny days. Currently, the majority of the photosynthetic activity withinBraidwood Lake is attributable to phytoplankton, which has decreased the water clarity andreplaced aquatic macrophtyes as the primary producer.

In a report submitted to Exelon by SEAin 2001 (Appendix Report B-I); it states that "Several perched cooling ponds in the Midwest havehad high macrophyte densities in their earlier years but usually become dominated byphytoplankton if they have heavy thermal loading.

A switch to phytoplankton dominance isusually accompanied by a reduction in water transparency.

Braidwood Lake appears to be relatively well buffered with only minor diurnal variation in pHreadings.

Examination of pH data collected during the present surveys show that pH ranged from8.5 to 8.8 during the first August sampling period and from 8.7 to 9.0 during the secondSeptember sampling period. The pH of water typically increases with increased photosynthetic activity and the resulting oxygen production can explain upward shifts in pH during the course ofbright sunny days.During the August sampling period, conductivity ranged from 1081 unmhos at Location E-6 on 23August to 1114 /umhos at Location TN-1 on 21 August. Conductivity during the September sampling period ranged from 1160 jumhos at Location TN-5 on 11 September to 1275 Amhos atLocations TN-1 and TN-2 on 10 September.

Conductivity readings were generally slightly highernear the Braidwood Station discharge compared to the Stations intake, while pH readings weresimilar throughout the entire length of Braidwood Lake. Surface to bottom readings were alsogenerally

similar, suggesting that the water throughout the cooling loop was well mixed duringboth the August and September sampling periods.3-23HDR Engineering, Inc.

RS-14-138 Enclosure Page 277 of 322Make-up water is pumped into Braidwood Lake on an irregular basis from the Kankakee Riverthroughout most of the year. As a result, water quality parameters can be expected to begenerally more favorable near the make-up water discharge (Location E-5) compared to theremainder of the sampling locations.

However, the affects of the make-up water discharge isquickly dissipated because of the relatively low volume of make-up flow being pumped into thelake. Make-up flow was not observed being pumped into Braidwood Lake during either the firstor the second sampling periods in August and September.

During the August sampling period, water temperatures were approaching the upper limitsacceptable for some warmwater fish species.

Air temperatures during July and early August wereunusually high throughout the Midwest in 2012, which accounted for most of the increase in thewater temperatures at Braidwood Lake during July and early August. Water temperatures weretypically 1-4 "C cooler during the September sampling period as air temperatures decrease notablyfrom those observed in July and early August. Conductivity measurements were slightly higherduring the September sampling period, while DO and pH measurements were similar during bothsampling periods.

The early morning dissolved oxygen reading that was measured on 11September (4.3 ppm) at Location TN-i was beginning to approach values that adversely affectmost fish species.

As previously noted, these diurnal oxygen fluctuations are common atBraidwood Lake during the summer months and can be attributed to oxygen depletion (respiration and decomposition) during the night and oxygen production (photosynthesis) during the day. Oncloudy calm days, photosynthesis and oxygen production can be slowed to levels that cannotcompensate for oxygen depletion that occurs throughout the night. When this occurs over anextended period of time (days), an oxygen deficit can develop and cause substantial fish die-offs ifsuitable refuges within the system are not available.

3.5 Historical bIfonnation 3.5.1 Water QualityWater quality parameters were measured on seven separate occasions at Braidwood Lake fromMay 29, 2001 through August 27-28, 2002 (Appendix Reports B-1 through B-7). The purposeand scope of these investigations varied, but the most intensive sampling was conducted during3-24HDR Engineering, Inc.

RS-14-138 Enclosure Page 278 of 322the August 27-28, 2002 sampling event. Results of these investigations indicated that abnormally high levels of total dissolved solids (TDS), alkalinity,

hardness, sulfates, magnesium, calcium,and total phosphorus existed throughout the cooling loop. These data were not unexpected basedon the evaporation that occurs within the cooling loop coupled with the relative low make-up andblow-down flows associated with the operation of the Station.

The cooling lake exhibited elevatedvalues for these parameters at levels of two to nearly eight times higher than those of the make-upwater from the Kankakee River. These elevated levels of water hardness can be of concern tothe Station because they have the potential to intensify problems associated with scaling.Phosphorus and nitrogen are two essential nutrients required by aquatic plants. Concentrations ofthese nutrients are typically low in water because phytoplankton and aquatic macrophytes quicklyassimilate and utilize these nutrients for growth and reproduction.

The studies conducted by SEAin 2002 indicated that the high levels of these nutrients within the cooling lake would continue tocause problems associated with phytoplankton blooms. Unlike most water bodies, phosphorus levels within Braidwood Lake were in excess and nitrates were the limiting factor. Bluegreen algae appeared to be the dominant summer form of algae within Braidwood Lake because they arenot as limited by low nitrate levels as other algal species.Water quality analysis has indicated that dissolved oxygen levels within the cooling lake canexhibit large diurnal variation in response to algal blooms that are most problematic during the} summer months (June through August).

The nutrient rich water of Braidwood Lake is ideal forthe development of algal blooms that produce large amounts of oxygen during the day(photosynthesis) and oxygen depletion in the dark (respiration and decomposition).

As oxygen isproduced through photosynthesis, pH tends to increase if the water is not well buffered.

Dissolved oxygen levels of 4-5 ppm (levels that most fish species become stressed) and lowerhave been recorded throughout the cooling loop 0.5 m below the waters surface.

The lowest DOreadings occur during the early morning period and typically increase throughout the day.Increases in DO of 4 to 5 ppm or more have been observed from morning to late afternoon atBraidwood Lake. In addition, stratification of the water column has also occasionally beenreported during the same period of time when DO readings are measured at less than 3 ppm.During these events, DO readings in the hypolimnion (the zone below the thermocline to thebottom of the lake) can approach zero. When this occurs, it further limits the refuge available forfish and other aquatic organisms.

3-25HDR Engineering, Inc.

RS-14-138 Enclosure Page 279 of 3223.5.2 Fish KillsHistorical fisheries data summarizing fish kills that have occurred at Braidwood Lake wasprovided to HDR by Exelon Nuclear, IDNR, and SEA (Appendix Reports B-2 through B-7).Five fish kills that occurred from 2001 through 2007 were identified in the information providedto HDR. Each of these events occurred during June, July, or August. Two of the kills occurredin 2001. The first took place in late July and the second on August 27-28. A third kill wasreported on July 30, 2004, the fourth on June 28, 2005, and the fifth occurred over an extendedperiod of time during August 21-28, 2007. No additional information regarding fish kills hasbeen provided to HDR since 2009. Therefore, it is assumed that no reportable fish kills havebeen observed at Braidwood Lake since August, 2007.Little information was provided for the fish kills that occurred in late July and August, 2001. TheJspecies involved and the extent of dead fish observed during the first event in July were notincluded in the information received by HDR. The second fish die-off in late August wasdominated primarily by gizzard shad that comprised more than 95% of all fish observed.

Theremaining species involved in the die-off in decreasing order of relative abundance

included, freshwater drum, quillback, carp, largemouth bass, channel catfish, redhorse spp., smalimouth bass, and bluegill.

With the exception of gizzard shad, the majority of the fish were located fromthe mid-point of the cooling loop to the intake. A report submitted by SEA indicated that warmwater temperatures and/or low dissolved oxygen levels were the most likely factors thatcontributed to the fish die-off in July. SEA also indicated that the die-off in late August was mostlikely the result of depleted dissolved oxygen levels that occurred in the lake following anextensive phytoplankton bloom collapse, which is a natural phenomenon that can occur in highlyproductive waters during summer months. Dissolved oxygen measurements throughout themajority of the lake were at or below minimum levels necessary to support most fish species.A third fish die-off at Braidwood Lake was investigated on July 30, 2004. Gizzard shad was thedominant species involved, although channel catfish were also observed.

The gizzard shadappeared to be in an advanced state of decay suggesting that the actual die-off occurred earlier inthe week. Water quality parameters at the time of the incident were not included in the briefsummary report provided to HDR, which suggests they were not measured concurrent with the3-26HDR Engineering, Inc.

RS-14-138 Enclosure Page 280 of 322fish die-off.

Water quality measurements were taken in early October following the fish die-off.During this period of time, DO levels of 3.8 ppm and a water temperature of 29.2 'C wererecorded at a depth of one foot below the surface, just north of the south boat ramp. At a locationseveral hundred feet from the lake make-up discharge from the Kankakee River, more favorable dissolved oxygen (7.6 ppm) and water temperatures (26.5 °C) were measured.

DO readings atthis location were stratified exhibiting a decline to 5.3 ppm at 40 feet, while water temperature showed minimal decrease with water depth.In 2005, an inspection of a fish die-off was conducted on 28 June. Formal counts of fish were notconducted at this time, but field assessments indicated that a fairly substantial die-off involving several species had occurred.

Gizzard shad was again the most numerous species affected andfish carcasses were observed throughout the majority of the lake. Additional species observedincluded threadfin shad, quillback, largemouth and smallmouth bass, carp, and channel catfish.Water quality measurements during this event were not provided to HDR and are assumed to beunavailable.

Rob Miller of IDNR and Jeremiah Haas of Exelon Nuclear investigated another fish die-off thatwas first reported at Braidwood Lake on August 21, 2007. The majority of the dead fishobserved were either large gizzard shad or threadfin shad up to five inches in length. Channelcatfish were also prevalent, with only a few carp, largemouth bass, and flathead catfish being} observed.

Most of the fish were distributed in close proximity to the north boat ramp due toprevailing south winds. The number of dead fish observed decreased towards the south (hot) endof the cooling loop. During the afternoon of 21 August, surface water temperature was 35.3 'Cand DO was near 3 ppm at a sampling point several hundred yards from the south ramp. Fourseparate water temperature and DO readings were also conducted at the north ramp between 1210hrs and 1658 hrs. Water temperature increased from 30.3 to 33.9 'C over the course of that timeinterval.

Dissolved oxygen was measured at 3.1 ppm at 1210 hrs and increased to 6.7 ppmduring the third reading at 1530 hrs. DO levels decreased during the last reading at 1658 hrs to5.9 ppm. Oxygen depletion appeared to be the factor responsible for the August fish kill thatoccurred at Braidwood Lake in 2007.3-27HDR Engineering, Inc.

RS-14-138 Enclosure Page 281 of 3224.0 SUMMARY AND RECOMMENDATIONS 4.1 Summary.

Braidwood Lake is a 2640 acre, partially perched cooling lake that was firstimpounded in 1980-1981 after several old strip-mine pits were inundated with water from theKankakee River. The lake has received supplemental stockings of both warmwater and coolwater fish species since the late 1970's. However, stocking efforts of species including

walleye, tigermuskie, smallmouth bass, and hybrid striped bass have not produced a sustainable quality fishery,which is due to the warm temperatures that are currently common in the cooling lake throughout the summer months. Water quality, particularly water temperature, improves as the water movesfrom the southern (hot) end of the cooling loop toward the northern (cool) end of the lake.Fisheries surveys have been conducted by IDNR at.Braidwood Lake annually from 1980 through1992, in 1994, and at two year intervals from 1997 through 2011. Forty-seven species of fish andtwo hybrid taxa (tiger muskie and hybrid sunfish) have been included among the 13 families offish collected.

Several of these species were rarely collected, were the result of supplemental stocking

efforts, or have not been collected during the past ten years of sampling.

Two species,mosquitofish and blue catfish, were collected for the first time in 2009 by the IDNR. Riverredhorse (one individual captured in 1999) is the only species that has been collected which iscurrently listed as protected in Illinois.

Fisheries surveys were again conducted by the IDNR in2011, but the data were not available prior to the preparation of this report.In 2009, HDR collected 24 species and two taxa (hybrid sunfish and small unidentified young-of-year sunfish species) among the 2143 fish collected.

Similar results were observed in 2010 when25 taxa representing eight families were included among the 2432 fish collected by electrofishing, trap netting, gill netting, and hoop netting.

In 2011, 18 taxa representing 16 species wereincluded among the 2298 fish collected by HDR. In 2012, 23 taxa and two hybrids were includedamong the 1914 fish that were collected by HDR. From 2009-2012, a total of 8787 fishrepresenting 34 taxa and 31 species were collected by HDR. Several taxa that were collected byIDNR from 1980 to 2009 were not collected by HDR during 2009-2012.

However, six species(shortnose gar, smallmouth

buffalo, bigmouth

buffalo, fathead minnow, rosyface shiner,shovelnose tiger catfish) and one taxa (hybrid striped bass) that have been captured by HDR have4-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 282 of 322not been captured by IDNR. No threatened or endangered species have been encountered byHDR during any of the three years of sampling.

Since 1980, 53 species of fish and three hybrids(tiger muskie, hybrid sunfish, and hybrid striped bass) have been collected at Braidwood Lake bythe IDNR and HDR. Two new taxa were collected by HDR in 2012. One was a shovelnose tigercatfish, an exotic species that can be purchased at pet stores, and the second individual was ahybrid striped bass that was recovered after a fish stocking of this taxa by IDNR into Braidwood Lake in 2011.The Braidwood Lake Fish and Wildlife Area evolved through three distinct phases since itsinception prior to the 1980's. Originally, several surface mined pits existed at the site until thelake was impounded with water from the Kankakee River during 1980 and 1981. The lakecontinued to function in this capacity until July 29 and November 17, 1988 when Braidwood Station began commercial operation of Units I and Unit II, respectively.

From 1980 through July1988, Braidwood Lake did not receive any thermal loading from Braidwood Station.

Since 1988,the lake has functioned as a cooling loop for the operation of the Station.

Currently, the lake isbest suited to support a warmwater fishery due to the warm temperatures prevalent in the lakethroughout the summer months. Dominant species currently found at Braidwood Lake includegizzard shad, threadfin shad, bluegill, channel catfish, and carp. Additional species such aslargemouth bass, green sunfish, flathead

catfish, spotfin shiner, bluntnose minnow, and sand3 shiner have also been commonly encountered.

Excluding the stocked fish that have beenintroduced into the Braidwood Lake, the taxa encountered have also been collected from theKankakee River, which is the source of make-up water for the lake. With the possible exception of common carp and channel catfish, these species are better suited to conditions that exist withinthe river. Survival of individuals that are introduced into the lake with the make-up water islimited by the elevated water temperatures that exist within the cooling loop during summermonths.Braidwood Lake can be currently described as a well buffered body of water with elevated watertemperatures, high levels of total dissolved solids (TDS), phosphates, and nitrates.

Phosphate andnitrate levels have declined in recent years, but these levels are still high compared to a naturalsystem. Primary productivity in the lake can be very high in conjunction with algal blooms thatoccur throughout the lake, especially during the June through August period. These blooms are4-2HDR Engineering, Inc.

RS-14-138 Enclosure Page 283 of 322driven by the high nutrient levels that exist within the lake. In recent years, phytoplankton hasreplaced aquatic macrophytes as the principal source of primary production.

The lake can alsodisplay relatively large diurnal fluctuations in dissolved oxygen measurements, particularly duringthe summer when oxygen is produced in large quantities by photosynthesis during the day andused in large quantities by respiration and decomposition during the night. In addition, Braidwood Lake can stratify during certain portions of the year, which has led to anoxic (oxygendepletion) or near anoxic conditions throughout the hypolimnion (stratified bottom layer of waterbelow the thermocline) as a result of respiration and decomposition from a collapsing algal bloom.Even in the surface waters of the epilimnion, dissolved oxygen readings of less than 4 ppm havebeen reported following an extensive and rapid die-off of an existing phytoplankton bloom. It isduring these periods of time when water temperatures are elevated and dissolved oxygen levelsare low that the fish die-offs are observed at the lake. The conditions described in this paragraph should not be expected to change at Braidwood Lake in the foreseeable future.4.2 Recommedations.

Five separate fish die-offs attributed to low DO levels were observed atBraidwood Lake between 2001 and 2007. It is expected that the conditions which led to thosefive events will not change or improve in the foreseeable future. Therefore, it should be assumedthat fish die-offs will continue to occur when algal blooms crash and oxygen depletion occurs.Substantial fish die-offs within the cooling loop could adversely affect both the operation andmaintenance of Braidwood Nuclear Station.Currently, there are no practical or simple solutions that could prevent the occurrence of fish die-offs at Braidwood Lake. It should be anticipated that fish die-offs will continue to occur at thelake on a fairly regular basis. Therefore, it would be advantageous if a reliable sampling protocolor set of procedures were developed that would reasonably predict fish die-offs that mayadversely affect the operation and/or maintenance of the Station.

With advanced warning theStation could be informed of a potential reportable

incident, regulatory agencies could be notified, and crews responsible for fish disposal could be put on alert to help manage the risk associated with a substantial fish die-off.

HDR believes this can be accomplished by conducting routinevisual inspections of the lake, monitoring dissolved oxygen levels, and by having a basicunderstanding of environmental conditions that may trigger these events, especially weatherconditions.

4-3HDR Engineering, Inc.

RS-14-138 Enclosure Page 284 of 322HDR recommends a two tier sampling procedure that may be utilized to help predict the onset ofa possible reportable fish die-off.

We recommend that visual inspections of the lake and waterquality measurements be conducted routinely throughout the year, particularly during the warmweather months, if budget and staff is available to monitor the lake. The frequency ofobservations and the intensity of the water quality measurements should be discussed by themanagement who would analyze risk management at Braidwood Station.

Historically, all the fishdie-offs at Braidwood Lake have occurred during the warm weather period of June throughAugust. This is the period of time when water in the cooling loop is the warmest and dissolved oxygen levels can fall substantially following die-offs of extensive phytoplankton blooms.Therefore, this is the most critical time to monitor existing conditions that could result in apotential problem (May through September).

Sampling on a less frequent basis throughout theremainder of the year may provide additional information that could be useful to the Station andpossibly alert the Station to an impending problem that may not have been identified in the past.Water quality measurements should include dissolved oxygen readings at a minimum becausefisheries biologists that have investigated these events in the past have concluded that the mortality of fish was the result of oxygen depletion, The most effective way to monitor dissolved oxygenlevels within the lake would be through the use of permanently fixed continuous water qualitysamplers and data loggers installed at several depths that could be programmed to takemeasurements at predetermined time intervals.

The number of water quality samplers purchased or the type of sampler utilized would be dependent upon the desired results and cost of theequipment.

Ideally, the best system would allow the sampling unit to take measurements atprogrammed time interval (perhaps every 15 minutes to daily), would measure at least DO, watertemperature, and pH, could provide instantaneous readouts to Braidwood staff without having tomanually go into the field to download data, and would require minimal maintenance orcalibration to operate.

The price range of this type of equipment is highly variable depending onthe unit selected, the anchoring mechanism for the unit if required, battery life, the number ofparameters

measured, etc. An alternative, to this approach would be to utilize a technician tomanually take these measurements.

The disadvantage of this approach is the number of readingsthat could be taken on a daily basis and the time involved to conduct the water quality analysis inthe field.4-4HDR Engineering, Inc.

RS-14-138 Enclosure Page 285 of 322Water quality and weather at Braidwood Lake should be monitored on a predetermined routinebasis. That could be at least weekly throughout the year or perhaps only through the more criticaltime period of approximately June through August. The two tiered sampling approach would beinitiated when dissolved oxygen readings hit a pre-determined trigger point (perhaps 5 to 6 ppm).Once DO readings decrease to the trigger point, sampling frequency should be increased.

Ifautomatic samplers are not used, field technicians should be in the field by sunrise when DOreadings are the lowest. If automatic samplers were utilized, dissolved oxygen, temperature andother water quality parameters could be tracked throughout the day. This would becomeimportant if DO readings ranged from 4 or 5 ppm in the morning to 7 or 8 ppm in the afternoon.

This information would indicate that photosynthesis is still occurring during the daylight period,which would replenish DO levels in the water and reduce the risk of a fish die-off.

However, ifDO levels were 4 or 5 ppm in the morning and only increased slightly throughout the day, thiswould indicate very little oxygen production due to photosynthesis.

This condition would lead toa greater oxygen deficit during the evening, and could indicate the onset of a phytoplankton die-off that could trigger a fish kill. Once DO levels approach 3 ppm, Station management could benotified of a potential

problem, increased visual inspections of the lake could be conducted, andfish cleanup and disposal crews could be notified and put on standby status.Additionally, Braidwood staff should be aware of weather patterns that can influence these events.When phytoplankton blooms are prevalent and several cloudy days with little or no wind areforecast, massive dies offs of the bloom and subsequent oxygen depletion throughout the watercolumn should be anticipated.

Increased sampling of DO during these weather patterns isadvisable in conjunction with an increase in the frequency of visual inspections at the lake formoribund or dead fish. An increase in water clarity or transparency within the lake would also beexpected to occur as the phytoplankton population crash is in progress.

Visual inspections for fish die-offs should be conducted around the entire cooling loop asprevailing winds may push most of the fish toward one end of the lake. HDR recommends waterquality measurements be conducted at a depth of approximately one meter, if multiple depths arenot sampled.

If only one sampling location is selected, that location should be located near theapproximate mid-point of the cooling loop. The number of water quality stations sampled shouldbe determined by Exelon management or an advisory staff. It is further recommended that an4-5HDR Engineering, Inc.

RS-14-138 Enclosure Page 286 of 322advisory team should be formed to devise an effective sampling program and set of procedures that can effectively monitor conditions within the lake. HDR is willing to participate and interactwith the advisory team to provide expertise in the development of an effective sampling program.4-6HDR Engineering, Inc.

RS-14-138 Enclosure Page 287 of 32

25.0 REFERENCES

CITEDBecker, G.C. 1983. Fishes of Wisconsin.

The University of Wisconsin Press. Madison, Wisconsin.

Environmental Science & Engineering.

1993. Kankakee River Fish Monitoring Program Braidwood Station 1993. Report to Commonwealth Edison Company,

Chicago, Illinois.

HDR Engineering, Inc. 2009. Braidwood Station Kankakee River Fish Monitoring

Program, 2008.Prepared for Exelon Nuclear, Warrenville, Illinois.

HDR Engineering, Inc. 2010. Braidwood Lake Additional Biological Sampling

Program, 2009.Prepared for Exelon Nuclear, Warrenville, Illinois.

HDR Engineering, Inc. 2011. Braidwood Lake Additional Biological Sampling

Program, 2010.SPrepared for Exelon Nuclear, Warrenville, Illinois.

HDR Engineering, Inc. 2012. Braidwood Lake Additional Biological Sampling

Program, 2011.Prepared for Exelon Nuclear, Warrenville, Illinois.

IHDR/LMS 2006. Braidwood Station Kankakee River Fish Monitoring

Program, 2005. Prepared forExelon Nuclear, Warrenville, Illinois.

HDR/LMS 2007. Braidwood Station Kankakee River Fish Monitoring

Program, 2006. Prepared forExelon Nuclear, Warrenville, Illinois.

HDR/LMS 2008. Braidwood Station Kankakee River Fish Monitoring

Program, 2007. Prepared forExelon Nuclear, Warrenville, Illinois.

Illinois Endangered Species Protection Board. 2009. Checklist of Endangered and Threatened Animals and Plants of Illinois.

Illinois Department of Natural Resources, Springfield, Illinois 18 pp.Lawler, Matusky and Skelly Engineers (LMS). 1992. Braidwood Station Kankakee River FishMonitoring

Program, 1991. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1996. Braidwood Station Kankakee River FishMonitoring

Program, 1995. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 1999. Braidwood Station Kankakee River FishMonitoring

Program, 1998. Report to Commonwealth Edison Company,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2001. Braidwood Station Kankakee River FishMonitoring

Program, 2000. Report to Exelon Nuclear,

Chicago, Illinois.

Lawler, Matusky and Skelly Engineers (LMS). 2005. Braidwood Station Kankakee River FishMonitoring

Program, 2004. Report to Exelon Nuclear,

Chicago, Illinois.

5-1HDR Engineering, Inc.

RS-14-138 Enclosure Page 288 of 322Piper, R.G. et al. 1983. Fish Hatchery Management.

United States Department of the Interior Fishand Wildlife Service.

Second Printing.

Washington, D.C. 517 pp.Pflieger, W.L. 1975. The Fishes of Missouri.

Missouri Department of Conservation.

Jefferson City, Missouri.

Smith, P.W. 1979. The Fishes of Illinois.

University of Illinois Press, Urbana, Illinois.

314 pp,Trautman, M.B. 1981. The Fishes of Ohio. Ohio State Press in Collaboration with the Ohio SeaGrant Program Center for Lake Erie Area Research.

782 pp.5ii5-HDR Engineering, Inc.

RS-14-138 Enclosure Page 289 of 322APPENDIX APHYSICOCHEMICAL DATA RS-14-138 Enclosure Page 290 of 322LIST OF TABLESTable No. Title Page No.A-1 Physicochemical Measurements Recorded Concurrently withElectrofishing Samples Collected from Braidwood Lake, 2012. A-1A-2 Physicochemical Measurements Recorded Concurrently withTrap Netting Samples Collected from Braidwood Lake, 2012. A-2A-3 Physicochemical Measurements Recorded Concurrently withGill Netting Samples Collected from Braidwood Lake, 2012. A-3A-40 Physicochemical Measurements Recorded Concurrently withHoop Netting Samples Collected from Braidwood Lake, 2012. A-4HDR Engineering, Inc.

TABLE A- IPHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH ELECTROFISHING SAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2012PARAMETER E-1 E-2 E-3 E-4 E-5 E-6 E-7 E-8Date (First Sample Period) AUG 23 AUG 23 AUG 23 AUG 23 AUG 23 AUG 23 AUG 23 AUG 23Time 0725 0815 0900 0945 0620 1210 1120 1030Temperature

(* C) 32.7 31.6 30.3 32.0 31.7 32.0 31.4 32.1Dissolved oxygen (ppm) 4.60 6.38 7.31 6.82 6.86 7.50 8.32 7.16pH 8.6 8.7 8.8 8.8 8.7 8.6 8.6 8.6Conductivity

([umhos/cm) 1112 1109 1106 1102 1106 1081 1097 1086Date (Second Sample Period) SEP 12 SEP 12 SEP 11 SEP 11 SEP 12 SEP 12 SEP 11 SEP 11Time 0825 0915 1425 1350 0725 1015 1610 1505Temperature (I C) 28.7 28.3 29.3 30.2 29.5 28.7 29.6 30.1Dissolved oxygen (ppm) 6.37 7.40 10.54 9.86 6.81 8.09 10.14 10.22pH 8.8 8.8 8.9 8.9 8.8 8.9 8.9 8.9Conductivity (junhos/cm) 1198 1178 1181 1210 1186 1184 1191 11900 ,.) CDW4 TABLE A-2PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH TRAP NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2012PARAMETER TN-1 TN-2 TN-3 TN-4 TN-5 TN-6 TN-7 TN-81,JDate (First Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (W.inhos/cm)

Date (Second Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (l.tmhos/cm) 1820"0742'35.133.811.155.598.88.7110511141815075535.133.811.115.628.88.711021112.1805071033.732.611.386.428.78.7109911121755065033.632.411.466.658.78.7110011001750082032.03.0.510.646.368.68.8109611081830062032.731.310.957.218.88.6110011041703085231.831.29.457.268.68.8109711061640084531.430.710.207.478.68.810941107AUG 20-21 AUG 20-21 AUG 20-21 AUG 20-21 AUG 20-21 AUG 20-21 AUG 20-21 AUG 20-21SEP 10-11 SEP 10-11 SEP 10-11 SEP 10-11 SEP 10-11 SEP 10-11 SEP 10-11 SEP 10-111715075533.631.111.874.318.88.8127512451705074533.631.211.874.738.88.8127512451730072532.230.312.176.239.08.8124212211715071032.330.412.256.859.08.7124012241650081530.927.613.207.368.98.9120311601745083231.229.511.947.609.08.9121912021615084529.729.09.297.568.88.9118511901605085529.727.411.807.368.8 -u8.9CD1185 m1164 2g.CDaTop number represents subsurface readings taken 0.5 meter below the surface when the nets were set in the evening.bBottor number represent subsurface readings taken 0.5 meter below the surface when the nets were retrieved the next morning approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> later.

TABLE A-3PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH GILL NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2012GN-1 in Shallow Water GN-2 in Deep Water(1-2 m) (8-10 m)PARAMETER Surface Bottom Surface BottomDate (First Sample Period) AUG 20Time 1630 a 1845 1845Temperature (0 C) 31.4 32.2 31.9Dissolved oxygen (ppm) 93a.3010.84 10.53pH 8.7 a 8.7 aConductivity (pirhoslcm) 1094 a 1098 1095Date (Second Sample Period) SEP 11Time 1020 a 1045 1045Temperature (C C) 29.3 a 29.5 29.3Dissolved oxygen (ppm) 8. 15 a 8.65 7.27"2pH 8.9 a 9.0 aWOConductivity (pmhos/cm) 1192 a 1193 1192 a-M co' Water quality measurement not taken.

TABLE A-4PHYSICOCHEMICAL MEASUREMENTS RECORDED CONCURRENTLY WITH TRAP NETTINGSAMPLES COLLECTED FROM BRAIDWOOD LAKEBraidwood Station -2012HN-I HN-2 HN-3 HN-4DEEP WATER BAITED DEEP WATER UNBAITED SHALLOW WATER SHALLOW WATERPARAMETER (8-10 m) (8-10 m) BAITED (1-2 m) UNBAITED (1-2 m)Date (First Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (pmhos/cm)

Date (Second Sample Period)TimeTemperature (0 C)Dissolved oxygen (ppm)pHConductivity (pamhos/cm)

AUG 20(SET)AUG 21(LIFT)AUG 20(SET)AUG 21(LIFT)AUG 20(SET)AUG 21(LIFT)AUG 20(SET)AUG 21(LIFT)171531.8'31. 8b9.459.228.510971097090531.331.27.357.168.711081108170531.831.89.458.228.510971097091531.27.357.168.711081108174531.99.458.51095092531.37.548.81104173531.99.458.5109509353 1.37.548.81104SEP 10(SET)164030.029.810.559.958.811881188SEP 11(LIFT)092029.229.27.647.428.911921192SEP 10(SET)164030.029.810.559.558.811881188SEP 11(LIFT)93029.229.27.647.428.911921192SEP 10(SET)163030. ISEP 11(LIFT)094529.4SEP 10(SET)163030. ISEP 11(LIFT)100029.410.908.911918.178.9119010.908.911918.17 -oCD8.9 P0 -1194 M'C co'Top number represents subsurface readings taken 0.5 meter below the surface.b Bottom number represent deep water readings taken 0.5 meter off the bottom.

RS-14-138 Enclosure Page 295 of 3221APPENDIX BHISTORICAL WATER QUALITY AND FISHERIES DATA RS-14-138 Enclosure Page 296 of 322LIST OF TABLESReport No. Title Page No.B-1 Results of Initial Braidwood Cooling Pond Survey by SEA Inc.,2001. B-1B-2 Investigation of Fish Kill on Braidwood Cooling Pond August27-28, 2001. B-5B-3 Results of Braidwood Cooling Pond Water Quality Analysisfrom August 27 and 28, 2002. B-9B-4 Fish Kill Reports going back to 2003. B-17B-5 Braidwood Lake Fish Kill, August 21, 2007. B-19B-6 Braidwood Fish Kill August 21, 2007. B-21B-7 Braidwood Fish Kill Clean-up August 21, 2007. B-22HDR Engineering, Inc.

RS-14-283 Enclosure Page 8 of 9APPENDIX REPORT B-1.Results of Initial Braidwood Cooling Pond Survey by SEA Inc.SEA Inc. was asked to conduct an initial water quality and ecological assessment of Braidwood Cooling Pond. The objective was to determine if the densemacrophytes were contributing to an increasing trend toward a higher pH in thepond. The results and discussion presented in this report are primarily basedupon the samples taken and observations made on May 29 and 30, 2001, and ona preliminary review of water quality data from three sites taken on May 18, andJune 14, 2001. SEA Inc. was also asked to investigate a fish kill on Braidwood Cooling Pond on August 27 and 28. The results of that investigation are in aseparate report but some of that information is referenced in this report.Overview of Methods and Results Presentation.

SEA's initial survey (May 29-30) consisted of:" water quality parameters at several key sites with a Hydrolab Surveyor Ill,during both daylight and night conditions,

" measuring phytoplankton community respiration (light & dark bottle method)." identification of macrophytes and observations on their distribution andabundance, and" monitoring temperatures throughout the cooling loop.The survey results are summarized in Tables 1,2, 3, and 4. Table 1 provides theresults from key sampling sites that were selected to characterize the coolingpond. These sites were sampled three to four times over a 36-hour period.Parameters sampled with the Hydrolab included:

Depth, Temperature, Dissolved Oxygen (D.O.), pH, Specific Conductance, and Redox Potential.

Sample timesincluded midday, just before sunset, and prior to sunrise.Table 2. includes results from two sites for depth profiles, 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration light& dark bottles, and the SX discharge.

Table 3. provides D.O. and temperatures sequentially around the cooling loop at midday. Table 4. lists the D.O. levels and% saturation at four sites prior to sunrise.

Table 5 list the water quality analysispreformed by Test America at three locations on two dates. Figure 1. is a mapidentifying the sample locations listed in the tables.Discussion of Results and Observations:

Braidwood Cooling Pond was characterized to SEA Inc. as a pond that wasdominated or choked by macrophytes.

Based on this characterization, we feelthat Braidwood Cooling Pond has undergone a transformation to a systemdominated by phytoplankton.

Although we were not prepared to sample thephytoplankton for densities and identification, it was very obvious that anB-I RS-14-138 Enclosure Page 298 of 322intensive phytoplankton bloom was in progress.

Secchi disc readings were only0.30 to 0.35 m throughout the pond. Although we were unable sample thephytoplankton, we would suspect it is dominated by Blue-Green algae(Cyanophyta),

based on the water temperatures, total phosphorous levels, highpH and apparent high densities.

Braidwood Cooling Pond appears to be a very dynamic system that receivesenergy subsidies in the form of heat, pumped circulation and make-up water fromthe Kankakee River. Several perched cooling ponds in the Midwest have hadhigh macrophyte densities in their earlier years but usually become dominated byphytoplankton if they have heavy thermal loading.

A switch to phytoplankton dominance is usually accompanied by a reduction in water transparency.

OurSecchi disc readings were about 0.3 m which is about one half of the 2 ft or0.6m)value listed in a privately produced fishing guide (Sportsman' Connection) published in 2000. Although we did not examine many of the isolated coves, wefound Milfoil ( Myriophyflum verticillatum) only in the last 1/3 of the cooling loop(Figure 1. sites7,8,9) and its abundance was spotty. The Sportsman' Connection fishing guide map had a much wider distribution of submerged, emergent andfloating vegetation and appeared to be more in line with earlier descriptions SEAInc. were given of Braidwood.

Nutrients that were previously tied up by themacrophytes are now likely being taken up by the phytoplankton.

The reducedwater transparency due to the phytoplankton bloom will limit light to thesubmerged macrophytes and likely cause further reductions.

The intensive phytoplankton bloom that Braidwood is currently experiencing mayhave more potential for adverse impacts to the biological community than onoperational impacts to the station.

The water seems to be fairly well buffered anddiurnal swings in pH were insignificant.

Analysis of the water for alkalinity couldconfirm the buffering capacity.

Blue-Green algae blooms may present problemswith D.O. levels and in some rare cases may release toxins with impact otheraquatic life.The light & dark bottle (Table 2.) and the pre-sunrise D. 0. levels (Table 4.)illustrated the intensity of the bloom. The light and dark bottles were at a 0.5 mdepth at end of the discharge canal for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Respiration in the dark bottleddepleted the initial D.O. from 10.8 mg/I (158% saturation) to 1.37 mg/I (20 %saturation).

The light bottle was supersaturated to the point the entire insidesurface was coated with oxygen bubbles and the D.O. was 11.8 (174%saturation).

The photosynthetic rate was much higher than could be measureddue to the extensive formation of oxygen bubbles in the light bottle. Thephotosynthetic rate was so high that the light bottle should have been limited to 6hours to obtain a better measurement of the gross plankton photosynthetic rate.The pre-sunrise D.O. measurements (Table 4.) also reflect the high respiration rate of the plankton community.

Most notable was Site #3 where D.O. levelsdropped to 4.1 mg/I. The midday sampling on the first day (Table 1.) wasconducted during bright and sunny conditions and D.O. levels at most sites werehigher than midday samples on the following day when it was overcast.

ThisB-2 RS-14-138 Enclosure Page 299 of 322plankton community is so productive that D.O. levels can be expected to swing*rapidly.

During our survey, air temperatures were mild (high 65 F) and it waswindy both days. Under a scenario of several hot summer days, with little wind,full operation of the station, followed by a cloudy day, D.O. levels could drop tothe point that fish kills could occur. Some fish species will be already stressed byheat, saturation levels for D.O. will be lower, and high, predawn respiration ratescould create a significant problem.

Unfortunately, there are no operational changes the station can make to reduce this risk. The fish kill that did occur inlate August was apparently a result of depleted DO that most likely resulted fromthe phytoplankton bloom die off.Thermal refuges are critical to the survival of fish in heavily loaded cooling ponds.The deeper areas in the warmer end of the lake will not be refuges sinceadequate levels of oxygen are already absent from depths below 4 meters (Table2.). However, the flow and slightly cooler temperatures at site 7 (figurel.)

havemaintained oxygen levels down to nearly 10 meters. If these refuges are erodedaway during the summer, fishes will be stressed.

Of the three key species listedin the Sportsman's Connection for Braidwood, both the walleye and crappiewould be sensitive to D.O. at higher temperatures.

Two fish kills occurred inBraidwood this summer, the first in late July was likely related to temperature, thesecond in lake August resulted from DO depletion.

Although our expertise is not in water chemistry, Braidwood Cooling Pond maybe facing some water quality issues. One of the objectives of the survey was todetermine if macrophytes were contributing to the increasing pH. A chart of pHvalues from 1989 to 1998 provided by the Braidwood Station indicated theincreasing trend in pH has become more pronounced since 1997. Since thissurvey indicated macrophytes abundance was in a sharp decline, it is clear theyare not contributing to the elevated pH of 9.1 to 9.2 (Table 1). The intensive phytoplankton boom present during the survey could have contributed to theelevated pH. The phytoplankton bloom had crashed by August 27 and 28 (fish killinvestigation) and the pH had dropped to 8.6. It was not possible from this limiteddata to determine to what extent several factors may be contributing to theelevated pH. The cooling pond's buffering

capacity, photosynthetic

activity, blowndown rate, and plant operations are all potential factors to be investigated.

The Test America analytical results from three sites on 5/18/01 and 6/14/01provides some information on water quality (Table 5). Orthro phosphate is areadily available form for plants and is quickly taken up. The detection limit listedby the lab was 0.06 ppm, which was too high to show any differences betweensites or sample dates. Orthro phosphate levels in many Illinois lakes would bebelow 0.025 ppm. Total phosphate at the plant discharge on 5/18/01 was 5.5ppm, which is very high. The Illinois General Use Water Quality standard is not toexceed 0.05 ppm in lakes or reservoirs over 20 acres. The plant appears to bethe phosphate source and one possible explanation may be scale inhibitors commonly used by power plants. Scale inhibitors are typically high in phosphates but it is generally in a form not available to aquatic plants. Total phosphate levelson 6/14/01 were lower (0.18 to 0.28 ppm) but still elevated relative to other lakes.B-3 RS-14-138 Enclosure Page 300 of 322Phosphates are a major concern as elevated levels can contribute to nuisancephytoplankton blooms.Total Suspended Solids (TSS) on 5/18/01 were high (164 ppm) at the discharge and generally higher than expected throughout the pond. It is suspected that theplankton bloom may have been responsible for much of that elevation.

This couldhave been confirmed by comparing the volatile to the non-volatile portion of theTSS.Total Dissolved Substances (TDS), total hardness,

calcium, sulfates and specificconductance are all correlated and generally exhibited increases from 5/18/01 to6/14/01.

The high evaporation rates in the cooling pond during the summerprobably contributed to this increase.

These parameters are of concern sincethey are indicators of potential scaling in heat exchangers.

Lowering these levelswould require an increase in make-up and blow-down rates. However it isrecognized there are restrictions on make up withdraws and blow-down concentrations are regulated.

SummaryIt appears that the Braidwood Cooling Pond plant community is changing fromone dominated by macrophytes to phytoplankton.

The phytoplankton bloom inMay was very rich and has the potential to deplete D.O. to the point that fish killscould occur. There are few operational changes that the plant can take to preventthese potential events. Monitoring the cooling pond and preparing regulatory agencies for these potential changes may be a way to help manage these risks.Unfortunately the fish kill in late August confirmed the potential for these kills.The phytoplankton bloom may a contributor to the increasing pH. The high totalphosphate level that appears to be coming from the plant may be fueling thephytoplankton bloom. Further investigation of the factors that may be contributing B-4 RS-14-283 Enclosure Page 9 of 9APPENDIX REPORT B-2.DRAFTInvestigation of Fish Kill on Braidwood Cooling PondAugust 27-28, 2001Executive Summary:Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of anon-going fish kill on Braidwood Cooling Pond on August 27 & 28, 2001. Theinvestigation consisted of surveying the shoreline to determine the extent of thekill and the species involved, and water quality analyses for pH, temperature, anddissolved oxygen.Most of the fish appeared to have been dead for about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than95% were gizzard shad. The other species involved in descending order ofrelative abundance were freshwater drum, quillback, carp, largemouth bass,channel catfish,

redhorse, smallmouth bass and bluegill.

Other than gizzard shadmost of the dead fish were located between the mid -point in the cooling loop tothe intake. Throughout most of the cooling pond, dissolved oxygen levels were ator below the minimum levels necessary to support most fish and was the mostlikely cause of the kill. Water clarity was very high and suggested a recent die offof much of the phytoplankton, which is usually followed by oxygen depletion.

Thisis a natural phenomenon that can occur in highly productive lakes during summermonths. Temperatures throughout most of the lake were within the tolerance limits of the species involved in the kill. It does not appear that operations of thepower station had a direct impact on the fish kill.Methods Overview and Results Presentation:

SEA Inc. arrived at 5:00 PM on August 27 and conducted an initial survey of themain portion of the cooling loop and checked temperature, dissolved oxygen(DO), and pH at two locations.

The investigation continued at sunrise on August28, and included investigation of many of the coves on the lake and water qualityanalyses at sixteen sites. Water quality analysis was conducted with a HydrolabSurveyor Ill. Measurements were for depth, temperature, DO, pH, specificconductance, and redox potential at the surface (0.5 Meters) and then at one-meter intervals to the bottom.The water quality sampling locations are shown on Figure 1. Dissolved oxygenprofiles from selected sites are illustrated in Figure 2. Figure 3 illustrates DOconcentrations at one-meter depth at all sites. The results of the water qualityanalyses are presented in Table 1. The station hourly inlet and outlet watertemperatures for August 24 through August 27 are listed in Table 2.B-5 RS-14-138 Enclosure Page 302 of 322Discussion of Results and Observations:

Upon arrival the investigation began at the south access boat ramp near Site 3(Figure 1.) and proceeded around the cooling loop toward the plant intake. NearSite 3 several gizzard shad in the 170 to 220 mm were observed.

They appearedto have been dead for 12 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In the portion of the pond between sites5.5 and 5.75 there were greater numbers of gizzard shad along the shoreline anda few largemouth bass. The largemouth bass appeared to have been dead formore than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The number of fish appeared to increase as theinvestigation progressed around the cooling loop. The largest concentrations ofdead fish were in several coves on the East side of the lake near Site 8. Theback 20 to 35 ft. of the cover were covered solid with dead fish. Gizzard shadcomprised more than 95% of the fish in these coves and were represented bythree size classes.

The other species involved in descending order of relativeabundance were freshwater drum, quillback, carp, largemouth bass, channelcatfish,

redhorse, smallmouth bass and bluegill.

There are two factors that may have influenced the distribution of dead fish. First,the temperature gradient becomes more favorable for fish toward the intake endof the cooling loop. Second, the circulation of water around the cooping loopwould tend to concentrate dead fish in the intake area of the cooling pond. Theconcentration of fish in coves at Sites 8 and 8.5 was most likely an accumulation resulting the above mention factors and wind direction.

However DO levels atSite 8.5 were only 2 ppm (Table 1, page 3) at a time of day when they shouldhave been much higher. This level of DO is not adequate to support most fishes.Several YOY freshwater drum were observed at the surface which had recentlydied or were about to. This kill did involve many fish, but during this survey manylive fish were observed on sonar in the cooler end on the lake. Bluegills exhibiting normal behaviors were observed in the cove just East of Site 2.5.Dissolved oxygen levels at the plant intake were 3.5 ppm at the surface and 1.2ppm at 3 meters (Table 3) during the evening of August 27. Percent DOsaturation was 49% and 17% respectively.

Surface DO level taken on May 29 bySEA Inc. at this same location, at the same time of day was 9.3 ppm and 117%saturation.

The DO levels at Site 3 were 3.8 ppm on August 27 which was muchlower than the 8.0 ppm taken at sunset on May 29. On August 28 just prior tosunrise the DO at Site 3 was 3.2 ppm only slightly lower than the previousevening indicating little diurnal variation.

On May 29 the overnight drop in DO atSite 3 was 50%.The surface DO level at Site 4 on August 28 was 2.9 ppm and dropped to 0.7ppm at 4 meters. Surface DO levels Sites 4.5, 5, 5.5, and 5.7 were even lowerB-6 RS-14-138 Enclosure Page 303 of 322ranging from 2.4 to 2.1 ppm. Site 6 had one of the higher DO levels at 4.4 ppm.Site 8 and 9 had the highest surface DO levels at 4.8-ppm (Table 1).Temperatures throughout most of the cooling pond were within the tolerance limits of most fish species and there had been no major temperature changes inthe last few days (Table 2). The oxygen levels throughout most of the lakesuggest that depleted oxygen levels were the most likely cause for the fish kill.Such kills can naturally occur in highly productive lakes or ponds that may exhibitlarge diurnal swings in DO levels due to high daytime photosynthetic rates andhigh respiration during the night. The survey SEA Inc. conducted on May 28 and29 suggested Braidwood Cooling Pond was a very productive and the potential existed for an oxygen depletion fish kill. This survey noted several changes in thecooling pond that suggested such a kill had occurred.

There was no indication that the fish kill was directly related to the operation of the power station.SEA Inc.'s initial investigation in May was to assess if the historically highabundance of macrophytes (rooted aquatic vegetation) was contributing anincreasing trend in pH. What was observed was an intensive phytoplankton bloom that limited light penetration and almost no healthy macrophytes remained.

Water transparency measured with a Secchi Disc was only 0.3meters. Diurnal swings in DO levels were very pronounced and at some locations dropped to 4 ppm just prior to sunrise and reached supersaturation levels by midday. Under these conditions any major change in nutrients, reduced lightintensity, increase in biological oxygen demand, or other factors could result inoxygen depletion.

Braidwood Cooling Pond appeared to be undergoing atransition from a system dominated by macrophytes to one dominated byphytoplankton.

One of the most notable changes during this investigation was the dramaticchange in water transparency.

There was no phytoplankton bloom and SecchiDisc readings had increased up to 2.7 meters. Plankton samples indicated verylow levels of phytoplankton but high abundance of zooplanktors (primarily Rotifers and Cladocera).

Oxygen levels were typically from 29% to 66% ofsaturation as opposed to May when most midday levels were at or abovesaturation.

As discussed

earlier, there were only minor differences in diurnaloxygen levels. All the above factors suggest the phytoplankton bloom hadrecently crashed.

There were no remaining macrophytes to fill the niche asprimary producers.

Not only was there a reduction in photosynthetic activity toproduce oxygen, there was an increased oxygen demand from decomposition and respiration of the abundant consumers.

It is suspected that oxygen levels aday or two prior to this investigation may have been even lower than observed.

The one-meter DO levels were lowest toward the center portion of the coolingloop (Figure 2). From Site 3 to Site 6.5 (with the exception of Site 6) DO levelswere 3. lppm or less. A similar pattern of low DO was noted at Sites 3 and 4 inearly morning samples taken in the May survey. Factors contributing to lower DOB-7 RS-14-138 Enclosure Page 304 of 322levels were not clear, but it suggest this may be one of the most sensitive areasof the cooling pond to oxygen depletion.

Additional sampling would be required toattempt to identify the cause and to eliminate any data bias associated with thetime of day samples were taken.The unique changes in water depths and flow velocities in Braidwood CoolingPond have a major influence on DO levels and temperature stratification.

Areasof the cooling pond which were deep and not in a high velocity areas exhibited amore normal DO curve from top to bottom (Figure 3). At Site 2.5, DO declinedquickly between 6 and 8 meters and coincided with thermal stratification.

At Site4, the DO declined rapidly between 2 and 3 meters where thermal stratification was apparent (Table 1). In contrast, Sites 5.5 and 7 were located in areas withhigh velocities and had fairly consistent DO levels and temperatures from top tobottom (Figure 3). This is quite different from the DO and temperature profiles inmore typical perched cooling ponds and better utilizes the entire volume forcooling and may also provide for better thermal refuges for fish. During this lastincident it is unlikely Site 5.5 was an effective refuge for DO since levels werebelow 2.5 ppm. These DO levels were however due to lower DO levelsthroughout the cooling pond rather than depletion at this site.Braidwood Cooling Pond appears to be undergoing a transition from a ponddominated by marcophytes to one dominated by phytoplankton.

During such atransition major swings may be expected as different components of thisecosystem adapt to this change. Over time one would expect the amplitude ofthese changes to moderate.

During the May survey the intense phytoplankton bloom appeared to eliminate the macrophytes.

There were major differences indiurnal DO levels suggesting a very productive system with heavy respiration anddecomposition demands at night and supersaturation from photosynthesis duringthe day. This survey indicated a major loss of the phytoplankton, no remaining macrophytes to carry on primary production and enough respiration anddecomposition to reduce oxygen below the levels to maintain many fishes.Additional studies on nutrients and the dynamics of the plankton would beneeded to better identify the changes that may be taking place in this coolingpond. Decisions on the operational management of this cooling pond as well asthe fishery management need to consider that this pond may be going throughtransitional changes.B-8 RS-14-138 Enclosure APPENDIX REPORT B-3. Page 305 of 322Results of Braidwood Cooling Pond Water QualityAnalysis from August 27 & 28, 2002SEA Inc. was asked to sample Braidwood Cooling Pond for a number of waterquality parameters on August 27, 2002. This sampling effort was to provide datato address operational concerns related to a trend toward an increasing pH andincreased scaling at the plant intake. This report provides the results of theAugust 27and 28, 2002 sampling and makes comparisons with data fromprevious sampling efforts by SEA Inc. and with other data provided by theBraidwood Station to SEA Inc.Executive Summary:Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with cooling pond blow down limits, and maintaining arecreational fishery.

Several of these parameters had significant increases in thepast year and could lead to greater operational costs and problems in the nearfuture.The excess of nutrients in the water has contributed to plankton blooms that haveeliminated the submerged aquatic plants, contributed to diurnal increases in pH,and lowered dissolved oxygen levels. Swings in the dissolved oxygen levelassociated with the plankton blooms could lead to fish kills.The plan to increase the blow down rate from the cooling pond is a good long-term solution to the continued viability of the cooling pond. Continued monitoring of the cooling lake water quality would be important in evaluating theeffectiveness of the increased blown down rate, the impacts of H2SO4 additions, and other water treatment changes.Overview of Methods and Scope of the Sampling Effort.The investigation on August 27 and 28 of 2002 consisted of collection of watersamples from various depths at six sites around Braidwood Cooling Pond (BCP),as well as in-situ profile measurements for temperature, conductivity, pH, anddissolved oxygen. A contract laboratory analyzed the water samples for theeleven chemical parameters as listed in Table 1. In addition to chemical samples,the primary production rate of the phytoplankton community was determined attwo sites by the light/dark bottle method, and plankton samples were taken forB-9 RS-14-138 Enclosure Page 306 of 322qualitative analysis.

Water transparency was measured with a Secchi disc ateach site. The sampling sites used in this investigation are identified on Figure 1.Additional investigations by SEA Inc. referenced in this report include June 28,2002, April 29,2002, March 6, 2002, January 10, 2002, August 28, 2001 and May29, 2001. The purpose and scope of each of these investigations varied but nonewere as extensive for water quality as the August 2002 investigation.

In severalcases SEA Inc. collected the water samples for Betz and the results were notmade available to SEA Inc. Data from the above referenced studies is included tohelp identify trends and provide a single summary of data for ongoinginvestigations.

The discussion of results is based on and limited to the studiesreferenced in this report and those provided to SEA Inc.Presentation of Results and Related Discussion:

The analytical results of the water quality analysis are presented in Table 1. Theeleven parameters were selected to provide input to the water quality issues thatwere described to SEA Inc. These issues include increasing trends for rising pH,scaling, algal blooms, and recent fish kills.Table 1 indicates abnormally high levels for TDS, alkalinity,

hardness, sulfates, magnesium,

calcium, and total phosphorus throughout the cooling pond. Thesevalues were not unexpected and support the ongoing program to increase theblow down rate from the cooling pond. These values can be put into perspective by comparing the cooling lake sites to the same values for the make -up waterpond (Site 7P in Table 1), which is the source water. The cooling pond values forthe above mentioned parameters ranged from 2X to nearly 9X higher than themake-up water.The alkalinity is a measure of water's capacity to neutralize acids and is a resultof the quantity of compounds in the water that shift the pH to the alkaline side.Bicarbonate and carbonate ions normally make up most of the alkalinity.

However in waters with a pH of greater than 8.3, carbonate alkalinity is theprimary form. Alkalinity is very high throughout the cooling pond and ranged from340 to 360 mg/I in the upper water layers (Table 1). In contrast, the make-upwater pond alkalinity was 150mg/l.

Other comparisons include a 14-year averagefor Clinton Lake of 168 mg/I and an IEPA survey of 63 lakes around the statewith alkalinity ranging from 20 to 270 mg/I. The high alkalinity gives Braidwood Cooling Pond has a great capacity to neutralize acids.Hardness is a measure of the divalent metallic cations present in water(such as calcium, magnesium, ferrous iron, and manganous manganese).

Calcium reacts with bicarbonate ions in water to form calcium carbonate B-10 RS-14-138 Enclosure Page 307 of 322scale. Magnesium typically reacts with sulfate; the ferrous ion withnitrate; and the manganous ion with silicates.

Hardness and alkalinity in water are related.

Carbonate hardness is the part oftotal hardness that is chemically equivalent to the bicarbonate plus carbonate alkalinities present in the water. If alkalinity is greater than total hardness thentotal hardness is equal to the carbonate hardness.

In cases such as in BCPwhere alkalinity is less than the total hardness then alkalinity equals carbonate hardness (as CaCO3) and the remaining part of hardness is the noncarbonate compounds such as magnesium sulfate.The total hardness in the upper layers of August 2002 samples ranged from 680to 720 mg/I (nearly twice the alkalinity level) so other ions are contributing significantly to the hardness.

The total hardness levels in 2002 were significantly higher than the 435 to 531mg/I range reported for two dates in 2001 by TestAmerica (Table 2). This increase in hardness is a reason for concern.Sulfate levels in the August 2002 samples ranged from 330 to 390 mg/i (Table 1).These levels are much higher than the make up water (58 mg/I) and to someextent may reflect the history of portions of the cooling pond as strip mine lakesthat are characteristically high in sulfates.

However there seems to be asignificant increase in sulfates in the past year. In the Test America data from twodates in 2001, sulfates ranged from 230 to 270 mg/I (Table 2). Sulfate levels insamples collected by SEA Inc. on April 29, 2002 were 250 mg/I (Table 3).Samples collected by SEA Inc. on June 28,2002 had levels ranging from 320 to340 mg/I (Table 4). The sulfate increase noted in the summer of 2002 may reflectthe use of H2SO4 to reduce pH levels in the cooling pond. This level of sulfatesmay be a concern since it significantly contributes to the non-carbonate hardnessand can be a factor in scaling.Calcium levels in the August 2002 samples were about twice the levels in2001 and ranged from 130 to 140 mg/I (Table 1). The 2001 Test America dataranged from 41 to 58 mg/I (Table 2) and the make-up water in August 2002 was57 mg/l. The increase in calcium may be a major concern since with the highcarbonate alkalinity there is a high potential for scaling.Magnesium levels in the August 2002 sampling ranged from 84 to 93 mg/l. Theselevels were essentially the same as the 81 to 91 mg/I reported by Test America in2001. Magnesium levels are however elevated compared to the make-up waterthat had only 20mg/I or when compared to the 14-year average for Clinton Lakeof 32.2 mg/l. Magnesium levels are also a concern due to their potential forscaling.Total dissolved solids include all of the above parameters and other dissolved solids in the water. As would be expected, the August 2002 samples are elevatedand are higher than the previous year. The August 2002 TDS ranged from 930 toB-Il RS-14-138 Enclosure Page 308 of 3221100 mg/I (Table 1) compared to a range of 684 to 788 in the 2001 Test Americadata (Table 2). The make-up water was 280 mg/I in the August 2002 sample.Sodium levels in the August 2002 samples ranged from 60 to 64 mg/I in theupper water layers. Comparable data from 2001 was not available, but thesodium levels in the make-up water was 9.1 mg/I in the August 2002 sample(Table 1).There were only minor variations in the concentrations of the above parameters from site to site in the upper water layers. Sulfates and TDS were slightly higherat the discharge (Site 2) end of the cooling pond. Levels for alkalinity,

sulfates, TDS, and total hardness were slightly lower near the bottom at the 10 and 11-meter depths at Site 4 and Site 7 respectively.

Phosphorus and nitrogen are essential nutrients for aquatic plants.Concentrations in the water are typically low since phytoplankton or macrophytes quickly assimilate these nutrients.

Total phosphate levels in the August 2002samples were at 1.5 mg/I throughout the cooling pond (Tablel).

Samplescollected on April 2002 ranged from 1.3 to 1.6 mg/I (Table 3). Total phosphates at two sites in the June 2002 samples were 1.8 mg/I (Table 4) in the upper waterlayers and 4.9 mg/I at a well stratified, 10-meter depth at Site 4. The TestAmerica data for 2001 had total phosphate levels from 0.16 to 5.5 mg/I (Table 2).The 5.5 mg/I occurred at the discharge on May 18 of 2001 and levels dropped to0.77mg/I at the plant intake on the same date. This suggests the Station was thesource of the phosphate.

Although the levels were slightly lower in 2002, theywere consistent throughout the cooling pond suggesting that phosphates are inexcess and not a limiting factor for phytoplankton.

The total phosphate levels inthe make- up water were 0.12 mg/I and 0.19mg/I in June (Table 4) and August of2002 respectively.

Relative to most lakes the phosphate level in BCP is quite high. Since BCP is acooling pond and not a lake, it is not subject to the Section 302.205 regulation that limits phosphorus in a lake of 20 acres or more to < 0.05mg/I.

The highphosphate level is of concern since these levels support phytoplankton bloomsand the breakdown of the phosphorus compounds can also contribute toincreased pH.Ortho-phosphate is the form that is most readily available to aquatic plants.These levels are usually very low in lakes since plants normally take it up withinminutes.

Ortho-phosphate levels were consistent throughout the lake in theAugust 2002 samples and ranged from 0.38 to 0.44mg/l.

Like the total phosphate levels, the ortho-phosphate levels are consistently high suggesting it is in excessof the needs of the phytoplankton.

The August 2002 levels were significantly higher than the <0.06mg/I reported by Test America in 2001 (Table 2). Ortho-phosphate level in the make-up water was 0.19 and although lower than the lakelevels is relatively high.B-12 RS-14-138 Enclosure Page 309 of 322Nitrate-nitrites are the other essential or potentially limiting nutrient forphytoplankton.

The August 2002 nitrate-nitrate levels were rather low in most ofBCP with the highest level of 0.1mg/I at the discharge.

The rest of the coolingpond ranged for <0.01 mg/I (below detection limit) to 0.08 mg/I in the upperwaters. Unlike most other parameters, the nitrate-nitrite level in the make-upwater was significantly higher at 2 mg/I (Table 1). Nitrate-nitrite data could not becompared to the 2001 Test America data because the detection limit of 1.0 mg/Iwas too high for a meaningful assessment.

The ratios of phosphates to nitrates-nitrites suggest BCP would be described asa nitrate-nitrites limited water rather than phosphate limited with respect tophytoplankton growth. However the limited phytoplankton data that SEA Inc. hascollected on BCP suggests that bluegreen algae dominate BCP for much of thesummer. Bluegreen algae have the unique ability to utilize atmospheric nitrogenand are not as limited by low nitrate-nitrite levels. Bluegreen algae made up 88.5% and 76.4% of the algae at Sites 3 and 7 respectively in the August 2002sample. The dominant bluegreen algae were Lynabya and Oscillatoria.

Bluegreen algae are the least desirable algae and are favored by high pH andwarmer temperatures.

Bluegreen blooms can impart a smell or taste to water,deplete dissolved oxygen, and in some cases generate toxins that may impactaquatic life.The ammonia levels appear reasonable relative to the high productivity in BCP.As productivity increases and oxygen is reduced at deeper depths there may beincreases in ammonia.

The abnormally high level at 5 meters at Site 9 (Table Imay have resulted from the water sampler disturbing the bottom sediments where ammonia is likely to be higher.The aquatic plant community in BCP appears to have undergone a change in thelast two years. SEA Inc.'s first investigation of BCP on May 29, 2001 was toassess the impact of the extensive growth of macrophytes (rooted aquatic plants)on the pond's increasing pH. That investigation found an extensive phytoplankton bloom and the few macrophytes that remained were being shaded out by thephytoplankton bloom. SEA Inc. projected that BCP was changing from amacrophyte dominated water to a phytoplankton-dominated water and that wouldsee more plankton blooms. The phosphate levels from the 2001 Test Americadata suggested there was an excess of phosphorus to support those blooms.Based upon SEA Inc.'s 2002 observations, BCP has transformed into aphytoplankton dominated water and is experiencing regular plankton blooms.This change not only reflects an increasing load of nutrients in BCP but alsocreates a higher risk to the fishery.

As plankton blooms come and go they cancreate oxygen depletion problems that impact fishes and other aquatic life.SEA Inc. has measured the primary production rates as an index to the activity ofthe plankton community.

The rate of oxygen production by the planktonB- 13 RS-14-138 Enclosure Page 310 of 322community is measured in a light (clear) bottle and the plankton respiration (oxygen depletion) is measured in a dark bottle. In the first measurement in Mayof 2001, there was so much oxygen production in the normal 24 hr measurement period that the oxygen was super saturated and only a portion could bemeasured (Table 5). Subsequent measurements were limited to shorter timeperiods and provided a more useful index. The highest primary production ratewas 1.525 mg/I of 02/hr at Site 9 (Intake) on June 28, 2002. This correlated wellwith the highest chlorophyll a level provided by the Braidwood Station (Figure 2).In the August 2002 measurement, the rate at Site 9 had dropped to 0.653 mg/I of02/hr. This rate correlated with lower chlorophyll levels that occurred throughout most of August. Temperatures during the August 28,2002 measurements werehigh enough at the discharge (Site 2) to suppress photosynthetic activity.

Thetemperature at the discharge was 115.10 F (Table 5) and the intake (Site 9)temperature was 92.20F and the corresponding production rates were 0.142 and0.653 mg/I of 02/hr respectively.

The temperature suppression of photosynthesis and an apparent die off of a phytoplankton bloom may account for the lowdissolved oxygen levels observed during the August 2002 sampling.

All of sampling by SEA Inc. has involved in-situ sampling with a HydroLab fortemperature, dissolved oxygen, pH, and specific conductivity.

The data from all2002 HydroLab sampling is presented in Tables 1,3,4,6, and 7.The dissolved oxygen (DO) levels on August 28 of 2002 were notably lower thanthe same date in 2001(Table 6). As lakes undergo eutrophication andproductivity increases, the DO level can exhibit wide diurnal changes that maystress aquatic life. Afternoon DO levels may rise to supersaturated levels, butduring the night and early morning hours respiration demands may nearlydeplete the DO and can result in fish kills. There also becomes a morepronounced difference in DO levels between the upper and lower layers of thewater column due to increased oxygen demand from decomposition.

Dissolved oxygen levels at the same four sites in August 2001 and 2002 arecompared in Figure 3. These comparisons indicate that the DO levels weregenerally lower at the same sites in 2002, were slower to rise during the day, andthere was a greater differences between depths. Site 2 and Site 2.5 illustrate thelower DO levels in 2002 even later in the day when it should rise. Oxygen levelswere less than 1 ppm at 2 meters and below. Site 4, 2002 levels reflect theincrease in DO later in the day compared to earlier in the day in 2001. Theconsistent drop in DO at 4 meters is typical of a stratified site. At Site 7 the higherDO in 2002 reflect the later time of day than the 2001 sample. However the moresignificant difference is the drop in DO with increasing depth in 2002. This dropsuggests a more productive system that has a higher demand for oxygen in2002. Site 7 has good flow and in 2001 had a nearly constant DO level down tothe bottom and provided a good thermal refuge for fish. In 2002 the area below 6meters would be stressful for most fish. The Site 9 AM chart again demonstrates the 2002 DO level was lower even when taken later in the morning than the 2001B-14 RS-14-138 Enclosure Page 311 of 322sample. The Site 9 PM chart shows some recovery of DO level in the midafternoon but levels are still below 4ppm. The more rapid drop in deeper samplesfrom the 2001 most likely reflects the loss of late afternoon light to the deeperdepths.The 2002 DO curves appear to reflect a more eutrophic environment that mayplace additional oxygen stress on the fishery.

During the August 2002 samplingthere were dead and dying gizzard shad from Site 2 to Site 4. The combinations of stress from the low DO and warmer temperatures were the most likelyexplanation for the loss of these fish. This loss was not extensive enough to havea significant impact on the fishery.

No other species were involved in the kill butsmall bluegills were exhibiting some signs of DO stress. As BCP continues tobecome more eutrophic the DO stress may be a greater problem for the fishery.The increasing pH levels have been a concern in BCP. Comparison of HydroLabdata from August 28 in 2001 (Table 6) and 2002 (Table 1) indicated only a littlevariation in pH. During the summer of 2002 the Station was adding H2SO4 intothe circulating water. The impact was only apparent at Site 2 (discharge canal)and Site 3. The 2002 samples collected in the morning hours at Site 2 rangedfrom 8.34 to 8.38 compared to 8.5 in 2001 (Table 2). At Site 3 the 2002 levelsranged from 8.35 in the morning to 8.54 at midday compared to a range of 8.4 to8.6 in 2001. The pH levels at Sites 4,7 and 9 had slight variations depending upon time of day but had similar ranges in 2001 and 2002. With the highalkalinity levels in BCP, it is not surprising that the addition of H2SO4 did notresult in larger changes.

This assessment is also based on only a few datapoints. Correlating H2SO4 feed rates with continuous pH monitoring at the intakewould provide more reliable information on the effects of the acid additions.

Questions have been raised on the impact of the phytoplankton on the increasing pH levels. As phytoplankton carries on photosynthesis and extract CO2 from thewater it increases the pH. This however may not be as apparent in BCP due tothe high buffering capacity (alkalinity).

In general the higher pH levels in theafternoon reflect the photosynthetic activity.

Conversely the lower pH levels in theearly morning samples reflect the increase in C02 resulting from respiration during the night. The role of phytoplankton in increasing pH is quantified in themeasurement of primary productivity.

A comparison of the starting pH with theending pH in the light bottles illustrates the change due to photosynthesis.

ThepH during the 24-hour measurement on May 29, 2001 at Site 2 went from 9.22 to9.52 (Table 5).Summary and

Conclusions:

Braidwood Cooling Pond has high levels of alkalinity, total hardness, TDS,sulfates, magnesium, calcium and total phosphates.

These parameters are ofconcern since they have the potential for increased problems with scaling,increasing pH, compliance with blow down limits, and maintaining a recreational B-15 RS-14-138 Enclosure Page 312 of 322fishery.

The additional of treatment chemicals and evaporative loss of therecycled cooling water with limited blown down rates are most likely the primaryfactor in the increased levels of these parameters.

The make-up water does nothave elevated levels of the above-mentioned parameters.

With increasing capacity factors and increasing concentrations for these parameters in thecooling water, water treatment costs and operational concerns are likely toincrease.

Baseline water quality data is important in evaluating options and solutions toaddress water quality in the cooling pond. The comparison of the August 2002sampling to the 2001 Test America data indicated significant increases in totalhardness,

sulfates, and calcium in the past year. Increases of this magnitude canbe important predictors of future problems.

Critical assessments of the impact ofH2SO4 additions and other treatment changes are dependent upon havingpretreatment and post treatment data. The plan to increase the blow down ratefrom BCP is a good long-term solution to the continued viability of the coolingpond. The effectiveness of increasing the blown down rate from BCP can bequantified by continued monitoring of the cooling lake concentrations.

The high nutrient levels in BCP will continue to cause plankton blooms. Unlikemany waters, phosphates appear to be in excess and nitrates are more of alimiting factor. However, bluegreen algae appear to be the dominant summerform and are not as limited by low nitrates as other algae. The primary production measurements did correlate fairly well with chlorophyll a levels and were a goodindex to the productivity of BCP. The primary production measurements alsoillustrated how much of an influence phytoplankton have on diurnal increases inpH.Algal blooms are occurring in the pond and based on two comparable samplings, appear to be influencing the DO levels. The DO levels in the early hours weregenerally lower in 2002 than in 2001 and the DO at a deep site experienced adecline with depth that did not occur in 2001. These changes suggest a trendtoward an increasing rate of eutrophication.

If nutrient levels continue to increasethe potential for fish kills associated with oxygen depletion resulting from theblooms would also increase.

Jim SmithsonSEA Inc.11/04/02B-16 Fish Kill Reports Going Back to 2003 Page 1 of 2APPENDIX REPORT B-4. Rs-14-138 Page 313 of 322Fish Kill Reports Going Back to 2003john.petro@exeloncorp.com

[john.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:42 PMTO: Jeremiah.Haas@exeloncorp.com 2003There were no fish kills in Braidwood Lake in 2003.u*3o, 2004Investigated a fish mortality on July 3Q,2_004.

Most fish were in the advanced state of decay.byhe tlimethe kill was investigcated.

Gizzard shad were the domilnant species involved although channel catfish wereobserved as well. During this investigation, the shallow water near shore was teaming with plankton whichunder magnification.proved to be daphnia as well as Cypris, which is an Ostacod resembling a small clam.Temperature/dissolved oxygen.prof iles were condu.icted in early October.

Water temperature just north ofthe south boat access was 29.2°C/8_.5°F at a de thn of one foot with a dissolved oxygn .relading gflrfppm a.pofh b8.03and a secchi diskreading of 2.1 feeat. Reaooine Were somewhat improved in the area nearthe rearing cove. In a location several hundred feet from the lake make-up.,

more favorable dissolved oxygen levels were found. At one foot, .1 wfterl temrperature of 26.5 °C/79.7 OF with a dissolved oxygenreading of 7.6 andaplH f 8.47 were observed.

Water temperature showed minimal decrease to 40 feetwhile the dissolved o1xygn declined to 5.3 ppm.June 28, 2005 Fish KillAn on the water inspection of a thermal fish kill was conducted on June 28, 2005. No formal counts weremade however field assessments indicate a fairly significant kill that involved a variety of species including (in no specific order) gizzard shad, threadf in shad, common carp, channel catfish, quillback carpsucker, black bass. Gizzard shad were the most numerous species effected by this kill and fish carcases wereobserved at most all areas of the lake that were checked.Agut27- 2_Q07.. Fish KilllPob Miller, IDNR investigated a thermal kill on August 27 and 28, 2007 and conducted temperature/dissolved oxygen evaluations.

The majority of the dead fish which were observed were largegizzard shad and threadf in shad up to 5 inches in length. Channel catfish were also prevalent.

Only a fewcommon carp and black bass were observed and no bluegills were noted. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in close proximity of the boat ramp and thebank fishing area. The number of dead fish observed decreased towards the south (hot) side of the lake.At a point several hundred yards from the south ramp surface water temperature was 35.3 C/95.9 F anddissolved oxygen was near 3ppm.The following are data which were collected at the north ramp at the time the fish kill was beingB-17littps://hdrwebinail.hdrinc.co-n/owa/?ae=Jtern&t=IPM.Note&id=RgAAAACNOxu whEeSR...

12/8/2009 Fish Kill Reports Going Back to 2003 Page 2 of 2RS-14-138 Enclosure investigated:

Page 314 of 322Time Temperature

(°C) Dissolved Oxygen (ppm)12:10 30.3 3.114:25 33.1 5.415:30 33.5 6.716:58 33.9 5.9Investigation of Fish Kill on Braidwood.Cooling PondApugust 27-28, 2007)Strategic Environmental Actions Inc. (SEA Inc.) conducted an investigation of an on-going fish kill onBraidwood Cooling Pond on August 27 & 28, 2007. The investigation consisted of surveying the shoreline todetermine the extent of the kill and the species involved, and water quality analyses for pH, temperature, and dissolved oxygen.Most of the fish appeared to have been dead f or about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and more than 95% were gizzardshad. The other species involved in descending order of relative abundance were freshwater drum,quillback, carp, largemouth bass, channel catfish,

redhorse, smallmouth bass and bluegill.

Other thangizzard shad most of the dead fish were located between the mid -point in the cooling loop to the intake.Throughout most of the cooling pond, dissolved oxygen levels were at or below the minimum levelsnecessary to support most fish and was the most likely cause of the kill. Water clarity was very high andsuggested a recent die off of much of the phytoplankton, which is usually followed by oxygen depletion.

This is a natural phenomenon that can occur in highly productive lakes during summer months.Temperatures throughout most of the lake were within the tolerance limits of the species involved in thekill. It does not appear that operations of the power station had a direct impact on the fish kill.B-18https://hdrwebmail.hdrinc.com/owa/?ae=ltem&t=IPM.Note&id=RgAAAACNOxuwh Fc8R... 12/8/2009 FW: Braidwood Lake Fish Kill Page 1 of 2RS-14-138 Enclosure APPENDIX REPORT B-5. Page 315 of 322FW: Braidwood Lake Fish Killjohn.petro@exeloncorp.com

[john.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:31 PMTo: Jeremlah.Haas@exeloncorp.com

---

Original Message -----From: ROB MILLER [Lnýilto:ROB.M.ILLEý@iilliinois.gov]

Sent: Tuesday, August 21, 2007 8:26 PMTo: JOE FERENCAK; STEVE PALLOCc: Petro, John R.; CHRIS MCCLOUD; LARRY DUNHAM; MIKE CONLIN

Subject:

Re: Braidwood Lake Fish KillI was contacted by John Petro and Tim Meents (Braidwood Station) thismorning at 11:20 but due to bad accident on 1-55 was somewhat delayed inarriving at the lake. When I got there (3:00) I met with Exelonbiologist Jeremiah Haas. Jeremiah had arrived earlier and had takendissolved oxygen/temperature readings.

He and I toured the lake via hisboat to assess the extent of the kill. Due to moderate prevailing southwinds, many dead fish were wind-rowed along the north shore in closeproximity of the boat ramp and the bank fishing area. The number of deadfish we observed decreased as we traveled towards the south (hot) sideof the lake. At a point several hundred yards from the south ramp, wetook a reading and returned to the north ramp to meet up with JohnPetro. At this location water temperature was 35.3C and dissolved oxygenwas near 3ppm. The following are data which were collected at the northramp:Time Temp. (C) Dissolved Oxygen (ppm)12:10 30.3 3.114:25 33.1 5.415:30 33.5 6.716:58 33.9 5.95i Based on the declining trend in d.o., it is possible that more lishcould succumb throughout the night.The majority of the dead fish which were observed were large gizzardshad and threadfin shad up to 5 inches. Channel catfish were alsoprevalent.

Only a few common carp and black bass were observed and nobluegills were noted. SET Environmental had arrived at the north rampand were conducting clean-up operations at 5:00. I will be attended theAFS Continuing Education course in Monticello tomorrow and thursday.

Ifyou need any further infonnation, or if there are any furtherdevelopments, please contact me at 815/409-2426.

Thanks.RobRob MillerB-19https://hdrwebmail.hdrinc.coif/owa/?ae=Iteti&t=lPM.Note&id=lgAAAAA CNONxI\.x hI.c8 R... 12;,8,2009 FW: Braidwood Lake Fish Kill Page 2 of 2RS-14-138 Enclosure Page 316 of 322District Fisheries Biologist Illinois Department of Natural Resources 13608 Fox RoadYorkville, Illinois 60560630/553-6680 rob.miller@illinois.gov

>>> STEVE PALLO 08/21/07 12:10 PM >>>Just got off phone with John Petro, Environmental Manager for Exelon.John wanted to report a moderate gizzard shad kill at Braidwood CoolingLake, and a minor kill of catfish.

Rob Miller, District Fisheries Manager was already notified.

Water temps in the lake had dropped some12F recently, there are no obvious power plant operational changes orpermit exceedances.

Exelon is arranging to have the fish picked up.B-20https://hdrwebmail.hdrinc.coii/owa/?ae=Itern&t=IPM.Note&id=RgAAAACNOxuwhEe8R...

12/8/2009 FW: Braidwood Fish Kill 8-21-07 Page 1 of']RS-1-4-138 APPENDIX REPORT B-6. Enclosure Page 317 of 322FW: Braidwood Fish Kill 8-21-07john.petro@exeloncorp.com bohn.petro@exeloncorp.com]

Sent: Wednesday, September 23, 2009 2:28 PMTo: Jeremiah.Haas@exeloncorp.com

---

Original Message--

From: Haas, Jeremiah

.Sent: Tuesday, August 21, 2007 9:02 PMTo: Petro, John R.; Tidmore, Joseph W.; Meents, Timothy P.Cc: Hebeler, Ronald L; Neels, Vicki J.; Steve Pallo (E-mail);

Haas, Jeremiah J.

Subject:

Braldwood Fish Kill B-21-07All,Here's the quick and dirty of the incident.

I'll right something more formal in the morning.I arrived at Braidwood Lake at 12:00 and took a dissolved oxygen (DO) reading from the ramp dock which extendsabout 30 feet into the lake. The DO was 3.1 ppm w/ a temp of 30.3 C. Several thousand gizzard and threadfin shadwere floating across most all visible areas of the lake. The currents within the lake were visible with the dead fishmovement.

Also seen were dozens of channel catfish, most of which were adults from 3-15 lbs. Shad ranged from 4 -13 inches with the shorter fish being predominately threadfin and the larger ones being gizzard.

At this time I informedJohn P. of the DO situation and began setting up the boat for additional surveys.

During the entire day, no otherspecies was observed that counted more than 2 individuals.

I took several water readings throughout the afternoon before Rob Miller (IDNR biologist responsible for Braidwood Lake) arrived.

We did a quick boat survey throughout the lake, including the pockets that are not part of the coolingloop. These areas showed the same readings as the rest of the lake. During this time we had a few hours of directsunshine and DO reading rose as high as 6.7 ppm @ 15:30.Rob and I determined that the DO crash was a result of the past several days cloud cover and subsequent die-off ofphytoplankton.

The decay of the phytoplankton would have been sufficient to lower the DO available to the fish duringthe overnight hours. We also observed the DO beginning to lower @ 16:58 (5.9 ppm) and believe that there is anopportunity to see similar results tomorrow and possibly a few more days depending on the weather conditions.

A local newspaper reporter did arrive on site, took photos, and asked questions.

She was familiar with Braidwood Station's Site Communicator and said she would be in contact with them. Rob explained the cycle that was occurring in the lake several times to the reporter.

All in all, I believe that Rob and I are both comfortable with the explanation for the action that occurred to cause thefish kill. This is similar to the "annual" fish kill seen at Braidwood, but the densities were higher than the past fewyears. There is a survey of the lake scheduled for October and, if possible, I will be at the site for that.ExelonJeremiah J HaasPrincipal Aquatic Biologist Quad Cities Nuclear Station309.227.2867 jeremiah.haas@exeloncorp.com B-21httDs://hdrwebinail.hdrinc.coii/owa/?ae=ltem&t=IPM.Note&id=RgAAAACNOx uwhEe8R...

12/8/2009 RS-14-138 Enclosure Page 318 of 322APPENDIX REPORT B-7.Braidwood Fish Kill Clean up8122&23107 I worked with SET Environmental to clean up a fish kill.This was a major kill and our clean up efforts were confined to the area nearNorth boat ramp on the intake end of the lake. SET had been working on the killfor one or two days when I was called to provide assistance.

A total of about 24cubic yards of fish were removed in this clean up. The species involved indecreasing order of abundance were: gizzard shad (large fish), channel catfish,bluegill, green sunfish, flathead

catfish, bigmouth

buffalo, quillback andlargemouth bass.I went up in the restricted arm toward the intake and found huge masses of fishin the back of several coves. There were areas 50 to 75 ft by 100 ft of solidfloating mats of fish in these coves. We picked up 12 flathead catfish that wouldhave averaged near 50 lb. each. On the second day when we returned to thesecoves we counted as many large flathead catfish that we had picked up theprevious day. They were in a state of decomposition that prevented up frompicking them up.We did not take any water quality measurements or examine other parts of thelake in this clean up effort. From my past work on this cooling pond, I wouldsuspect a combination of DO depletion and high water temperatures caused thisfish kill. The plant did not report any abnormal operation conditions prior to thekill. Since 2001 when we first worked on this cooling pond we have seen a switchfrom macrophytes to phytoplankton with blue green dominating.

We havemeasured wide diurnal swings in DO levels even in the upper part of the watercolumn in late summers.

Even with the strong circulation from the circulating water pumps there is mid summer stratification and DO depletion in the deeperareas.Jim SmithsonSEA Inc.B-22 RS-14-138 Enclosure Page 319 of 322RAI #: AQ-12c Category:

Aquatic Resources Statement of Question:

Section 2.2.5, Page 2-16 of the ER states that "HDR [HDR Engineering]

assessed water qualityand fish populations in the cooling pond in late summer 2009 and 2010 to develop a betterunderstanding of the factors contributing to fish kills and design a water quality or fishmonitoring program that could be used to predict (and conceivably mitigate) fish kills in thepond."c. Has Exelon implemented any mitigation to reduce the number of fish kills in the coolingpond? If so, describe such mitigation.

Response

As the response to RAI # AQ-12b explains, based on the annual summer aquatic samplingresults since 2009, Exelon Generation has not been able to identify a practical way to preventfish kills or reduce their effects in the Braidwood cooling pond. Therefore, mitigation measures to reduce the number of fish killed during such events have not been implemented.

List of Attachments Provided:

None.

RS-14-138 Enclosure Page 320 of 322RAI #: AQ-13 Category:

Aquatic Resources Statement of Question:

Sections 4.2 and 4.3 of the ER discuss the effects resulting from entrainment and impingement of Kankakee River aquatic biota at the makeup water intake or associated river screen house. Inits analysis of entrainment and impingement, the NRC will consider the effects of entrainment and impingement that occurs at both the river screen house and the lake screen house. Tosupport this analysis, please provide any studies that assess entrainment or impingement at thecooling pond's lake screen house.Response:

The Braidwood cooling pond is a wastewater treatment system, and as such it is not classified as "waters of the United States" under the Clean Water Act. As a result, assessment ofentrainment or impingement effects at the cooling pond's lake screen house is not required, andno studies of such effects have been performed.

List of Attachments Provided:

None.

RS-14-138 Enclosure Page 321 of 322RAI #: AQ-14 Category:

Aquatic Resources Statement of Question:

Section 4.4 of the ER considers the effects of heat shock on aquatic biota in the KankakeeRiver. In its analysis, the NRC will consider the effects of heat shock on aquatic biota in boththe Kankakee River and the cooling pond. To support this analysis, please provide any thermalstudies that have been conducted on the cooling pond.Response:

The Braidwood cooling pond is a wastewater treatment system, and as such it is not classified as "waters of the United States" under the Clean Water Act. As a result, assessment of thermaleffects in the cooling pond is not required, and no studies of such effects have been performed.

List of Attachments Provided:

None.

RS-14-138 Enclosure Page 322 of 322RAI #: AQ-15 Category:

Aquatic Resources Statement of Question:

Submit the following ER references for docketing:

a. (Exelon Nuclear 2011c) Exelon Nuclear.

2011. Braidwood Station -Braidwood LakeAdditional Biological Sampling

Program, 2010.Response:

The requested document is attached to the response for RAI # AQ-1 2a,above.List of Attachments Provided:

None.