ML090480334

Lake Norman Maintenance Monitoring Program: 2007 Summary

ML090480334
Person / Time
Site:	Mcguire, McGuire
Issue date:	02/09/2009
From:	Brandi Hamilton Duke Energy Carolinas, Duke Energy Corp
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NC0024392
Download: ML090480334 (146)

Text

BRUCE H HAMILTON PDuke Vice President EEnergy. McGuire Nuclear Station Duke Energy Corporation MG01 VP / 12700 Hagers Ferry Road Huntersville, NC 28078 704-875-5333 704-875-4809 fax bhhamilton@duke-energy.com February 9, 2009 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-0001

SUBJECT:

Duke Energy Carolinas, LLC McGuire Nuclear Station Docket No. 50-369, 370 Lake Norman Maintenance Monitoring Program:

2007 Summary Please find attached a copy of the annual "Lake Norman Maintenance Monitoring Program:

2007 Summary," as required by the National Pollutant Discharge Elimination System (NPDES) permit NC0024392. This report includes detailed results and data comparable to that of previous years. The report was submitted to the North Carolina Department of Environment and Natural Resources on February 1, 2009.

Questions regarding the attached report should be directed to Kay L. Crane at (704) 875-4306.

Brr Bruce Hamilton www. duke-energy.com

U. S. Nuclear Regulatory Commission February 9, 2009 Page 2 Mr. L. A. Reyes, Regional Administrator U.S. Nuclear Regulatory Commission, Region II Atlanta Federal Center 61 Forsyth St., SWW, Suite 23T85 Atlanta, GA 30303 Mr. Jon H. Thompson NRC Senior Project Manager U. S. Nuclear Regulatory Commission Mail Stop 8G9A Washington, DC 20555-0001 Joe Brady NRC Senior Resident Inspector McGuire Nuclear Station

LAKE NORMAN MAINTENANCE MONITORING PROGRAM:

2007

SUMMARY

McGuire Nuclear Station: NPDES No. NC0024392 Principal Investigators:

Michael A. Abney John E. Derwort William J. Foris DUKE ENERGY Corporate EHS Services McGuire Environmental Center 13339 Hagers Ferry Road Huntersville, NC 28078 December 2008

LAKE NORMAN MAINTENANCE MONITORING PROGRAM:

2007

SUMMARY

McGuire Nuclear Station: NPDES No. NC0024392 Principal Investigators:

Michael A. Abney John E. Derwort William J. Foris Prepared By: &At"0 -- Date:

Reviewed By: Date: 1126//,ZIccg Checked By: C.d~2)A~& Date:

2-1, O Approved By: IDate:

DUKE ENERGY Corporate EHS Services McGuire Environmental Center 13339 Hagers Ferry Road Huntersville, NC 28078 December 2008

ACKNOWLEDGMENTS The authors wish to express their gratitude to a number of individuals who made significant contributions to this report. First, we are much indebted to the EHS Scientific Services field staff in carrying out a complex, multiple-discipline sampling effort that provides the foundation of this report. Kim Baker, Dave Couglian, Bob Doby, Duane Harrell, Bryan Kalb, Glenn Long, and Todd Lynn conducted fisheries collections and sample processing.

Jan Williams, Brandy Starnes, Bill Foris and Glenn Long performed water quality field collections. John Williamson assembled the plant operating data. Jan Williams, Brandy Starnes, Glenn Long, and John Derwort conducted plankton sampling, sorting, and taxonomic processing.

We would also like to thank the following reviewers for their insightful commentary and suggestions: Ron Lewis, and John Velte. Sherry Reid compiled this report.

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TABLE OF CONTENTS EXECUTIVE SUM M ARY ............................................................................................... v LIST OF TABLES ......................................................................................................... x LIST OF FIGURES .............................................................................................................. xii CHAPTER 1- MCGUIRE NUCLEAR STATION............................................................ 1-1 INTRODUCTION .......................................................................................................... 1-1 OPERATIONAL DATA FOR 2007 ............................................................................... 1-1 CHAPTER 2- WATER CHEM ISTRY .............................................................................. 2-1 INTRODUCTION ............................................... 2-1 M ETHODS AND MATERIALS ....................... .......................... ... 2-1 REsuLTs AND DISCUSSION....... ....... .......... ............................ 2-4 Precipitation and Air Temperature............................................................................... 2-4 Temperature and Dissolved Oxygen ........................................................................... 2-5 Reservoir-W ide Temperature and Dissolved Oxygen ................................................. 2-8 Striped Bass Habitat ................... I................................................................. ............. 2-9 Turbidity and Specific Conductance .............................................. ................... 2-10 pH and Alkalinity ....................................................................................................... 2-11 M ajor Cations and Anions ........................................................................................ 2-11 Nutrients ..................................................................................................................... 2-11 M etals ............................................................................................. .......................... 2-12 FUTURE STUDIES ...................................................................................................... 2-13 SUMM ARY ................................................................................................................. 2-13 CHAPTER 3- PHYTOPLANKTON ................................................................................... 3-1 INTRODUCTION ....................................................... 3-1 METHODS AND M ATERIALS ................................................................................... 3-1 RESULTS AND DISCUSSION...................................................................................... 3-2 Standing Crop ............................................................................................................. 3-2 Chlorophyll a ............................................................................................................ 3-2 Total Abundance ........................................................................................................... 3-4 S esto n ........................................................................................................................... 3-5 Secchi Depths ............................................................................................................... 3-5 Community Composition ............................................................................................ 3-5 Species Composition and Seasonal Succession ......... :................................................. 3-6 FUTURE STUDIES ....................................................................................................... 3-7 SUMM ARY ................................................................................................................... 3-8 CHAPTER 4- ZOOPLANKTON ......................................................................................... 4-1 INTRODUCTION ........................................................................ 4-1 METHODS AND M ATERIALS ........................................... 4-1 41.........................

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RESULTS AND DISCUSSION ...................................................................................... 4-2 Total Abundance .......................................................................................................... 4-2 Community Composition ............................................................................................. 4-4 Copepoda ................................................................................................................. 4-4 Rotifera ............................................ ........................... .............................................. 4 -5 FUTURE STUDIES ........................................................................................................ 4-5

SUMMARY

..................................................................................................................... 4-5 CHAPTER 5- FISHERIES .................................................................................................. 5-1 INTRODUCTION ........................................................................................................... 5-1 METHODS AND MATERIALS . 5-1 Spring Electrofishing Surveys ...................................................................................... 5-1 Fall Electrofishing Surveys for Young-of-Year Bass .................................................. 5-2 Summer Striped Bass M ortality Surveys ..................................................................... 5-2 Striped Bass Netting Survey ........................................................................................ 5-2 Fall Hydroacoustics and Purse Seine Surveys ........................... 5-3 Crappie Trap-Net Survey ............................................................................................. 5-3 RESULTS AND DISCUSSION ............................................................................... ....... 5-3 Spring Electrofishing Surveys .................................................................................... 5-3 Fall Electrofishing Young-of-Year Bass Surveys ...................................................... 5-5 Summer Striped Bass Mortality Surveys . 5-6 Striped Bass Netting Survey ........................................................................................ 5-6 Fall Hydroacoustics and Purse Seine .......................................................................... 5-6 Crappie Trap-Net Study .......................................... 5-7 FUTURE STUDIES .............................................. 5-7

SUMMARY

.................................................... 5-7 LITERATURE CITED ................................................................................................... L-1 iv

EXECUTIVE

SUMMARY

In accordance with National Pollutant Discharge Elimination System (NPDES) permit number NC0024392 for McGuire Nuclear Station (MNS), the Lake Norman Maintenance Monitoring Program continued during 2007. Overall, no obvious long-term impacts of station operations were observed in water quality or phytoplankton, zooplankton, and fish communities. The 2007 station operation data are summarized and continue to demonstrate compliancewith thermal limits and cool water requirements.

The monthly average capacity factors for MNS in 2007 were 101.9, 101.4, and 101.6%

during July, August, and September, respectively. The average monthly discharge temperature was 97.2 'F (36.2 'C) for July, 98.8 'F (37.1 'C) for August, and 97.9 'F (36.6

'C) for September 2007, below the 99.0 'F (37.2 'C) thermal limit for these months. The volume of cool water in Lake Norman in 2007 was adequate to comply with both the Nuclear Regulatory Commission Technical Specification requirements and the NPDES discharge water temperature limits. Annual precipitation in the vicinity of MNS in 2007 totaled 78.2 cm and was the third lowest measurement reported over the period 1975 - 2007, with lower values being recorded only in 1981 (64.4 cm) and 1986 (76.5 cm). Air temperatures near the MNS in 2007 were warmer than both 2006 and the long-term mean for the months of March, August, September, and October.

Temporal and spatial trends in water temperature and DO in 2007 were similar to those' observed historically, and all data were within the range of previously measured values.

Water temperatures in 2007 for the months of January, March, and April ranged from 0.1 to 3.8 'C warmer than measured in 2006 in both the mixing and background zones, whereas 2007 February temperatures were as much as 2.2 'C cooler than observed in 2006. These interannual differences in water temperatures paralleled differences exhibited in monthly air temperature data, but with about a one-month lag. Reduced operations of Unit 1 at MNS in March and April 2007 also contributed to these interannual differences during the winter and early spring.

Summer water temperatures in 2007 were generally similar to those observed in 2006 in both zones, with one notable exception. Surface water temperatures in the mixing zone in June 2007 were up to 2.7 'C cooler than observed in 2006, and appeared to be related primarily to reduced operations of Unit 1 rather than to interannual differences in air temperature. Late summer, fall, and early winter water temperatures in 2007 were consistently warmer in both v

zones than those measured in 2006, and followed the trend exhibited in air temperatures. The most striking differences were observed, in the mixing zone in November when 2007 temperatures were as much as 4.4 'C warmer than measured in 2006. Temperatures at the discharge location in 2007 were generally similar to 2006 and historical data. Temperatures in 2007 were slightly cooler in the spring, and warmer in the fall than observed in 2006. The warmest discharge temperature of 2007 at Location 4 (37.8 'C) occurred in September and was identical to the maximum measured in 2006.

Seasonal and spatial patterns of DO in 2007 were reflective of the patterns exhibited for temperature, i.e., .generally similar in both the mixing and background zones. Winter and spring DO values in 2007 were either equal to or slightly lower, in both the background and mixing zones, than measured in 2006 and appeared to be related predominantly to the differences in water column temperatures in 2007 versus 2006. Summer DO values in 2007 were highly variable throughout the water column in both the mixing and background zones ranging from highs of 6.0 to 8.0 mg/L in surface waters to lows of 0.0 to 2.0 mg/L in bottom waters. This pattern is similar to that measured in 2006 and earlier years. All dissolved oxygen values recorded in 2007 during this period were within the historical range.

Considerable differences were observed between 2007 and 2006 late summer and fall DO values in both the mixing and background Zone, especially in the metalimnion and hypolimnion during the months of September, October, and November. The 2007 late summer and autumn DO data indicated that fall convective reaeration proceeded slower and was less complete throughout the water column than observed in the corresponding months in 2006. Consequently, 2007 DO levels in either a portion or all of the water column were less than observed in 2006. The seasonal pattern of DO in 2007 at the discharge location was similar to that measured historically, with the highest values observed during the winter and lowest observed in the summer and early fall. Fall DO levels in 2007 at Location 4.0 were slightly lower than observed in 2006 due to warmer temperatures. The lowest DO concentration measured at the discharge location in 2007 (5.5 mg/L) occurred in September and was identical to that measured in August, 2006; it was also 1.4 mg/L higher than the historical minimum measured in August 2003 (4.1 mg/L).

Reservoir-wide isotherm and isopleth information for 2007, coupled with heat content and hypolimnetic oxygen data, illustrated that Lake Norman exhibited thermal and oxygen dynamics characteristic of historical conditions and similar to other Southeastern reservoirs of comparable size, depth, flow conditions, and trophic status.. Suitable pelagic habitat conditions for adult striped bass in 2007 were most recently similar to conditions measured in Vi

2006 when habitat elimination was observed for a period of about 50 to 60 days during the summer. Observed striped bass mortalities in 2007 totaled thirteen fish.

All chemical parameters measured in 2007 were similar to 2006 and within the concentration ranges previously reported for the lake during both preoperational and operational years of MNS. Specific conductance and nutrient values and all concentrations of cations and anions were low. Concentrations of metals were also low and often below analytical reporting limits. All values reported for cadmium, lead, zinc, and copper in 2007 were below the State water quality standard or action level for each of these metals. Manganese and iron concentrations in the surface and bottom waters were generally low in 2007, except during summer and fall when bottom waters became anoxic, thereby creating a chemical environment conducive for the release of these species into the water column. Only one iron value recorded in the bottom waters at Location 5.0 in August, exceeded the State action level of 1.0 mg/L. Manganese levels, however, exceeded the State action level (200 [tg/L) in the bottom waters at various locations throughout the lake in the summer and fall. This phenomenon, i.e., the release of iron and manganese from bottom sediments into the water column, in response to low oxygen levels, is common in stratified waterbodies.

Chlorophyll concentrations were generally within historical ranges during 2007. Several record low chlorophyll concentrations were recorded in November. Lake-wide mean chlorophyll increased from February through August, then declined to the annual minimum in November. Maximum chlorophyll concentrations were typically observed up-lake at Location 69.0, while minimum chlorophyll concentrations were recorded from down-lake at Locations 2.0 through 9.5. The highest chlorophyll value in 2007 (13.66 jtg/L) was well below the NC State Water Quality standard of 40 gtg/L.

Phytoplankton densities and biovolumes were generally higher in 2007 than in 2006. Higher standing crops were usually observed at up-lake locations, while lower values were noted down-lake. Standing crop values were lower than the NC guidelines for algae blooms Seston dry and ash-free weights were most often lower in 2007 than in 2006. Down-lake to up-lake differences were apparent during all quarters. Maximum dry and ash-free weights were generally observed at Location 69.0, while minimum values occurred at Locations 2.0 through 8.0.

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Secchi depths reflected suspended solids, with shallow depths related to high dry weights.

The lake-wide mean secchi depth was slightly higher in 2007 than in 2006 and within historical ranges observed since 1992.

Diversity of phytoplankton taxa in 2007 was the highest recorded since the beginning of this.

monitoring program. The taxonomic composition during 2007 was similar to many previous years. Cryptophytes were dominant in February, while diatoms were dominant during May and November. Green algae were dominant during August. Blue-green algae were slightly more abundant in 2007 than in 2006, however, their contribution to total densities was rarely over 3%.

The cryptophyte Rhodomonas minuta was the most abundant alga each year of the Lake Norman Maintenance Monitoring Program. The diatom Fragillariacrotonensis was the most abundant diatom in May, while Tabellariafenestrata and Melosira ambigua were dominant in November. The small desmid, Cosmarium asphearosporumvar. strigosum was dominant in August 2007. These taxa have been common and abundant throughout the program.

Maximum zooplankton densities occurred most often in the spring of 2007. Minimum zooplankton densities were generally noted in the fall. Epilimnetic densities were higher than whole-column densities as in previous years. Mean zooplankton densities were usually higher among background locations than among mixing zone locations in 2007. Spatial trends of zooplankton population densities increased from down-lake to up-lake locations. A year-to-year spring trend of increasing zooplankton densities among mixing zone locations was observed from around 1997 through 2005. Densities at these locations declined sharply in 2006 followed by an increase in 2007. Long-term trends showed much higher year-to-year variability at background locations than at mixing zone locations.

Epilinmetic zooplankton densities were generally within the ranges of densities observed in previous years. 'Record high densities were observed during winter at Location 15.9 and summer at Location 9.5.

Since the Lake Norman Maintenance Monitoring Program began in 1987, 123 zooplankton taxa have been observed in samples. Of these, 49 were identified in 2007. Additionally, two previously unreported taxa were identified during 2007.

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Overall relative abundance of copepods decreased from 2006 to 2007. Copepods were dominant in only three samples. Cladocerans were dominant in two samples and rotifers were dominant in all other samples. The relative abundance of microcrustaceans increased slightly in the epilimnion of the mixing zone, although they decreased among whole-column samples since 2006. At background locations, relative abundances of microcrustaceans in 2007 were similar to those of 2006. Historically, copepods and rotifers have most often shown annual peaks in the spring, while cladocerans continued to demonstrate year-to-year variability.

Copepods were dominated by immature forms. Adults rarely accounted for more than 7% of zooplankton densities. As in previous years, the most important adult copepod was Tropocyclops. Bosmina was the dominant cladoceran, as in most previous years of the program. Bosminopsis dominated several cladoceran populations during the summer. The most abundant rotifers observed in 2007, as in many previous years, were Plyarthra, Keratella, and Ptygura. Conochilus, Asplanchna, and Syncheata were also important among rotifer populations.

In accordance with the Lake Norman Maintenance Monitoring Program fish monitoring programs continued during 2007. Spring electrofishing indicated that numbers and biomass of fish in 2007 were generally similar to those noted since 1993. Additionally, electrofishing indicated that 12 to 20 fish species and two hybrid complexes comprised fish populations in the three sampling areas. Largemouth bass numbers and biomass continue to decline, and the 2007 numbers and biomass were some of the lowest recorded since sampling began in 1993.

While displacement of largemouth bass since the introduction of spotted bass in the lower lake is apparent, the direct effect on largemouth bass recruitment is indeterminate, possibly due to confounding effects of other introductions including alewife and white perch. During 2007, the number of summer striped bass mortalities (13) and winter mean relative weight (79.5) were similar to those of previous years. Hydroacoustic sampling estimated the 2007 forage fish population at approximately 72 million. This is comparable to previous years.

After an increase in 2006, purse seine sampling indicated a decrease in the percentage of alewives in 2007 to the lowest percent composition since their 1999 introduction. Threadfin shad lengths remained at pre-alewife introduction sizes.

Lake Norman Maintenance Monitoring results from 2007 are consistent with results from previous years. No obvious short-term or long-term impacts were observed in water quality or biota of Lake Norman.

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LIST OF TABLES Table Title Page 1-1 Average monthly capacity factors (%) and monthly average discharge water temperatures for M N S during 2007 ............................................................................ 1-2 2-1 Water chemistry program for the McGuire Nuclear Station NPDES Maintenance Monitoring Program on Lake Norman ................................................ 2-17 2-2 Analytical methods and reporting limits employed in the McGuire Nuclear Station NPDES Maintenance Monitoring Program for Lake Norman ...................... 2-18 2-3 Heat content calculations for the thermal regime in Lake Norman for 2006 and 2007 ................................................................................. .................................. 2-19 2-4 A comparison of areal hypolimnetic oxygen deficits (AHOD), summer chlorophyll a (Chl a), Secchi depth, and mean depth of Lake Norman and 18 TV A reservoirs ..................................................................................................... 2-20 2-5 Quarterly surface (0.3 m) and bottom (bottom minus 1 m) water chemistry for the McGuire Nuclear Station discharge, mixing zone, and background locations on Lake Norman during 2006 and 2007 .................................................... 2-21 3-1 Mean chlorophyll a concentrations (jtg/L) in composite samples and Secchi depths (m) observed in Lake Norman in 2007 ....................................... 3-10 3-2 Mean phytoplankton densities (units/mL) and biovolumes (mm3/m 3) by location and sample month from samples collected in Lake Norman, NC, during 2007... ................ ....................... 3-11 3-3 Total mean seston dry and ash free dry weights (mg/L) from samples collected in Lake Norm an during 2007 ......................................................... I........... 3-11 3-4 Phytoplankton taxa identified in quarterly samples collected in Lake Norm an each year from 1992 to 2007 ....................................................................... 3-12 3-5 Dominant classes, their most abundant species, and their percent composition (in parentheses) at Lake Norman locations during each sampling period of 2007.......................................... 3-23 4-1 Total zooplankton densities (Number X 1000/M 3), densities of major zooplankton taxonomic groups, and percent composition (in parentheses) of major taxa in the epilimnion and whole column net tow samples collected from Lake Norman in February, May, August, and November 2007 ......................... 4-8 4-2 Zooplankton taxa identified from samples collected quarterly on Lake Norm an from 1987 - 2007 ........................................................................................ 4-10 4-3 Dominant copepod (adults), cladoceran, and rotifer taxa and their percent composition (in parentheses) of the copepod, cladoceran and rotifer densities by location and sample period in Lake Norman in 2007 ........................... 4-13 5-1 Common and scientific names of fish collected in Lake Norman, during 2 0 0 7 ................ .............................................................................................................. 5-8 x

LIST OF TABLES, Continued Table Title Page 5-2 Numbers and biomass of fish collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman M arch/A pril 2007 ....................................................................................................... 5-9 5-3 Mean total lengths (mm) at age for spotted bass (SPB) and largemouth bass (LMB) collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman March/April 2007 ........................................... 5-9 5-4 Comparison of mean total length (mm) at age for largemouth bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman March/April 2007 to historical largemouth bass m ean lengths ........................................................... ................................................. 5-10 5-5 Striped bass mortalities observed in Lake Norman during weekly surveys during July and A ugust 2007 ................................................................................. .. 5-11 5-6 Lake Norman forage fish densities (number/hectare) and population estimates from hydroacoustic surveys in September 2007 .................. 5-11 5-7 Total numbers and percent composition of forage fish, and modal length class of threadfin shad collected in purse seine samples from Lake Norman during late summ er/fall, 1993 - 2007 ...................................................................... 5-12 xi

LIST OF FIGURES Figure Title Page 2-1 Water quality sampling locations (numbered) for Lake-Norman.

Approximate locations of Marshall Steam Station, and McGuire Nuclear Station are also shown ............................................................................................... 2-24 2-2a Annual precipitation totals in the vicinity of McGuire Nuclear Station ................... 2-25 2-2b Monthly precipitation totals in the vicinity of McGuire Nuclear Station in 2006 and 2007 ........................................................................................................... 2-25 2-2c Mean monthly air temperatures recorded at McGuire Nuclear Station beginning in 1989 .......................... I............................ ......................................... 2-26 2-3 Monthly mean temperature profiles for the McGuire Nuclear Station background zone in 2006 and 2007. ................................ 2-27 2-4 Monthly mean temperature profiles for the McGuire Nuclear Station mixing zone in 2006 and 2007 .............................................................................................. 2-29 2-5 Monthly surface (0.3 m) temperature and dissolved oxygen data at the discharge location (Location 4.0) in 2006 and 2007 ................................................. 2-31 2-6 Monthly mean dissolved oxygen profiles for the McGuire Nuclear Station background zone in 2006 and 2007 .......................................................................... 2-32 2-7 Monthly mean dissolved oxygen profiles for the McGuire Nuclear Station m ixing zone in 2006 and 2007 .................................................................................. 2-34 2-8 Monthly reservoir-wide temperature isotherms for Lake Norman in 2007 ............... 2-36 2-9 Monthly reservoir-wide dissolved oxygen isopleths for Lake Norman in 2007....................................................... 2-39 2-10a Heat content of the entire water column and the hypolimnion in Lake Norman in 2007 .............................................. 2-42 2-l Ob Dissolved oxygen content and percent saturation of the entire water column and the hypolimnion of Lake Norman in 2007, ............................ .... 2-42 2-11 Striped bass habitat in Lake Norman in June, July, August, September, and October 2007 ............................................................. 2-43 2-12 Lake Norman lake levels, expressed in meters above mean sea level (mmsl) for 2002, 2003, 2004, 2005, 2006, and 2007. Lake level data correspond to the water quality sampling dates over this time period .................... 2-45 3-1 Phytoplankton chlorophyll a, densities, biovolumes, and seston weights at locations in Lake Norman, NC in February, May, August, and November 2007 ..................................................... .......... 3-24 3-2 Lake Norman phytoplankton chlorophyll a seasonal maximum and minimum lake wide means since August 1987 compared with the long term seasonal lake wide means and lake wide means for 2007 .................. 3-25 3-3 Phytoplankton mean chlorophyll a concentrations by location for samples collected in Lake Norman, NC, from February and May 1988 -2007 ..................... 3-26 3-4 Phytoplankton mean chlorophyll a concentrations by location for samples collected in Lake Norman, NC, from August and November 1987 - 2007 .............. 3-27 xii

LIST OF FIGURES, Continued Figure Title Page

• 3-5 Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 2.0 in Lake Norman, NC, durin g 2007 ............................................................................................................... 3-2 8 3-6 Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 5.0 in Lake Norman, NC during 2007 ............................................................................................................... 3-29 3-7 Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 9.5 in Lake Norman, NC during 2007 ............................................................................................................... 3-30 3-8 Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 11.0 in Lake Norman, NC during 2007 ............................................................................................................... 3-3 1 3-9 Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 15.9 in Lake Norman, NC during 2007 .............................................................................................................. 3-32 4-1 Total zooplankton density by location for samples collected in Lake Norman in 2 0 0 7 ............................................... ................... ............................................... 4 -15 4-2 Zooplankton community composition by sample period and location for epilinmetic samples collected in Lake Norman in 2007 ........................................... 4-16 4-3 Total zooplankton densities by location and year for epilimnetic samples collected in Lake Norman, NC, in the winter periods of 1988 - 2007 ..................... 4-17 4-4 Total zooplankton densities by location and year for epilimnetic samples collected in Lake Norman in the spring periods of 1988 - 2007 .............................. 4-18 4-5 Total zooplankton densities by location and year for epilimnetic samples collected in Lake Norman in the summer periods of 1987 - 2007 ........................... 4-19 4-6 Total zooplankton densities by location and year for epilimnetic samples collected in Lake Norman in the fall periods of 1987 - 2007 ................................... 4-20 4-7 Annual percent composition of major zooplankton taxonomic groups from mixing zone locations (Locations 2.0 and 5.0 combined) during 1988 -

2007 (Note: Does not include Location 5.0 in the fall of 2002 or winter samples from 2005) .................................................................................................. 4-2 1 4-8 Annual percent composition of major zooplankton taxonomic groups from background Locations (Locations 9.5, 11.0, and 15.9 combined) during 1988 - 2007 (Note: Does not include winter samples from 2005) ............................ 4-22 4-9 Copepod densities during each season of each year among epilimnetic samples collected in Lake Norman from 1990 - 2007 (mixing zone = mean of Locations 2.0 and 5.0; background = mean of Locations 9.5, 11.0, and 15 .9) . ......................................................................................................................... 4-2 3 xiii

LIST OF FIGURES, Continued Figure Title Page 4-10 Cladoceran densities during each season of each year among epilimnetic samples collected in Lake Norman from 1990 - 2007 (mixing zone = mean of Locations 2.0 and 5.0; background = mean of Locations 9.5, 11.0, and 15 .9 ). ......................................................................................................................... 4 -2 4 4-11 Rotifer densities during each season of each year among epilimnetic samples collected in Lake Norman from 1990 - 2007 (mixing zone = mean of Locations 2.0 and 5.0; background = mean of Locations 9.5, 11.0, and 15.9) ......... 4-25 5-1 Sampling locations and zones associated with fishery assessments in Lake Norm an ...................................................................................................................... 5-13 5-2 Total a) number and b) biomass of fish collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, 1993 - 1997 and 1999 - 2007 ................................................................................... 5-14 5-3 Total a) number and b) biomass of spotted bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF,MNS) in Lake Norman, 200 1 - 20 07 ............................................................ ................................................. 5-15 5-4 Size distributions of a) spotted bass and b) largemouth bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in L ake Norm an, 2007................................................................................................... 5-16 5-5 Mean relative weights (Wr) for a) spotted bass and b) largemouth bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, M NS) in Lake Norman, 2007 ........................................................ 5-17 5-6 Total a) number and b) biomass of largemouth bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, 1993 - 1997 and 1999 - 2007 .......................... 5-18 5-7 Total number of young-of-year black bass collected from electrofishing five 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, 2005 - 2007 .................. ....................................................................................... 5-19 5-8 Mean total length and mean relative weight (Wr) for striped bass collected from Lake Norman, December 2007. Numbers of fish associated with mean length are inside bars ........................................................................................... 5-19 5-9 Zonal and lake-wide population estimates of pelagic forage fish in Lake Norm an, 1997 - 2007 ................................................................................................ 5-20 5-10 Size distributions of threadfin shad (TFS) and alewives (ALE) collected'in purse seine surveys of Lake Norman, 2007 ............................................................... 5-20 xiv

CHAPTER 1 MCGUIRE NUCLEAR STATION INTRODUCTION The following, annual report was prepared for the McGuire Nuclear Station (MNS) National Pollutant Discharge Elimination System (NPDES) permit # NC0024392 issued by North Carolina Department of Environment and Natural Resources (NCDENR). This report summarizes environmental monitoring of Lake Norman during 2007.

OPERATIONAL DATA FOR 2007 Station operational data for 2007 are listed in Table 1-1. Operational maintenance was performed on Unit 1 during the period March - April. The monthly average capacity factors for MNS were 101.9, 101.4, and 101.6% during July, August, and September, respectively.

These are the months when conservation of cool water is most critical and compliance with discharge temperatures is most challenging. These three months are also when the thermal limit for MNS increases from a monthly average of 95.0 'F (35.0 'C) to 99.0 'F (37.2 'C).

The average monthly discharge temperature was 97.2 'F (36.2 °C) for July, 98.8 'F (37.1 'C) for August, and 97.9 'F (36.6 'C) for September 2007. The volume of cool water in Lake Norman was tracked throughout the year to ensure that an adequate volume was available to comply with both the Nuclear Regulatory Commission Technical Specification requirements and the NPDES discharge water temperature limits.

1-1

Table 1-1. Average monthly capacity factors (%) and monthly average discharge water temperatures for MNS during 2007.

MONTHLY AVERAGE MONTHLY AVERAGE NPDES DISCHARGE CAPACITY FACTORS (%). TEMPERATURES Month January Unit 105.1 IT Unit2 105.7 Station 105.4 OF 71.4 oc 21.9 February 105.0 105.7 105.3 67.9 19.9 March 30.5 98.5 64.5 70.1 21.2 April 0.0 105.4 52.4 72.8 22.7 May 1.7 104.5 53.1 76.6 24.8 June 96.4 103.6 100.0 91.8 33.2 July 101.6 102.3 101.9 97.2 36.2 August 101.5 101.4 101.4 98.8 37.1 September 101.4 101.8 101.6 97.9 36.6 October 102.7 103.0 102.9 92.2 33.4 November 104.5 104.5 104.5 80.7 27.1 December 105.0 105.2 105.1 75.9 24.4 Average 79.4 103.4 91.4 82.8 28.2 1-2

CHAPTER 2 WATER CHEMISTRY INTRODUCTION The objectives of the water chemistry portion of the MNS NPDES Maintenance Monitoring Program are to:

1. maintain continuity in the chemical data base of Lake Norman to allow detection of any substantial station-induced and/or natural change in the physicochemical structure of the lake; and

2. compare, where applicable, these physicochemical data to similar data in other hydropower reservoirs and cooling impoundments in the Southeast.

This report focuses primarily on 2006 and 2007., Where appropriate, reference to pre-2006 data will be made by citing reports previously submitted to the NCDENR.

METHODS AND MATERIALS The complete water chemistry monitoring program for 2007, including specific variables, locations, depths, and frequencies is outlined in Table 2-1. Sampling locations are identified in Figure 2-1. Measurements of temperature, dissolved oxygen (DO), DO saturation, pH, and specific conductance were taken, in situ, at each location with a Hydrolab Data-Sonde (Hydrolab 2006) starting at the lake surface (0.3 m) and continuing at one-meter intervals to lake bottom. Pre- and post-calibration procedures associated with operation of the Hydrolab were strictly followed, and documented in hard-copy format. Hydrolab data were captured and stored electronically, and following data validation, converted to spreadsheet format for archive.

Water samples for laboratory analysis were collected with a Kemmerer or Van Dorn water bottle at the surface (0.3 in), and from one meter above bottom, where specified (Table 2-1).

Samples not requiring filtration were placed directly in single-use polyethylene terephthalate 2-1

(PET) bottles which were rinsed in the field with lake water just prior to obtaining a sample.

Samples requiring acidification, but no filtration, were placed directly in pre-acidified high density polyethylene (HDPE) bottles. Samples requiring filtration were first processed in the field by filtering through a 0.45-pm filter (Gelman AquaPrep 600 Series Capsule) which was rinsed with 500 mL of sample water, and then placed in pre-acidified HDPE bottles (Table 2-1). Upon collection, all water samples were immediately stored in the dark, and on ice, to minimize the possibility of physical, chemical, or microbial transformation.

Analytical methods, reporting limits and sample preservation techniques employed were identical to those used in 2006, and are summarized in Table 2-2. All laboratory water quality analyses were performed by the Duke Energy analytical laboratory located in Huntersville, NC. This laboratory is certified to perform analytical assessments for inorganic and organic parameters in North Carolina (North Carolina DWQ Laboratory Certification program, certificate number 248), South Carolina (South Carolina Department of Health and Environmental Control, certificate number 99005), and New York (New York Department of Health, certificate number 11717).

A comprehensive Quality Assurance/Quality Control Program (QA/QCP) is fundamental to the collection, reporting, and interpretation of water quality data, and most investigators implement some type of QA/QCP to identify, quantify, and document bias and variability in data resulting from the collection, processing, shipping, handling and analysis of samples by field and laboratory personnel. Both the United States Environmental Protection Agency (USEPA 1998a, b) and the United States Geological Survey (USGS 1998, 2002) require that any agency-funded project have an approved quality assurance program, and that this program incorporate both a field and laboratory component. USGS also requires that any agency funded study that includes laboratory assessments must also participate in their Standard Reference Program (SRP). This program was originally developed by USGS in the 1960's and currently involves analysis by participating laboratories of standards (blind unknowns) created by the agency on a biannual schedule (USGS 2002).

The QA/QCP employed for this study followed the recommendation of the USEPA and USGS, and included both a field and laboratory component. Field blanks, i.e. Milli-Q water placed in sample bottles,. were subjected to the same sample collection and handling procedures, including filtration, applied to actual samples. Periodically, samples were also split prior to submitting to the laboratory for analysis with the goal of quantifying intra-sample analytical variability. The laboratory QA/QCP involved a variety of techniques 2-2

commonly used in analytical chemistry and included reagent blanks, spikes, replicates, and performance samples. To supplement this program, additional performance samples were run on the major ions and nutrients. Beginning in 2005, standards were purchased from the USGS, through the agency's SRS program, and submitted biannually to Duke's laboratory to serve as a "double blind" assessment of analytical performance. These standards allowed quantification of the uncertainty of the analytical results against known values that were within the same concentration matrix as actual samples. The goal of this effort is to assemble analytical uncertainty data for chemical analytes which can be incorporated into statistical analyses assessing trends in time or space.

Water quality data were subjected to various graphical and statistical techniques in an attempt to describe spatial and temporal trends within the lake, and interrelationships among constituents. Whenever analytical results were reported to be equal to or less than the method reporting limit, these values were set equal to the reporting limit for statistical purposes. Data were analyzed using two approaches, both of which were consistent with earlier Duke Power Company, Duke Power, and Duke Energy studies on the lake (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; and Duke Energy 2006, 2007). The first method involved partitioning the reservoir into mixing, background, and discharge zones, consolidating the data into these sub-sets, and making comparisons among zones and years. In this report, the discharge includes only Location 4; the mixing zone, Locations 1 and 5; the background zone includes Locations 8, 11, and 15 (Figure 2-1). The second approach, applied primarily to the in situ data, emphasized a much broader lake-wide investigation and encompassed the plotting of monthly isotherms and isopleths, and summer striped bass habitat. Several quantitative calculations were also performed on the in situ data; these included the calculation of the areal hypolimnetic oxygen deficit (AHOD), maximum whole-water column and hypolimnion oxygen content, maximum whole-water column and hypolimnion heat content, mean epilimnion and hypolimnion heating rates over the stratified period, and the Birgean heat budget.

Heat content (Kcal/cm2), oxygen content (mg/cm2 ), and mean oxygen concentration (mg/L) of the reservoir were calculated according to Hutchinson (1957), using the following equation:

Lt = AoleJ TO 9 Az dz where; 2-3

Lt = reservoir heat (Kcal/cm 2) or oxygen (mg/cm2) content Ao = surface area of reservoir (cm 2)

TO = mean temperature (°C) or oxygen content (mg/L) of layer z Az = area (cm 2) at depth z dz = depth interval (cm) z= surface zm = maximum depth (m)

Precipitation and air temperature data were obtained from a meteorological monitoring site established near MNS in 1975. These data are employed principally by Duke Energy as input variables into meteorological modeling studies as required by the- Nuclear Regulatory Commission to address safety issues associated with potential radiological releases into the atmosphere by MNS (Duke Power 2004b). The data also serve to document localized temporal trends in air temperatures and rainfall patterns. Data on lake level and hydroelectric flows were obtained from Duke Energy-Carolinas Fossil/Hydro Generation, which monitors these metrics hourly.

RESULTS AND DISCUSSION Precipitation and Air Temperature Annual precipitation in the vicinity of MNS in 2007 totaled 78.2 cm (Figures 2-2a, b) or 26.8 cm less than observed in 2006 (105.0 cm), and 39.4 cm less than the long-term precipitation average for this area (117.6 cm), based on Charlotte, NC airport data. Annual precipitation totals for 2007 measured at the MNS site were also the third lowest over the period 1975 - 2007 with lower values being recorded only in 1981 (64. 4 cm) and 1986 (76.5 cm). Monthly rainfall in 2007 was greatest in March with 10.57 cm, and the least in November with 1.98 cm.

Duke Energy reported that air temperatures near the McGuire Nuclear Station in 2007 were generally warmer than the long-term mean, based on monthly average data (Duke Energy 2006). Monthly mean air temperatures in 2007 near the nuclear facility were warmer than both 2006 and the long-term mean for the months of March, August, September and October (Figure 2-2c). The temporal differences were most pronounced in September and October 2-4

2007 when temperatures averaged 2.8 and 4.1 'C warmer, respectively, than recorded in 2006.

Temperature and Dissolved Oxygen Water temperatures measured in 2007 illustrated similar temporal and spatial trends in the background and mixing zones (Figures 2-3 and 2-4), as they did in 2006. This similarity in temperature patterns between zones has been a dominant feature of the thermal regime in Lake Norman since MNS began operations in 1983. When between-zone differences in temperatures are observed, they occur predominately during the cooling period, and can be traced to the influence of the thermal discharge at MNS. Additionally, interannual differences in, water temperatures in Lake Norman, particularly in surface waters in the background zone, typically parallel differences in air temperatures but with a one-month lag time (Duke Power 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

Water temperatures in 2007 for the months. of January, March, and April ranged from 0.1 to 3.8 'C warmer than measured in 2006, whereas 2007 February temperatures were as much as 2.2 'C cooler than observed in 2006 (Figures 2-3 and 2-4). These interannual differences in water temperatures paralleled differences in air temperatures (Figure 2-2c), but because lake sampling is generally performed in the first week of each month, the observed data reflects the cumulative influences of meteorology and hydrology during the previous month.

Reduced operations of Unit 1 in March 2007 (Table 1-1) undoubtedly also contributed to slightly cooler temperatures in April 2007. Minimum water temperatures in 2007 were recorded in early February and ranged from 7.5 'C to 10.8 'C in the background zone and from 8.0 'C to 13.1 'C in the mixing zone. Minimum water temperatures measured in 2007 were within the observed historical range (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

Summer (June, July, and August) water temperatures in 2007 were generally similar to those observed in 2006 in both zones, with one notable exception. Surface water temperatures in the mixing zone in June 2007 were as much as 2.7 'C cooler than observed-in 2006, and appeared to be related primarily to reduced operations of Unit 1 (Table 1-1) rather than to interannual differences in air temperatures (Figure 2-2c).

2-5

Late-summer, fall and early winter water temperatures (September, October, November, and December) in 2007 were consistently warmer in both zones than those measured in 2006, and.

followed the trend exhibited in air temperatures (Figures 2-2c, 2-3). The most striking differences were observed in the mixing zone in November when 2007 temperatures were as much as 4.4 'C warmer than measured in 2006. Interannual differences in December temperature profiles were minimal.

Temperatures at the discharge location in 2007 were generally similar to 2006 (Figure 2-5) and historical data (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007). Temperatures in 2007 were slightly cooler in the spring (March temperatures were taken during a station outage), and warmer in the fall, than observed in 2006. The warmest discharge temperature of 2007 at Location 4 (37.8 'C) occurred in September and was identical to the maximum measured in 2006.

Seasonal and spatial patterns of DO in 2007 were reflective of the patterns exhibited for temperature, i.e., generally similar in both the mixing and background zones (Figures 2-6 and 2-7). As observed with water column temperatures, this similarity in DO patterns between zones has been a dominant feature of the oxygen regime in Lake Norman since MNS began operations in 1983.

Winter and spring DO values in 2007 were generally equal to or slightly lower, in both the background and mixing zones, than measured in 2006, except in February when 2007 DO values ranged from 0.4 to 1.2 mg/L higher than in 2006 (Figures 2-6 and 2-7). The interannual differences in DO values measured during this period appear to be related predominantly to the differences in water column temperatures in 2007 versus 2006. Warmer water would be expected to exhibit a lesser oxygen content because of the direct effect of temperature on oxygen solubility, which is an inverse relationship, and indirectly via a restricted convective mixing regime which would limit water column reaeration. Conversely, cooler water column temperatures, as measured in February 2007, would be expected to exhibit higher oxygen values because of increased oxygen solubility, and an. enhanced convective mixing regime which would promote water column reaeration.

Summer DO values in 2007 were highly variable throughout the water column in both the mixing and background zones ranging from highs of 6.0 to 8.0 mg/L in surface waters to lows of 0.0 to 2.0 mg/L in bottom waters. This pattern is similar to that measured in 2006 2-6

and earlier years (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a,, 2005; Duke Energy 2006, 2007). Unlike most previous years, summer DO profiles in 2007 and 2006 were remarkably similar throughout the water column in both zones, suggesting that those physical and metabolic processes that influence DO within the reservoir were proceeding at about the same rates in 2007 and 2006. All dissolved oxygen values recorded in 2007 during this period were within the historical range.

Considerable differences were observed between 2007 and 2006 late summer and fall DO values in both the mixing and background zone, especially in the metalimnion and hypolimnion during the months of September, October, and-November (Figures 2-6 and 2-7).

These interannual differences in DO levels during the cooling season are common in Catawba River reservoirs and can be explained by the effects of variable weather patterns on water column cooling (heat loss) rates and mixing. Warmer air temperatures delay water column cooling which, in turn, delays the onset of convective mixing of the water column and the resultant reaeration of the metalimnion and hypolimnion. Conversely, cooler air temperatures increase the rate and magnitude of water column heat loss, thereby promoting convective mixing and resulting in higher DO values earlier in the year.

The 2007 late summer and autumn DO data indicate that fall convective reaeration proceeded slower and was less complete throughout the water column than observed in corresponding months in 2006. Consequently, 2007 DO levels in either a portion or all of the water were less than observed in 2006. These between-year differences in DO corresponded strongly with the degree of thermal stratification which, as discussed earlier, correlated with interannual differences in air temperatures (Figures 2-2c, 2-3, and 2-4). Interannual differences in DO patterns are common not only within the Catawba River Basin, but throughout Southeastern reservoirs and can reflect yearly differences in hydrologic, meteorologic, and limnologic forcing variables (Cole and Hannan 1985; Petts, 1984).

The seasonal pattern of DO in 2007 at the discharge location was similar to that measured historically, with the highest values observed during the winter and lowest observed in the summer and early fall (Figure 2-5). Fall DO levels in 2007 at location 4:0 were slightly lower than observed in 2006 due to warmer temperatures. The lowest DO concentration measured at the discharge location in 2007 (5.5 mg/L) occurred in September, and was identical to that measured in August, 2006; it was also 1.4 mg/L higher than the historical minimum, measured in August 2003 (4.1 mg/L).

2-7

Reservoir-Wide Temperature and Dissolved Oxygen The monthly reservoir-wide temperature and DO data for 2007 are presented in Figures 2-8 and 2-9. These data are similar to that observed in previous years and are characteristic of cooling impoundments and hydropower reservoirs in the Southeast (Cole and Hannan 1985; Hannan et al. 1979; Petts 1984). Detailed discussions on the seasonal and spatial dynamics of temperature and dissolved oxygen during both the cooling and heating periods in Lake Norman have been presented previously (Duke Power Company 1992, 1993, 1994, 1995, 1996).

The seasonal heat content of both the entire water column and the hypolimnion for Lake Norman in 2007 are presented in Figure 2-10a; additional information on the thermal regime in the reservoir for the years 2006 and 2007 is presented in Table 2-3. Annual minimum heat content for the entire water column in 2007 (8.88 Kcal/cm2; 8:92 'C) occurred in early February, whereas the maximum heat content (28.79 Kcal/cm2 ; 28.98 'C) occurred in late August. Heat content of the hypolimnion exhibited a somewhat different temporal trend as that observed for the entire water column. Annual minimum hypolimnetic heat content also occurred in early February and measured 4.77 Kcal/cm 2 (7.53 -C), but the maximum occurred in early September and measured 15.77 Kcal/cm 2 (25.04 'C). Heating of both the entire water column and the hypolimnion occurred at approximately a linear rate from minimum to maximum heat content. The mean heating rate of the epilimnion equaled 0.110

'C/day and 0.089 'C/day for the hypolimnion; both rates were slightly greater than observed in 2006 (Table 2-3). The 2007 heat content and heating rate data for Lake Norman were generally similar to that observed in previous years (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

The seasonal oxygen content and percent saturation of the whole water column, and the hypolimnion, are depicted for 2007 in Figure 2-10b. Additional oxygen data can be found-in Table 2-4 which presents the 2006 AHOD for Lake Norman and similar earlier estimates for 18 Tennessee Valley Authority (TVA) reservoirs. Reservoir oxygen content was greatest in mid-winter when DO content measured 10.4 mg/L for the whole water column and 10.3 mg/L for the hypolimnion. Percent saturation values at this time approached 90% for the entire water column and 86%'for the hypolimnion. Beginning in early spring, oxygen content began to decline precipitously in both the whole water column and the hypolimnion, and continued to decline linearly until reaching a minimum in late summer. Minimum summer 2-8

volume-weighted DO values for the entire water column measured 3.9 mg/L (52%

saturation), whereas the minimum for the hypolimnion was 0.18 mg/L (2.2% saturation).

The mean rate of DO decline in the hypolimnion over the stratified period, i.e., the AHOD, was 0.039 mg/cm 2/day (0.061 mg/L/day) (Figure 2-1Ob), and is similar to that measured in 2006 (Duke Energy 2007).

Hutchinson (1938, 1957) proposed that the decrease of DO in the hypolimnion of a waterbody should be related to the productivity of the trophogenic zone. Mortimer (1941) adopted a similar perspective and proposed the following criteria for AHODs associated with various trophic states; oligotrophic _<0.025 mg/cm 2/day, mesotrophic 0.026 mg/cm 2/day to 0.054 mg/cm 2/day, and eutrophic > 0.055 mg/cm 2 /day. Employing these limits, Lake Norman should be classified as mesotrophic based on the calculated AHOD value of 0.039 mg/cm 2/day for 2007. The oxygen-based mesotrophic classification agrees well with the mesotrophic classification based on chlorophyll a levels (Chapter 3). The 2007 AHOD value is also similar to that found in other Southeastern reservoirs of comparable depth, chlorophyll a status, and Secchi depth (Table 2-4).

Striped Bass Habitat Suitable pelagic habitat for adult striped bass, defined as that layer of water with temperatures

<26 'C and DO levels _>2.0 mg/L, was found lake-wide from mid September 2006 through early July 2007. Beginning in late June 2007, habitat reduction proceeded rapidly throughout the reservoir both as a result of deepening of the 26 'C isotherm and metalimnetic and hypolimnetic deoxygenation (Figure 2-11). Habitat reduction was most severe from mid July through early September when no suitable habitat was observed in the reservoir. These conditions were similar to those observed in most previous years except that in 2007 no habitat existed in the upper, riverine segments of the reservoir. Historically, a small, but spatially variable zone of habitat is typically observed near and upstream of the confluence of Lyles Creek with Lake Norman. Habitat measured in the upper reaches of the reservoir appears to be influenced by both inflow from Lyles Creek and discharges from Lookout Shoals Hydroelectric facility, which generally are somewhat cooler than ambient conditions in Lake Norman. Upon entering Lake Norman, this water mixes with ambient waters and then proceeds as a subsurface underflow as it migrates downriver (Ford 1985).

An additional refuge was also observed in the metalimnion and hypolimnion near the Cowans Ford dam during this period, but this lasted only until 23 July when dissolved oxygen was 2-9

reduced to < 2.0 mg/L by microbial demands, thereby eliminating suitable habitat in the lower portion of the reservoir. Summer-time habitat conditions for adult striped bass in 2007 were more severe than 2004 when the largest striped~bass die-off ever was observed in the reservoir (2610 fish). Conditions in 2007 were most recently similar to those measured in 2006 when habitat elimination was observed for a period of about 50 to 60 days. Observed striped bass mortalities in 2007 totaled thirteen fish (Chapter 5).

Physicochemical habitat expanded appreciably by mid September, primarily as a result of epilimnion cooling and deepening, and in response to changing meteorological conditions.

The temporal and spatial pattern of striped bass habitat expansion and reduction observed in 2007 was generally similar to that previously reported in Lake Norman, and many other Southeastern reservoirs (Coutant 1985; Matthews et al. 1985; Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power .1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

Turbidity and Specific Conductance Surface turbidity values were generally low at the MNS discharge, mixing zone, and mid-lake background locations during 2007, ranging from 0.95 to 5.60 NTU's (Table 2-5). Bottom turbidity values were also low over the 2007 study period, ranging from 1.0 to 8.4 NTU's (Table 2-5). Turbidity values observed in 2007 were within the historical range (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000,.2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

Specific conductance in Lake Norman in 2007 ranged from 51 to 105 umnho/cm, and was generally similar to that observed in 2006 (Table 2-5), and historically (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007). Specific conductance values in surface and bottom waters in 2007 were similar throughout the year except during the period of intense thermal stratification, i.e., August and November, when an increase in bottom conductance values was observed at locations within the mixing and background zones. These increases in bottom conductance values appeared to be related primarily to the release of soluble iron and manganese from the lake bottom under anoxic conditions (Table 2-5). This phenomenon is common in both natural lakes and reservoirs that exhibit extensive hypolimnetic oxygen depletion (Hutchinson 1957, Wetzel 1975), and is' an annually recurring phenomenon in Lake Norman.

2-10

pH and Alkalinity During 2007, pH and alkalinity values were similar among MNS discharge, mixing, and background zones (Table 2-5). Values of pH were also generally similar to values measured in 2007 (Table 2-5), and historically (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007). Values of pH in 2007 ranged from 7.2 to 8.2 in surface waters, and from 6.0 to 7.9 in bottom waters. Alkalinity values in 2007 ranged from 13.0 to 16.0 mg/L, expressed as CaCO 3, in surface waters and from 11.5 to 22.5 mg/L in bottom waters.

Major Cations and Anions The concentrations of major ionic species in the MNS discharge, mixing, and mid-lake background zones are provided in Table 2-5. Lake-wide, the major cations were sodium, calcium, magnesium, and potassium, whereas the major anions were bicarbonate, sulfate, and chloride. The overall ionic composition of Lake Norman during 2007 was generally similar to that reported for 2006 (Table 2-5) and previously (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

Nutrients Nutrient concentrations in the discharge, mixing, and mid lake background zones of Lake Norman for 2006 and 2007 are provided in Table 2-5. Overall, nutrient concentrations in 2007 were well within historical ranges (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007). Nitrogen and phosphorus levels in 2007 were low and generally similar to those measured in 2006 (Duke Energy 2006). Historic total phosphorus (TP) and ortho-phosphorus (OP) concentrations were typically measured at or below the analytical reporting limits (ARL) for these constituents, i.e., 5 jig/L. For total phosphorus, all 44 samples analyzed in 2007 exceeded the ARL, but most measurements (40 of 44) were < 10 jtg/L. The maximum TP value reported in 2007 was' 114 Jtg/L and was observed at the bottom at Location 2.0. Similarly, almost all measurements of OP (43 of 44) were recorded as < 5 gg/L, the lone exception being a value of 13 jig/L reported at the bottom 2-11

depth at Location 2.0. Nutrients in 2007 were generally somewhat higher uplake than downlake, but the differences were slight and not statistically significant (p < 0.05). Spatial variability in various chemical constituents, especially nutrient concentrations, is common in long, deep reservoirs (Soballe et al. 1992). Nitrite-nitrate and ammonia nitrogen concentrations were low at all locations sampled in 2007 (Table 2-5), and also were generally similar to 2006 and historical values (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

Metals Metal concentrations in the discharge, mixing, and mid lake background zones of Lake Norman for 2007 were similar to those measured in 2006 (Table 2-5) and historically (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

Iron concentrations in surface and bottom waters were generally low (_ 0.4 mg/L) during 2007, the lone exceptions being a 0.82-mg/L value measured in the bottom waters at Location 2.0 in November, and a 1.26-mg/L value measured at the bottom depth at Location 5.0 in August. This latter value is the only instance in 2007 that an iron measurement exceeded the North Carolina water quality action level for iron (1.0 mg/L; NCDENR 2004).

Similarly, manganese concentrations in the surface and bottom waters were generally low (<

100 pgg/L) in 2007, except during the summer and fall when bottom waters were anoxic (Table 2-5). Manganese concentrations in the bottom waters rose above the State water quality action level for this constituent (200 gig/L; NCDENR 2004) at various locations throughout the lake in summer and fall of 2007, and were characteristic of historical conditions (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007). This phenomenon, i.e., the release of manganese (and iron) from bottom sediments in response to low redox conditions (low oxygen levels), is common in stratified waterbodies (Stumm and Morgan 1970, Wetzel 1975).

Concentrations of other metals in 2007 were typically low, and often below the analytical reporting limit for the specific constituent (Table 2-5). These findings are similar to those observed for earlier years (Duke Power Company 1985, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996; Duke Power 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2-12

2005; Duke Energy 2006, 2007). All values for cadmium and lead were reported as either equal to or below the ARL with the lone exception being a lead value of 3.4 pg/L measured at the bottom depth at Location 2.0 in February. Zinc values were consistently above the ARL and ranged from < 1.0 gg/L to 24.9 gg/L; this maximum was measured at the bottom depth at Location 2.0 in February. All copper concentrations, measured as total recoverable copper, were less than 4 gg/L, and over half (24 of 44) of the values were less than the ARL.

The maximum copper concentration recorded in 2007 (3.13 gg/L) was measured in the surface waters (0.3 m) at Location 11.0 in May.' All values reported for cadmium, lead, zinc, and copper in 2007 were below the State action level for each of these metals (NCDENR 2004).

FUTURE STUDIES No changes are planned for the water chemistry portion of the Lake Norman Maintenance-Monitoring Program.

SUMMARY

Annual precipitation in the vicinity of MNS in 2007 totaled 78.2 cm and was the third lowest measurement reported over the period 1975 - 2007, with lower values being recorded only in 1981 (64.4 cm) and 1986 (76.5 cm). Air temperatures near the McGuire Nuclear Station in 2007 were warmer than both 2006 and the long-term mean for the months of March, August, September and October. The temporal differences were most pronounced in September and October 2007 when temperatures averaged 2.8 and 4.1 'C warmer, respectively, than recorded in 2006.

Temporal and spatial trends in water temperature and DO in 2007 were similar to those observed historically, and all data were within the range of previously measured values.

Water temperatures in 2007 for the months of January, March, and April ranged from 0.1 to 3.8 'C warmer than measured in 2006 in both the mixing and background zones, whereas 2007 February temperatures were as much as 2.2 'C cooler than observed in 2006. These interannual differences in water temperatures paralleled differences exhibited in monthly air temperature data but with about a one month lag. Reduced operations of Unit 1 at- MNS in 2-13

March and April 2007 also undoubtedly contributed to these interannual differences during the winter and early spring.

Summer (June, July, and August) water temperatures in 2007 were generally similar to those' observed in 2006 in both zones, with one notable exception. Surface water temperatures in the mixing zone in June 2007 were up to 2.7 'C cooler than observed in 2006, and appeared to be related primarily to reduced operations of Unit 1 rather than to interannual differences in air temperature. Late-summer, fall, and early winter water temperatures (September, October, November, and December) in 2007 were consistently warmer in both zones than those measured in 2006, and followed the trend exhibited in air temperatures. The most striking differences were observed in the mixing zone in November when 2007 temperatures were as much as 4.4 'C warmer than measured in 2006.

Temperatures at the discharge location in 2007 were generally similar to 2006 (Figure 2-5) and historical data. Temperatures in 2007 were slightly cooler in the spring (March temperatures were taken during a station outage), and warmer in the fall than observed in 2006. The warmest discharge temperature of 2007 at Location 4 (37.8 'C) occurred in September and was identical to the maximum measured in 2006.

Seasonal and spatial patterns of DO in 2007 were reflective of the patterns exhibited for temperature, i.e., generally similar in both the mixing and background zones. Winter and spring DO values in 2007 were generally equal to or slightly lower, in both the background and mixing zones, than measured in 2006, except in February when 2007 DO values ranged from 0.4 to 1.2 mg/L higher than in 2006. The interannual differences in DO values measured during this period appeared to be related predominantly to the differences in water column temperatures in 2007 versus 2006. Summer DO values in 2007 were highly variable throughout the water column in both the mixing and background zones ranging from highs of 6.0 to 8.0 mg/L in surface waters to lows of 0.0 to 2.0 mg/L in bottom waters. This pattern is similar to that measured-in 2006 and earlier years. Unlike most previous years, summer DO profiles in 2007 and 2006 were remarkably similar throughout the water column in both zones, suggesting that those physical and metabolic processes that influence DO within the reservoir were proceeding at about the same rates in 2007 and 2006. All dissolved oxygen values recorded in 2007 during this period were within the historical range.

Considerable differences were observed between 2007 and 2006 late summer and fall DO values in both the mixing and background zone, especially, in the metalimnion and 2-14

hypolimnion during the months of September, October, and November. The 2007 late summer and autumn DO data indicated that fall convective reaeration proceeded slower and was less complete throughout the water column than observed in the corresponding months

.in 2006. Consequently, 2007 DO levels in either a portion or all of the water column were less than observed in 2006. These between-year differences in DO corresponded strongly with the degree of thermal stratification and interannual differences in air temperatures.

The seasonal pattern of DO in 2007 at the discharge location was similar to that measured historically, with the highest values observed during the winter and lowest observed in the summer and early fall. Fall DO levels in 2007 at location 4.0 were slightly lower- than observed in 2006 due to warmer temperatures. The lowest DO concentration measured at the discharge location in 2007 (5.5 mg/L) occurred in September, and was identical to that measured in August, 2006; it was also 1.4 mg/L higher than the historical minimum, measured in August 2003 (4.1 mg/L).

Reservoir-wide isotherm and isopleth information for 2007, coupled with heat content and hypolimnetic oxygen data, illustrated that Lake Norman exhibited thermal and oxygen dynamics characteristic of historical conditions and similar to other Southeastern reservoirs of comparable size, depth, flow conditions, and trophic status. Suitable pelagic habitat for adult striped bass, defined as that layer of water with temperatures < 26 'C and DO levels >

2.0 mg/L, was found lake-wide from mid September 2006 through early July 2007.

Beginning in late June 2007, habitat reduction proceeded rapidly throughout the reservoir both as a result of deepening of the 26 'C isotherm and metalimnetic and hypolimnetic deoxygenation. Habitat reduction was most severe from mid July through early September when no suitable habitat was observed in the reservoir. Summer 2007 habitat conditions were most recently similar to those measured in 2006 when habitat elimination was observed for a period of about 50 to 60 days. Observed striped bass mortalities in 2007 totaled thirteen fish.

All chemical parameters measured in 2007 were similar to 2006, and within the concentration ranges previously reported for the lake during both preoperational and operational years of MNS. Specific conductance values, and all concentrations of cation and anion species measured, were low. Nutrient concentrations were also low with most values reported close to or below the analytical reporting limit for that test. Concentrations of metals in 2007 were low, and often below the analytical reporting limits. All values reported for cadmium, lead, 2-15

zinc, and copper in 2007 were below the State water quality standard or action level for each of these metals.

Iron concentrations in surface and bottom waters were generally low (< 0.40 mg/L) during 2007, the only exceptions being a 0.82-mg/L value measured in the bottom waters at Location 2.0 in November, and a 1.26-mg/L value measured at the bottom depth at Location 5.0 in August. This latter value is the only instance in 2007 that an iron measurement exceeded the North Carolina. water quality action level for iron (1.0 mg/L). Similarly, manganese concentrations were generally low (_< 100 ýtg/L) in 2007, except during the summer and fall when bottom waters were anoxic. Manganese concentrations in the bottom waters rose above the State water quality standard for this constituent (200 Jtg/L) at various locations throughout the lake in summer and fall of 2007, and were characteristic of historical conditions. This phenomenon, i.e., the release of manganese (and iron) from bottom sediments in response to low redox conditions (low oxygen levels), is common in stratified waterbodies.

2-16

Table 2-1. Water chemistry program for the McGuire Nuclear Station NPDES Maintenance Monitoring Program on Lake Norman.

2007 McGUIRE NPDES SAMIPLING PROGRAM PARAMETERS LOCATIONS. 2 "4 5 8 9.5 11 13 14 15 15.9 62 69 72 80 '16 DEPTH (m) 33 33 5 20 32 23 27 21 10 23 23 15 7 5 4 3 IN-SrIU ANALYSIS Method Temperature Dissolved Oxygen Hydrolab In-situ measurements are collected monthly at the above locations at lm intervals from 0.3m to Im above bottom.

pH Hydrolab Measurements are taken weekly from July-August for striped bass habitat.

Conductivity Hydrolab NUTRIENT ANALYSES Ammonia AA-Nut Q/TB Q/T,B Q/T Q/TB Q/TB Q/T,B Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/TB S/T Nitrate+Nitrite AA-Nut Q/TB Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B S/T Orthophosphate AA-Nut Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/TB Q/T,B Q/TB Q/T Q/T,B Q/T,B Q/T,B S/T Total Phosphorus AA-TP,DG-P Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/TB Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/TB S/T Silica AA-Nut QtT,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/T,B S/T Cl AA-Nut Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/TB S/T TKN AA-TKN Q/T,B Q/T,B Q/T Q/T,B .Q/TB Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B S/T Total Organic Carbon TOC Q/TB Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/TB Q/TB S/T Dissolved organic carbon DOC Q/TB Q/T,B Q/T Q/T,B Q/TB Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/TB Q/TB S/T ELEMENTAL ANALYSES Aluminum ICP-MS-D Q/T,B S/TB Q/T Q/TB Q/T,B Q/*TB Q/T,B Q/T,B Q/T QiT,B Q/T,B Q/T,B S/T Calcium ICP-24 Q/TB Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B _Q/T,B Q/T Q/T,B Q/T,B Q/T,B S/T Iron ICP-MS-D Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B . Q/T,B Q/T Q/TB Q/T,B Q/TB S/T Magnesium ICP-24 Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/TB S/T Manganese ICP-MS-D Q/T,B Q/TB Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/TB S/T Potassium 306-K Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/T,B S/T Sodium ICP-24 Q/T,B Q/T,B Q/T Q/TT,B Q/1,B Q/T,B Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/T,B S/T Zinc ICP-MS-D Q/T,B Q/TB Q/T Q/T,B 'Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/T,B QiT,B S/T Arsenic ICP-MS-D Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/TB Q/T,B S/T Cadminum ICP-MS-D. Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/TB QiT,B S/T Copper (Total Recoverable) ICP-MS-D Q/T,B Q/T,B QIT Q/T,B Q/TB Q/T,B . Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/T,B S/T Copper (Dissolved) ICP-MS Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/TB Q/T,B Q/TB S/T Lead ICP-MS-D Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/TB Q/T,B S/T Selenium ICP-MS-D Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B SIT ADDITIONAL ANALYSES Hardness Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B QiT Q/T,B Q/T,B Q/T,B S/T Alkalinity T-ALKT Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B QIT,B Q/T Q/T,B Q/T,B Q/T,B S/T Turbidity F-TURB Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B Q/T QiTB Q/T,B Q/T,B S/T Sulfate UV_S04 Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B Q/T,B Q/T,B QiT QIT,B Q/T,B Q/T,B S/T Total Solids S-TSE QITB Q/T,B Q/T QIT,B QIT,B Q/T,B Q/T,B ' QIT,B QIT Q/IT,B Q/T,B Q/T,B SIT Total Suspended Solids S-TSSE Q/T,B Q/T,B Q/T Q/T,B Q/T,B Q/T,B QIT,B Q/T,B QIT Q/TB Q/T,B Q/T,B SIT CODES: Frequency Q = Quarterly (Feb, May, Aug, Nov) S = Semi-annually (FebAug) T = Top (0.3m) B = Bottom (Im above bottom)

Table 2-2. Analytical methods and reporting limits employed in the McGuire Nuclear Station NPDES Maintenance Monitoring Program for Lake Norman.

Parameter Method (EPA/APHA) Preservation Reporting Limit Alkalinity, Total Total Inflection Point, EPA 310.1 4 "C 0.01 meg/L Aluminum ICP, EPA 200.7 0.5% HNO 3 0.05 mg/L Cadmium, Total Recoverable ICP Mass Spectroscopy, EPA 200.8 0.5% HNO 3 0.5 pg/L/1.0 IJg/L a Calcium ICP, EPA 200.7 0.5% HNO 3 30 pg/L Chloride Colorimetric, EPA 325.2 4 "C 1.0 mg/L Copper, Total Recoverable ICP Mass Spectroscopy, EPA 200.8 0.5% HNO 3 2.0 Ipg/L Copper, Dissolved ICP Mass Spectroscopy, EPA 200.8 0.5% HNO 3 2.0 Ig/L Iron, Total Recoverable ICP, EPA 200.7 0.5% HNO 3 10 pg/L Lead, Total Recoverable ICP Mass Spectroscopy, EPA 200.8 0.5% HNO 3 2.0 pg/L Magnesium Atomic Emission/ICP, EPA 200.7 0.5% HNO 3 30 Ipg/L Manganese, Total Recoverable ICP Mass Spectroscopy, EPA 200.8 0.5% HNO 3 1.0 pg/L Nitrogen, Ammonia Colorimetric, EPA 350.1 0.5% H2SO4 20 pg/L Nitrogen, Nitrite + Nitrate Colorimetric, EPA 353.2 0.5% H2SO4 20 pg/L Nitrogen, Total Kjeldahl Colorimetric, EPA 351.2 0.5% H2SO 4 100 pg/L Phosphorus, Orthophosphorus Colorimetric, EPA 365.1 4 'C 5 pg/L Phosphorus, Total Colorimetric, EPA 365.1 0.5% H2SO4 5 pg/L Potassium ICP, EPA 200.7 0.5% HNO 3 250 pg/L Silica APHA 4500Si-F 0.5% HNO 3 500 pg/L Sodium Atomic Emission/ICP, EPA 200.7 0.5% HNO 3 1.5 mg/L Solids, Total Gravimetric, EPA 160.2 4 'C 0.1 mg/L Solids, Total Suspended Gravimetric, EPA 160.2 4 'C 0.1 mg/L Sulfate Ion Chromatography 4 °C 0.1 mg/L Turbidity Turbidimetric, EPA 180.1 0.5% H2SO 4 0.05 NTU Zinc, Total Recoverable ICP Mass Spectroscopy, EPA 200.8 0.5% HNO 3 1 IJg/L

References:

USEPA 1983, and APHA 1995 a- Reporting limit for May samples 00

Table 2-3. Heat content calculations for the thermal regime in Lake Norman for 2006 and 2007.

2006 2007 Maximum Areal Heat Content (g-cal/cm 2 ) 28,880 28,787 Minimum Areal Heat Content (g-cal/cm ) 10,846 8,882 Birgean Heat Budget (g-cal/ cm 2 ) 18,034 19,905 Epilimnion (above 11.5 m) Heating Rate (°C /day) 0.091 0.110 Hypolimnion (below 11.5 m) Heating Rate (°C /day) 0.068 0.089 2

2-19

Table 2-4. A comparison of areal hypolimnetic oxygen deficits (AHOD), summer chlorophyll a (Chl a), Secchi depth, and mean depth of Lake Norman and 18 TVA reservoirs.

AHOD Summer Chl a Secchi Depth Mean Depth Reservoir (rng/cm 2 /day) (ug/L) (M) (M)

Lake Norman 0.039 4.5 1.7 10.3 TVA a Mainstem Kentucky 0.012 9.1 1.0 5.0 Pickwick 0.010 3.9 0.9 6.5 Wilson 0.028 5.9 1.4 12.3 Wheelee 0.012 4.4 5.3 Guntersville 0.007 4.8 1.1 5.3 Nickajack 0.016 2.8 1.1 6.8 Chickamauga 0.008 3.0 1.1 5.0 Watts Bar 0.0i2 6.2 1.0 7.3 Fort London 0.023 5.9 0.9 7.3 Tributary Chatuge 0.041 5.5 2.7 9.5.

Cherokee 0.078 10.9 1.7 13.9 Douglas 0.046 6.3 1.6 10.7 Fontana 0.113 4.1 2.6 37.8 Hiwassee 0.061 5.0 2.4 20.2 Norris 0.058 2.1 3.9 16.3 South Holston 0.070 6.5 2.6 23.4 Tims Ford 0.059 6.1 2.4 14.9 Watauga 0.066 2.9 2.7 24.5 a Data from Higgins et al. (1980), and Higgins and Kim (1981) 2-20

Table 2-5. Quarterly surface (0.3 m) and bottom (bottom minus 1 m) water chemistry for the McGuire Nuclear Station discharge, mixing zone, and background locations on Lake Norman during 2006. and 2007. Values less than detection were assumed to be equal to the detection limit for calculating a mean.

Mixing Zone Mixing Zone MNS Discharge Mixing Zone Background Background LOCATION: 1.0 2 4.0 5.0 8.0 11.0 DEPTH: Surface Bottom Surface Bottom Surface Surface Bottom Surface Bottom Surface Bottom PARAMETERS YEAR: 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 Turbidity (NTU)

Feb NA 2.3 NA 2.30 NA 2.70 NA- 3.60 NA 2.70 NA 2.40 NA 2.90 1.6 2.20 2.3 3.50 2.2 5.60 2.8 5.70 May 1.10 2.0 0.98 1.30 1.2 1.30 1 1.50 1.2 1.50 1.3 1.00 1.2 1.10 1.4 0.95 1.1 1.60 1.1 1.20 1.5 1.60 Aug 10.00 1.3 20.00 1.00 9.8 1.40 18 1.00 22 1.50 9.8 1.40 9 8.40 1.4 1.30 1.7 1.60 1.9 1.40 1.8 1.60 Nov 2.00 2.6 3.3 3.40 2.40 2.70 2.70 4.30 3.70 2.70 5.30 2.80 4.90 4.30 2.30 1.70 6.50 3.00 3.70 3.10 -7.00 3.40 Annual Mean 4.37 2.05 8.09 2.0 4.47 2.0 7.23 2.6 8.97 2.1 5.47 1.9 5.03 4.2 1.68 1.5 2.90 2.4 2.23 2.8 3.28 3.1 Specific Conductance (umho/cm)

Feb 53.0 53.8 52.9 52.6 53.3 53.8 53.1 53.1 53.7 54.7 53.4 54.3 52.6 53.2 '52.6 53.8 53.1 53.8 53.1 51.5 53.2 51.4 May 53.9 55.8 53.5 55.2 53.9 55.7 53.2 55 54.4 56.3 54.2 56 53.1 54.7 53.2 55.9 53.3 55.1 53.5 56.6 53.4 55.2 Aug 57.7 61.1 62.6 73.9 58.2 60.9 67.4 71.2 58.4 61 58.2 61 65.9 68.9 58.0 61.1 59.9 65.6 58.2 64.3 64.1 68 Nov 57.7 64.8 57.8 104.7 57.8 64.9 57.7 67.2 58.5 65.7 58.0 65.3 58.3 65.3 58.0 64.5 57.8 64.4 56.6 69.1 56.7 69.2 Annual Mean 55.6 58.9 56.7 71.6 55.8 58.8 57.9 61.6 56.3 59.4 56.0 59.2 57.5 60.5 55.5 58.8 56.0 59.7 55.4 60.4 56.9 61.0 pH (units)

Feb 7.2 7.3 7.0 6.7 7.3 7.3 7.0 7.1 7.3 7.3 7.4 7.4 7.1 7.5 7.1 7.4 6.8 7.3 7.0 7.3 6.8 7.1 May 7.4 7.2 6.5 6.8 7.4 7.5 6.6 6.5 7.3 7.4 7.4 7.4 ' 7.0 6.5 7.8 7.6 6.7 6.5 7.5 7.5 6.5 6.5 Aug 7.6 7.6 6.2 6.0 7.6

• 7.4 6.4 6.0 7.1 7.2 7.3 7.5 6.4 6.5 7.7 8.2 6.2 6.5 7.9 7.9 6.3 6.5 Nov 7.3 7.4 7.0 7.1 7.3 7.5 7.2 7.3 7.5 7.4 7.5 7.4 7.4 7.4 7.5 . 7.6 7.5 7.6 7.3 7.6 7.3 7.4 Annual Mean 7.37 6.66 6.66 6.65 .7.37 7.43 6.80 6.73 7.29 7.10 7.39 7.43 6.96 6.98 7.52 7.70 6.79 6.9 8 7.42 7.58 6.73 6.88 Alkalinity (mg CaCO3/L)

Feb 12.5 13.5 12.0 13.5 11.5 14.0 12.5 13.5 12.5 13.5 12.0 14.0 12.0 13.5 . 12.5 14.0 12.5 14.0 12.0 13.0 12.5 13.0 May 12.0 13.5 12.0 14.0 12.5 13.5 12.5 13.5 13.0 13.5 12.5 14.0 " 12.5 13.5 12.0 13.5 12.5 13.5 12.5 13.5 12.5 13.5 Aug 14.0 15.0 15.5 15.5 14.0 15.0 16.0 16.0 14.0 15.0 14.0 15.0 19.5 22.5 14.0 15.0 15.5 19.0 14.5 15.5 17.5 19.0 Nov 14.5 16.0 15.0 17.0 15.0 16.0 15.0 20.0 14.5 16.5 15.0 16.0 13.0 16.5 14.5 15.5 15.0 11.5 14.5 16.0 14.5 16.0 Annual Mean 13.3 14.5 13.6 15.0 13.3 14.6 14.0 15.8 13.5 14.6 13.4 14.8 14.3 16.5 13.3 14.5 13.9 14.5 134 14.5 14.3 15.4 Chloride (mg/L)

Feb 4.5 4.6 4.6 4.7 4.4 4.6 4.4 4.6 4.5 4.5 4.3 4.7 4.5 4.5 4.4 4.7 4.6 4.7 4.5 4.5 4.7 4.6 May 4.8 5.1 4.8 4.7 4.7 4.9 4.9 4.8 4.8 5.0 4.8 4.8 4.8 4.8 4.9 5.1 4.7 5.1 4.8 5.3 4.6 5.3 Aug 4.6 5.4 4.4 4.8 4.6 5.4 4.1 4.7 4.6 5.4 4.5 5.2 4.4 5.0 4.5 5.3 4.9 4.9 4.7 5.9 4.2 4.6 Nov 5.0 6.6 5.0 6.5 4.9 6.5 4.9 6.3 5.0 6.5 5.0 6.7 5.0 6.5 5.0 6.7 5.1 6.6 5.1 7.6 5.1 7.6 Annual Mean 4.7 5.4 4.7 5.2 4.7 5.4 4.6 5.1 4.7 5.4 4.7 5.4 4.7 5.2 4.7 5.5 4.8 5.3 4.8 5.8 4.7 5.5 Sulfate (mg/L)

Feb 4.3 3.8 4.3 3.6 4.4 3.6 4.2 3.9 4.3 3.6 4.3 3.7 5.1 3.7 4.3 3.7 4.2 3.7 4.4 3.6 4.2 3.8 May 4.7 4.2 4.7 '4.2 4.7 4.2 4.7 4.1 4.7 4.2 4.7 4.2 4.7 -4.2 4.7 4.2 4.6 4.2 4.6 4.1 4.4 4.1 Aug 4.2 4.8 4.0 4.3 4.2 4.5 4.0 4.3 4.2 4.6 4.2 4.6 . 3.8 3.8 4.2 4.5 3.7 4.2 4.1 4.5 3.9 4.1 Nov , 4.1 4.5 4.0 4.4 4.2 4.6 . 4.2 3.9 4.1 4.5 4.1 4.6 5.0 4.6 4.2 4.7 4.1 9.6 4.0 4.8 4.0 4.8 Annual Mean 4.3 4.3 4.3 4.1 4.3 4.2 4.3 4.1 4.3 4.2 4.3 4.3 4.6 4.1 4.4 4.3 4.1 5.4 4.2 4.3 6.7 4.2 Calcium (mg/L)

Feb 2.96 3.23 2.96 3.21 2.95 3.23 2.94 3.26 2.97 3.19 2.96 3.18 2.97 3.22 '2.97 3.19 3.02 3.18 3.07 3.52 3.15 3.41 May 3.02 3.44 3.05 3.43 3.02 3.50 3.04 3.44 3.01 3.47 3.00 3.42 3.02 3.40 3.00 3.49 3.09 3.60 3.08 3.92 3.17 3.83 Aug 3.08 3.76 3.43 3.90 3.10 3.78 3.51 3.93 3.12 3.77 3.11 3.78 3.64 4.26 3.11 3.82 3.49 3.97 3.18 4.14 3.54 4.03 Nov 3.17 4.10 3.11 4.13 3.17 4.09 3.17 4.23 3.16 4.11 3.15 4.11 3.14 4.07 3.15 4.11 3.08 4.09 3.02 4.44 3.06 4.44 Annual Mean 3.06 3.63 3.14 3.67 3.06 3.65 3.17 3.72 3.07 3.64 3.06 3.62 3.19 3.74 3.06 3.65 3.17 3.71 3.09 4.01 3.23 3.93 Magnesium (mg/L)

Feb 1.51 1.66 1.51 1.65 1.51 1.65 1.49 1.64 1.52 1.64 1.52 1.65 1.52 1.65 1.52 1.65 1.51 1.66 1.51 1.63 1.50 1.61 May 1.48 1.64 1.48 1.64 1.47 1.64 1.48 1.64 1.48 1.65 1.47 - 1.65 1.48 1.63 1.47 1.67 1.48 1.67 1.47 1.74 1.49 1.74 Aug 1.58 1.89 1.61 1.81 1.59 1.90 1.64 1.84 1.59 1.89 1.58 1.89 1.69 1.94 1.58 1.89 1.64 1.87 1.59 2.06 1.65 1.88 Nov 1.71 2.06 1.70 2.O5 1.71 2.05 1.71 2.06 1.70 2.06 1.71 2.06 1.70 2.05 1.71 2.08 1.71 2.06 1.69 2.22 1.71 2.22 Annual Mean 1.17 1.81 1,58 1.79 1.57 1.81 1.58 1.80 1. 57 7 1.81 1.60 1.82 1.57 1.82 1.59 1.82 1.57 1.91 1.59 1.86 NS = Not Sampled: NA= Not Applicable; FQC = Failed Quality Control

0 Table 2-5 (Continued)

MixingZone Mixing Zone MNS Discharge Mixing Zone Background Background LOCATION: 1.0 2 4.0 5.0 8.0 11.0 DEPTH: Surface - Bottom Surface Bottom Surface Surface Bottom Surface Bottom Surface Bottom PARAMETERS YEAR: 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 Potassium (mg/L)

Feb 1.79 1.89 1.80 1.91 1.80 1.91 1.78 2.10 1.82 1.86 1.83 1.89 1.79 1.89 1.60 1.93 1.75 1.89 1.75 1.84 1.67 1.84 May 1.70 1.78 1.71 1.84 1.69 1.83 1.69 1.80 1.67 1.81 1.69 1.81 1.71 1.76 1.69 1.75 1.66 1.72 1.63 1.65 1.61 1.66 Aug 1.72 1.87 1.73 1.88 1.70 1.90 1.73 1.88 1.72 1.88 1.72 1.87 1.76 1.94 1.72 1.92 1.71 1.89 1.68 1.86 1.73 1.90 Nov 1.87 1.93 1.89 1.90 1.86 1.94 1.87 1.93 1.86 1.92 1.87 1.91 1.67 1.88 1.89 1.92 1.91 1.90 1.95 1.89 1.95 1.91 Annual Mean 1.77 1.87 1.78 1.88 1.76 1.90 1.77 1.93 1.77 1.87 1.78 1.87 1.78 1.87 1.78 1.88 - 1.76 1.85 1.75 1.81 1.74 1.83 Sodium (mg/L)

Feb 4.65 5.00 4.66 5.03 4.63 5.03 4.60 4.90 4.67 4.94 4.66 4.96 4.64 4.93 4.64 4.03 4.67 5.04 4.69 4.21 4.62 4.41 May 4.51 4.49 4.49 4.47 4.51 4.51 4.48 4.52 4.49 4.49 4.51 4.51 4.57 4.48 4.51. 4.41 4.46 4.33 4.5 4.21 4.42 4.19 Aug 4.84 4.71 4.53 4.52 4.85 4.71 4.53 4.48 4.82 4.68 4.83 . 4.67 4.61 4.56 4.82 4.75 4.56 4.48 4.38 4.73 4.54 4.51 Nov 5.27 4.75 5.27 4.73 5.24 4.75 5.26 4.73 5.27 . 4.78 5.26 4.76 5.25 4.71 5.26 4.82 5.28 4.76 5.36 5.08 5.38 5.04 Annual Mean 4.81 4.74 4.74 4.69 4.81 4.75 4.72 4.66 4.81 4.72 4.81 4.73 4.77 4.67 4.81 4.50 4.74 4.65 4.73 4.56 4.74 4.54

,luminum (mg/L)

Feb 0.050 0.066 0.056 0.070 0.050 0.075 0.050 0.118 0.050 0.082 0.050 0.073 0.060 0.088 0.050 0.077 0.057 0.083 0.050 0.145 0.050 0.157 May 0.055 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.051 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.057 0.050 0.054 Aug 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 0.050 Nov 0.050 0.068 0.050 0.077 0.050 0.060 0.050 0.050 . 0.050 0.067 0.050 0.070 0.050 0.055 0.050 0.060 0.050 0.062 0.050 0.064 0.050 0.069 Annual Mean 0.051 0.062 0.052 0.062 0.050 0.059 0.050 0.067 0.050 0.062 0.050 0.061 0.053 0.061 0.050 0.059 0.052 0.061 0.050 0.079 0.050 0.083 ron (mg/L)

Feb 0.118 0.110 0.245 0.110 0.124 0.120 0.237 0.240 0.138 0.130 0.123 0.110 0.315 0.170 0.132 0.090 0.281 0.160 0.202 0.300 0.278 0.320 May 0.050 0.060 0.077 0.070 0.061 0.060 0.074 0.080 0.054 0.090 0.061 0.090 0.064 0.070 0.051 0.040 0.106 0.070 0.049 0.050 0.142 0.080 Aug 0.040 0.050 0.063 0.060 0.036 0.050 0.260 0.060 0.049 0.040 0.042 0.040 0.556 1.260 0.032 0.050 0.098 0.090 0.052 0.040 0.110 0.250 Nov 0.115 0.160 0.201 0.370 0.121 0.170 0.119 0.820 0.113 0.190 0.106 0.170 0.232 0.250 0.087 0.160 0.318 0.360 0.147 0.180 0.324 0.250 Annual Mean 0.081 0.095 0.147 0.153 0.086 0.100 0.173 0.300 0.089 0.113 0.083 0.103 0.292 0.438 0.076 0.085 0.201 0.170 0.113 0.143 0.214 0.225 Manganese (ug/L)

Feb 17 12 51 12 18 14 71 82 17 15 17 14 48 25 14 11 42 13 28 26 57 28 May 9 5 33 9 8 6 33 7 8 6 .8 7 9 8 6 5 30 6 8 11 54 12 Aug 23 17 1079 493 23 28 1584 979 48 36 34 30 2038 2542 20 16 838 1698 33 47 1550 1550 Nov 44 138 54 552 43 142 42 1324 41 253 45 163 89 245 31 58 55 87 56 74 101 92 Annual Mean 23 43 304 267 23 48 433 598 29 78 26 54 546 705 18 23 241 451 31 40 441 421 Zadmium (ug/L)

Feb - 0.5 . 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0,5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 May 0.5 1.0 0.5 1.0 .0.5 1.0 0.5 1.0 0.5 1.0 0.5 1.0 0.5 1.0 0.5 . 1.0 0.5 1.0 0.5 1.0 0.5 1.0 Aug . 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Nov 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Annual Mean 0.5 0.6 0.5 0.6 0.5 0.625 0.5 0.5 0.5 0.6 0.5 0.6 0.5 0.6 0.5 0.5 0.5 0.5 0.5 0.6 0.5 0.6

.opper (ug/L)

Feb 2.0 2.0 2.1 2.0 2.0 2.0 2.2 2.6 2.0 2.0 2.5 2.0 2.1 2.1 2.0 2.0 2.1 2.0 2.5 3.0 2.1 2.6 May . 2.0 2.2 2.1 2.4 2.0 2.3 2.0 2.3 2.0 2.8 2.0 2.3 2.0 2.4 2.0 2.5 2.0 2.5 2.5 3.1 2.0 3.0 Aug 2.1 2.0 2.0 2.0 2.1 2.0 2.0 2.0 2.1 2.0 2.2 2.0 2.0 2.0 2.0 2.1 2.0 2.0 2.8 2.2 2.0 2.0 Nov 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.8 2.2 2.8 2.3 Annual Mean 2.0 2.1 2.1 2.1 2.0 2.1 2.1 2.2 2.0 2.2 2.2 2.1 2.0 2,1 2.0 2.2 2.0 2.1 2.7 2.6 2.2 2.5

.ead (ug/L)

Feb 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 .2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 May 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 .2,0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Aug 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2,0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Nov 2.0 2.0 2.0

• 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2,0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Annual Mean 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 NS = Not Sampled: NA= Not Applicable; FQC = Failed Quality Control

0 Table 2-5 (Continued)

Mixing Zone Mixing Zone MNS Discharge Mixing Zone Background Background LOCATION: 1.0 2.0 4.0 5.0 8.0 11.0 DEPTH: Surface Bottom Surface. Bottom Surface Surface Bottom Surface Bottom Surface Bottom PARAMETERS YEAR: 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 Zinc (ug/L)

Feb 1.0 1.4 1.0 1.6 1.0 1.0 1.0 24.9 1.4 1.3 1.0 1.4 1.0 5.4 1.0 2.8 4.1 2.5 1.1 2.4 1.1 3.6 May 1.0 6.3 1.0 10.2 1o.0 10.9 1.0 5.2 1.0 6.9 1.0 4.7 1.0 6.5 1.0 4.6 1.0 4.4 5.6 6.5 1.0 5.0 Aug 1.8 2.1 1.1 2.6 1.4 1.4 1.0 1.9 1.0 1.0 1.0 1.3 1.0 2.2 1.2 2.8 1.0 2.1 2.7 1.6 1.0 1.8 Nov 4.7 1.7 1.1 1.6 2.0 1.3 1.0 1.4 1.0 1.7 1.0 1.0 1.0 .2.4 1.0 2.4 1.0 1.8 1.0 1.8 1.2 1.8 Annual Mean 2.1 2.9 1.1 4.0 1:4 3.7 1.0 8.4 1.1 2.7 1.0 2.1 1.0 4.1 1.0 3.2 1.8 2.7 2.6 3.1 1.1 31 Nitrite-Nitrate (ugIL)

Feb 200 160 230 170 210 180 220 190 200 200 200 160 210 170 210 160 240 160 260 290 310 350 May 200 190 290 190 210 190 280 200 ,210 190 210 190 210 190 190 200 290 210 190 230 290 240 Aug 50 70 530., 440 60 180 240 450 110 150 90 170 120 450 50 190 220 330 40 210 200 350 Nov 150 130 300 570 90 120 140 80 180 100 120 130 110 120 130 130 140 230 160 260 390 290 Annual Mean 150.0 137.5 337.5 342.5 142.5 167.5 220.0 230.0 175.0 160.0; 155.0 162.5 162.5 232.5 145.0 170.0 222.5 232.5 162.5 247.5 297.5 307.5 Ammonia (ug/L)

Feb 120 42 140 40 84 37 110 54 87 69 86 72 120 57 110 38 98 50 85 46 100 56 May 35 20 40 24 30 23 38 20 35 29 31 20 28 25 24 29 45 20 35 21 56 20 Aug 90 20 150 39 80 25 170 68 92 31 90 29 200 180 84 28 120 98 100 43 140 110 Nov 65 92 65 120 65 93. 63 220 63 100 69 94 69 110 60 79 56 78 56 60 73 85 Annual Mean 77.5 43.5 98.8 55.8 64.8 44.5 95.3 90.5 69.3 57.3 69.0 53.8 104.3 93.0 69.5 43.5 79.8 61.5 69.0 42.5 92.3 68.3 Total Phosphorous (ug/L)

Feb 7 9 9 8 8 10 9 114 8 9 8 8 10. 11 9 9 9 9 10 17 14 14 May 8 7 8 6 8 7 7 7 7 7 7 7 7 7 7 6 8 9 7 7 9 7 Aug 7 7 8 10 7 8 10 7 7 7 7 7 8 7 7 8 7 7 8 8 8 8 Nov 8 7 11 7 9 7 9 8 9 8 8 7 9 8 8 7 12 9 10 9 15 9 Annual Mean 7.5 7.5 9.0 7.8 8.0 8.0 8.8 34.0 7.8 7.8 7.5 7.3 8.5 8.3 7.8 7.5 9.0 8.5 8.8 10.3 11.5 9.5 Orthophosphate (ug/L)

Feb 5 5 5 5 5 5 5 13 5 5 5 5 5 5 5 5 5 5 5 5 5 5 May 5 5. .5 .5 5 5 5 5 9 5 5 5 5 5 5 5 5 5 5 5 6 5 Aug 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 Nov 5 5" 5 5 5 5 13 5. 5 5 5 5 6 5 5 5 5 5 5 5 5 5 Annual Mean 5.0 5.0 5.0 5.0 5.0 5.0 7.0 7 6.0 5 5.0 5 5.3 5 5.0 5 5.0 5 5.0 5.0 5.3 5 Silicon (mg/L)

Feb , 4.6 4.2 4.6 3.9 4.6 4.0 4.6 4.0 4.5 4.0 4.5 4.0 4.6 4.1 4.5 4.0 4.6 3.7 4.4 4.8 4.6 4.7 May 4.5 4.2 4.8 4.7 4.5 4.2 4.8 4.6 4.5 4.3 4.4 4.0 4.5 4.0 4.4 3.9 4.9 3.7 4.2 3.6 4.8 3.6 Aug 4.0 3.8 5.5 5.0 4.1 3.7 5.5 5.2 4.1 3.7 4.1 3.7 5.4 5.4 4.1 3.6 5.4 5.1 4.1 3.9 5.3 5.1 Nov 4.6 - 4.6 '4.4 4.9 4.4 4.7 4.4 5.0 4.4 4.7 4.4 4.7 4ý5 4.7 4.4 4.6 4.3 4.6 4.6 5.1 4.5 5.1 Annual Mean 4.4 4.2 4.8 4.6 4.4 4.2 4.8 4.7 4.4 4.2 44 4.1 4.8 4.6 4.4 4.0 4.8 4.3 4.3 44 4.8 4.6 NS = Not Sampled: NA= Not Applicable; FQC = Failed Quality Control t)

80 72 69 62.

IV 15.9 0 1 2 3 Kbmluers 0 2 4 1

1.0 4.0 Figure 2-1. Water quality sampling locations (numbered) for Lake Norman. Approximate locations of Marshall Steam Station, and McGuire Nuclear Station are also shown.

2-24

180 70 160 60 140 50 120 100 40 5"

E ?g 80 30 60 20 40 10 20 0 0 Figure 2-2a. Annual precipitation totals in the vicinity of McGuire Nuclear Station.

7 112006 132007]

5

,4 0 I JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 2-2b. Monthly precipitation totals in the vicinity of McGuire Nuclear Station in 2006 and 2007.

2-25

30 28 26

-%-A* __.__

24 22 P" 20 218

~16

//

14 A, 10 2

S I t II I I I III I I I I I O8 f Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

-0O- .Long-term average --U--2006 -- k-.2007 va Figure 2-2c. Mean monthly air temperatures recorded at McGuire Nuclear Station beginning in 1989. Data were complied from L* average daily temperatures which, in turn, were created from hourly measurements.

0 0 JAN FEB MAR Temperature ('C) Temperature ('C) Temperature CC) 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 - 10 15 20 25 30 35 E 15 020 APR MAY JUN Temperature ('C) Temperature (C)

Temperature ('C) 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 10 E 15 0020 25 30 35 Figure 2-3. Monthly mean temperature profiles for the McGuire Nuclear Station background zone in 2006 (**) and 2007 (xx).

toj

0 0 JUL AUG SEP Temperature ('C) Temperature (C) Temperature ('C) 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0

5 10 020 25 30 35 OCT NOV DEC Temperature ('C) Temperature ('C) Temperature ('C) 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0

5 10 E 15 mis 20 c20 25 30 35 Figure 2-3. (Continued).

00

S 0 JAN FEB MAR Temperature ('C) Temperature ('C) Temperature ('C) 0 5 10 15 20 , 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 10 Ei 15 o20 25 30 35 APR MAY JUN Temperature ('C) Temperature ('C) Temperature ('C) 0 5 10 15 20 25 30 ' 35 0 5 10 15 20 25 30 35 0 5 10 - 15 20 25 30 35 0 (1 . . . . I . . . . I . . . . I . . . . [ . . .. . I . . . . I . . . . 0 5 5. 5 10 10 It 10 Ei15-E 15 mis. E15 020 020. 020 25 25 25 30 30 30 35 35- 35 Figure 2-4. Monthly mean temperature profiles for the McGuire Nuclear Station mixing zone in 2006 (*) and 2007 (xx).

t'i

0 JUL AUG SEP Temperature ('C) Temperature ('C) Temperature ('C) 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35

• 15-

-,20 25 30 35 OCT NOV DEC Temperature ('C) Temperature ('C) Temperature ('C) 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 0

5 10 E15

'20 25 30 35 Figure 2-4. (Continued).

t'J t.J

40 35 30 0

25 20 (D

I-10 5

0 -1 I I I IIIi Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

'12 11 10 9

8 7

0) 6 Co 5

44 3-2-

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Figure 2-5. Monthly surface (0.3m) temperature and dissolved oxygen data at the discharge location (Location 4.0) in 2006 (0) and 2007 (0).

2-31

JAN FEB MAR Dissolved Oxygen (mgIL) Dissolved Oxygen (mgIL) Dissolved Oxygen (mgIL) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0

5 10 E 15 o20 C3 25 30 35

. APR MAY JUN Dissolved Oxygen (mg/L) Dissolved Oxygen (mg/L) Dissolved Oxygen (mg/L) 0 2 .4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 Figure 2-6. Monthly mean dissolved oxygen profiles for the McGuire Nuclear Station background zone in 2006 (xx) and 2007 (,,).

JUL AUG SEP Dissolved Oxygen (mgIL) Dissolved Oxygen (mg/L) Dissolved Oxygen (mg/L) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 0 5 5 10 10 Ii 15 215

-20 -20 25 25 30 30 35 35 OCT NOV DEC Dissolved Oxygen (mag/L) Dissolved Oxygen (mg/L) Dissolved Oxygen (mgIL) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 E 15 i-

• 20 ca tJ~ Figure 2-6. (Continued).

I0 0 JAN FEB MAR Dissolved Oxygen (mgILj Dissolved Oxygen mgILj Dissolved Oxyen (MqgL) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0

5 10 E15

-20 25 30 35 APR MAY JUN Dissolved Oxygen (mgIL) Dissolved Oxygen (mg/L) Dissolved Oxygen (mgJL) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 E 15

• 20 Figure 2-7. Monthly mean dissolved oxygen profiles for the McGuire Nuclear Station mixing zone in 2006 (xx) and 2007 (,,).

0 JUL AUG SEPT Dissolved Oxygen (mg/L) Dissolved Oxygen (mgIL) Dissolved Oxygen (mgIL) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 E 15 9m OCT NOV DEC Dissolved Oxygen (mgJL) Dissolved Oxygen (mg/L) Dissolved Oxygen (mgiL) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12

^

u 5 2 2

10 2

E15 w20 2*

25 30 35 Figure 2-7. (Continued).

(/1

24 Sampling Locations Sampling Locations 235- 8.0 11.0 13.0 15.0 15.9 "62.0 69.0 72.0 80.0 23 1.0 0.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 0.O 1.0 I I 4. .- .I. - I I1 230- MI n1~ 1 1 225- 225:

220-9 1D220:

8 215- 215-

[] 210- 210:

205- 205-200- Temperature (deg C) 200- Temperature (deg C)

Jan 10, 2007 Feb 12, 2007 19b 95

-b -o-5-.-.-.- 15 - 203 55 10 15 20 255 I 30 35 40 45 50 55 .... ---....

lb"-t . 2 e1'5

- f.r...Fo.r wans

. .(b....... . ..... ..... .....

Distance from Cowans Ford Dam (kin) Distance from Cowans Ford Dam (kin)

,Z4L T Sampling Locations 235- 1.0 8.0 11.0 13.0 15.0 15.0 62.0 69.0 72.0 80.0 230- --- * *- -°Di ,--~-,.

225 S i 220-1i 215:

12' 210-205-200- Temperature (deg C)

Apr 3, 2007 19............

6 A 1"0.. 15 ... 2o0---- 275 ---- 3b - S ....

3- 4b .... 4s .... e'5 Distance from Cowans Ford Dam (kmi) Distance from Cowans Ford Dam (km)

Figure 2-8. Monthly reservoir-wide temperature isotherms for Lake Norman in 2007.

240 240 Sampling Locations Sampling Locations 23 1.0 8.0 11.0 13.0 15.0 15.9 62.0. 69.0 72.0 80.0 235 1.6 8.0 11.0 13.0 15.0 15.0 02.0 60.0, 72.0 00.0 23 ~ 2A TO2-~ 19 23G 2>) I-f 22 79 225-5~22 21

~220 8 215 21 -

215-D 210-20 205 20 N Temperature (deg C) 200Temperature (deg C) 1 May 10, 2007 Jun 5, 2007 0 5 10 15 20 25 30 35 40 45 50 055 5 10 15 20 25 30 35 40 45 50 .55 Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (kin) 240 240 Sampling Locations Sampling Locations 235 1.0 8.0 11.0 13.0 15.0 15.0 62.0 69.0 72.0 00.0 23 1.0 8.0 11.0 13.0 15.0 15...

. 62. 09.0 72.0 80.01 230 .. . . 23 -- * (

27, 22 215 F3 21 2100 W. 21 20 20 ,___,____-_ .__

Temperature (deg C) Temperature (deg C)

JTeau1 7(e p CAug 6, 2007 19 5 . . . . . . . . I. . . . . I . . . . t . . . . I . . . . * ' , 1 95 . .. .

0 5 10 15 20 25 30 35 40 45 50 55 0 5 10 15 20 25 30 35 40 45 50 55 Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (kmn Figure 2-8. (Continued).

0 240 Sampling Locations 23 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 J.*tl 225-220- 29 F

_5 215-210-19 205-

---

_ ___ ___ T 200- emperature (deg C)

Sep 4, 2007 5 10 15 20 25 30 35 40 45 .... .... !5 Distance from Cowans Ford Dam (kim) . Distance from Cowans Ford Dam (km) 22 I

8 21 8 21 S 205 20* Temper.

Nov 195 1 . . .. . . . .. .* . .

0 5 10 15 20 25 30 35 Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (kra) 00 Figure 2-8. (Continued).

0 0 240 . 240 Sampling Locations Sampling Locations 235- 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 23 1.O 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0

$ I I I3 I 1 .

230-225- 225-

~220*- i 220-8 215- [ 215-E 210- 210-205- 205-200- Dissolved Oxygen (mg/L) 200- Dissolved Oxygen (mg/L)

Jan 10, 2007 Feb 12, 2007 19 . ........................................................ 0 5 10 15 195.....................................................i i i, , i , .

. . . D.15 istan c C 5 n 3f0F 5r i 4D0 45 50 55 20 25 30 ,, i....i 35 40 , i 45

• • • i, 50

,i 55 Distance from Cowans Ford Dam (kin) Distance from Cowans Ford Dam (km) 249 Sampling Locations 235-1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 4 4 1 1 4 4 4 72.0 0.0 230-225-I 220-S -

215-210-205-200- Dissolved Oxygen (mg/L)

Apr 3, 2007

... 0... , 5... . .10 . . 15... , 20 I, .. ..

25 ,,,......3.0, 30335 40 455 ... 0....45....115.

.... .... .... .... . ' . ...S ' A. ... 40. .... ... '90.

50 .... d 55 Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (km)

Figure 2-9. Monthly reservoir-wide dissolved oxygen isopleths for Lake Norman in 2007.

24 240 Sampling Locations Sampling Locations 23 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69'.0 72.0 80.0 23 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 23 r.i ) " 23 4 c6 220 0 7 22 215 215 22 M 21 03 21

• 20 20 20 Dissolved Oxygen (mg/L) 20 Dissolved Oxygen (mg/L)

" May 10, 2007 . . --Jun 5, 2007 0 5 10 15 20 25 30 35 40 45 50 55 0 5 10 15 20 25 30 35 40 45 50 55 Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (km) 240 240 Sampling Locations Sampling Locations 23 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 23 1.0 8.0 11.0 13.0 18.0 15.9 62.0 69.0 72.0 80.0 4 4 j 4 4 4 4 4 4 14 4 .

23 ,- b; 23 '4 22 22 '~'5

22. 22 S 21 21 212 20 20 20 " Dissolved Oxygen (mg/L) 20 Dissolved Oxygen (mg/L)

Jul 2, 2007 Aug 6, 2007 0 5 10 15 20 25 30 35 40 45 50 55 010 15 20 25 30 35 40 45 50 55 Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (kin)

.i. Figure 2-9. (Continued).

220-:

215-

[]

W 210-205-200-195-Distance from Cowans Ford Dam (kin) Distance from Cowans Ford Dam (km) 240 240 Sampling Locations Sampling Locations 235- 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 235- 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 I I* I I 2I 9 , J I 230-225- 22-Z S220* 220.

E-8 215- 215-3 210-210-:

205- 205-200- Dissolved Oxygen (mg/L) 200-Dissolved Oxygen (mg/L)

Nov 8, 2007 Dec 11, 2007 I1QE-4 -- 195- ...................................

0 5 10 A 15 25 30 35 40 45 50 55 0 . . . . 10

, . .. . 15

. - 20,.. - - -25 . . . 30 . . . 35 -. -

. 40

. , . . . 45

. WS.. . .5055 Distance from Cowans Ford Dam (krnI Distance from Cowans Ford Dam (kin)

Figure 2-9. (Continued).

35 30 25-E 20-CO 0 15- 0,000-0,,M

• .0-*

.. "-, 0

.. . 0 .0o .. O 10 -

0 0.O .-0-- -- 0'

- . 5-0 0 50 100 150 200 250 300, 350 Julian Date Figure 2-10a. Heat content of the entire water column (i) and the hypolimnion (o) in Lake Norman in 2007.

12 ---- 100 90 10 80 C

-J 70 0

.8 601 C

6 50 40 4

30 20 2

10 0 0 1 31 61 91 121 151 181 211 241 271 301 331 361 Julian Date Figure 2-10b. Dissolved oxygen content (-) and percent saturation (---) of the entire water column (i) and the hypolimnion (o) of Lake Norman in 2007.

2-42

244 LAKE NORMAN STRIPED BASS HABITAT LAKE NORMAN STRIPED BASS HABITAT 23 10 80 110 130 150 15.9 620 690 720 800 23 10 8.0 11.0 130 150 159 620 690 720 80.

2323 2 _225 ......  : 22 22o 22*

26 deg C E 26degC 2152 mg/L/ 12 2mg/L 2o0I! .. Jun 18, 2007 20 Jul 2, 2007 2020 19195...,

10 1. 2 25 35 ... 40 4"5 50 o 5 10 15 20 25 30 3 4 45 50 5 Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (kin).

24024 LAKE NORMAN STRIPED BASS HABITAT LAKE NORMAN STRIPED BASS HABITAT 23 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 23 1.0 8.0 11.0 13.0 15.0 15.9 62.0 69.0 72.0 80.0 23 23 S22-, 225 22 22O S.26 degC.92deC 21* - 2 nmg/L M210  : 210 205* *;* Jul 9, 2007 20 07 200-

• 200

1. .....

Ao 1 15 A A 0... 3 4.0.. --- 0 "0

'101 "- "51V 2'0 25 30 35A... 40 4'-5 50 5E Distance from Cowans Ford Dam (kin) Distance from Cowans Ford Dam (km)

SFigure 2-11. 'Striped bass habitat (shaded areas; temperatures < 26 'C and dissolved oxygen > 2 mg/L) in Lake Norman in June, July, August, September, and October 2007.

0 8

ED Distance from Cowans Ford Dam (km)

Distance from Cowans Ford Dam (kin) 24-LAKE NORMAN STRIPED BASS HABITAT 235- 10 8.0 110 13.0 15.0 15.9 62.0 69.( 0 72.0 800 4 4 1 4 4 4 4 I I m

230-220, I

8 220-ED Distance from Cowans Ford Dam (km) Distance from Cowans Ford Dam (kW)

Figure 2-11. (Continued).

4.1

232.0 Full Pond @231.65 mmsl 231.5 231.0 (D 230.5 230.0 229.5 229.0 . .

N Cq N Nq CY)Cf) C) Cr) LO LO U 0 "f CO CO I- I- I-. N-0 0 0 0 0 0 0 000 0 0 00 0 C0 RO00 00 0-00 00 0 00 0000 0 666:

Figure 2-12. Lake Norman lake levels, expressed in meters above mean sea level (mmsl) for 2002, 2003, 2004, 2005, 2006, and 2007.

Lake level data correspond to the water quality sampling dates over this time period.

CHAPTER 3 PHYTOPLANKTON INTRODUCTION Phytoplankton standing crop parameters were monitored in 2007 in accordance with the NPDES permit for McGuire Nuclear Station (MNS). The objectives of the phytoplankton study of the Lake Norman Maintenance Monitoring Program are to:

1. Describe quarterly patterns of phytoplankton standing crop and species composition throughout Lake Norman; and

2. Compare phytoplankton data collected during this current study with data collected in prior study years.

In previous studies on Lake Norman considerable spatial and temporal variability in phytoplankton standing crops and taxonomic composition have been reported (Duke Power Company 1976, 1985; Menhinick and Jensen 1974; Rodriguez 1982). Rodriguez (1982) classified the lake as oligo-mesotrophic (low to intermediate productivity) based on phytoplankton abundance, distribution, and taxonomic composition. Past maintenance monitoring program studies have confirmed this classification (Duke Energy 2007).

METHODS AND MATERIALS Quarterly sampling was conducted at Locations 2.0, 5.0 (mixing zone), 8.0, 9.5, 11.0, 13.0, 15.9, and 69.0 in Lake Norman (Figure 2-1). Duplicate grabs from 0.3, 4.0, and 8.0 m (i.e.,

the estimated euphotic zone) were taken and then composited at all locations, except Location 69.0, where grabs were taken at 0.3, 3.0, and 6.0 m due to the depth. Grab samples were composited for each location. Sampling was conducted in February, May, August, and November 2007. Secchi depths were recorded from all sampling locations. As in previous years and based on the original design study (Duke Power Company 1988), phytoplankton density, biovolume, and taxonomic composition were determined for samples collected at Locations 2.0, 5.0, 9.5, 11.0, and 15.9; chlorophyll a concentrations and seston dry and ash-free dry weights were determined for samples from all locations. Chlorophyll a and total 3-1

phytoplankton densities and biovolumes were used in determining phytoplankton standing crop. Field sampling and laboratory methods used for chlorophyll a, seston dry weights, and population identification and enumeration were identical to those used by Rodriguez (1982).

Data collected in 2006 were compared .with corresponding data from quarterly monitoring beginning in August 1.987.

RESULTS AND DISCUSSION Standing Crop Chlorophyll a Chlorophyll a concentrations (mean of two replicate composites) ranged from a low of 1.96 jig/L at Location 8.0 in November, to a high of 13.66 gig/L at Location 69.0 in August (Table 3-1, Figure 3-1). All values were below the North Carolina water quality standard of 40 jig/L (NCDENR 1991). Lake-wide mean chlorophyll concentrations were within ranges of those reported in previous years, but were all below the long-term lake-wide means (Figure 3-2).

Seasonally, chlorophyll concentrations increased from February through May to the annual maximum in August then declined to the annual lake-wide minimum in November. Based on quarterly mean chlorophyll concentrations, the trophic level of Lake Norman was in the oligotrophic (low) range during February and November and in the mesotrophic (intermediate) range in May and August 2007. Over 59% of the mean chlorophyll a values were less than 4 ptg/L (oligotrophic), while all but one of the remaining chlorophyll a values were between 4 and 12 pgg/L (mesotrophic). The chlorophyll concentration from Location 69.0 in August was the only one greater than 12 jtg/L (eutrophic, or high range). Historically, quarterly mean concentrations of below 4 pgg/L have been recorded on fourteen previous occasions, while lake-wide mean concentrations of greater than 12 jtg/L were only recorded during May of 1997 and 2000 (Duke Power 1998, 2001; Duke Energy 2007).

During 2007 chlorophyll a concentrations showed typical spatial -variability. Maximum concentrations among sampling locations were observed at Location 69.0 (furthest up-lake) during all sampling periods, while minimum concentrations occurred at Location 9.5 in February, Location 2.0 in May, Location 5.0 in August, and Location 8.0 in November (Table 3-1). The trend of increasing chlorophyll concentrations from down-lake to up-lake, which 3-2

had been observed during many previous years, was apparent to some extent during all sampling periods (Table 3-1, Figure 3-1).

Flow in the riverine zone of a reservoir is subject to wide fluctuations depending, ultimately, on meteorological conditions (Thornton, et al. 1990), although influences may be moderated due to upstream dams. During periods of high flow, algal production and standing crop would be depressed due in great part to washout. Conversely, production and standing crop would increase during periods of low flow resulting in higher retention time. However, over long periods of low flow, production and standing crop would gradually decline once more.

These conditions result in the comparatively high variability in chlorophyll concentrations observed between Locations 15.9 and 69.0 throughout many previous years, as opposed to Locations 2.0 and 5.0 which have usually shown similar concentrations during sampling periods.

Mean quarterly chlorophyll concentrations during the period of record (August 1987 -

November 2007) have varied considerably, resulting in moderate to wide historical ranges.

During February 2007, chlorophyll values at all but Location 69.0 were lower than in previous February periods, while the value at Location 69.0 was higher than average (Figure 3-3). Long-term February peaks at Locations 2.0 through 9.5 occurred in 1996, while the long-term February peak at Location 11.0 was observed in 1991. Long-term maxima at Locations 13.0 and 15.9 occurred in 2003. The highest February value at location 69.0 occurred in 2001. All locations had higher chlorophyll concentrations in February 2007 than in February 2006 (Duke Energy 2007).

During May, mean chlorophyll concentrations at Locations 2.0 and 5.0 were in the mid historical range, while concentrations at Locations 8.0 through 15.9 were in the low range.

The concentration at Location 69.0 was once again in the high range (Figure 3-3). Long-term May peaks at Locations 2.0 and 9.5 occurred in 1992; at Location 5.0 in 1991; at Locations 8.0, 11.0, and 13.0 in 1997; at Location 15.9 in 2000; and at Location 69.0 in 2001. May 2007 mean chlorophyll concentrations at all but Location 13.0 were higher than those of 2006 (Duke Energy 2007).

Although the lake-wide mean chlorophyll concentration in August 2007 was the highest of the four sampling periods, mean chlorophyll concentrations at all but Location 69.0 were in the low historical range, with Location 69.0 having a concentration in the high range (Figures 3-2 and 3-4). Long-term August peaks at Locations 2.0 and 5.0 were observed in 1998, while 3-3

August peaks at Locations 8.0 and 9.5 occurred in 1993. Long-term August peaks at Locations 11.0 and 13.0 were observed in 1991 and 1993, respectively. The highest August chlorophyll concentration from Location 15.9 was observed in 1998, while Location 69.0 experienced its long-term August peak in 2001. Mean chlorophyll concentrations for August 2007 were higher than those of August 2006 at all but Location 5.0 (Duke Energy 2007).

The lake-wide mean chlorophyll concentration in November 2007 was the lowest~among all four sampling periods (Figure 3-2). Chlorophyll concentrations at all but Location 69.0 were in the low historical range and concentrations from Locations 5.0, 8.0, 9.5, and 15.9 were the lowest November concentrations recorded from these locations (Figure 3-4). As was the case during the previous sampling periods, the chlorophyll concentration at Location 69.0 was in the high historical range. Long-term November peaks at Locations 5.0 and 8.0 occurred in 2006, while November maxima at Locations 11.0 and 15.9 occurred in 1996. The highest November value at Location 13.0 was recorded for 1992, while the November maxima at Locations 2.0 and 9.5 were observed in 1997. The highest November chlorophyll concentration at Location 69.0 occurred in 1991. November 2007 chlorophyll concentrations at all but Location 69.0 were lower than during November 2006 (Duke Energy 2007).

Total Abundance Density and biovolume are measurements of phytoplankton standing crops. In most cases, standing crop parameters mirror the temporal trends of chlorophyll concentrations. During 2007, mean seasonal standing crops increased from the annual minimum in February through to the annual peak in August then declined through November. The lowest density (761 units/mL) and biovolume (551 mmn3 /M 3) occurred at Location 9.5 in February (Table 3-2, Figure 3-1). 'The maximum density (6,232 units/mL) and biovolume (4,860 mm3/m 3 ) were observed at Location 15.9 in August. Most standing crop values during February, May, and August 2007 were higher than those of 2006, while values from November 2007 were lower than in November of the previous year (Duke Energy 2007). Phytoplankton densities during 2007 never exceeded the NC guidelines for algae blooms of 10,000 units/mL density and 5,000 mrn3/m3 for biovolume (NCDENR 1991). Densities or biovolumes in excess of NC guidelines were recorded in 1987, 1989, 1997, 1998, 2000, 2003, and 2006 (Duke Power Company 1988, 1990; Duke Power 1998, 1999, 2001, 2004a; Duke Energy 2007). During all sampling periods phytoplankton densities and biovolumes demonstrated a spatial trend similar to that of chlorophyll; that is, lower values at down-lake locations verses up-lake locations (Table 3-2, Figure 3-1).

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Seston Seston dry weights represent a combination of algal matter and other organic and inorganic material. Dry weights during 2007 were most often lower than those of 2006. As was observed with chlorophylls and algal standing crops, a general pattern of increasing values from down-lake to up-lake was observed during 2007 (Table 3-3 and Figure 3-1). From 1995 through 1997 seston dry weights had been increasing (Duke Power 1998). Values from 1998 through 2001 represented a reversal of this trend, and were in the low range at most locations during 1999 through 2001 (Duke Power 2002). Low dry weights during these years were likely a result of prolonged drought conditions resulting in low sedimentation from runoff (Figure 2-2a). From 2002 through 2006, dry weights gradually increased throughout the lake, followed by a dramatic decline in 2007. The lake-wide average dry weight in 2007 was the lowest since dry weights were recorded in 1988. These exceptionally low values were likely due to severe drought conditions throughout the watershed during 2007.

Seston ash-free dry weights represent organic material and may reflect trends of chlorophyll

a. This relationship held true for the most part during 2007, especially with respect to increasing values from down-lake to up-lake areas, as was the case with chlorophyll concentrations and standing crop values (Tables 3-1 through 3-3).

Secchi Depths Secchi depth is a measure of light penetration. Secchi depths were often the inverse of suspended sediment (seston dry weight), with the shallowest depths at Locations 13.0 through 69.0 and deepest from Locations 9.5 through 2.0 down-lake. Depths ranged from 1.10 m at Location 13.0 in February and 69.0 in August, to 3.7 m at Location 8.0 in May (Table 3-1). The lake-wide mean Secchi depth during 2007 was slightly higher than in 2006 and was within historical ranges for the years since measurements were first reported in 1992.

The deepest lake-wide mean Secchi depth was recorded for 1999 (2.26 m) (Duke Power 2000).

Community Composition One indication of "balanced indigenous populations" in a reservoir is the diversity, or number of taxa observed over time. Lake Norman typically supports a rich community of 3-5

phytoplankton species. This was certainly true in 2007. Ten classes comprising 98 genera and 257 species, varieties, and forms of phytoplankton were identified in samples collected during 2007, as compared to 91 genera and 243 lower taxa identified in 2006 (Table 3-4).

The 2007 total represented the highest number of taxa recorded in any year since monitoring began in 1987 (Duke Energy 2007). Fifteen taxa previously unrecorded during the Maintenance Monitoring program were identified during 2007.

Species Composition and Seasonal Succession The phytoplankton community in Lake Norman varies both seasonally and spatially.

Additionally,. considerable variation may occur between years for the same months sampled.

During February 2007, cryptophytes (Cryptophyceae) dominated densities at all locations (Table 3-5, Figures 3-5 through 3-9). During most previous years, cryptophytes and occasionally diatoms dominated February phytoplankton samples in Lake Norman. The most abundant cryptophyte during February 2007 was the small flagellate Rhodomonas minuta. R.

minuta has been one of the most common and abundant forms observed in Lake Norman samples since monitoring began in 1987. Cryptophytes are characterized as light limited, and are often found deeper in the water column or near surface under low light conditions, which are common during winter (Lee 1989).

In May, diatoms (Bacillariophyceae) were dominant at all locations (Table 3-5, Figures 3-5 through 3-9). The most abundant diatom at all locations was the pennate, Fragillaria crotonensis. Diatoms have typically been the predominant forms in May samples of previous years;, however, cryptophytes dominated May samples in 1988, and were co-dominants with diatoms in May 1990, 1992, 1993, and 1994 (Duke Power Company 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997; Duke Power 1998, 1999, 2000, 2001, 2002, 2003, 2004a, 2005; Duke Energy 2006, 2007).

During August 2007, green algae (Chlorophyceae) dominated densities at all locations (Figures 3-5 through 3-9). The most abundant green alga was the small desmid, Cosmarium asphearosporum var. strigosum (Table 3-7). During August periods of the Lake Norman study prior to 1999, green algae, with blue-green. algae (Myxophyceae) as occasional dominants or co-dominants, were the primary constituents of summer phytoplankton assemblages, and the predominant green alga was also C. asphearosporum var. strigosum (Duke Power Company 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997; Duke Power 3-6

1998, 1999). During August periods of 1999 through 2001, Lake Norman phytoplankton assemblages were dominated by diatoms, primarily the small pennate, Anomoeoneis vitrea (Duke Power 2000, 2001, 2002). A. vitrea has been described as typically periphytic and widely distributed in freshwater habitats and was identified as a major contributor to periphyton communities on natural substrates during studies conducted from 1974 through 1977 (Derwort 1982). The possible causes of this significant shift in summer taxonomic composition were discussed in earlier reports and included deeper light penetration (the three deepest lake-wide secchi depths were recorded from 1999 through 2001); extended periods of low water due to drawdown, and shifts in nutrient inputs and concentrations (Duke Power 2000, 2001, 2002). Whatever the cause, the phenomenon was lake-wide and not localized near MNS or Marshall Steam Station (MSS), therefore, it was most likely due to a combination of environmental factors, and not station operations. Since 2002, taxonomic composition during the summer has shifted back to green algae predominance (Duke Power 2003, 2004a, 2005, Duke Energy 2006, 2007).

During November 2007, densities at all locations were again dominated by diatoms. The most abundant species at Locations 2.0, 11.0, and 15.9 was the pennate diatom, Tabellaria fenestrata (Table 3-5, Figures 3-5 through 3-9). At Locations 5.0 and 9.5, the most abundant diatom was the centrate, Melosira ambigua. These diatoms have been among the most common and abundant forms found in Lake Norman throughout the Lake Norman Maintenance Monitoring program.

Blue-green algae, which are often implicated in nuisance blooms, were never abundant in 2007 samples (Duke Energy 2007). Their overall contribution to phytoplankton densities was slightly higher than in 2006, but densities seldom exceeded 3% of totals. Prior to 1991, blue-green algae were often dominant at up-lake locations during the summer (Duke Power Company 1988, 1989, 1990, 1991, 1992).

FUTURE STUDIES No changes are planned for the phytoplankton portion of the Lake Norman Maintenance-Monitoring Program.

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SUMMARY

Lake Norman continues to be classified as oligo-mesotrophic based on long-term, annual mean-chlorophyll concentrations. Chlorophyll concentrations during 2007 were most often within historical ranges, however, several record low chlorophyll concentrations were recorded in November. Lake-wide mean chlorophyll increased from February through August then declined to the annual minimum in November. Some spatial variability was observed in 2007, however, maximum chlorophyll concentrations were typically observed up-lake at Location 69.0, while minimum chlorophyll concentrations were recorded from down-lake at Locations. 2.0 through 9.5. The highest chlorophyll value recorded in 2007, 13.66 ptg/L, was well below the NC State Water Quality standard of 40 ptg/L.

Phytoplankton densities and biovolumes during 2007 were generally higher than in 2006.

Phytoplankton densities during 2007 never exceeded the NC guidelines for algae blooms.

Standing crop values in excess of bloom guidelines have been recorded during seven previous years of the program. As in past years, higher standing crops were usually observed at up-lake locations, while comparatively lower values were noted down-lake.

Seston dry and ash-free weights were most often lower in 2007 than in 2006 and down-lake to up-lake differences were apparent during all quarters. Maximum dry and ash-free weights were generally observed at Location 69.0. Minimum values were noted at Locations 2.0 through 9.5.

Secchi depths reflected suspended solids with shallow depths related to high dry weights.

The lake-wide mean Secchi depth in 2007 was slightly higher than in 2006 and was within historical ranges recorded since 1992.

Diversity or the number of taxa of phytoplankton in 2007 was the highest yet recorded. The taxonomic composition of phytoplankton communities during 2007 was similar to those of many previous years. Cryptophytes were dominant in February, while diatoms were dominant during May and November. Green algae dominated phytoplankton assemblages during August. Blue-green algae were slightly more abundant during 2007 than during 2006, but their contribution to total densities seldom exceeded 3%.

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The most abundant alga, on an annual basis, was the cryptophyte R. minuta. The most abundant diatom in May was F. crotonensis, while the most abundant diatoms during November were T. fenestrata and M ambigua. The small desmid, C. asphearosporumvar.

strigosum was dominant in August 2007. All of these taxa have been common and abundant throughout the Lake Norman Maintenance Monitoring program.

Lake Norman continues to support highly variable and diverse phytoplankton communities.

No obvious short-term or long-term impacts of station operations were observed.

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Table 3-1. Mean chlorophyll a concentrations (jtg/L) in composite samples and Secchi depths (m) observed in Lake Norman in 2007.

CHLOROPHYLL A FEB MAY AUG NOV Location 2.0 2.91 2.94 4.47 2.07 5.0 2.94 3.04 3.60 2.18 8.0 3.58 3.11 4.77 1.96 9.5 2.80 3.26 5.02 2.35 11.0 3.78 3.98 5.35 3.32 13.0 3.94 4.41 4.10 3.43 15.9 4.61 5.46 7.70 3.86 69.0 6.19 10.46 13.66 5.59 SECCHI DEPTHS FEB MAY AUG OCT*

Location 2.0 2.10 3.20 2.90 2.36 5.0 2.25 2.90 2.40 1.82 8.0 2.60 3.70 2.71 2.26 9.5 2.40 3.10 2.70 2.44 11.0 1.30 2.10 2.35 2.48 13.0 1.10 1.90 1.25 1.50 15.9 1.32 1.20 2.80 1.63 69.0 1.20 1.20 1.10 1.26 Annual mean from all Locations: 2007 2.11 Annual mean from all Locations: 2006 1.94

• Secchi depths were not available for November.

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Table 3-2. Mean phytoplankton densities (units/mL) and biovolumes (mm 3 /m 3 ) by location and sample month from samples collected in Lake Norman, NC, during 2007.

Density Locations Month 2.0 5.0 9.5 11.0 15.9 Mean FEB 911 961 761 1,100 1,884 1,123 MAY 1,454 1,566 1,737 2,730 3,181 2,134 AUG 2,800 1,943 2,957 3,385 6,232 3,463 NOV 783 869 970 1,402 1,723 1,149 Biovolume Locations Month 2.0 5.0 9.5 11.0 15.9 Mean FEB 590 551 468 1,395 2,014 1,004 MAY 1,257 1,238 1,366 2,368 2,370 1,720 AUG 1,285 938 1,238 2,540 4,860 2,172 NOV 867 1,373 1,657 1,883 2,799 1,716 Table 3-3. Total mean seston dry and ash free dry weights (mgiL) from samples collected in Lake Norman, NC during 2007.

Dry weights Locations Month 2.0 5.0 8.0 9.5 11.0 13.0 15.9 69.0 Mean FEB 0.97 0.99 1.02 0.94 1.46 1.35 1.61 2.37 1.34 MAY 0.58 0.76 0.82 1.01 1.28 0.96 1.01 2.75 1.15 AUG 1.29 1.11 1.23 1.29 1.19 1.87 2.01 2.46 1.55 NOV 1.40 1.48 1.17 1.57 1.81 1.85 1.58 2.78 1.70 Ash free dry weights Month FEB 0.41 0.46 0.48 0.36 0.57 0.61 0.81 0.83 0.56 MAY 0.41 0.46 0.47 0.50 0.60 0.55 0.59 0.86 0.55 AUG 0.86 0.76 0.87 0.86 0.89 0.89 1.36 1.19 0.96 NOV -0.57 0.52 0.33 0.85. 0.70 0.65 0.67 1.01 0.66 3-11

Table 3-4. Phytoplankton taxa identified in quarterly samples collected in Lake Norman each year from 1992 to 2007.

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 CLASS: CHLOROPHYCEAE AcanthosphaerazachariasiLemm. X Actidesmium hookeri Reinsch X Actinastrum hantzchii Lagerheim X X X X -

Ankistrodesmus braunii(Naegeli) Brunn X X X X X X X X X X X X X A. convolutus Cofda X A. falcatus (Corda) Ralfs X X X X X X X X X X X X X X X X A. fusiformis Corda sensu Korsch. X X X A. nannoseleneSkuja X A. spiralis (Turner) Lemm. X X A. spp. Corda X Arthrodesmus convergens Ehrenberg X X X X X X A. incus (Breb.) Hassall X X X X X X X X X A. octocornis Ehrenberg X X X X X A. ralfsiiW. West X X X A. subulatus Kutzing X X X XX X X X X X X A. validus v. increassalatusScott & Gron. X A. spp. Ehrenberg XX Asterococcus limneticus G. M. Smith X X X X X X X X X A. superbus (Cienk.) Scherffel X X Botryococcus brauniiKutzing X CarteriafrtzschiiTakeda X X X X X X C. globosa Korsch X X X C. spp. Diesing X X X x Characiumambi:guum Hermann X C. limneticum Lemmerman X C. spp. Braun 1 Chlamydomonas spp. Ehrenberg X X X X X X X X X X X X X X X X Chlorella vulgaris Beyerink X X X Chlorogonium euchlorum Ehrenberg X X X -X X X X C. spirale Scherffel & Pascher X X X X X X Closteriopsis longissimaW. & West X X X X X X X X X X X X X X X X Closterium acutum Breb. X X C. cornu Ehrenberg X X C. gracile Brebisson X X C. incurvum Brebisson X X X X X X X X X X X X X X C. parvulum Nageli - X C. tumidum Johnson X C. spp. Nitzsch X Coccomonas orbicularisStein X X X X X X Coelastrum cambricum Archer X X X X X X X X X X X X X X X X C. microporum Nageli X X X X X X X X C. proboscideum Bohlin 1 C. reticulatum (Dang.) Sinn. X X X C. sphaericumNageli X X X X X X X X X X X C. spp. Nageli 1 Cosmarium angulosum Yv.concin. (Rab) W&W X X X X C. asphaerosporumv. strigosum Nord. X X X X X X *X X X X X X X X X X 3-12

Table 3-4. (Continued).

TAXON 92 93 94 95 96 .97 98 99 00 01 02 03 04 05 06 07 C. contractum Kirchner X X X X X X X X X X X X X X C. moniliforme (Turp.) Ralfs X X X X X C. notabileBrebisson X  :

". phaseolus f. minor Boldt. X X X X X X X C. pokornyanum (Grun.) W. & G.S. West X X X X C polygonum (Nag.) Archer .- X X X X X X X X X X X X X C. raciborskiiLagerheim __X X X X C regnellii Wille X X X X X X X X XX X X X C. regnesi Schmidle - X X - X C. subreniforme Nordstedt X X X C. subprotumidum Nordst. X C. tenueArcher _ X X X X X X X X X X X X X C.tinctum Ralfs X X X X X X X X X X X X X X X C. tinctum v. subretusum Messik. X C. tinctum v. tumidum Borge. X X X X X X X X X X C. trilobatum v. depressum Printz X C. tumidum Borge X C. spp. Corda X X X Crucigenia apiculata(Lemm.) Schmidl X X X X C crucifera (Wolle) Collins X X X X X X X X X X X X X C. fenestrata Schmidle X X X X X X C. irregularisWille X X X X X X X X. X X _

C. quadrataMorren X C. rectangularis(A. Braun) Gay X X.X C. tetrapedia (Kirch.) West & West X X X X X X X X X X X X X X X X Dictyospaerium ehrenbergianumNageli X X X X X X X D.pulchellumWood X X X X X X X X X X X X X X X X Dimorphococcusspp. Braunl ElakatothrixgelatinosaWille X X X X X X X X X X X X X X X X Errerellabornheimiensis Conrad X X X X X Euastrum ansatum v. dideltiforme Ducel. X E. banal (Turp.) Ehrenberg X E. denticulatum (Kirch.) Gay. X X -X X X X X X X X X X X E. elegans Kutzing X E. spp. Ehrenberg XX X X Eudorinaelegans Ehrenberg X X X X X Franceiadroescheri (Lemm.) G. M. Sm. X X X X X X X X X X X X X F. ovalis (France) Lemm. X X X - X X X X X X X F. tuberculataG. M. Smith X Gloeocystis botryoides (Kutz.) Nageli X X X X X G. gigas Kutzing X X X X X X XX X X X X G. major Gerneck ex. Lemmermann X I X G. planktonica(West & West) Lemm. X X X X X X X X X X X X X *X X X G. vesciculosa Naegeli X X X X X X X G. spp. Nageli X X X GolenkiniapaucispinaWest & West X X X X X X G. radiataChodat - X X X XX X X X X X X X X X X X Gonium pectoraleMueller X X X X X 3-13

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 G. sociale (Duj.) Warming _ X X X X X X X X X Kirchneriellacontorta (Schmidle) Bohlin X X X X XX X _

K. elongata G.M. Smith X X X K. lunaris (Kirch.) Mobius X X K. lunaris v. dianae Bohlin X X X X X X X X K. lunaris v. irregularisG.M. Smith X X K. obesa W. West X X X X K. subsolitariaG. S. West X X X X X X X X X X X X K. spp. Schmidle X X X X X X Lagerheimia ciliata (Lagerheim) Chodat X X L. citriformis (Snow) G. M. Smith X X X L. longiseta (Lemmerman) Printz X X X X X L. quadriseta (Lemm.) G. M. Smith X L. subsala Lemmerman X X X X X X X X X X X X X Mesostigma viride Lauterbome X X X X X X X X X X X X Micractiniumpusillum Fresen. X X X X X X X X X X X X X X X X Monoraphidium contortum Thuret X X X M pusillum Printz X X X Mougeitia elegantula Whittrock X X X X X X X X X X X X X M spp. Agardh X X X X Nephrocytium agardhianumNageli X X X X X X N. ecdysiscepanum W. West X N. limneticum (G.M. Smith) G.M. Smith X X X X X N. obesum West & West X Oocystis borgii Snow X X X_ X X X X X

0. ellyptica W. West X X X X X

0. lacustrisChodat X X X X

0. parva West & West X X X X X X X X X X X X X

0. pusilla Hansgirg X X X X X X X X X X X X X X X

0. pyriformis Prescott X X 0.solitariaWittrock X X 0.submarinaLagerheim X

0. spp. Nagelil Pandorinacharkowiensis Kprshikov X X P. morum Bory X X X X XX Pediastrum biradiatumMeyen X X X P. duplex Meyen X X X X X X X X X X X X X P. duplex v. clatheatum (A. Braun) Lag. X P. duplex v. gracillimum West and West X XX X X X X X X P. tetras v.tetroadon(Corda) Rabenhorst X X X X X X X X X X X X X X X X P. spp. Meyen 1 PlanktosphaeriagelatinosaG. M. Smith X X X X X Quadrigulaclosterioides (Bohlin) Printz X X XX X X X X X Q. lacustris (Chodat) G. M. Smith X X X X X X Scenedesmus abundans (Kirchner) Chodat X X IX S.abundans v. asymetrica (Schr.) G. Sm. X X X X X X X X X X X S. abundans v. brevicauda G. M. Smith X X X X S. abundans v. longicaudaG.M. Smith X S. acuminatus (Lagerheim) Chodat X X X X X X X X XX X X X X X 3-14

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 S. armatusv. bicaudatus(Gug.-Pr..)Chod X X X X X X X X X X X X X X X X S. biuga (Turp.) Lagerheim X X X X X X X X X X X X X X X S. byjuga v. alterans (Reinsch) Hansg. X X S. brasiliensisBohlin X X X X X X X X X X X X X S. denticulatusLagerheim X X X X X X X X X X X X X X X S. denticulatusv. recurvatus Schumacher X X X X X S. dimorphus (Turp.) Kutzing X X X X X X X X X X, X X X S. incrassulatusG. M. Smith 1 S. opoliensis P. Richter X S. parisiensisChodat X X S. quadricauda(Turp.) Brebisson X X X X X X X X X X X X X X X X S. smithii Teiling X X X X X S. serratus(Corda) Bohlin X S. spp. Meyen X X X Schizochlamys compacta Prescott X X X X X X X S. gelatinosaA. Braun X X X X X X Schoederia setigera (Schroed.) Lemm. X Selenastrum bibraianumReinsch X X S. gracile Reinsch X X X X S. minutum (Nageli) Collins X X X X X X X X X X X X X X X X S. westii G. M. Smith XX X X X X X X X X X Sorastrum americanum (Bohlin) Schm. X X Sphaerocystis schoeteri Chodat X X X X X X X X X X Sphaerozosma granulatum Roy & BI. 1 Stauastrum americanum!(W&W) G. Sm. X X X X X X X X X X X X X S. apiculatum Brebisson X X X XX X X X X X X S. aspinosum v. annulatum WA& G.S.Wst. X S. brachiatumRalfs X X X X X X X X S. brevispinum Brebisson X S. chaetocerus (Schoed.) G. M. Smith X X X S. capitulum Brebisson X S. curvatum W. West X X X X X X X X XX X X X X XX S. curvatum v. elongatum G.M. Smith X S. cuspidatum Brebisson X XXXX X X X X X X S. dejectum Brebisson X X X X X S. dickeii v. maximum West & West 1 X S. dickeii v. rhomboidium W.& G.S. West X S.*,ladiosum Turner X S. leptocladum Nordstedt X S. leptocladum v. sinuatum Wolle 1 S. manfeldtii v.fluminense Schumacher X X X X X X X X X X X S. megacanthum Lundell X X I X X Xx S. ophiura v. cambricum (Lund) W. & W. X X S. orbiculareRalfs X X S. paradoxum Meyen X X X X X X X X X S. paradoxumv. cingulum W. & W. X X X X S. paradoxumv. parvum W. West X I X X X X X X S. pentacerum (Wolle) G. M. Smith X X X S.subcruciatum Cook & Wille - X X X X X X X X X X X 3-15

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 S. tetracerum Ralfs X X X X X X X X X X X X X X X X S. turgescens de Not. X X S. vestitum Ralfs X x x S. spp. Meyen X X Stichococcus scopulinus Hazen X S. spp. Nageli X Stigeoclonium spp. Kutzing X X Tetraedronarthrodesmiforme(W.) Wol. X X X X T. bifurcatum v. minor Prescott X T. caudatum (Corda) Hansgirg X X X X X X XX X X X X X X T limneticum Borge X X T. lobulatum (Naegeli) Hansgirg X T. lobulatum v. crassum Prescott X X X T minmum (Braun) Hansgirg XXX X X XX X X X X XX T. muticum (Braun) Hansgirg X X X X X X T. obesum (W & W) Wille ex Brunnthaler X T. pentaedricumWest & West X X X X T. planktonicum G. M. Smith X X X X X X X X T. regulare Kutzing X X X X T. regulare v. bifurcatum Wille X T regularev. incus Teiling X IX T trigonum (Nageli) Hansgirg X X X X - X X X X X X X X T trigonum v. gracile(Reinsch) DeToni X X X X X T. spp. Kutzing X Tetrallantos lagerheimiiTeiling X X X X Tetrasporalamellose Prescott X T. spp. Link X X Tetrastrum heteracanthum (Nor.) Chod. X X X T. staurogeniforme (Schroeder) Lemm. X Treubariasetigerum (Archer) G. M. Sm. X X X X X X X X X X X X X X X X Westella botryoides (W. & W.) Wilde.. X X I X X X X W linearisG. M. Smith X X X X X X X Xanthidium antilopariumv.floridense Sc & Gron. X X cristatatum v. uncinatum Breb. X X X X X X spp. Ehrenberg X X CLASS: BACILLARIOPHYCEAE Achnanthes lanceolataBrebisson X X A. microcephala Kutzing ",X X X X X X X X X X X X X A. spp. Bory X X X X X Amphiproraornate Bailey X Amphora ovalis Kutzing X Anomoeoneis vitrea (Grunow) Ross X X X X X X X X X X X X X A. spp. Pfitzer X AsterionellaformosaHassall X X X X X X X X X X X X X X X Attheya zachariasiJ. Brun X X X X X X X X X X X X X X X Cocconeis placentulaEhrenberg X X X X C. spp. Ehrenberg X Cyclotella comta (Ehrenberg) Kutzing _ _ X X X X X X X X X X X X X X 3-16

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 C. glomerata Bachmann X X X X X X X X X X C. meneghinianaKutzing X X X X X X X X -X X X X X C. pseudostelligeraHustedt 1 C. stelligera Cleve & Grunow X X X X X X X X X X x X X X X C. spp. Kutzingl Cymbella affinis Kutzing X X C. gracilis (Rabenhorst) Cleve X X C. minuta (Bliesch & Rabn.) Reim. X X X X X X X X X X X X C. naviculiformisAuersw. ex Heib. X C. tumida (Brebison) van Huerck X_

C. turgida(Gregory) Cleve 1 C. spp. Agardh 1 Denticula elegans Kutzing X X X D. thermalis Kutzing X X X Diploneis ellyptica (Kutzing) Cleve X D. marginestriataHustedt X D. ovalis (Hilse) Cleve X D. puella (Schum.) Cleve X D. spp. Ehrenberg 1 Eunotia flexuosa v. eurycephalaGrim. X E. zasuminensis (Cab.) Koerner X X X X X X X X X X X X X X X Fragilariacrotonensis Kitton X X X X X X X X X X X X X X X X F. construens (Ehrenberg) Grunow X Frustuliarhomboides (Ehr.) de Toni1 F. rhomboides v. saxonica (Rabh.) de T. X Gomphonema angustatum (Kutz.) Rabh. X G. gracile (Her.) Van Huerk X G. parvulum Kutz. X X X X G. spp. Agardh X Melosira ambigua(Grunow) 0. Muller X X X X. X X X X X X X X X X X X M distans (Ehrenberg) Kutzing X X X X X X X X X X X X X X X X M granulata(Ehrenberg) Ralfs X X X M granulatav. angustissimaO. Muller X X X X X X X X X X X X X X X X M italica(Ehrenberg) Kutzing 1 M italicav. tennuissima (Grun.) O.Mull x M varians Agardh X X X X XX M spp. Agardh X X X X X XXX X X XX Meridion circulareAgardh X Navicula cryptocephalaKutzing X X X N. exigua (Gregory) 0. Muller X X X N. exigua v. capitataPatrick X X N. radiosa Kutzing X X N. radiosa v. tenella (Breb.) Grun. X X X X N. subtilissima Cleve X X X X X X N. spp. Bory X XX X X Nitzschia acicularisW. Smith X X X X X X X X X X X X X X N. agnita Hustedt X X X X X X X X X X X X X X X X N. communis Rabenhorst II_=X 3-17

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 N. holsatica Hustedt x x x xx x x x x x x x N. kutzingiana Hilse X X X N. linearisW. Smith X X X N.palea (Kutzing) W. Smith x x x x x x x x x x N. sublinearisHustedt x x x x x N. spp. Hassall x x x x x x Pinnulariabiceps Gregory x P. mesolepta (Her.) W. Smith X P. spp. Ehrenberg x x x x Rhizosolenia spp. Ehrenberg x x x x x x x X X X X x X X x x Skeletonema potemos (Weber) Hilse X x x x x x x x x x x Stephanodiscus astraea(Her.) Grunow x x S. spp. Ehrenberg X X X x x x x x x X X Surirella angustata Kutz. X S. linearisv. constricta(Her.) Gr. X X S.tenuis Mayer x Synedra actinastroidesLemmerman X S. acusKutzing x X x x x x X Xx X x S. amphicephalaKutzing x X S. delicatissimaLewis x x x S. fiformis v. exilis Cleve-Euler x x x x x X x x X S. planktonica Ehrenberg x x x x x xX X X X X x x x x x S. rumpens Kutzing _ x x x x x x x x x x x x S. rumpens v. fragilarioidesGrunow 1 S. rumpens v. scotica Grunow 1 S. ulna(Nitzsch) Ehrenberg X x x x X X X x x x X X S. spp. Ehrenberg x x x Tabellariafenestrata(Lyngb) Kutzing x X X X x x x X. x X X x x x X X T.flocculosa (Roth.) Kutzing x x x x CLASS: CHRYSOPHYCEAE Aulomonas purdyii Lackey x X x x x x X X x x x X X Bicoeca petiolatum (Stien) Pringsheim x x Calycomonaspascheri (Van Goor) Lund X x x CentritractusbelanophorusLemm. x Chromulinanebulosa Pascher X C. spp. Chien. x x x X X Chrysococcus rufescens Klebs x ChrysosphaerellasolitariaLauterb. x x x x x x x x x x x x x x x x Codomonas annulataLackey x x x x x x x x x X X Dinobryon acuminatum Ruttner x D. bavaricum Inhof X X X x x x X X X X X x x x x x D. cylindricum Imhof X X X x x x x x x x D. divergens Imhof X X X X X x X xX x x X D. pediforme (Lemm.) Syein. x D. sertulariaEhrenberg X X x x x x x D. spp. Ehrenberg x x x x x x x x x x x x x Domatomococcus cylindricum Lackey X x x Erkinia subaeguicilliataSkuja X X X X x x x X X x x x x X 3-18

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Kephyrion campanuliforme Conrad X K. littorale Lund X A X X X X X K. petasatum Conrad X K. rubi-claustriConrad A X X X X X K. skujae Ettl 1 K. valkanovii Conrad X X K. spp. Pascher X X X XX X X X X X X X X X X X Mallomonas acaroidesPerty X X X X M akrokomos (Naumann) Krieger X X X X X X X M allantoidesPerty X M allorgii (Deft.) Conrad X M alpinaPascher X X M caudataConrad X X X X X X X X X X X M globosa Schiller X X X X X X X X X M producta Iwanoff X X X X X M pseudocoronataPrescott X X X X X X X X X X X X X X X X M tonsurataTeiling X X X X X X X X X X X X X X X-X M spp. Perty X X X X X Ochromonas granularisDoflein X X X X X X X X X X

0. mutabilis Klebs X X X 0.spp. Wyss X X X X X X XX X X X X X X Pseudokephyrionconcinum (Schill.) Sch. X P. schilleri Conrad X X X X X X P. tintinabulum Conrad X P. spp. Pascher X X X RhizochrisispolymorphaNaumann X X X X X X X X X R. spp. Pascher 1 Salpingoecafreguentissima(Zach.) Lem. X X X X X Stelexomonas dichotomaLackey X X X X X X X X X X X X X Stokesiella epipyxis Pascher X X X X Synura sphagnicolaKorschikov X S. spinosaKorschikov X X XXX XX X X X X XX S. uvella Ehrenberg X X X X S. spp. Ehrenberg X X X Uroglenopsis americana(Caulk.) Lemm. X X X X CLASS: HAPTOPHYCEAE Chrysochromulinaparva Lackey X X X X X X X X X X X X X X X X CLASS: XANTHOPHYCEAE CharaciopsisacutaPascher X X X X C. cylindrica (Lambert) Lemm. X C. dubia Pascher X X X X X X X X X X X X Dichotomococcus curvata Korschikov 1 Ophiocytium capitatum v. longisp. (M) L - X X - X X X XX Stipitococcus vas Pascher X CLASS: CRYPTOPHYCEAE Cryptomonas erosa Ehrenberg I X X X X X X X X X X X X X X X X 3-19

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 C. erosa v. reflexa Marsson X X X XX XX X XX X C.graciliaSkuja X C marsonii Skuja X X X - X C. obovata Skuja X X X C. ovata Ehrenberg X X X X -X X X X X X X X X X X X C.phaseolus Skuja X X X C. reflexa Skuja X X X X X X X X XX X X X X X X C. spp. Ehrenberg X X X X Rhodomonas minuta Skuja X X X X X X X X X X X X X X X X CLASS: MYXOPHYCEAE Agmenellum quadriduplicatumBrebisson X X X X X X X X X X X X X X X A. thermale Drouet and Daily X Anabaena catenula (Kutzing) Born. X X I A. inaegualis(Kutzing) Born. X X A. scheremetievi Elenkin X X X X X X A. wisconsinense Prescott X X X X X X X X X X X X X A. spp. Bory XX X X X X X X X X Anacystis incerta (Lemm.) Druet & Daily X X X X - X X A. spp. Meneghini 1 Chroococcuisdispersus (Keissl.) Lemm. X X X C. giganteous W. West X C. limneticus Lemmermann X X X X X X X X X X C. minor Kutzing X X X X X C. turgidus (Kutz.) Lemmermann X C. spp. Nageli X X X X X X X X X XX X X X X X Coelosphaeriumkuetzingiana Nageli C. nea*leanum Unger X X Dactylococcopsis irregularisHansgirg X X X X X D. musicola Hustedt X D. raphidiopsisHansgirg X D. rupestrisHansgirg X D. smithii Chodat and Chodat X X X X X X X D. spp. Hansgirg X Gomphospaeria lacustris Chodat X X X - X Lyngbya contorta Lemmermann X L. limnetica Lemmermann X X X L. ochracea (Kutzing) Thuret X X X X L. subtilis W. West X X L. tenue Agardh X L. spp. Agardh X X X X X X X X X X. X X X X X X Merismopedia tenuissima Lemmermann X Microcystis aeruginosaKutzing X X X X X X X X X X X X X Oscillatoriaamoena (Kutz.) Gomont X O. amphibia Agardh X X X X X O. geminata Meneghini . X X X X X X X X X X X X X O. limnetica Lemmermann _ X X X X X X. X X X X X X X 0.splendida Greville X X X _ X

0. subtilissima Kutz. X X X XX X XIX X 3-20

Table 3-4, (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 O. spp. Vaucher XX X x Phormidium angustissimumWest & West X P. spp. Kutzing X X Raphidiopsis curvata Fritsch & Rich X X X X X X X X X X X R. mediterraneaSkuja X R. spp. Fritsch & Rich X Rhabdodermasigmoidea Schm. & Laut.1 SpirulinasubsalaOersted X Synecococcus lineare (Sch. & Lt.) Kom. X X X X X X X X X X X CLASS: EUGLENOPHYCEAE Euglena acus Ehrenberg X X X E. deses Ehrenberg X X E. minuta Prescott X X X X X E. polymorpha Dangeard X X X X X E. proxima Dangeard X X X X E. spp. Ehrenberg X X X X X X - X X X X Lepocinclus acicularisFrance X L. acuta Prescott X L. glabra Drezepolski X L. ovum. (Ehr.) Lemm. X X X L. spp. Perty X Phacus cuvicauda Swirenko X P. longicauda(Her.) Dujardin X X P. orbicularisHubner X X P. tortus (Lemm.) Skvortzow X P. triguter Playfair X P. spp. Dujardn I Trachelomonasabrupta (Swir.) Deflandre X T. abruptav. minor Deflan. .X--

T acanthostoma(Stk.) Defi. X X X X X T. ensifera Daday X X T. hispida (Perty) Stein X XX X X X X _ X T. lemmermanii v. acuminataDeflandre X X T. pulcherrimaPlayfair 1 T. pulcherrimav. minor Playfair X T. varians (Lemm.) Deflandre X T. volvocina Ehrenberg X X X X X X X T. spp. Ehrenberg X CLASS: DINOPHYCEAE Ceratium hirundinella(OFM) Schrank X X X X X X X C. hirundinellav, brachyceras(Day.) Est. X Glenodinium borgei (Lemm.) Schiller X G.g ymnodinium Penard X X I - - X X-G. palustre (Leimm.) Schiller X G. penardiforme (Linde.) Schiller X X X X1X G. quadridens (Stein) Schiller X X X 3-21

Table 3-4. (Continued).

TAXON 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 G. spp. (Ehrenberg) Stein X, Gymnodinium aeruginosum Stein X X X X X X X G. spp. (Stein) Kofoid & Swezy X X X X X X X X X X X X X X Peridiniumaciculiferum Lemmermann 1 P. cinctum (Muller). Ehrenberg X X P. inconspicuum Lemmermann X X X X X X X X X X X X X X X X P. intermedium Playfair X X X X X X X X X X P. limbatum (Stokes) Lemm. X X P. pusillum (Lenard) Lemmermann X X X X X X X X X _X X X X X X P. umbonatum Stein X X X P. willei Huitfeld-Kass X X X P. wisconsinense Eddy XX X X X X X X X XX X X X X X P. spp. Ehrenberg X X X _

CLASS: CHLOROMONADOPHYCEAE Gonyostomum depresseum Lauterborne X X X X X X X X X G. spp. Diesing X 1 = taxa found during 1987 - 91 only 3-22

Table 3-5. Dominant classes, their most abundant species, and their percent composition (in parentheses) at Lake Norman locations during each sampling period of 2007.

LOCATION FEBRUARY MAY 2.0 Cryptophyceae (51.7) Bacillariophyceae (77.8)

Rhodomonas minuta (45.5) Fragillariacrotonensis (42.7) 5.0 Cryptophyceae (52.4) Bacillariophyceae (63.9)

R. minuta (48.2) F. crotonensis (39.8) 9.5 Cryptophyceae (47.1) Bacillariophyceae (65.7)

R. minuta (44.0) F. crotonensis (39.9) 11.0 Cryptophyceae (64.6) Bacillariophyceae (70.4)

R. minuta (49.0) F. crotonensis (34.6) 15.9 Cryptophyceae (64.9) Bacillariophyceae (64.9)

R. minuta (45.7) F. crotonensis (22.2)

LOCATION AUGUST NOVEMBER 2.0 Chlorophyceae (52.2) Bacillariophyceae (52.7)

Cosmarium asphearosporum variety Tabellariafenestrata (12.3) strigosum (28.5) 5.0 Chlorophyceae (62.7) Bacillariophyceae (65.2)

C. asphear. var. strig. (34.2) Melosira ambigua (28.8) 9.5 Chlorophyceae (61.1) Bacillariophyceae (69.6)

C. asphear.var. strig. (32.4) M. ambigua (28.9) 11.0 Chlorophyceae (59.9) Bacillariophyceae (54.0)

C. asphear. var. strig. (30.7) T. fenestrata (36.0) 15.9 Chlorophyceae (44.2) Bacillariophyceae (55.6)

C. asphear.var. strig. (24.3) T. fenestrata (29.8) 3-23

CHLOROPHYLL a (I'g/L) DENSITY (units/ml-)

16- ................................ 7000 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

.14- ............................... 6000 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12- .............................. .

5000 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10- ............................. .

........................... . .. 4000 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8-6- ........................ 3000 . . . . . . . . . . . . . . .. . . . . . .

4 24 0-

................. 2000 1000 0

c' o* uoc 0' 0 o. o0 -0 c. u.0') o~

0O C C 0 S U') 0D 0)

T-- T- Co C, L- G 1- L6 SESTON DRY WEIGHT (mg/L) B1OVOLUME (MM 3Im3 )

3.0 6000 2.5 5000 2.0 4000 1.5 3000- .... 0 . 0.. .. Co ... 0. .. 0..

1.0 2000 0.5J 10004 0.0 0 I I I I R. q q Co q q 0ý q N Co M 0)  ;-

M' Co M

CO U)

(ND 0 -

LOCATIONS FEB MAY AUG NOV 0-Figure 3-1. Phytoplankton chlorophyll a, densities, biovolumes, and seston weights at locations in Lake Norman, NC in February, May, August, and November 2007.

3-24

14 -r ---------------------------------------------------------------

_12.41 -MAY 1997 .

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

i.. . . ,. . . . . . . .

1111.0066-NOV 1996

' 9:8"9"'E'B" i9................................

_J

-C 0

2

• FEB.MA AUG 198E

• FEB MAY .AUG NOV

-U-MAX -- MIN 2007 -- MEAN Figure 3-2. Lake Norman phytoplankton chlorophyll a seasonal maximum and minimum lake wide means since August 1987 compared with the long term seasonal lake wide means and lake wide means for 2007.

3-25

MEAN CHLOROPHYLL a (pg/L)

FEB MAY

-'--2.0 -a-5.0 1--'-2.0 --m-5.01 30- 30- .............................

ZONE------ ---- MIXING ZONE 25- 25- ..............................

20- 20- .............................

15- 15- .............................

10- 10-5- 11 5-n 111W nA. 4 ------------ ----

V 87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07

-'-8.0 --- 9.5 I---8.0 -- 9.5-30 25 30-25-p ...............

20 20-15 15-10 10.

5 5 0 0 87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07

...II......-'-11.0

-.- 13.0 1-0-11.0 ý3.0 30- .............................

30 25 25- .............................

20 20- ..............................

15 15- ... . .............. .....

10 10- ..............

5 5-(A .4 .......... ----------------

0 0 87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07 EI-* E159 69.0 30- ...................... 30 ..............................

25- ....................... ..... 25 ............... ... ..........

20- ....................... ..... 20 .............. . .. .........

15- .............. ...... 15 .......... .. ..... ........

10- ---------- - 10 5- 5 .. . . . ... . ..

0 n V

87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07 Figure 3-3. Phytoplankton mean chlorophyll a concentrations by location for samples collected in Lake Norman, NC, from February and May 1988 -2007.

3-26

MEAN CHLOROPHYLL a (pg/L)

AUG NOV

--2.0 -- 2.0 --- 5.0 3 5 --------------- ----- ------- --

35- MIXING ZONE 30- 30 MLXJN.G.

i- ZONE -- ........

25- 2 5 -------- ------- -------------- -

2 0 ------ ---- - -- --------- --- ----

20-

,15 ............................

15- .

10- 10 .. .

51 0- 0 87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07 35 ----------------------

30+/---------------------------

25- --------------------

20- --------------------

15+/-. 30 87--89--

15 - 10 10 ... . . . . .-.01-03-05-07 50-------------S. 5 5

0 87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07

-. 11.0 13.0 35O - - - - - - - - - - - - - - 35 30 25 20 15 15 10 0 5 0

87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07 1+15.9 -, 6. I -- 59-,-69.0 30 ----- - - -- - -- -- - -- 35

.30 25 -- - - - - - -- - -- -

25

-- 20 15 - - ..

15 10 10 5 0

87 89 91 93 95 97 99 01 03 05 07 87 89 91 93 95 97 99 01 03 05 07 Figure 3-4. Phytoplankton mean chlorophyll a concentrations by location for samples collected in Lake Norman, NC, from August and November 1987 - 2007.

3-27

4000 oCHLOROPHYCEAE SBACILLARIOPHYCEAE MlCHRYSOPHYCEAE I=CRYPTOPHYCEAE 3500 E MYXOPHYCEAE O DINOPHYCEAE MOTHERS E 3000 2500 2000 1500

........... . ....... L . .

LU z31000 ...... ......... .....

500 0

FEB MAY AUG NOV 3000 ................................................................

,2500 ................................................................

E oo E 2000 ................................................................

El u 1500 ................................................................

-J o 1000 ................... ......... ---------------------

m 500 Lq --------- 0 --------- -----

0 FEB MAY AUG NOV Figure 3-5. Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 2.0 in Lake Norman, NC, during 2007.

3-28

4000 0 CHLOROPHYCEAE 6 BACILLARIOPHYCEAE 3500 ---30CHRYSOPHYCEAE 8CRYPTOPHYCEAE -- ---

1 MYXOPHYCEAE E0 DINOPHYCEAE J 3000 0 OTHERS 2500 --------------------------------------------------------------------

2000 -------------------- - - - - - - - - - - - - - - - - - - - - - - -

201500 ---------...........

ZS1000l3 - .  ! ............. ........ . ....................

500 .------ . . . .. -- ---- ---- . . .

00 FEB MAY AUG NOV 3000 ------------------------------------------------------------------

,2500 --------------------------------------------------------------------

E E 2000 . .................................................................

E21000-------------------------------------------------------------

o 1000 ............................................

0 500 ------ -- - -- 1 ..-.....

FEB MAY AUG NOV Figure 3-6. Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 5.0 in Lake Norman, NC during 2007.

3-29

5000------CHLOROPHYCEAE OBACILLARIOPHYCEAE 4500 ------- CHRYSOPHYCEAE 8 CRYPTOPHYCEAE -m 0 MYXOPHYCEAE I DINOPHYCEAE 4000 ------ OTHERS

-- I E35000-----------------------------------------------------------

2300 ---------------------------------------......................

"- 2500 .. . . . . . . . . . . . .... . . . -. . . . . . . . . . .

2000 ----------------------------- - -

co Z.......... ...... ..........

1000 --------.......... .. ....... ....

500 - ....................

0- J FEB MAY AUG NOV 3000 ---...--------------------------------------------------

-2500 ------------------------------------------------- - -----------------

E 2000 --------------------------------------------------------------------

.U 1500 --------------------------------------------------.....

-j 0 1000 ----------------------..........I ..............

0 500 ... ..- -. .. .....

0-FEB MAY AUG NOV Figure 3-7. Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 9.5 in Lake Norman, NC during 2007.

3-30

5000-0 CHLOROPHYCEAE CS BACILLARIOPHYCEAE 4500- ........ IIICHRYSOPHYCEAE SCRYPTOPHYCEAE -.

.. MYXOPHYCEAE 0 DINOPHYCEAE 4000-MOTHERS 3500-3000-2500-2000-U)

Z wU1500-13 1000-500-0-

FEB MAY AUG NOV 3000

-__2500 E

C.)

E 2000

=E LU 1500

-j 0 1000 0

M 500 0

FEB MAY AUG ý NOV Figure 3-8. Class c.mposition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Location 11.0 in Lake Norman, NC during 2007.

3-31

8000 - O CHLOROPHYCEAE 3BACILLARIOPHYCEAE DJ CHRYSOPHYCEAE 8 CRYPTOPHYCEAE 7000 - 1 MYXOPHYCEAE 0 DINOPHYCEAE MOTHERS 6000 --------------------------------------- .....................

5000 -------------------------------------......................

4000 ---------------------------------------- ---------------------

3000 .............................................

Z U. 2000 .............................. ....................

1000 "- . . ...- "  :.. . .. . .

0-FEB MAY AUG NOV 5000 -------------------------------------------------------------------

E. 4 0 0 0 .. . . . . . . . . . . . . . . . . . ... . . . . . . . . . .. . . .

E30

"=3000 ..................... .................. ......... *............

LU 92000 200 --- --......... . .. . . ........ .......

0 0

M 1000 ..........................

0 1 FEB MAY AUG NOV Figure 3-9. Class composition (mean density and biovolume) of phytoplankton from euphotic zone samples collected at Locati6n 15.9 in Lake Norman, NC during 2007.

3-32

CHAPTER 4 ZOOPLANKTON INTRODUCTION The objectives of the Lake Norman Maintenance Monitoring Program for zooplankton are to:

1. Describe and characterize quarterly patterns of zooplankton standing crops at selected locations on Lake Norman and

2. compare and evaluate, where possible, zooplankton data collected during 2007 with historical data collected during the period 1987 - 2006.

Previous studies of Lake Norman zooplankton populations, using monthly data, demonstrated a bimodal seasonal distribution with highest values generally occurring in the spring, and a less pronounced fall peak. Considerable spatial and year-to-year variability has been observed in zooplankton abundance in Lake Norman (Duke Power Company 1976, 1985; Hamme 1982; Menhinick and Jensen 1974). Since quarterly sampling was initiated in August 1987, distinct bimodal seasonal distribution has been less apparent, due to the lack of transitional data between quarters.

METHODS AND MATERIALS Duplicate 10 m to surface, and bottom to surface net tows were taken at Locations 2.0, 5.0, 9.5, 11.0, and 15.9 in Lake Norman (Figure 2-1) during each season: winter (February),

spring (May), summer (August), and fall (November) 2007. For discussion purposes the 10 m to surface tow samples are called "epilimnetic" samples and the bottom to surface net tow samples are called "whole-column" samples. Locations 2.0 and 5.0 are defined as the "mixing zone" and Locations 9.5, 11.0 and 15.9 are defined as "background" locations. Field and laboratory methods for zooplankton standing crop analysis were the same as those reported in Hamme (1982). Zooplankton standing crop data from 2007 were compared with corresponding data from quarterly monitoring begun in August 1987.

4-1

RESULTS AND DISCUSSION Total Abundance Highest epilimnetic zooplankton densities at Lake Norman locations have predominantly been observed in the spring, with winter peaks observed about 25% of the time, and peaks observed only occasionally in the summer and fall (Duke Energy 2007). During 2007, annual epilimnetic maxima were recorded from Locations 2.0, 5.0, and 15.9 in the spring.

while Locations 9.5 and 11.0 demonstrated peak annual densities in February (Table 4-1, Figures 4-1 and 4-2). The lowest epilinnetic densities occurred in the fall at all but Location 15.9, which had the annual minimum density in the summer. Epilimnetic zooplankton densities ranged from a low of 33,564/M 3 at Location 2.0 in the fall, to a high of 394,182/m 3 at Location 15.9 in the spring.

Maximum densities in 2007 whole-column samples were observed during different seasons at different locations. At Locations 9.5 and 11.0, maximum values occurred in the winter, annual maxima at Locations 2.0 and 15.9 were observed in the spring, and the highest density from Location 5.0 occurred in the summer (Table 4-1 and Figure 4-1). Minimum whole-column densities were observed in the summer at Locations 11.0 and 15.9 and in the fall at Locations 2.0, 5.0, and 9.5. Whole-column densities ranged from a low of 30,61 1/m3 at Location 2.0 in the fall, to 218,242/1n 3 at Location 15.9 in the spring.

Consistent with historical data, during 2007 total zooplankton densities were most often higher in epilimnetic samples than in whole-column samples (Duke Energy 2007). This is related to the ability of zooplankton to orient vertically in the water column in response to physical and chemical gradients and the distribution of food sources, primarily phytoplankton, which are generally most abundant in the euphotic zone (Hutchinson 1967).

Since epilimnetic zooplankton communities are far more representative of overall seasonal and temporal trends, most of the following discussion wilt focus primarily on zooplankton communities in this area of the water column.

Although spatial distribution varied among locations from season to season, a general. pattern of lower average densities from the mixing zone, as compared to background locations, was observed during 2007 (Table 4-1, Figures 4-1 and 4-2). Location 15.9, the uppermost background location, had higher epilimnetic densities than mixing zone locations during all sampling periods (Table 4-1). This spatial trend was similar to that of the phytoplankton 4-2

(Chapter 3). In most previous years of the program, background locations had higher mean densities than mixing zone locations (Figures 4-3 through 4-6; and Duke Energy 2007).

Historically, both seasonal and spatial variability of epilimnetic zooplankton densities have been much higher among background locations than among mixing zone locations. The uppermost Location 15.9, showed the greatest range of densities during 2007 (Table 4-1, Figures 4-3 through 4-6). Apparently, epilimnetic zooplankton communities are more greatly influenced by environmental conditions at the up-lake locations than at the down-lake locations. Location 15.9 represents the transition zone between river and reservoir where*

populations would be expected to fluctuate due to the dynamic nature of this region of Lake Norman. At the locations nearest the dam (Locations 2.0 and 5.0), seasonal variations are dampened and the overall production would be lower due to the relative stability of this area (Thornton, et al. 1990). Additionally, the effects of MNS once-through cooling could cause somewhat lower production at these locations. A similar trend was observed in the phytoplankton communities (Chapter 3).

Epilimnetic zooplankton densities during 2007 were most often within historical ranges (Figures 4-3 through 4-6). The exceptions were at Location 9.5 in the summer and Location 15.9 in the winter. On both occasions, these locations demonstrated long-term seasonal maximum densities (Figures 4-3 and 4-6).

The highest winter densities recorded from Locations 2.0 and 11.0 occurred in 1996, while the winter maximum at Location 9.5 was recorded in 1995 (Figure 4-3). The winter maxima from Locations 5.0 and 15.9 occurred in 2004 and 2007, respectively. Long-term maximum densities for spring were observed at Locations 2.0 and 5.0 in 2005, while the highest spring values from Locations 11.0 and 15.9 occurred in 2002. The highest spring peak at Location 9.5 was observed in 2005 (Figure 4-4). Long-term summer maxima occurred in 1988 at Locations 2.0, 5.0, and 11.0, while summer maxima at Locations 9.5 and 15.9 occurred in 2007 and 2003, respectively (Figure 4-5). Long-term maxima for the fall occurred at all but Location 15.9 in 2006, while the long-term maximum at Location 15.9 was recorded in 1999 (Figure 4-6).

From 1990 - 2003, the densities at mixing zone locations in the spring, summer, and fall demonstrated moderate degrees of year-to-year variability, and the long-term trend at mixing zone locations in the spring had been a gradual increase through 2005. During the spring of 2006, zooplankton densities in the mixing zone declined sharply, as compared to 2005, and 4-3

were well within earlier historical ranges. During 2007, mixing zone locations demonstrated increases. Year-to-year fluctuations of densities in the mixing zone during the winter have

.occasionally been quite striking, particularly between 1991 and 1997. The background locations continue to exhibit considerable year-to-year variability in all seasons (Figures 4-3 through 4-6).

Community Composition One hundred and twenty-three zooplankton taxa have been identified since the Lake Norman Maintenance Monitoring Program began in August 1987 (Table 4-2). Forty-nine taxa were identified during 2007, as compared to 44 recorded for 2006 (Duke Energy 2007). Two previously unreported taxa, the copepod Eucyclops prionophorusand the rotifer, Keratella americana,were identified in 2007.

In 2006, copepods were the most abundant zooplankters in eight samples; one in the winter and seven in the summer (Duke Energy 2007).. During 2007, copepods were dominant in only three samples: the epilimnion at Locations 2.0 and 5.0 in the spring, and the whole column sample from Location 2.0 in the summer (Table 4-1). - Cladocerans, most often the least abundant forms in Lake Norman, were dominant in two whole column samples, one from Location 2.0 in the spring and another from Location 9.5 in the winter (Table 4-1).

Rotifers were dominant in all other samples collected in 2007. During most years, microcrustaceans (copepods and cladocerans) dominated mixing zone samples, but were less important among background locations (Figures 4-7 and 4-8). Compared to 2006, microcrustaceans showed a slight increase in relative abundances in the epilimnion of the mixing zone, while they demonstrated a slight decrease among whole-column samples at these locations (Figure 4-7). At background locations microcrustacean relative abundances were similar to those of 2006 (Figure 4-8)

Copepoda As has always been the case, copepod populations were consistently dominated by immature forms (primarily nauplii) during 2007. Adult copepods seldom comprised more than 7% of the total zooplankton density at any location. Tropocyclops was the most important genus in adult populations, particularly during summer and fall (Table 4-3). Epishurawas important among winter and spring samples, while Cyclops and Diaptomus were occasionally abundant.

4-4

Similar patterns of copepod taxonomic distributions were observed in previous years (Duke Energy 2007).

Copepods tended to be somewhat more abundant at background locations than at mixing zone locations during 2007, and their densities peaked at all locations in the spring, as was typically recorded during past years (Table 4-1; Figure 4-9).

Rotifera Polyarthrawas the most abundant rotifer at all locations during the fall of 2007, when it demonstrated dominance among all rotifer populations (Table 4-3). Keratellawas the most abundant rotifer in most spring samples, while Plygura was most often dominant among summer populations. During the winter, Asplanchna was the most abundant rotifer in epilimnetic samples from Locations 2.0, 5.0, and 9.5 and among whole column samples at Locations 2.0 and 9.5. Conochilus and Synchaeta were occasionally dominant in samples from winter, spring, and summer. All of these taxa have been identified as important constituents of rotifer populations, as well as zooplankton communities, in previous studies (Duke Energy 2007, Hamme 1982).

Long-term tracking of rotifer populations indicated high year-to-year seasonal variability.

Peak densities have most often occurred in the winter and spring, with occasional peaks in.

the summer and fall (Figure 4-11). During 2007, peak rotifer densities were observed at mixing zone locations in the summer and at background locations in the spring.

FUTURE STUDIES No changes are planned for the zooplankton portion of the Lake Norman Maintenance-Monitoring Program:

SUMMARY

Maximum zooplankton densities most often occurred in the spring of 2007, while minimum zooplankton densities were generally noted in the fall. As in past years, epilimnetic densities were higher than whole-column densities. Mean zooplankton densities tended to be higher 4-5

among background locations than among mixing zone locations during 2007. Spatial trends of zooplankton populations were similar to those of the phytoplankton, with increasing densities from down-lake to up-lake. From around 1997 through 2005, a year-to-year trend of increasing zooplankton densities was observed among mixing zone locations in the spring.

Densities at these locations declined sharply in 2006, followed by an increase in 2007. Long-term trends showed much higher year-to-year variability at background locations than at mixing zone locations.

Epilimnetic zooplankton densities were generally within ranges of those observed in previous years. The exceptions were record high densities during winter at Location 15.9 and during the summer at Location 9.5.

One hundred and twenty-three zooplankton taxa have been recorded from Lake Norman since the Program began in 1987 (49 were identified during 2007). Two previously unreported taxa were identified during 2007.

Overall, relative abundance of copepods in 2007 decreased over 2006, and they were dominant in only three samples. Cladocerans were dominant in two samples, while rotifers were dominant in all remaining samples. The relative abundance of microcrustaceans increased slightly in the epilimnion of the mixing zone since 2006, but decreased among whole-column samples since the previous year. At background locations, relative abundances of microcrustaceans in 2007 were similar to those of 2006. Historically, copepods and rotifers have most often shown annual peaks in the spring, while cladocerans continued to demonstrate year-to-year variability.

Copepods were dominated by immature forms with adults rarely accounting for more than 7% of zooplankton densities. The most important adult copepod was Tropocyclops, as was the case in previous years. Bosmina was the predominant cladoceran, as has also been the case in most previous years of the program. Bosminopsis dominated several cladoceran populations during the summer. The most abundant rotifers observed in 2007, as in many previous years, were Polyarthra, Keratella, and Ptygura. Conochilus, Asplanchna, and Syncheata were also important among rotifer populations.

4-6

Lake Norman continues to support a highly diverse and viable zooplankton community.

Other than somewhat lower productivity from MNS induced mixing at Locations 2.0 and 5.0, no impacts of plant operations were observed.

4-7

Table 4-1. Total zooplankton densities (No. X 1000/rn 3 ), densities of major zooplankton taxonomic groups, and percent composition (in parentheses) of major taxa in the epilimnion and whole column net tow samples collected from Lake Norman in February, May, August, and November 2007.

Locations Sample Date Sample Type Taxa 2.0 5.0 9.5 11.0 15.9 2/27/2007 Epilimnion Copepoda 20.4 26.0 33.9 45.9 41.8 (30.5) (37.0) (20.9) (22.9) (19.7)

Cladocera 8.6 12.7 60.5 26.6 12.6 (12.9) (18.0) (37.2) (13.2) (5.9)

Rotifera 37.8 31.7 68.0 128.3 157.9 (5(56.6)

.0) (41.9) (63.9) (74.4)

Total 66.8 70.4 162.4 200.8 "212.3 Whole Column 2.0 5.0 9.5 11.0 15.9 Depth 30 m 19 m 20 m 25 m 21 m Copepoda 11.9 16.7 24.7 27.7 24.2 (29.2) (30.5) (21.8) (22.1) (23.0)

Cladocera 6.8 9.4 47.5 21.2 12.3 (16.8) (17.2) (42.0) (16.9) (11.7)

Rotifera 21.9 28.6 41.0 76.5 68.8 (54.0) (52.3) (36.2) (61.0) (65.3)

Total 40.6 54.7 113.2 125.4 105.3 Locations Sample Date Sample Type Taxa 2.0 5.0 9.5. 11.0 15.9 5/24/2007 Epilimnion ,Copepoda 31.2 62.1 30.1 51.0 47.4 (36.5) (41.0) (34.3) (28.5) (12.0)

Cladocera 24.8 27.4 20.0 37.4 47.4 (29.0) (18.1) (22.9) (20.9) (12.0)

Rotifera 29.5 61.8 37.5 90.6 299.3 (34.5) 40.9) (42.8) (50.6) (76.0)

Total 85.5 151.3 87.6 179.0 394.1 Whole Column 2.0 5.0 9.5 11.0 15.9' Depth 30 m 19 m 20 m 25 m 21 m Copepoda 16.0 34.5 24.2 28.6 32.6 (39.1) (40.2) (34.9) (26.2) (14.9)

Cladocera 16.8 15.9 16.7 26.1 30.3 (41.1) (18.5) (24.1) (23.8) (13.9)

Rotifera 8.1 35.5 28.4 54.6 155.4 (19.8) (41.3) (41.0) (50.0) (71.2)

Total 40.9 85.9 69.3 109.3 218.3 4-8

Table 4-1. (Continued).

Locations Sample Date Sample Type Taxa 2.0 5.0 9.5 11.0 15.9 8/13/2007 Epilimnion Copepoda 18.8 22.5 29.3 23.4 37.5 (37.5) (20.4) (19.7) (16.8) (33.1)

Cladocera 7.1 5.2 10.1 15.8 10.8 (14.2) (4.7) (6.8) (11.4) (9.5)

Rotifera 24.2 82.3 109.3 100.0 65.0 (48.3) (74.9) (73.5) (71.8) (57.4)

Total 50.1 1.10.0 148.7 139.2 113.3 Whole Column 2.0 5.0 9.5 11.0 15.9 Depth 30 m 19 m 20 m 25 m 21 m Copepoda 15.6 22.6 27.0 18.4 20.9 (48.6) (22.5) (26.2) (25.8) (36.3)

Cladocera 5.0 3.4 9.1 6.9 6.0

'(15.6) (3.3) (8.8) (9.7) (10.4)

Rotifera 11.5 74.7 67.0 46.0 30.5 (35.8) (74.2) (65.0) (64.5) (53.0)

Total 32.1 100.7 103.1 71.3 57.6*

Locations Sample Date Sample Type Taxa 2.0 5.0 9.5 11.0 15.9 11/20/2007 Epilimnion Copepoda 7.6 12.4 19.6 32.2 14.6 (22.6) (28.3) (32.6) (23.8) (11.4)

Cladocera 4.0 11.1 7.3 8.1 12.8 (12.1) (25.1) (12.2) (6.0) (10.0)

Rotifera 21.9 20.4 33.3 94.8 100.7 (65.3) (46.6) (55.2) (70.2) (78.6)

Total 33.5 43.9 60.2 135.1 128.1 Whole Column 2.0 5.0 9.5 11.0 15.9 Depth 29 m 19 m 20 m 24 m 20 m Copepoda 12.2 13.5 19.0 32.5 16.4 (40.0) (36.2) (33.3) (34.2) (17.4)

Cladocera 4.5 8.6 3.6 8.1 7.7 (14.6) (23.1) (6.3) (8.6) (8.2)

Rotifera 13.9 15.2 34.5 54.5 70.3 (45.4) (40.7) (60.4) (57.3) (74.4)

Total 30.6 37.3 57.1 95.1 94.4

• = Chaoborus (Insecta) observed in a whole water sample from Location 15.9 in August (197/m 3 , 0.34%).

4-9

Table 4-2. Zooplankton taxa identified from samples collected quarterly on Lake Norman from 1987 - 2007.

TAXON 87-92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07

-COPEPODA Cyclops thomasi Forbes X X X X X X X X X X X X X X C. vernalis Fischer X C .spp. O. F. Muller X X X X X X X X X X Diaptomus birgei Marsh X X X D. mississippiensisMarsh X X X X X X X X X X X X X X X X D. pallidus Herick X X X X X X X X D. reighardiMarsh D. spp. Marsh X X X X X X X X X X X EpishurafluviatilisHerrick .X X X X X X X X X X X X X Ergasilus spp. Smith X X Eucyclops agilis (Koch) X E. prionophorusKiefer X Mesocyclops edax (S. A. Forbes) X X X X X X X X X X X X X X X M spp. Sars X X X X X X X X X Paracyclops limbricatusv. poppei X Tropocyclops prasinus (Fischer) X X X X X X X X X X X X X X T spp. (Fischer) X X X X X X X X X X X CLADOCERA Alona spp.Baird XX -X Alonella spp. (Birge) X X Bosmina longirostris(O. F.M.) X X X X X X X X X X X X X B. spp. Baird X X X X X X X _ X X Bosminopsis dietersi Richard X X X X X X X X X X X X X X X X Ceriodaphnialacustris Birge X X X X X X X X X X X C. spp. Dana X X X XX X X X X XX X Chydorusspp. Leach X X X X X X X X X X X Daphnia ambigua Scourfield X X X X X X X X X D. catawba Coker X X X D. galeata Sars X I D. laevis Birge X X D. longiremis Sars X X X X X- X D. lumholzi Sars X X X X X X X X X D. mendotae (Sars) Birge X X X X X X D. parvulaFordyce X X X X X X X X X X X X X X D. pulex (de Geer) X X X D. pulicariaSars X X D. retrocurvaForbes X X X X X X X X X D. schodleri Sars X D. spp. Mullen X X XX X X X X X X X XX X X X Diaphanosomabrachyurum X X X X X X X X X X X (Lievin)

D. spp. Fischer X X X X X X X. X X X X X Disparalonaacutirostris(Birge) X Eubosmina spp. (Baird) X Holopediium amazonicum Stin.. X X X X X X X X X X X H. gibberum Zaddach X X X 4-10

Table 4-2, (Continued).

TAXON 87-92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 H. spp. Stingelin X X X X X X X X X X Ilyocryptus sordidus (Lieven) X I. spinifer Herrick X I. spp. Sars X X X X X Latona setifera (O.F. Muller) X Leptodora kindtii (Focke) X X X X X X X X X X X X X X X X Leydigia acanthoceroides (Fis.) X L. spp. Freyberg X X X X X X X X Moina spp. Baird X Monospilus disparSars X Oxurella spp. (Sars) X Pleuroxus hamulatus Birge X P. spp. Baird X Sida crystallina0. F. Muller X Simocephalus expinosus (Koch) X Simocephalus spp. Schodler X ROTIFERA Anuraeopsisfissa(Gosse) X X A. spp. Lauterborne X X X X X. X X X Asplanchna brightwelli Gosse X X A. priodontaGosse X X X X A. spp. Gosse X X X X XX X X X X X X X XX Brachionuscalyciflorus Halb. X Brachionus caudata Bar. & Dad. X B. bidentataAnderson X B. havanensis Rousselet X X B. patulus0. F. Muller X X B. spp. Pallas X X X X X Chromogasterovalis (Berg.) X X X X X X X C. spp. Lauterborne X X X X X - I Collotheca bdlatonica Harring X X X X X X X X X X X C. mutabilis (Hudson) X X X X X X X X X X

. spp. Harring X X X X X X X X X X X Colurella spp..Bory de St. Vin. X ConochiloidesdossuariusHud. X X X X X X X X X X X C. spp. Hlava X X X X X X X X Conochilus unicornis (Rouss.) X X X X X X X X X X X X C. spp. Hlava X X X X X X X X Filiniaspp. Bory de St. Vincent X X X X Gastropusstylifer Imhof X X X X X X X G. spp. Imhof X X X X X X X X Hexarthramira Hudson X X X X X X X H. spp. Schmada X X X X X X X Kellicottia bostoniensis (Rou.) X X X X X X X X X X X X X X X K. longispinaKellicott X X X X X X X X X X X K. spp. Rousselet X X X X X X X X X X X Keratella Americana Carlin X 4-1i

Table 4-2. (Continued).

TAXON 87-92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 K. cochlearisBory de St. Vinc. X X X X K. taurocephalaMyers X X X X X K spp. Bory de St. Vincent X X X X X X X X X X X X X X X Lecane spp. Nitzsch X X X X X X X X X X _

MacrochaetussubquadratusP. X X M spp. Perty X X X X X X X Monommata spp. X Monostyla stenroosi (Meiss.) X M spp. Ehrenberg X X X X X X Notholca spp. Gosse X X X Platyiaspatulus Harring X Ploeosoma hudsonii Brauer X X X X X X X X X X X X X X X P. truncatum (Levander) X X X X X X X X X X X X X X X P. spp. Herrick X X X X X X X Polyarthraeuryptera (Weir.) X X X X X P. major Burckhart X X X X X X X X X P. vulgaris Carlin X X X X X X X X X X X P. spp. Ehrenberg X X XX X X X X X X X X X X X X Pompholyx spp. Gosse X Ptygura libra Meyers X X X X X X X X X P. spp. Ehrenberg X X X X X X X X Synchaeta spp. Ehrenberg X X X X X X X X X X X X X X X X Trichocercacapucina (Weir.) X X X X X X X T. cylindrica(Imnhof) X X X X X X X X X X X X X T. longiseta Schrank X X X T. multicrinis (Kellicott) X X X X X X X X X T. porcellus (Gosse) X X X X X X X T. pusilla Jennings X T. similis Lamark X X T spp. Lamark X X X X XX X X X -X X X X X X X Trichotriaspp. Bory de St. Vin. X X X Unidentified Bdelloida X X X X X X X X Unidentified Philodinidae X Unidentified Rotifera X X X X X X X X X INSECTA Chaoborus spp. Lichtenstein X X X X X X X X X X OSTRACODA (unidentified) X X X 4-12

Table 4-3. Dominant copepod (adults), cladoceran, and rotifer taxa and their percent composition (in parentheses) of the copepod, cladoceran and rotifer densities by location and sample period in Lake Norman in 2007.

Locations. FEBRUARY MAY AUGUST NOVEMBER 2.0 Tropocyclops (5.6) Epishura (0.7) Tropocyclops (6.2)* Tropocyclops (7.2) 5.0 Epishura (2.9) Epishura (3.3) Tropocyclops (6.0)* Tropocyclops (4.9) 9.5 Cyclops (3.8) Epishura (7.4) Tropocyclops (2.3)* Tropocyclops (18.2)*

11.0 Tropocyclops (0.8) Epishura (2.7) Tropocyclops (9.4)* Tropocyclops (5.6) 15.9 Cyclops (1.2) No adults Tropocyclops (4.6)* Tropocyclops (30.8) 2.0 Epishura (4.9) Epishura (8.2) Tropocyclops (5.1) Diaptomus (10.0) 5.0 Tropocyclops (10.8) Epishura (5.2) Tropocyclops (6.9) Tropocyclops (7.1) 9.5 Epishura (4.9) Tropocyclops (8.4) Tropocyclops (2.2)* Tropocyclops (25.4) 11.0 Tropocyclops (1.4) Epishura (6.0) Tropocyclops (9.0) Diaptomus (12.8) 15.9 Cyclops (4.0) Diaptomus (1.8) Tropocyclops (7.6) Tropocyclops (17.1) 2.0 Bosmina (88.8) Diaphanosoma(38.4) Bosminopsis (65.3) Bosmina (100.0) 5.0 Bosmina (88.2) Bosmina (61.3) Bosminopsis (64.6) Bosmina (98.7) 9.5 Bosmina (95.1) Diaphanosoma(39.9) Bosminopsis (76.8) Bosmina (94.0) 11.0 Bosmina (98.7) Diaphanosoma (40.2) Bosminopsis (74.0) Bosmina (91.6) 15.9 Bosmina (86.5) Bosmina (92.0) Bosmina (60.9) Bosmina (97.4) 2.0 Bosmina (91.5) Bosmina (57.2) Bosmina (42.8) Bosmina (93.1) 5.0 Bosmina (90.6) Bosmina (55.9) Bosminopsis (73.3) Bosmina (89.3) 9.5 Bosmina (94.3) Diaphanosoma (51.8) Bosminopsis (64.7) Bosmina (91.6) 11.0 Bosmina (92.1) Diaphanosoma (49.3) Bosminopsis (65.6) Bosmina (58.5) 15.9 Bosmina (88.4) Bosmina (92.2) Bosmina (63.4) Bosmina (96.9)

• = Only adults present in samples.

4-13

Table 4-3. (Continued).

Locations FEBRUARY MAY AUGUST NOVEMBER 2.0 Asplanchna (29.4) Keratella (34.3) Ptygura (38.3) Polyarthra(88.5) 5.0 Asplanchna (37.0) Keratella (35.6) Ptygura (83.7) Polyarthra(91.1) 9.5 Asplanchna (80.3) Keratella (60.0) Ptygura (76.8) Polyarthra(68.8) 11.0 Synchaeta (47.5) Keratella (39.1) Ptygura (60.9) Polyarthra(78.7) 15.9 Keratella (37.0) Keratella (51.5) Conochilus (84.5) Polyarthra(76.0) 2.0 Asplanchna (37.7) Conochilus (27.9) Ptygura (52.4) Polyarthra(78.8) 5.0 Keratella (45.7) Conochilus (41.1) Ptygura (87.6) Polyarthra(93.2) 9.5 Asplanchna (62.7) Keratella (60.9) Ptygura (79.0) Polyarthra(61.0) 11.0 Synchaeta (49.2) Keratella (38.7) Ptygura (69.6) Polyarthra(74.1) 15.9 Keratella (41.9) Keratella (55.8) Cocochilus (79.2) Polyarthra(75.3) 4-14

EPILIMNETIC

-- FEB --- MAY -e-AUG -X- NOV 40 0 -___ - - - - - - - --- - - - - - - - - --- - - - - - - - -

30

,a03 0 0 --- -------- ------------------- . . ---

x

• 1001 0

2.0 5.0, 9.5 11.0 15.9 Location WHOLE COLUMN FEB --w-MAY -u-AUG --- NOV 2, 5 0 - - - - - -- ----- - - -- - -- - - -- - -- - - -- - - -- - -- - - -- - -- - - -- - -- - -- - - -- - -- - - -

2500 10 SO .

100 2.0 5.0 9.5 '11.0 15.9 Location Figure 4-1. Total zooplankton density by location for samples collected in Lake Norman in 2007.

4-15

FEBRUARY MAY 400 TDCOPEPODS ECLADOCERANSI .... 400 BROTIFERS ZROTIFERS Sn350-- 9-350 SCLADOCERANS OCOPEPODS 0 - --- -- - 2 .............................. .

x x o150 150..................

............ .100 ... n 100 .

• 0 .0 2.0 5.0 9.5 11.0 15.9 2.0 5.0 9.5 11.0 15.9 Location Location AUGUST NOVEMBER 200 DCOPEPODS O I CLADOCERANS .... 200 DCOPEPODS - CLADOCERANS 2 175 -ROTIFERS .... 175 9ROTIFERS o1o ........................ 150o

-125 ............... . 125 -------------------------

100......... ... .100.

-75 ........... .. 75

, 25 ... , 25 ...

00 2.0 5.0 9.5 11.0 15.9 2.0 5.0 9.5 11.0 15.9 Location Location Figure 4-2. Zooplankton community composition by sample period and location for epilimnetic samples collected in Lake Norman in 2007.

4-16

MIXING ZONE LOCATIONS WINTER 225 -- 2.0 .................................................................

S200 ................................................ ................

- 175 150 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

100 o25

• 0 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Year BACKGROUND LOCATIONS I00 225 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Year Figure 4-3. Total zooplankton densities by location and year for epilimnetic samples collected in Lake Norman, NC, in the winter periods of 1988 - 2007.

4-17

MIXING ZONE LOCATIONS SPRING 225 - ............. .................................................-.-

200 2.0 -u-5.0 -

• 67 10 250 ... ............................................................................

O - 1 1 1 I I - I - - - I - I . . I 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 6007 -* 1. .49. ... .*1..................... ............ ....

• 100 Year BACKGROUND LOCATIONS

"-600oo0 9.......

. 0....9......................................... ............

E 500 --------------------------- --------------------------- ------------------------

40 .0 .....................  :...............................

>, 2 0 0 - - -

88 89 90 91 92 93 9495 96 97 98 99 00 01 02 03 04 05 06 07 Year Figure 4-4. Total zooplankton densities by location and year for epilimnetic samples collected in Lake Norman in the spring periods of 1988 - 2007.

4-18

MIXING ZONE LOCATIONS SUMMER 150-- .-- 2.0 -,-E.o .

CDE C) 100 . ..............................................................................

x z

• 0 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Year BACKGROUND LOCATIONS E250 o 00 9. --a 110-a-159 x.

00 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Year Figure 4-5. Total zooplankton densities by locationI and year for epilimnetic samples collected in Lake Norman in the summer periods of 1987 - 2007.

4-19

MIXING ZONE LOCATIONS FALL 200 -1.2.0-3-5.0

• " 175 ---------- ------------------------------------------------------------------------

-E 150 ---------------------------------------------------------------- ....

CD) --.-- .......-

0 0 S 75 - - ------------------------------ - --- - - -

'- 250 - .... -

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Year BACKGROUND LOCATIONS

-'--9.5 --m-11.0 -*- 15.91 E 400 .............................................. ---------------

00 x

100 87 88 89 90 91 92 93 94 95 96 97 98 99'00 01 02 03 04 05 06 07 Year Figure 4-6. Total zooplankton densities by location and year for epilimnetic samples collected in Lake Norman in the fall periods of 1987 - 2007.

4-20

MIXING ZONE: EPILIMNION E COPEPODS L3 CLADOCERANS E ROTIFERS 100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

O OO0) OM O) O) O) ) 0 0 0 0 0 0 0 0-MIXING ZONE: WHOLE-COLUMN 100%

90%

80%

.70%

60%

50%

40%

30%

20%

10%

0%

QO O OO**0") 0) 0) 0) 0) 0") 0 0 0 0 0 0 0 0 YEARS Figure 4-7. Annual percent composition of major zooplankton taxonomic groups from mixing zone locations (Locations 2.0 and 5.0 combined) during 1988 - 2007 (Note: Does not include Location 5.0 in the fall of 2002 or winter samples from 2005).

4-21

BACKGROUND: EPILIMNION 0 COPEPODS 100% - .. .- - S9. CLADOCERANS .-. - - -U ROTIFERS 90 % .. . . . . -

80% - -

70% - .. .- - - .-. - - - -

60 % .. .. ...

5b% ....

40% - .. .. . . .

30% - .. .- - - - - ..- --. - - -

2 0% -.-.- -. -.

10%

0%

CO 0 t'- N)

N M ,t M.0 r-- O0 OD N C-* 't*" U 0 ,-

cO 0O 0 ) CM CD0) 0) M 0D 0)MO 0 0D 0 C0000 0 CDO0 M0) 0) 0)0 D O) 0*0) O)

OM a 000000

- - - - - - -- - - - N N N N N N N.4 N4 BACKGROUND: WHOLE-COLUMN 100% - .. .- -....- - - -

90% .... -

80% - ...- - -.- - - - - - -

70 % - ...- -...-- - - - - -

6 0 % -..- - - - - - - - - - "

50% .

40% -

10% -

0%

CO M* O N- M" V" LO (0 r-. 0o M) CD Nr M4 't -O t~o I,-

oo Wo M' oM MDMD M' M, M) M) oMDo o o o Co ao M* MD oCoD M M M* ' C* oD MD M M* MD o o o Co o o YEARS Figure 4-8. Annual percent composition of major zooplankton. taxonomic groups from background locations (Locations 9.5, 11.0, and 15.9 combined) during 1988 -

2007 (Note: Does nof include winter samples from 2005).

4-22

0 120 ................. M................

G

...... .............. .............. ....... ...... ............. I....... .............. ...........

I -.- MIXING ZONE -m-BACKGROUND LOCATIONS  :

i i.

100 --------

CD 80 ........ ------

-- I.- ........... .. ..~~

n r ............

6 60 ....... ...... . . ... ................

Z t

C) 40 N 20 t i 0

I19 I 99 I< 1999 I I,00M.0II2° I I IK00I M.4 I M.0 1996 1997 1998 1999 2000 2001 2002' 2003 2004 2005 2006 *2007 Seasons and Years Figure 4-9. Copepod densities during each season of each year among epilimnetic samples collected in Lake Norman from 1990 -

2007 (mixing zone = mean of Locations 2.0 and 5.0; background = mean of Locations 9.5, 11.0, and 15.9).

t'J

[ :-MIXING ZONE -- BACKGROUND LOCATIONS 50 .

40 .. .. . . . . . .. .. .. . . .. . . . .. .. . . . . . ... .. . . . . . .. . . . . . . .. . . . . . . .

E ................................. ..... ......... ...... ...... . .

X' d,30 ----......... ....... ..... .. . ........... .... .. . ....... ....

0 20 ." ' ""'.......... *........ ,....... :........ . . . ... ." . .. .. . . .. . .. . .... .. ..... .. '

10 -- - --. --- -...

0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2600 '2001 2002 2003 2004 2005 2006 2007 Seasons and Years Figure 4-10. Cladoceran densities during each season of each year among epilimnetic samples collected in Lake Norman from 1990 -

2007 (mixing zone = mean of Locations 2.0 and 5.0; background = mean of Locations 9.5, 11.0, and 15.9).

.i*

350 ---------...................................... I....... I...... I ..... I....... : ... ............. ...... .............. ....... ...... .......

-.- MIXING ZONE -- BACKGROUND LOCATIONS]

250 . - , ,

0 - 5.S S S S SSl 0:

Z.10 l.

CD 15 0 ................................... .........---. - -I

---I..................

-2 00 --- - -- .. --- .... ... . . . . . . .. . . . . . . ---

100 --------......... ' ...... ....... 4........... .............................- --... .. . . T . .. .. . . ... .. .... . ....

.*10 ..... ~I~ .............

50 .*...... ................... ... . ... ... .

§ ;-,IooT-l1 < 1Z LL .-IM.LL lLn oo COIIIL ° 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2001 2 003 2004 2005 2006 2007 Seasons and Years Figure 4-11. Rotifer densities .during each season of each year among epilimnetic samples collected in Lake Norman from 1990 -

2007 (mixing zone = mean of Locations 2.0 and 5.0; background = mean of Locations 9.5, 11.0, and 15.9).

CHAPTER 5 FISHERIES INTRODUCTION In accordance with the NPDES permit for McGuire Nuclear Station (MNS) and associated requirements from the North Carolina Wildlife Resources Commission (NCWRC),

monitoring of specific fish population parameters in Lake Norman continued during 2007.

The components of this program were:

1. spring electrofishing survey of littoral fish populations with emphasis on age, growth, size distribution, and condition of spotted bass and largemouth bass;

2. fall electrofishing survey to assess largemouth and spotted bass young-of-year abundance;

3. summer striped bass mortality surveys;

4. winter striped bass gill net survey with the NCWRC with emphasis on age, growth, and condition;

5. fail hydroacoustic and purse seine surveys of pelagic fish abundance and species composition;

6. fall crappie trap-net survey with the NCWRC with emphasis on age and growth.

METHODS AND MATERIALS Spring Electrofishing Surveys A spring electrofishing survey was conducted in March and April at three locations: (1) near Marshall Steam Station (MSS) in Zone 4, (2) a reference (REF) area located between McGuire Nuclear Station (MNS) and MSS in Zone 3, and (3) near MNS in Zone 1 (Figure 5-1). The locations sampled in 2007 were identical to historical locations sampled since 1993 and consisted of ten 300-m shoreline transects at each location. Transects included habitats representative of those found in Lake Norman. Shallow flats where the boat could not access within 3-4 m of the shoreline wer'e excluded. All sampling was conducted during daylight, when water temperatures were expected to be between 15 and 20 'C. All stunned fish were 5-1

collected and identified to species (scientific names of fish collected are listed in Table 5-1).

Fish were enumerated and weighed in aggregate by taxon, except for largemouth and spotted bass, where total lengths (mm) and weights (g) were obtained for each individual collected.

Sagittal otoliths were removed from all bass > 125 mm long (bass < 125 mm were assumed to be age 1 because young-of-year bass are historically not collected in spring samples) and sectioned for age determination (Devries and Frie 1996). Growth was calculated with the mean length for all fish of the same age. Condition based on relative weight was calculated for largemouth bass >150 mm long and spotted bass >100 mm long, using the formula Wr =

(W/Ws) x 100, where W = weight of the individual fish (g) and Ws = length-specific mean weight (g) for a fish as predicted by a length-weight equation for that species (Anderson and Neumann 1996).

Fall Electrofishing Surveys for Young-of-Year Bass A fall electrofishing survey was conducted in November at the same three locations as the spring survey and consisted of five 300-m shoreline transects at each location. Again, shallow flats where the boat could not access within 3-4 m of the shoreline were excluded.

All stunned bass were collected, identified to species, and individually measured and weighed. A year class "cut off' of 150 mm was determined for all black bass by examining length-frequency data.

Summer Striped Bass Mortality Surveys Mortality surveys were conducted weekly during July and August to specifically search for dead or dying striped bass in Zones 1-4. All observed dead striped bass were collected during these surveys and their location was noted. Individual total lengths were measured prior to disposal.

Striped Bass Netting Survey Striped bass were collected for age, growth, and condition (Wr) determinations in early December by Duke Energy (DE) personnel. Four monofilament nets (76.2 mn long x 6.1 m deep), two each containing two 38.1-m panels of 38- and 51-mm square mesh and two each containing 38.1-in panels of 63- and 76-mm square mesh, were set overnight in areas where striped bass were previously located. Individual total lengths and weights were obtained for 5-2

all striped bass collected. Sagittal otoliths were removed to determine age, growth, and condition (Wr), as described previously for largemouth bass. Additionally, all' catfish collected were identified and enumerated by species.

Fall Hydroacoustics and Purse Seine Surveys The abundance and distribution of pelagic prey fish in Lake Norman were determined using mobile hydroacoustic (Brandt 1996) and purse seine (Hayes et al. 1996) techniques. The lake was divided into six zones (Figure 5-1) due to its large size and spatial heterogeneity. A mobile hydroacoustic survey of the entire lake was conducted in mid-September with multiplexing, side- and down-looking transducers to detect surface-oriented-fish and deeper fish (from 2.0-m depth to the bottom), respectively. Both transducers were capable of determining target strength directly by measuring fish position relative to the acoustic axis.

Purse seine samples were also collected in mid-September from the downlake (Zone 1),

midlake (Zone 2), and uplake (Zone 5) areas of the reservoir. The purse seine measured 118 x 9 m with a mesh size of 4.8 mm. A subsample of forage fish collected from each area was used to estimate taxa composition and size distribution.

Crappie Trap-Net Survey Duke Energy personnel provided logistical support to the NCWRC during Lake Norman crappie population sampling in early November as described by Nelson and Dorsey (2005).

Crappie were collected with trap nets, identified to species, measured for individual total length and weight, and sagittal otoliths were removed for age and growth determinations.

RESULTS AND DISCUSSION Spring Electrofishing Surveys Electrofishing was conducted at water temperatures ranging from 14.6 to 20.0 'C. One thousand three hundred forty fish (19 species and two hybrid complexes) weighing 125.3 kg were collected in the MSS area, 1,673 fish (20 species and two hybrid complexes) weighing 77.8 kg in the REF area, and 1,563 fish (12 species and one hybrid complex) weighing 50.6 5-3

kg in the MINS area (Table 5-2). Overall, bluegill dominated samples numerically, while common carp, largemouth bass, and spotted bass dominated samples gravimetrically.

Total numbers of fish collected in spring 2007 were highest in the REF area, intermediate in the MNS area, and lowest in the MSS area (Figure 5-2). There is no apparent trend in the number of fish collected within or among areas since 1993.

Total biomass of fish was highest in the MSS area, intermediate in the REF area, and lowest in the MNS area, following the trend of previous years. This spring trend in Lake Norman fish biomass supports the spatial heterogeneity theory noted by Siler et al. (1986). The authors reported that fish biomass was higher uplake than downlake, due to higher levels of nutrients and resulting higher productivity uplake versus downlake. The spatial heterogeneity theory is further supported by higher concentrations of chlorophyll a, greater phytoplankton standing crops, and elevated epilimnetic zooplankton densities in uplake compared to downlake regions of Lake Norman (Chapters 3 and 4).

Spotted bass, thought to have originated from angler introductions, were first collected in Lake Norman in the MNS area during a 2000 fish health assessment survey. They have increased in numbers and biomass since 2001 spring electrofishing samples (Figure 5-3) and, in 2007, were most abundant in the MSS area, intermediate in the REF area, and least abundant in the MNS area. Biomass was highest in the MNS area, intermediate in the REF area, and lowest in the MSS area.

In 2007, small spotted bass (< 150 mm) dominated the black bass catch in all areas sampled (Figure 5-4), and their growth was generally similar among all areas sampled (Table 5-3).

Spotted bass Wr ranged from 66.4 for fish 100-.149 mm long in the MNS area to 85.5 for fish 350-399 mm long in the MSS area (Figure 5-5), Overall, spotted bass Wr values were highest in the MSS area (75.3), intermediate in the REF area (75.1), and lowest in the MNS area (71.6); a decrease relative to 2006 values (MSS=77.2, REF=80.7, MNS=77.4) and within the range of observed historical values (71.4-82.3) (Duke Power unpublished data, 2004, 2005; Duke Energy 2006, 2007).

Relative to 2006, 2007 largemouth bass numbers increased slightly in the REF and MNS areas and decreased slightly in the MSS area (Figure 5-6). Largemouth bass biomass increased in the MSS and REF areas and decreased in the MNS area. Numbers and biomass values at all locations were generally similar to 2006, the lowest recorded since sampling 5-4

began in 1993. As in most years, 2007 largemouth bass numbers and biomass were highest in the MSS area, intermediate in the REF area, and lowest in the MNS area.

Since 2000, largemouth bass >300 mm dominated the catch in all three sampling areas (Duke Power 2001, 2002, 2003, 2004, 2005; Duke Energy 2006), with largemouth bass < 150 mm low in abundance. An exception was in 2006, where a high abundance of largemouth bass <

150 mm occurred in the MSS area (Duke Energy 2007). In 2007, largemouth bass >300 were relatively abundant, but not dominant (Figure 5-4).

There was no trend in largemouth bass growth among areas in 2007 (Table 5-3); however, largemouth bass mean lengths for ages 2, 3, and 4 were generally higher beginning in 2003, relative to historical data (1974 - 78, 1993, and 1994)(Table 5-4). While displacement of largemouth bass since the introduction of spotted bass in the lower lake is apparent, the direct effect on largemouth bass recruitment is indeterminate, possibly due to confounding effects of other introductions including alewife and white perch (Kohler and Ney 1980, Madenjian et al. 2000).

Largemouth bass Wr ranged from 79.1 for fish 200-249 mm long to 89.9 for fish 300-349 mm long, both in the REF area (Figure 5-5). Overall, largemouth bass Wr values were highest in the MNS area (84.8), intermediate in the MSS area (84.6), and lowest in the REF area (82.5); a decrease relative to 2006 values (MNS=86.3, MSS=87.2, REF=88.0) and within the range of observed historical values (76.0-89.9). (Duke Power unpublished data, 2004, 2005; Duke Energy 2006, 2007).

Fall Electrofishing Young-of-Year Bass Surveys Fall 2007 electrofishing resulted in the collection of 109 spotted and five largemouth bass young-of-year (< 150 mm), compared to 95 spotted and four largemouth bass in 2006 and 94 spotted and 20 largemouth bass in 2005 (Figure 5-7). Additionally, no hybrid bass young-of-year were collected in 2007. As in 2005 and 2006, young-of-year black bass numbers were highest in the MSS area.

5-5

Summer Striped Bass Mortality Surveys In 2007, a total of 13 dead striped bass were collected during the July-August surveys (Table 5-5). Since the survey began in 1983, summer mortalities in excess of 25 dead striped bass occurred in three years: 163 in 1983, 43 in 1986, and 2,610 in 2004.

Striped Bass Netting Survey Dominated by age 1 and age 2 fish, 181 striped bass were collected in early December 2007 (Figure 5-8). Striped bass growth was fastest through age 3 and slowed with increasing age.

Additionally, mean Wr was highest for age 1 fish and declined with age. Mean Wr was 79.5 for all striped bass in 2007, within the range of observed historical values (78.5-84.1).

Growth and condition in 2007 were similar to historical values since consistent gillnetting began in 2003 (Duke Power 2004, 2005; Duke Energy 2006, 2007).

The December striped bass gillnetting also yielded 76 catfish. Blue catfish (63) dominated the catch, followed by flathead catfish (11), and channel catfish (2).

Fall Hydroacoustics and Purse Seine Average forage fish densities in the six zones of Lake Norman ranged from 1,338 (Zone 1) to 13,421 (Zones 5 and 6) fish/ha in September 2007 (Table 5-6). Zone 6 fish densities were assumed to be the same as Zone 5, as the shallow nature of the riverine Zone 6 limits habitat available for acoustic sampling. The lake-wide population estimate in September 2007, approximately 72 million fish, was within the range of annual estimates since 1997 and well above the lowest estimate of 47.1 million recorded in 2004 (Figure 5-9). As in most years since 1997, Zone 5 had the highest forage fish density estimates. No temporal trends are evident in lakewide pelagic fish population estimates in Lake Norman from 1997 through 2007.

Purse seine sampling in 2007 indicated that the forage fish population estimated by hydroacoustics was comprised of 98.3% threadfin shad and 1.7% alewives (Table 5-7). As in 2006, no gizzard shad were collected in the 2007 purse seine samples, and the modal length of threadfin shad was between 41 and 45 mm (Figure 5-10). Alewives were first detected in low numbers in 1999 and increased to approximately 25% of the pelagic forage fish community by 2002. The percent composition of alewives declined from 2002 to 2005, 5-6

increasing to approximately 5.1% in 2006, and down to 1.7%of the forage fish catch in 2007.

The overall increase and subsequent decrease in the percent composition of alewife was concurrent with an increase in the threadfin shad modal length class and subsequent decrease to values measured prior to the alewife introduction.

Crappie Trap-Net Study In 2007, NCWRC personnel set 90 overnight trap-nets in Lake Norman. They collected 350 black crappie and 24 white crappie. Various life history data were collected for use in fish management decisions.

FUTURE STUDIES In addition to the 2007 Lake Norman Monitoring Program surveys, DE will conduct biennial fall trap-net surveys with the NCWRC for crappies, with emphasis on age and growth.

Additionally, DE will conduct purse seine sampling in late June/early July 2008 to assist NCWRC in evaluating the changing forage fish community. These changes were approved by NCWRC in a letter dated March 7, 2008.

SUMMARY

In accordance with the Lake Norman Maintenance Monitoring Program for the MNS NPDES permit, specific fish monitoring programs continued during 2007. Spring electrofishing indicated that 12 to 20 species of fish and two hybrid complexes comprised fish populations in the three sampling areas, and numbers and biomass of fish in 2007 were generally similar to those noted annually since 1993. Largemouth bass numbers and biomass continue to decline in recent years and the 2007 numbers and biomass were some of the lowest recorded since sampling began in 1993. During 2007, the number of summer striped bass mortalities (13) and winter mean relative Weight (79.5) were similar to those of previous years.

Hydroacoustic sampling estimated a forage fish population of approximately 72 million in 2007, comparable to previous years. After an increase in 2006, purse seine sampling indicated a decrease in the percentage of alewives in 2007 to the lowest percent composition since their 1999 introduction. During 2007, threadfin shad lengths remained at pre-alewife introduction sizes.

5-7

Table 5-1. Common and scientific names of fish collected in Lake Norman, 2007.

Common name Scientific name Alewife A losa pseudoharengus Gizzard shad Dorosoma cepedianum Threadfin shad Dorosoma petenense Greenfin shiner Cyprinella chloistia Whitefin shiner Cyprinella nivea Common carp Cyprinus carpio Bluehead chub Nocomis leptocephalus Golden shiner Notemigonus crysoleucas Spottail shiner Notropis hudsonius Quil Iback Carpiodescyprinus Shorthead redhorse, Moxostoma macrolepidotum Blue catfish Ictalurusfurcatus Channel catfish Ictaluruspunctatus Flathead catfish Pylodictis olivaris White perch Morone americana Striped bass Morone saxatilis Redbreast sunfish Lepomis auritus Green sunfish Lepomis cyanellus Warmouth Lepomis gulosus Bluegill Lepomis macrochirus Redear sunfish Lepomis microlophus Hybrid sunfish Lepomis hybrid Spotted bass Micropteruspunctulatus Largemouth bass Micropterussalmoides Hybrid black bass Micropterushybrid White crappie Pomoxis annularis Black crappie Pomoxis nigromaculatus Tessellated darter Etheostoma olmstedi Yellow perch Perca flavescens 5-8

Table 5-2. Numbers and biomass of fish collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, March/April 2007.

MSS REF MNS Taxa No. kg No. kg No. kg Gizzard shad 9 3.93 10 4.89 1 0.49 Threadfin shad 292 1.75 Greenfin shiner 1 < 0.01 1 < 0.01 7 0.02 Whitefin shiner 43 0.27 20 0.08 Common carp 20 52:60 5 11.80 5 11.27 Bluehead chub 1 < 0.01 Golden shiner 2 0.01 1 < 0.01 Spottail shiner 14 0.17 42 0.30 2 0.01 Quillback 1 0.30 Blue catfish 1 2.25 Channel catfish 8 2.80 4 1.34 2 0.72 Flathead catfish 1 0.38 5 2.30 White perch 1 0.02 Redbreast sunfish 139 2.89 392 5.72 240 4.03 Green sunfish 51 0.81 2 0.02 Warmouth 23 0.19 52 0.30 26 0.17 Bluegill 713 8.08 895 7.88 830 7.72 Redear sunfish 113 10.93 98 8.12 51 4.18 Hybrid sunfish 63 1.71 40 0.73 30 0.73 Spotted bass 72 7.39 62 11.94 60 13.68 Largemouth bass 55 29.58 31 17.09 17 5.86 Hybrid black bass 5 1.92 3 0.50 Black crappie 5 1.64 5 2.21 Tessellated darter 1 < 0.01 2 < 0.01 Yellow perch 1 < 0.01 Total 1340 125.34 1673 77.81 1563 50.62 Table 5-3. Mean total lengths (mm) at age for spotted bass (SPB) and largemouth bass (LMB) collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, March/April 2007.

Age Taxa Location 1 2 3 4 5 6 7 8 9 10 11 SPB MSS 192 287 344 401 REF 175 307 378 421 410 MNS 193 314 389 390 LMB MSS 215 261 363 394 418 412 463 411 465 436 REF 186 285 371 367. 369 429 456 MNS 355 402 433 382 382 5-9

Table 5-4. Comparison of mean total length (mm) at age for largemouth bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS)-in Lake Norman, March/April 2007, to historical largemouth bass mean lengths.

Age Location and year 1 2 -3 4 MSS 1974-78a 170 266 310 377 MSS 1993b 170 277 314 338 MSS 1 9 9 4 b 164 273 308 332 MSS 2003c 216 317 349 378 MSS 2004d 176 309 355 367 MSS 2005e 190 314 358 396 MSS 2006' 184 347 346 408 MSS 2007 215 261 363 394 REF 19 9 3b 157 242 279 330 REF 19 94b 155 279 326 344 REF 2003c 139 296 358 390 REF 20 04 d 143 288 364 415 REF 2005e 139 307 357 386 REF 2006f 180 300 363 378 REF 2007 186 285 371 367 MNS 1971-78a 134 257 325 376 MNS 1993b 176 256 316 334 MNS 1 9 9 4 b 169 256 298 347 MNS 2003c 197 315 248 389 MNS 2004d 170 276 335 370 MNS 2005e 136 342 359 429

• MNS 2006f 169 308 361 402 IMNS 2007 - 355 402 433 aSiler 1981; bDuke Power unpublished data; c Duke Power 2004a; d Duke Power 2005;

'Duke Energy 2006; f Duke Energy 2007 5-10

Table 5-5. Striped bass mortalities observed in Lake Norman during weekly surveys during July and August 2007.

Date Number Zone Total length (mm)

Jul 2 5 1 562,602 4 464, 582, 590 Jul 9 2 2 550 4 520 Jul23 1 2 583 Aug 6 3 1 572, 580 4 586 Aug 30 2 1 608 3 465 Table 5-6. Lake Norman forage fish densities (number/hectare) and population estimates from hydroacoustic surveys in September 2007.

Zone No./ha Population Estimate

.1 1,338 3,052,557 2 3,176 9,789,539 3 5,461 18,871,072 4 4,531 5,577,740 5 13,421 28,264,588 6' 13,421a 6.415.229

• o Lakewide total 71,970,725 95% Cl 65,300,347 - 78,641,103 a Zone 6 fish density was assumed to be the same as Zone 5 5-11

Table 5-7. Total numbers and percent composition of forage fish, and modal length class of threadfin shad collected in purse seine samples from Lake Norman during late summer/fall, 1993 - 2007.

Species Composition Threadfin shad modal Year No. Threadfin Gizzard Alewife length class (mm) 1993 13,063 100.00% 0.00% 0.00% 31-35 1994 1,619 99.94% 0.06% 0.00% 36-40 1995 4,389 99.95% 0.05% 0.00% 31-35 1996 4,465 100.00% 0.00% 0.00% 41-45 1997 6,711 99.99% 0.01% 0.00% 41-45 1998 5,723 99.95% 0.05% 0.00% 41-45 1999 5,404 99.26% 0.26% 0.48% 36-40 2000 4,265 87.40% 0.22% 12.37% 51-55 2001 9,652 76.47% 0.01% 23.52% 56-60 2002 10,134 74.96% 0.00% 25.04% 41-45 2003 33,660 82.59% 0.14% 17.27% 46-50 2004 21,158 86.55% 0.24% 13.20% 51-55 2005 23,147. 98.10% 0.00% 1.90% 41-45 2006 14,823 94.87% 0.00% 5.13% 41-45 2007 27,169 98.34% 0.00% 1.66% 41-45 5-12

9 Electrofishing locations A Purse seine locations 5

4 A-A r"Zone 2

1 Y

I' Zone 1 Cowena Ford 0 1 2 3 Miles Hydro McGuire Nuclear Station Figure 5-1. Sampling locations and zones associated with fishery assessments in Lake Norman.

5-13

2000-.

1500--

200- [ MSS i 387b 180- m REF o] MNS 160-140--

120-100-j 80-Ia:

60-40-20-0 Year Figure 5-2. Total a) number and b) biomass of fish collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, 1993 - 1997 and 1999 - 2007.

• 5-14

140-120-Ei MNSI mREF a

100 E

0 80-I 0

ii z 60-Uo 40- K 20+

0 I 2001 2002 2003 I

I12004 2005

-I 2006 H-2007

-H Year 18 16 b

E12 14 F- I-K c) o 10

-C

-*8 u- 6 4

2 0 -I 2001 2002 2003 2004 2005 2006 2007 Year Figure 5-3. Total a) number and b) biomass of spotted bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF,MNS) in Lake Norman, 2001 -

2007.

5-15

45 1 M MSS

• REF a

40 +

o.MNS 35+-

30+

25+-

20 4-15-10+-

54-04-I

<150 150-199 200-249 250-299 300-349 350-399 400-449 >450 Length group (mm) 15-r []MSS

• REF b o] MNS 12t 9+

IN NIýýM NIN III 6+

IN III NX 3+

0 < 150 150-199 200-249 250-299 300-349 350-399 400-449 >450 Length group (mm)

Figure 5-4. Size distributions of a) spotted bass and b) largemouth bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, 2007.

5-16

20 100 *IMSSI

• IREFI a

[%i1MNJ F-

ý,M S70 I.-

a 60 k E

CO 50 I-

~0S40' co 30-20-10+

OI- j I rI.X- I*

, ,1 , I , I 100-149 150-199 200-249 250-299 300-349 350-399 400-449 >450 Length group (mm) 100 [MiS b REF 90+

IMNSI 80+--

70-cc a)

E 60+

cc 50-0 40+

E aD

2) 30-20-10-0- -i M l-F 150-199 200-249 250-299 300-349 350-399 400-449 >450 Length group (mm)

Figure 5-5. Mean relative weights (Wr) for a) spotted bass and b) largemouth bass collected from electrofishing ten 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, 2007.

5-17

300 250 IOMNSI

-, 200 E

0 150 u_ 100-0 CYea

.50-0

0) 0CD)0) 0 0 0 i-V r r N N NN4 20 10

"- 0 M I SO 8 N 0O ( ro Year Figure 5-6. Total a) number and b) biomass of largemouth bass collected from electrofishing ten 300-i transects each, at three areas (MSS, REF, MNS) in Lake Norman, 1993 -1997 and 1999 -2007.

5-18

120 -r g Spotted bass m Largemouth bass 100+ [3 Hybrid bass 80+

60+

40-20+I-0 -

2005 2006 2007 Year Figure 5-7. Total number of young-of-year black bass collected from electrofishing five 300-m transects each, at three areas (MSS, REF, MNS) in Lake Norman, 2005 -

2007.

700 90 650 85 600 80 550 i~i 500 75 450 70 400 65 350 300 60 1 2 3 4 5 6 7 8 9 Age Figure 5-8. Mean total length and mean relative weight (Wr) for striped bass collected from Lake Norman, December 2007. Numbers of fish associated with mean length are inside bars.

5-19

100

-U-I_ -4*-2 84 90--5 80 70-

• 50--

S40 30-20-10o_

0-1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Year Figure 5-9. Zonal and lake-wide population estimates of pelagic forage fish in Lake Norman, 1997 -2007.

500 450 400 350 300 ZO250 200 150 100 50 0 -- t -t  %

20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 Length group (mm)

Figure 5-10. Number and size distributions of threadfin shad (TFS) and alewives (ALE) collected in purse seine surveys of Lake Norman, 2007.

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