ML20246L880
| ML20246L880 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/31/1989 |
| From: | Ostrowski P, Woomer N, Wrenn W TENNESSEE VALLEY AUTHORITY |
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| ML20246L859 | List: |
| References | |
| NUDOCS 8909070056 | |
| Download: ML20246L880 (99) | |
Text
. _ _ - - _ _ - _ _ _ _
'y TENNESSEE VALLEY AUTHORITY River Basin Operations
)
i i
l A PREDICTIVE SECTION 316(a) DEMONSTRATION FOR AN ALTERNATIVE WTNTER THERMAL DISCHARGE LIMIT FOR SEOUOYAH NUCLEAR PLANT.
CHICKAMAUGA RESERVOIR. TENNESSEE TVA/WR/ AB- --39 /11 Chattanooga, Tennessee August 1989 8909070056 890730_.,
ppg ADOCK 05000h' FDC p
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4
. TENNESSEE VALLEY AUTHORITY-Resource Development-
.1 Nuclear Power t,
- A PREDICTIVE SECTION 316(a) DEMONSTRATION FOR AN ALTERNATIVE WINTER
- THERMAL-DISCHARGE' LIMIT FOR SE000YAH NUCLEAR PLANT.
- CHICKAMAUGA RESERVOIR.' TENNESSEE
- TVA/WR/AB--89/11 -
Prepared by l-William B. Wrenn and Neil M. Woomer Aquatic Biology Department Resource Development.
L Peter Ostrowski, Jr.
l and Walter L. Harper Engineering Laboratory Resource Development.
Edwin B. Robertson, Jr.
Environmental Protection Program Nuclear Power 4_ f Chattanooga, Tennessee
,(
. August 1989 ps
+
i i
EXECUTIVE
SUMMARY
l Section 316(a) of the Federal Water Pollution Control Act Amendments. of 1972 provides for alternative point source thermal limits.
The owner of a point source must demonstrate that the effluent limits intended for control of a thermal discharge are more stringent than necessary.to assure protection and propagation of a balanced, indigenous population of fish and wildlife.
If the appropriate regulatory' agency agrees 'with the demonstration, alternate limits -that will assure protection of such populations may be granted.
The present thermal limits for the discharge of cooling water from the Tennessee Valley Authority (TVA) Sequoyah Nuclear Plant (SQN) into Chickamauga Reservoir include a maximum temperature rise of 3 C' (5.4 F'),
applicable throughout the year.. Occasionally, f rom November through March, the weather becomes sufficiently cold that tiie only feasible way to meet this limit (short of derating the plant) is to operate the cooling towers.
Operation of the cooling towers under these extreme cold weather conditions can cause severe ice damage to the internal structure of the towers that must be repaired each spring to meet potential requirements for summer operation.
The purpose of this document is to demonstrate to the state of Tennessee that the existing temperature rise limit is more stringent than necessary to protect the balanced, indigenous population of fish and wildlife in Chickamauga Reservoir; and that an alternate rise limit of 5 C*
(9 F'), applicable only f rom November through March, will provide the required protection.
The present thermal standards for Tennessee were imposed: by the Environmental Protection Agency (EPA) at a time when the environmental effects of thermal discharges had not been fully studied and were not well known.
As a result, the thermal criteria reflect conservative safety factors that subsequent research has of ten shown overcompensated for that lack of background data.
The success of the 316(a) i demonstration fur alternative thermal criteria at Browns Ferry Nuclear i
ii Plant, which relied heavily on recent research, demonstrates the EPA thermal criteria initially imposed can be adjusted based on our current t
understanding of thermal effects.
l According to EPA, protection of balanced communities of aquatic organisms is best accomplished by protecting the most temperature-sensitive fish species judged important, desirable, or both.
The thermal rise criterion is included in the-standards to protect the reproduction-and winter survival of these important temperature-sensitive species.
Tennessee has identified sauger, threadfin shad, and white crappie as representative important species in Chickamauga Reservoir.
Therefore, reproduction and winter survival were evaluated for these species in the demonstration.
Tennessee has further identified other concerns relating to concentrations of fish in a heated discharge:
impingement, -fishing pressure and predation,
- disease, and sampling methods. Therefore, these concerns were also evaluated.
A general concern in setting thermal rise criterion for winter survival is potential cold shock.
Nuclear plant shutdown results in a relatively slow decrease in discharge temperature.
Fish mortality resulting from cold shock has never been reported following shutdown of any TVA power plant, nuclear or otherwise.
Where such fish kills have occurred at non-TVA facilities, the temperature decline was three to four times greater than the 5 C' (9 F') temperature rise being considered in this demonstration.
TVA's monitoring during operation of SQN has shown that there is minimal winter attraction of sauger to the SQN thermal plume, and little or no imp'ngement or increased fishing pressure in the vicinity of SQN.
It has also been shown that no sauger spawning occurs near SQN and that the only significant sauger spawning area in Chickamauga Reservoir is i
more than 35 miles upstream from SQN.
Threadfin shad are sensitive to cold and may be attracted to thermal discharge areas by thermoregulatory behavior.
Even though such attraction undoubtedly occurs at SQN, it is unlikely that this attraction would result in increased impingement, because the intake is well 1
l I
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iii upstream from the heated discharge.
The heated discharge could, however, have a positive effect on shad survival during very cold winters when massive shad die-of fs commonly occur af ter ambient temperatures drop to L-4 to $*C (39 to 41*F).
Attraction to the thermal plume could result in increased susceptibility to predation;
- however, the absence of a
concentrated sport fishery indicates a lack of large numbers of predator fish in the vicinity.
Most threadfin shad spawning occuts throughout the reservoir in April and May, a time when the ambient reservoir temperature is higt.er than the temperature in the warmest part of the thermal plume in late March.
This indicates that any advanced spawning caused by the proposed thermal rise limit would be minimal.
White crappie are widely distributed throughout the reservoir l
and show little attraction to the SQN discharge or to thermal discharges in general.
Spawning occurs almost exclusively in protected coves and embayments; very little spawning occurs in or along the main river channel.
Advanced spawning has not occurred under the present rise limit; and because the proposed additional rise would not alter the l
thermal plume to include primary spawning areas, no advanced spawning would be expected to occur.
Increased fishing pressure would not be expected to occur, because crappie are not attracted to the thermal discharge and therefore do not become concentrated in the thermal plume.
A decline in nun of adult crappie (and sauger) in Chickamauga Reservoir, documented by TVA in special targeted studies from 1986 through 1988, occurred during a time when no thermal discharges were occurring at SQN.
According to studies reported at two national symoosia on thermal ecology, discharges of condenser cooling water f rom power plants, regardless of the temperature rise, have not caused significant fish disease problems.
There is no evidence that such problems have c; curred or will occur at SON.
Lcw dissolved oxygen levels in the reservoir at SON originate upstream and are restricted to summer months when the reservoir is thermally stratified.
Because the reservoir is f ully mixed f rcm November I
l l
J
L iv through March and average dissolved oxygen levels are high throughout the water column,- the proposed increase in temperature rise limit would have s
little effect on' winter levels of dissolved oxygen downstream from the plant.
In any case, under average flow conditions, the water in Chickamauga Reservoir downstream from SQN is displaced in about two days.
Thus, any ef fect of SQN operation in March would pass out of the reservoir well before thermal stratification occurred.
Hydroacoustic. sampling has indicated some degree of fish attraction to both thermal and nonthermal (structural) factors in the vicinity of the diffuser discharge.
- However, observations to date indicate that exceptionally largs concentrations of game and prey species of any kind have not occurred there in winter.
i Computer simulations of worst-case plant operation show that under the proposed temperature rise limit the present 3 C* (5.4 F') limit would have been exceeded an average of 27 percent of the time (on an hourly basis) between November and March during the last 13 years.
Temperature rises larger than 4 C'
(7 F') would have occurred about 4 percent of the time.
Although TVA is not requesting that the existing i
j hourly compliance interval be changed at this time, it is important to
)
note that EPA's current recommendations for applying temperature criteria to protect fish growth, reproduction, and winter survival are based on maximum weekly average temperature conditions.
Consequently, hourly l
temperature measurements are extremely conservative, and hourly excursions above the present 3 C*
(5.4 F') limit, or the proposed 5 C*
(9 F*) limit, are not biologically significant.
For example, considering only 24-hour average temperatures for the period of
- record, the temperature rise downstream of SQN would only infrequently have exceeded 4 C' (7 F').
The present temperature rise limit at SQN can impose significant costs to TVA.
To meet the existing limit, TVA balances changes in hydro operations, the use of cooling towers, and plant load reductions.
Present operational schemes and a historical 12-year meteorological and river temperature data base were used to determine the econcmics of the present temperature rise limit.
An average of 1990 and 1995 SQN
{
l i
J
v operation costs and future power costs resulted in average yearly costs of. $635,000 to meet the present limit.
In addition to these operating costs, $16-20 million would be needed to modify the cooling towers to increase their resistance to ice damage; or yearly repair of ice damage would be needed which, based on experience with previous events, would cost $0.5-1.5 million.
vi l
l ACKNOWLEDGMENTS l
i The authors would like to acknowledge the important contributions of Wayne K. Wilson, Johnny P.
Buchanan, Gary D.
- Hickman, and Thomas A. McDonough to the biological portions of this demonstration; l
to Ming C.
Shiao for initial engineering studies on the hydrothermal I
ef fects of the diffuser discharge; Ogbo I.
Ossai, James A. Parsly, and Ellen B.
Speaks for aid in obtaining information and for computer processing of the physical reservoir data; and to Janis L.
- Dintsch, Charles B. Feagans, Jan S. Jensen, and Heinz-Dieter Waf fel for supporting 4
economic evaluations.
Acknowledgment is also extended to Bruce A.
Brye, Michael 1.
Friedman, Jan S.
Jensen, John R. Henson, and Robert J. Pryor for their critical review of the manuscript.
The authors wish to thank Donald J. Rucker for technical editing of the manuscript.
Finally, thanks to Cynthia M. Coker, Teresa s. McBee, Catherine J.
Patty, and Sheila S. Whittle for their help in word processing and editing the final copy, and also to Steven C. Bolden for final draf ting of figures.
l l
vii-CONTENTS Y
Page Executive Summary......:..,...................
i e
Acknowledgments..........................
vi' List of: Figures...........................
ix-s L
List'of Tables ix Introduction 1
- History of the-Development of Temperature Criteria.
for Sequoyah Nuclear Plant and Heat Dissipation System Issues................ -...........
4 Development-of Tennessee Temperature Criteria 4
Temperature Criteria Issues 5
-Sequoyah Nuclear Plant Heat Dissipation System........
7 Design Criteria.....................
8 Diffuser System.....................
8 L
Cooling Towers 10 Heat Dissipation System Operation Issues 11 Wintertime Operation 11 Biological Determination
'13 Fish Species Composition, Relative Abundance, and Sportfish Harvest 13 Temperature Requirements and Life History Aspects of Representative Important Species 17 Winter Survival 21 Reproduction.........................
24 Fish Concentration in the. Thermal Plume 31 Impingement.........
33-Fishing Pressure anc Predation 35 Disease.........................
37 Sampling Nethods 38 Status of Important Species 41 White Crappie......................
43 Sauger 44 Hydrothermal Aspects of Chickamauga Reservoir...........
47 Natural Hydrothermodynamics of Chickamausa Reservoir.....
47 Chickamauga Reservoir Geometry 47 Reservoir Elevations................
47 Longitudinal Geometry 47 Shallow Regions 50 River Flow and Residence Times 51 Historical Reservoir Operations 51 Potential Changes in Reservoir Operations 54
viii CONTENTS n
(continued)
Page Observed Natural Water Temperature Patterns.......
-54 Time Scales and Magnitudes of Variation 56-Temperature Patterns in the Main Channel......
56 Temperature Patterns in Shallow Regions 59 Fully Mixed Conditions at SQN 59
' Changes in Temperature Patterns Resulting From Potential Changes in Reservoir Operations....................
59 Hydrothermodynsmits of Chickamauga Reservoir Under Proposed Winter Temperature Rise Limit...
60 Description of Model for Diffuser Mixing 60 Results of the Diffuser Mixing Model 61 Effects of the Proposed Winter Temperature Rise Limit on Chickamauga Reservoir Downstream from the Mixing Zone............................
67 Thermal Limit Compliance Verification Techniques 69 Economic Evaluation of Alternative Thermal Limit 70 Cooling Tower Operation and Repair Costs...........
70 Economics of Meeting the Temperature Rise Limit Based on Available Historical Record............
70 Economics of Meeting the Proposed Temperature Rise Limit....
72 References 73 Appendices-79 A.
Frequency of Hourly River Flow at Seouoyah Nuclear Plant for t.h2 Winters 1976-89 79 B.
Frequency of Hourly Temperature Rises at Sequoyah Ncclear Plant for the Winters 1976-89........
82 L.
Frequency of 24-Hour Average Temperature Rises 6t Sequoysh Nuclear Plant for the Winters 1976-89........
85
i iX CONTENTS.
(continued)
Page LIST OF FIGURES 1.
Sequoyah Nuclear Plant Thernal Discharge Features '.......
9 2.
Ambient Daily Average River Temperatures Upstream From Sequoyah Nuclear Plant..................
32
- 3. -Reservoir Operating Guide Curve for Chickamauga Reservoir...........................
48 4.
Chickamauga Reservoir Depth Profile and Longitudinal Volume Distribution......................
49 5.
Typical River Flows at Sequoyah Nuclear Plant During Low and Average Flow Months 53 6.
Flow Duration Curves for Releases From Chickamauga Dam During March, Based on Reservoir Operation Planning and Review Simulations................
55 7.
Annual Water Temperatures at Sequoyah Nuclear Plant Intake, 1984 57 8.
Daily Variation of River Temperatures Upstream From Sequoyah Nuclear Plant 58 9.
Water Temperature Monitoring Stations Near Sequoyah Nuclear Plant.......................
62
- 10. Sequoyah Nuclear Plant Temperature Rise Simulations for January 1981 63 11.
Sequoyah Nuclear Plant Temperature Rise Simulations for February 1980.......................
64 LIST OF TABLES 1.
Common and Scientific Names'of Fish Collected from Chickamauga Reservoir Before and During Operation of Sequoyah Nuclear Plant, 1970-85 14 2.
Number of Samples and Mean Annual Standing Stock of all Young, Intermediate, and Harvestable Fish Collected in Cove Rotenone Samples from Chickamauga Reservoir,1970 Througt 1988 16 3.
Estimated Biomass Harvested by Anglers on Chickamauga Reservoir, Tennessee, January 1972 Through December 1987,.........
18 4.
Numbers and Biomass of Each Size Group of Threadfin Shad in Cove Rotenone Samples, Chickamauga Res?rvsir, 1970-88...........................
20
r----
x CONTENTS (continued)
Page j
i 5.
Densities and Mean Lengths of Crappie Larvae Collected at Three Transects in Chickamauga Reservoir, Spring 1986.........................
27 6.
Estimated Fish Impingement at Sequoyah Nuclear Plant 28 7.
Number of Targets Detected Per Cubic Meter by Transect-
'Ouring Hydroacoustic Surveys Conducted on Chickamauga Reservoir Near.Sequoyah Nuclear Plant, January 12 and February 7, 1989 -................
42 8.
Monthly Average River Flow Statistics at Sequoyah
' Nuclear Plant.........................
51
- 9. - Monthly Average Travel Times in Chickamauga.
Reservoir From Sequoyah Nuclear Plant to Chickamauga Dam.......................
52
- 10. Surface Heat Transfer Data for the Effect of
.Sequoyah Nuclear Plant on Chickamauga Reservoir.......
67 11.
Downstream Extent of Impact From the Thermal Plume From Sequoyah Nuclear Plant.
71
L A PREDICTIVE SECTION 316(a) DEMONSTRATION FOR AN ALTERNATIVE WINTER THERMAL DISCHARGE LIMIT FOR SE000YAH NUCLEAR PLANT.
n CHICKAMAUGA RESERVOIR. TENNESSEE INTRODUCTION Section 316(a) of the Federal Water Pollution Control Act Amendments of 1972 provides for alternative point source thermal limits.
The owner of a point source must demonstrate that the ef fluent limits intended for control of a thermal discharge are more stringent than necessary to assure protection and propagation of a balanced, indigenous population of fish and wildlife.
If the appropriate regulatory agency agrees with the demonstration, alternate limits that will assure protection of such populations may be granted.
l The purpose of a thermal discharge limit is for the protection and propagation of balanced, indigenous populations of shellfish, fish, and wildlife in the receiving water body.
According to protocol established by the Environmental Protection Agency (EPA), this is best accomplished by protecting the most temperature-sensitive fish species judged important, desirable, or both.
Sauger, threadfin shad, and white crappie were identified by Tennessee Wildlife Resources Agency (TWRA) and Tennessee Division of Water Pollution Control (TDWPC) as representative important species in Chickamauga Reservoir.
Therefore, these species are emphasized in this demonstration for a
winter (Novetaber-March) temperature rise limit cf 5 C' (9 F'), as oppc-sad to the present 3 C'
. l (5.4 F') limit, for the thermal discharge from TVA's Sequoyah Nuclear Plant (SON).
This assessmet t is based on preseret EPA guidelines for applying j
water' quality t.riteria for temperature, other 316(a) studies by the Tennessee Valley Authority ( fVA), results of the biological monitoring program for
- SQN, EPA-TVA cooperative research on development of temperature criter'ea, _ and the hydrother:ul conditions of the SQN heated discharge irsto Chickamauga Reservoir.
I
2 Water quality temperature criteria related to fish and aquatic life in trout and nontrout waters in Tennessee were established in the early 1970s.
For nontrout wate rs, such as Chickamauga Reservoir, the 4
main components of thermal discharge limits are:
maximum temperature, 30.S*C (86.9'F); temperature change (rise), 3 C' (5.4 F'), relative to an upstream control point; and maximum rate of change, not to exceed 2 C'/ hour (3.6 F'/ hour).
It is important to recognize that the temperature maximum and temperature rise are not functionally independent.
Previously, an independent relationship could have been inferred because guidelines for setting a temperature rise limit were not clearly defined in EPA's preliminary recommendations in 1971.
The purpose of the temperature maximum and temperature rise was later clarified in EPA's published recommendations for applying numerical temperature criteria for protection of freshwater fish (EPA,1976; Brungs and Jones, 1977).
However, requirements for a temperature rise limit, as now applied at SQN, were not included because other methods were thought to be more appropriate.
According to these recommendations, appropriate thermal discharge limits that protect important or desirable fish species should be established on the basis of (1) seasonal maximum temperatures for growth, reproduction, and winter survival and (2) survival of short-term, 24-hour, exposure to temperatures higher than those suitable for growth or reproduction.
Seasonal maximum limits are based on maximum weekly average temperature (MWAT).
In this approach, which emphasizes the importance of exposure duration (time) and season as well as temperature, a
temperature rise limit is not specified.
These recommendations fttrther emphasize that temperv.cre criteria should be applied with adequate understanding of the nornai seasons 1 distribution of the importar>t species.
Because elevated temperatures resaltitig fiom a thernal discharge are obviously a funcnon of the temperature rise, seasonal temperatures for gr uth, reproduction, or winter survival can be controlled by a temperature rise
- limit, especially during winter and spring.
A temperature rist limit also could be used to control the mar.imum temperature durii* summer; however, in the case of SON, the summer maximum is usually limited by the summer ambient temperature regime.
3 According to the most recent EPA recommendations, the 3 C*
(5.4 F*)
temperature rise limit was originally included to set, indirectly, seasonal maximum limits for reproduction and winter survival, a
whereas the 30.5'C (86.9'F) maximum limit was applied as the maximum summer temperature for growth.
However, the 30.5'C (86.9'F) maximum temperature limit frequently has been incorrectly interpreted as the upper limit for survival.
There are no provisions in the present Tennessee thermal criteria for a short-term maximum temperature limit for survival.
If there were such a limit, it would obviously have to be higher than 30.5'C (86.9'F) in the summer because fish survive higher l
water temperatures that occur f requently under natural conditions when l
there is no thermal discharge.
This 316(a) demonstration for SQN addresses only the temperature rise (change) limit, which is presently 3 C' (5.4 F').
It evaluates l
potential effects of a proposed 5 C*
(9 F*) temperature rise limit relative to seasonal requirements for reproduction and winter survival of the representative important species.
It also evaluates other conc?rns identified by the TDWPC and TWRA related to concentration of fish in a heated discharge, including impingement, fishing pressure and predation, disease, and sampling methods.
1 I
4 l
l HISTORY OF THE DEVELOPMENT OF TEMPERATURE CRITERIA FOR SEQUOYAH NUCLEAR PLANT AND HEAT DISSIPATION SYSlEM ISSUES The TVA Board of Directors authorized construction of SQN in August 1968.
Construction started in mid-1970.
Unit 1 began commercial operation July 1, 1981, and unit 2 began commercial operation June 1, 1982.. Both. units operated more or less continuously until August 1985, when both units were shut down because of safety concerns.
Unit 2 was restarted in May 1988, and unit 1 was restarted in January 1989.
An important consideration -in the initial planning of the plant was the design of a heat dissipation system that would allow efficient plant operation and at the same time protect the aquatic resources of Chickamauga Reservoir.
However, during the design and construction period, resolution of that issue was di/ficult because of a changing and uncertain basis for the development of temperature criteria.
As a result, when numerical criteria were eventually established, the heat dissipation system. required substantial retrofitting.
Simultaneously, further research was initiated to evaluate the appropriateness of the numerical criteria.
SQN-is located at approximately mile 484 of the Tennessee River (TRM 484) on Chickamauga Reservoir.
This segment of the Tennessee River is classified by the state of Tennessee for the following uses:
municipal, industrial and agricultural water supply; propagation of warmwater fish and other aquatic life; water-contact recreation; navigation; and the. final disr.osal of treated municipr1 and industrial
'~
wastewrter.
To proter.t the quality t.f water for thest uses, Tennessee I
has adepted various water quality criteria, incluGtr4 temperature cr;tt:ria.
Opvelopmen_t_of Ttnnessee Tencerature Criteria _
e 1
The Federe's Water Pollution Control Act, as amended by the Water
}
Quality Act of 1965, required tsch state to adopt water quality criteria for interstate waters and submit them to the Federal Water Pollution Control Administration (FWPCA) for approval.
At the time of the initial i
s 5
planning for SQN, Tennessee had submitted proposed temperature criteria to the FWPCA that called for a maximit.n temperature of 33.9'C (93*F) and a maximum temperature rise of 5.6 C' (10 F').
These criteria were similar to those being proposed to the FWPCA by other states in the Southeast, and son.? States had already received approval.
However, questions continued to arise about the adequacy of the temperature criteria, and the FWPCA rejected the Tennessee proposals.
In April 1971, FWPCA's successor agency, EPA, conducted a Water Quality Standards Setting Conference in connection with its announced intention to promulgate standards for Alabama.
A review of that conference is relevant here because the discussion of issues influenced
/
the outcome of temperature criteria debates in all states in the Tennessee Valley region, and because the debate illustrates the diversity of professional opinion and the f ragile technical basis upon which rests the present temperature criteria for these states.
Temperature Criteria Issues The 1971 Water Quality Standards Setting Conf erence of fered an y
opportunity for interested parties to present their points of view on Alabama's standards
- and, by extension, on regional water quality standtids in general.
The opinions expressed by the participants clearly indicated recognition of the potential impacts of the discharges of 1
I heated effluents to surface waters.
Numerous such impacts were cited, 1
l including mortality, reproductive impairment, increased toxicity of certain pollutants, reduced assimilative
- capacity, and shift of phytoplankton populations towari undesirtt e species.
Although all i
f participants agreed that temperature c,steria were necessary for l
protecting aquatic life, the degree of protection necessary was disputed.
The state of Alabama, Alabama Power Company, and TVA each supported the criteria of 33.9'C (93*F) maximum temperature and 5.6 C' (10 F*)
temperature rise favored by most of the regional
- states, l
including Tennessee.
They contended that natural stream temperatures f requently exceeded EPA's proposed 30*C (86*F) maximum without causing
- M/q eq Y
~
B 6
observable impact.
TVA cited experience with numerous heated discharges a
where both the 30*C (86'F) maximum and the 2.8 C' (5 F') rise were exceeded without causing adverse impact.
In addition, these groups cited g
the difficulties and high costs a wciated with the more stringent criteria.
They strongly urged EPA to car fully consider and balance all the water uses in developing criteria, g
At that time, two states adjoining Alabama (Georgia and Florida) l had received EPA approval for temperature criteria less stringent than those that had been proposed by Alabama and rejected by EPA.
The remaining states adjoining Alabama had proposed temperature criteria comparable to those proposed by Alabama.
Because Federal guidelines required that state standards be consistent and comparable with those of downstream or adjacent states, and because EPA rejected similar criteria proposed by the remaining states, EPA eventually withdrew its approval of the Georgia criteria and required the adoption of more stringent temperature criteria.
TVA suggested that, in view of the many ur. certainties regarding temperature impacts on aquatic life, the adoption of final temperature criteria should await completion of research in progress at TVA's Browns Ferry Biothermal Research Station.
This research had been proposed by TVA in 1967 as a means of obtaining an adequate data base for the
~
s development of temperature criteria.
EPA (and its predecessor) agreed to the need for such research, as evidenced by EPA's active participation in project planning and, beginning in 1970, their funding of a portion of the project costs.
In 1971 EPA's participation was formalized with the signing of a memorandum of agreement wherein TVA agreed to conduct a cooperative research program to investigate the effects of heat on aquatic life.
The preceding review illustrates the uncertainty and divergence of professional opinion during development of temperature criteria for the Southeast and the Tennessee Valley region.
Today, many years after the adoption of these criteria, unresolved questions remain.
These include questions about the temperature maximum and temperature rise e
cr*teria actually necessary to protect aquatic life, and about the proper
,n g
7 methods of applying such criteria.
The research completed at Browns Fe rr.v showed that the basis for many of the prior decisions made during the development of temperature criteria were questionable.
The results from this joint EPA-TVA research will be a fundamental basis for the present demonstration for SQN.
In 1983, TVA submitted to Alabama and EPA a demonstration for alternative temperature criteria for its Browns Ferry Nuclear Plant (BFN) on Wheeler Reservoir in north Alabama.
The BFN demonstration relied extensively on results of the joint EPA-TVA biothermal research.
As a result of the demonstration, the temperature criteria for BFN were revised from the 30*C (86*F) maximum temperature and 2.8 C' (5 F')
temperature rise criteria established following the 1971 EPA conference to a 32.2*C (90*F) maximum 24-hour average temperature, a 5.6 C' (10 F')
24-hour average temperature rise, a 33.9'C (93*F) maximum instantaneous temperature, and a 33.4*C (92*F) maximum temperature for any 6-hour period during a 24-hour period.
These alternative criteria for BFN apply throughout the year.
Both Alabama and EPA determined that these revised criteria would provide sufficient safeguards to protect the aquatic resources of the Tennessee River in north Alabama.
The economic effect of these alternative temperature criteria, which still provide adequate protection for the aquatic resources of the Tennessee River, is an average annual savings of more than $4 million (1983 dollars) wh,. the plant is operating.
Seouovah Nuclear Plant Heat Dissipation System The initial design of the heat dissipation system for SQN and subsequent modifications to it were discussed in detail in the final environmental impact statement (issued February 13,1974).
Certain aspects of the history are summarized here to provide continuity with l
events subsequent to the release of the final environmental impact statement.
I i
,2 8
Desion Criteria The heat dissipation system for SQN was originally designed and constructed to meet criteria permitting a maximum ter9erature of 33.9'C (93'F), a maximum rate of temperature change of 1.7 C* (3 F') per hour, and a maximum temperature rise of 5.6 C' (10 F').
These criteria were identical to those that had at the time been proposed to EPA by Tennessee as adequate to protect aquatic life and all other beneficial uses.
In Epplying these criteria, however TVA recognized in the early stages of plant design that the condenser water should not be discharged directly into the surface stratum of water in Chickamauga Reservoir.
Instead, TVA decided to discharge the heated water through a submerged diffuser system to speed initial mixing of the heated water with the river water and restrict the mixing zone to a relatively small area.
On December 14,197', the Tennessee Water Quality Board adopted, and EPA subsequently approved, the presently applicable temperature criteria.
TVA then determined that the diffuser system alone would not be adequate to assure acceptable compliance with these revised criteria.
Af ter evaluating a number of alternatives, TVA decided that the best long-term solution to meet the more stringent standards was to supplement the dif fuser system with two natural-draf t cooling towers.
Diffuser System At SQN, heated water is discharged either from the condensers or f rom the cooling towers directly into a 32-acre pond, f rom which it can either be recirculated to the intake canal or discharged to the reservoir through two diffusers.
Each diffuser line extends across a 600-foot wide overbank area into the 900-foot wide navigation channel and terminates in a 350-foot long diffuser section (Figure 1).
The downstream dif fuser pipe is 16 feet in diameter and extends 350 feet into the main channel; the upstream dif fuser pipe is 17 feet in diameter and extends 700 feet into the channel.
This leaves a 200-foot zone of passage in the side of the channel away from the plant. The diffuser pipes collectively contain about 12,000 2-inch ports, through which water is discharged for mixing t) with the reservoir water.
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Flow through the dif fuser pipes is controlled by the dif ference in elevation (i.e.,
driving head) between the dif f user pond and the reservoir.
At maximum pump capacity (three condenser cooling water (CCW) pumps per unit), the two dif fusers discharge a total of about 3,000 cubic feet per second (cfs) with a driving head up to 6.0 feet.
During fall, winter, and spring ? hen upstream temperatures are less than 13*C (55'F),
better plant perfot unce and protection of the low-pressure turbines warrants using two CCW pumps per unit to maintain suitable condenser turbine backpressure.
Maximum diffuser discharge for two CCW pumps per unit is a total of 2,000 cfs.
An underwater dam constructed of quarry rock is located about 250 feet upstream from the dif fusers. The crest of this dam is at elevation 654 feet above mean sea level (msl).
This dam retards upstream movement of the warm water layer formed during low reservoir flows and impounds cooler water in the lower layer of the reservoir to make it available at the plant intake.
Coolino Towers The condenser cooling water drawn frcm Chickamauga Reservoir can be routed back to the reservoir in one of three ways: (1) directly to the dif fuser pond and out the dif fusers (open mode); (2) through the cooling towers and then to the dif fuser pond and out the dif fusers (helper mode);
or (3) through the cooling towers and back to the intake canal (closed mode).
The cooling towers are used in the latter two modes when conditions are such that temperature criteria cannot be met by open mode operation.
Such conditions may occur during hot weather when tower operation may be required to meet the maximum temperature limit or during cold weather when the towers may be needed to meet the temperature rise limit.
However, because of plant design, closed mode operation during the sur.imer is not feasible.
The two CCW cooling towers at SQN are hyperbolic natural-draft design with external, cross-flow heat exchangers.
The towers are constructed of a
combination of
- precast, prestressed, and poured-in-place, reinforced concrete.
The 41 heat exchanger sections in each tower have concrete louver blades, polyvinyl chloride (PVC) fill,
11 and PVC drif t eliminate *s, with asbestos cement divider walls between the sections.
During cooling tower operations, hot circulating water is pumped to the hot water fiume's that circle the top of the heat exchanger.
The hot water is supplied to the to6 ers by a common pumping station. The hot water in the fiumes is dist,ibuted by spray nozzles over the fill material for cooling by evaporation.
Heat Dissipation System Operation Issues The cooling towers must be operated to meet the current temperature rise criterion during extreme cold wuather. This can lead is icing, which in turn can cause serious structural damage to the cooling towers.
Wintertime Operation The present temperature rise criterion of 3 C' (5.4 F*) cannot always be met by open mode operation during low river flow and cold weather.
TVA has three possible alternatives during those times:
reduce plant load, augment river flow, or operate the cooling towers.
Reduction of plant load is obviously an undesirable alternative at any time, especially when demand is high during cold weather.
It is not always l
possible to achieve compliance by augmenting reservoir flow, because the required amount of water may not be available in the reservoir system.
The third alternative, operating the cooling towers, is the least undesirable choice under the present circumstances.
However, operation of the cooling towers may cause ice damage to the towers, which must be repaired each year 50 that the towers can be operated at maximum efficiency to help meet the temperature limits.
l The crossflow design of the cooling towers can cause localized l
ice formation when air temperatures are below freezing.
During cold weather in 1984 and 1905, cooling tower cperations resulted in ice buildup that caused substantial damage to the PVC fill and concrete louvers of the towers.
No damage has yet occurred to the external supporting structure of the towers as a result of icing.
- ;; f ~; p L t
12 If the present 3 C* (5.4 F*) temperature rise limit remains in effect, TVA must either (1) repair the preseat damage and modify the towers to be more resistant to ice damage or (2) repair the present tower damage, be ready to run SQN in closed mode if icing conditions are forecast, and repair the damage each spring as needed to meet summer operation requirements.
Therefore, TVA is seeking to demonstrate that an increase in the temperature rise criterion f rom 3 C* (5.4 F*) to 5 C* (9 F*) f or November through March will assure the protection and propagation of a balanced, indigenous population of shellfish, fish, and wildlife in the receiving water, and thereby avoid or minimize the need for operating the cooling I
towers during this period.
l l
13 BIOLOGICAL DETERMINATION Fish Species _ Composition. Relative Abundance, and Sportfish Harvest Since starting monitoring studies on Chickamauga Reservoir in 1970, 73 fish species have been collected by various methods (Table 1).
Total standing stock estimates (number and biomass), derived f rom cove rotenone samples, have ranged from about 36,000/ha with a biomass of 187 kg/ha in 1980 to 46,000/ha and 528 kg/ha in 1985 (Table 2; TVA, 1986).
Typically, cove population samples have been dominated by a few species.
Through 1985, four species have exceeded 10 percent of the total number of fish caught:
bluegill, 44 percent; gizzard shad, 13 percent; threadfin shad, 13 percent; and redear sunfish,12 percent.
Biomass has been dominated by gizzard shad, 43 percent;
- bluegill,
~
9 percent; f reshwater drum. 8 percent; and common carp, 8 percent.
Mean percentage biomass of the representative important species in rotenone o
samples since 1970 has been threadfin shad, 4 percent, white crappie, 0.73 percent; and sauger, 0.07 percent.
In gill net
- samples, 14 species qualified as important (dominant) on the basis of the species occurring in 50 percent or more of samples and comprising at least 1 percent (number) of the catch. Again, only three species (gizzard shad, skipjack herring, and mooneye) ever comprised more than 10 percent of the catch (TVA,1985b).
In contrast to their relatively low occurrence in rotenone samples, the following species were common in gill net samples: skipjack herring, blue catfish, channel catfish, white bass, spotted bass, white crappie, and sauger.
A reservoimide creel survey, planned jointly by TWRA and TVA, has been conducted periodically before and during operation of SQN.
Also, f rom April 1982 through June 1985, TVA collected angler harvest data in the vicinity of the plant, TRM 482-485.6 (the SQN diffuser discharge pipes are located at TRM 483.6).
In the 1983 creel-year (July 1983-June 1984), an estimated 263,000 fish with a total biomass of 102,000 kg were harvested from Chickamauga Reservoir by sport fishing (TVA, 1986).
Estimated biomass harvested in 1984 declined to about 61,000 kg.
However, mean annual biomass harvested during the 5-year l
-14<
Table 1.
Common and Scientific Names
- of Fish Collected from Chickamauga Reservoir Before and During Operation of Sequoyah Nuclear Plant, 1970 to 1985.
b Gill Creel Meie7 Speeles Conmon name Group Rotonone not census nettino lethvomyron castaneus Chestnut lamprey C
X Polvodon spathula Paddlefish C
X X
Lepisosteus oculatus Spotted gar C
X X
Lepisosteus osseus 1.ongnose gar C
X X
Lepisosteus platostomus Shortnose gar C
X X
Alosa chrysochloris Skipjack herring C
X X
X Dorosame cepedianum Gizzard shed P
X X
X Dorosoma,potenense Threadfin shad P
X X
Hiodon terolsus Mooneye C
X X
X Ccmpostoma anomalum Stoneroller P
X Carassius auratus Goldfish P
X X
C orinus carpio Carp C
X X
X X
y htppsis storerlana Silver chub P
X X
Notemfoonus crysoleucas Golden shiner P
X X
X Notropis otherinoides Emerald shiner P
X X
Notropis buchanant Ghost shiner P
X X
Notropis chrysocephalus Striped shiner P
X Notropis cornutus Cortrnon shiner P
X Notropis emiIise Pugnose minnow P
X Notropis calacturus Whitetall shiner P
X Notropis spilopterus Spotfin shiner P
X Notropis volucellus Mimic shiner P
X Notropis whipplel Steelcolor shiner P
X Pimophales notatus Bluntnose minnow P
X X
Pimephales vicitax Bullhead minnow P
X X
Pimephales promelas Fathead minnow P
X Carolodes carpio River carpsucker C
X Xe Carolodes cyprinus Quillback carpsucLrr C
X Catostomus cornersoni White sucker C
X X
Hypentellum nioricans Northern hogsucker C
X X
letiobus bubalus Smallmouth buffalo C
X X
Xc Ictiobus evprinellus Bigmouth buffalo C
X letlobus nicer Black buffalo C
X Minytrema melanops Spotted sucker C
X X
Moxostoma carinatum River redhorse C
X X
Moxostoma duouesnel Black redherse C
X Moxostoma erythrurum Golden redhorse C
X X
Moxostoma macrolepidotum Shorthead redhorse C
X Igtalurus furcatus Blue catfish C
X X
X X
letalurus metas Black bullhead C
X X
letalurus natalls Yellow bullhead C
X X
letalurus nebulosus Brown bullhead C
X X
letalurus punctatus Channel catfish C
X X
X X
15 Table I (Continued)
P b
GIIi Creei Meter Speeles Common name Group Rotenone not census nettina Pylodictis oliverts Flathead catfish C
X X
X X
Fundulus notatus Blackstripe topminnow P
X Fundulus olivaceus Blackspotted topminnow P
X Gambusla affinis Mosquitofish P
X Labidesthes sleculus Brook silverside P
X X
Morone chrysops White bass G
X X
X X
Morone mississippiensis Yellow bass G
X X
X X
Ambloplites rupestris Rock bess G
X X
X Lepomis auritus Redbreast sunfish G
X X
Lepomis evanellus Green sunfish G
X Lepomis culosus Warmouth G
X X
Lepomis humills Orangespotted sunfish P
X Lepomis macrochirus Bluegill G
X X
X X
Lepomis meaalotis Longear sunfish G
X X
Leoomis microlophus Redear sunfish G
X X
X X
Micropterus dolomieu1 Smallmouth bass G
X X
Micropterus punctulatus Spotted bass G
X X
X Micropterus salmoldes largemouth bass G
X X
X Xc Pomoxis annularis White crapple G
X X
X X
PomoxIs nioromaculatus Black crapple G
X X
X Etheostoma esprioene Mud darter P
X Xc Etheostoma caeruleum Rainbow darter P
X Ethaostoma kennicotti Stripetali darter P
X Etheostoma spectablie Orangethroat darter P
X Perca flavescens Yellow perch G
X X
X X
Percina coprodes Logperch P
X Stirostedion canadense Seeger G
X X
X X
Aplodinotus crunniens Freshwater drum C
X X
X X
Stirostedion vitraum Walleye G
X X
Morone saxatills Striped Bass G
X X
a Taken from Conrnon and Scientific Names of Fishes, American Fisheries Society Special Publication No. 12, Fourth Edition, 1980.
b P = prey, C = conrnercial, G = game.
c Unidentified specimens within family or genus.
16 Table 2.
Number of Samples and Mean Annual Standing Stock of all Young, Intermediate, and Harvestable Fish Collected in Cove Rotenone Samples from Chickamauga Reservoir, 1970 Through 1968.
No.
Youno Intermediate Harvestable Total Year Samples No./ha kc/ha No./he kc/ha No./he kc/ha No./ha ko/ha 1970 12 7,353 12.61 534 24.80 951 182.49 8,819 219.91 1971 4
7,018 17.27 724 97.95 863 168.04 8,604 283.26 1972 4
12,872 63.06 932 30.96 I,394 271.21 15,199 565.23 1973 4
15,092 72.52 955 56.44 1,572 290.20 15,619 399.15 1974 4
9,737 54.25 673 21.98 1,263 194.91 11,673 251.13 1975 4
12,684 37.18 443 14.94 1,564 187.09 14,49i 239.21 1976 5
14,662 37.20 1,179 26.39 1,400 272.B4 17,241 356.43 1977 5
33,121 96.18 1,164 26.41 1,44l 223.97 35,981 346.56 1978 5
19,883 31.70 960 19.98 2,5B4 IBA.51 23,427 256.19 1979 5
17,973 22.91 1,375 27.41 2,872 209.04 22,220 259.56 1980 5
34,424 44.71 537 10.08 1,020 132.58 35,981 187.37 1981 5
53,515 66.21 1,590 54.14 2,278 327.68 57,583 428.03 1982 5
33,655 56.25 977 24.37 1,919 209.92 36,551 209.52 1983 5
46,500 70.74 1,209 26.60 2,513 544.07 50,223 441.41 19B4 5
24,814 43.58 937 22.47 5,545 383.25 29,296 449.50 1985 5
43,064 143.49 9B6 26.B8 2, 361 357.54 46,411 527.91 19B6 5
33,393 63.82 962 30.37 1,832 251.51 56,188 545.70 1987 5
43,547 89.91 1,420 26.96 1,677 233.85 46,644 350.72 1988 5
55,086 109.33 1,214 23.59 1,350 204.04 57,650 356.96 l
i l
17 4
l monitoring period af ter 'SQN began operating was 93,000 kg, compared -to a mean biomass of 68,000 kg. during the 6-year monitoring period before it f
. began operating.
The four dominant species (biomass) in 1983 and 1984
-were largemouth bass, channel catfish, blue catfish, and white crappie (Table 3),.
Largemouth bass comprised 28 percent of the total biomass
^
harvested in both years.
Overall, white crappie has dominated the harvest. but ' numbers and biomass harvested have been cyclic.
Harvest
' estimates for some species since 1984 are not directly comparable because TWRA changed the reporting period to the calendar year and made some programming changes.
These changes have resulted in some apparent omissions and changes in the database, which are being evaluated by TWRA and TVA.
Fishing pressure on Chickamauga Reservoir has increased significantly since ~ 1972, but yearly variations have been substantial.
Since 1976, annual fishing pressure has ranged from 273,882 hours0.0102 days <br />0.245 hours <br />0.00146 weeks <br />3.35601e-4 months <br /> in 1977 to 523,780 hours0.00903 days <br />0.217 hours <br />0.00129 weeks <br />2.9679e-4 months <br /> in 1983.
For the 6-year period before operation of SQN, mean annual pressure was about 337,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />; for the 5-year period during operation of 'SQN, it was 479,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.
Generally, the increase in fishing pressure has been reflected in lower harvest rates (number of fish per hour of effort) but higher total harvest (TVA, 1985b; 1986).
Temperature Requirements and Life History Aspects of Representative Important Species The fish community in Chickamauga Reservoir is dominated by warmwater species.
With the exception of the percids (e.g.,
- sauger, waileye, and yellow perch) and striped bass, all important game and commercial species are in this category.
Percids are generally recognized as coolwater species that occur in conjunction with both warmwater and coldwater species (Hokanson, 1977;
- Kendall, 1978).
According to a temperature classification of temperate-climate freshwater fish (Hokanson, 1977),
some of the distinguishing requirements that separate the three categories are as follows:
1
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19 Spawning Upper Lethal Classification
'C
'F
- C
'F P
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>34
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Although temperature requirements for sauger and walleye are similar, sauger 'is-the dominant of the two species in 'Chickamauga Reservoir.
Both species exhibit negative phototaxis (light sensitivity),
sauger more than walleye.
The dominance of sauger in mcinstream reservoirs of the Tennessee River system is attributed to. the relatively high turbidity of these waters (Schlick,1978).
Sauger prefer areas of moderate current over rock, gravel, or mixed rubble substrates. Although they may be found throughout the reservoir from late spring through summer, they apparently spend little time in areas of mud or silt substrate.
Sauger are highly migratory, and by Novemtier or early December they usually concentrate below Watts Bar Dam.
Also, they are known to frequent thermal discharge basins in the TVA system during autumn to spring (Wrenn, 1975).
However, creel surveys and gill net samples indicate attraction to the SQN discharse area during winter has been minimal.
Principal spawning areas in Chickamauga Reservoir, as in other TVA mainstream reservoirs (TVA, 1983; 1985b), are in the upper l
reaches.
In contrast to most warmwater
- species, which survive temperatures ' near freezing (less than 4*C, 39'F), threadfin shad are stressed at temperatures below 10'C (50*F), and temperatures below 4*C (39'F) are usually lethal (Griffith, 1978).
This schooling, planktivorous species is a desirable forage fish found throughout Chickaraauga Reservoir.
Intolerance of cold temperature, which f requently causes mass mortalities, coupled with a high fecundity rate, results in
' dramatic population fluctuations for this species.
This phenomenon is demonstrated in cove rotenone samples in Chickamauga Reservoir, where biomass estimates for this species have ranged from less than 1 kg/ha f rom 1978 through 1980, to 92 kg/ha in 1985 (Table 4).
However, some of the lower estimates may have been influenced by dense aquatic vegetation
(.
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i
.. Table 4 Numbers. and Biomass of-Each Size Group of Threadfin Shad in Cove Rotenone Samples, i
p:
Chickamauga Reservoir, 1970-1988.
a Youno of Year Intermodlate Adult Total l
No./he Ln/ha-No./he ko/ha fJo./ha km/ha No./ha kn/he l!
1970 ~
2,732.68 2.94 0.31-0.01 2,732.99 2.95 1971 3,351.72
- 7.19 0.00 0.00.
3,351.72 7.19 1972 8,094.18 41.72 52.33 1.46 8,146.51 43.18 1973 7,248.00 50.51 6.21 0.20 7,254.21 50.72
.1974 6,916.67 28.02 3.10 0.13 6,919.78 28,16 1975 3,906.97 23.05 122.96 4.07 4,029.94 27.12
'1976' 3,401.95.
11.75 0.00 0.00 3,401.95 11.75 1977 1,566.42 17.31 0.00 1
- 0. 0 1.566.42 17.31 0
1978 53.10 0.34 0.00 0.00 53.10 0.34
-1979' 363.60 0.80 0.47 0.01 364.06 0.81 1980 448.09 0.79 0.00 0.00 448.09 0.79 1981 3,294.25 8.29 0.00 0.00 3,294.25 8.29 1982
'368.97 1.00 1.43 0.03 370.40 1.03 1983-8,838.26 23.67 0.00 0.00 8,838.26 23.67 1984 866.60 2.13 0.00 0.00 866.60 2.13 1985 22,913.04 92.19 0.48 0.02 22,913.52 92.21 1986 4,912.88 8.64 0.00 0.00 4,512.88 8.64
'1987 12,454.17 18.07 0.00 0.00 12,454.17 18.07 1988 21,816.41 43.31 0.00 0.00 21,816.41 43.51 a No Intennodiate size class considered.
21
'in coves'.
In the absence of aquatic vegetation, Houser and Bryant (1967)
I reported. that cove standing crops were equal to open-water standing crops L
in' Beaver and Bull Shoals Reservoirs in Arkansas.
Threadfin. shad-apparently spawn throughout Chickamauga Reservoir, but spawning usually L
occurs at the surface in ficating debris or near the shoreline (Lambou, 1965).
Although temperature requirements for white crappie are similar to those for other centrarchids, Mathur et al., (1981) noted that white
~
crappie preferred lower temperatures than five other centrarchids for a given acclimation temperature. in laboratory tests for temperature preference.
Under field conditions during the summer, a temperature preference of 22 to 27*C (72 to 81*F) was reported for white crappie and
.27.8 to 29.B*C (82 to 86*F) for black crappie (Coutant, 1975).
Wnite crappie are distributed throughout Chickamauga Reservoir, but in late winter they usually concentrate in the larger creek embayments. Spawning occurs.in protected bays and coves and in shallow areas around islands.
Nest depths for white crappie are related to water clarity and are reported to range from 0.02 to 6 m.
White crappie prefer to spawn among
- stumps, roots, and along overhanging banks (Carlander, 1977; Vasey, 1972).
Winter Survival Seasonal maximum temperature criteria for growth, reproduction, and winter survival normally apply to temperature conditions in most of the receiving water body (outside the approved mixing zone).
Because fish may concentrate in a mixing zone, winter maximum temperatures within the mixing zone should be considered.
Fish congregating in thermal discharges of power plants can acclimate to elevated temperatures.
If the temperature of the discharge declines rapidly, these fish could be suddenly exposed to ambient temperature.
Responses of fish to this situation depend on the extent and duration of the temperature reduction and physiological condition of the fish.
At the extreme, cold shock (a condition characterized by disorientation, loss of equilibrium, or death)
22 can occur.
Fish are most. susceptible to cold shock when the temperature decline is too rapid to allow acclimation'to the lower temperatures and when -the fish are confined (for example, in discharge, channels or confined basins) so that they. cannot escape to areas with warmer
. temperatures.
If the ' temperature ' decline is small,. even immediate cooling can be tolerated unless lower lethal limits are exceeded.
In laboratory studies used to establish tolerance levels for low temperatures, fish typically are exposed to reduced temperatures almost
. instantaneously.
In contrast, nuclear power plants usually continue to discharge heated water for hours or days following shutdown, resulting in a gradual temperature decline.
Therefore, such laboratory studies do not accurately simulate-the conditions of power plant shutdowns and cannot be used to predict occurrence of cold shock.
Such laboratory studies should be viewed as " worst case" situations.
From various laboratory studies conducted to establish the relationship between acclimation temperature and tolerance for low temperature, Brungs and Jones (1977) concluded that the temperature rise should not exceed 10 to 13 C* '(18 to 23 F*) during winter.
Although specific laboratory studies have not been conducted for sauger and white crappie, tolerance levels reported for closely related species indicate that both sauger and white crappie can tolerate a temperature decline of 10 C* (18 F*) or more.
Smith and Koenst (1975) reported that walleye mortality did not occur until the temperature dropped 17.6 C'
(31 F*).
Both smallmouth bass (Horning and Pearson, 1973) 'and largemouth bass (Hart,1952) tolerated a temperature decline of 13 C*
(23 F').
During a series of long-term temperature experiments conducted by TVA in large, outdoor channels at Browns Ferry Nuclear Plant (EPA-TVA joint research project),
sudden temperature declines of 5 to 8 C*
(9 to 14 F*) in winter were tolerated by bluegill, f athead minnows, smallmouth bass, and white crappie (Wrenn, 1980, 1984; and Heuer,1983).
In Chickamauga Reservoir essentially all fish species except threadfin shad normally tolerate an annual temperature decline of 20 C' (36 F*) or more.
Unquestionably, threadfin shad would be the species most vulnerable to cold shock associated with a temperature decline in l
l
23 the SQN thermal discharge.
However, the situation for threadfin shad is more complex.
b According to Griffith (1978),
the most important factor influencing equilibrium loss (equated to mortality) for threadfin shad is the final low temperature, not the magnitude of the decrease.
He reported that, in laboratory tests, this species was stressed at temperatures below 10*C (50*F) but displayed no loss of equilibrium in test temperatures above 6'C (43*F); 50 percent of the threadfin shad died after the temperature remained at 5'C (41*F) for one day, and none survived exposure of 4*C (39'F) for three days.
Similar lower lethal limits have been observed under field conditions.
McLean et al., (1979) reported mass mortalities of threadfin shad in Watts Bar Reservoir when the temperature dropped below 4*C (39'F), but they noted that some threadfin shad survived in coves with groundwater seepage (9'C, 48'F) and in the Kingston Fossil Plant thermal discharge.
Griffith and Tomljanovich (1976) indicated that threadfin shad in TVA reservoirs could be exposed to temperatures that approached stress levels by late November, but that they apparently were able to tolerate these sustained low temperatures for several weeks or were able to follow gradients to areas with warmer temperature.
Historically, no fish mortalities have been reported following shutdown of any TVA coal-fired or nuclear generating plant.
Therefore, data from vario0s fishkills known to have occurred as a result ci shutdowns of other thermal discharges at non-TVA facilities were reviewed.
These data indicate that f reshwater fishkills occurred only when the temperature decline was extreme,16 C' (32 F') or more.
This suggests that the EPA nomograph (Brungs and Jones, 1977) may be conservative when applied to freshwater fish, l!nder the proposed maximum river temperature rise limit of 5 C*
(9 F') for November through March at SQN, cold shock would be unlikely for any fish species except threadfin shad.
Threadfin shad in most of Chickamauga Reservoir will be susceptible to naturally occurring cold shock regardless of the SON thermal discharge limit.
In relation to the much greater effect of the periodic occurrence of adverse winter
24-
- temperatures on this species throughout much of the reservoir, the possibility of cold shock from shutdown of SQN thermal discharge does not '
represent a significant additional impact on this species. Over the long e
term, raising the SQN thermal discharge limit would be expected to improve winter survival for threadfin shad because of the higher 5
temperature in the thermal plume.
Reproduction Temperature is important for initiation and completion of fish' spawning, and the potential for adverse impacts resulting. from power plant thermal discharges-has been recognized.
Because the influence of temperature on spawning depends on the thermal history of adults before the spawning period as well as on the temperature in the spawning area, thermal ' discharges that are restricted to zones outside of suitable spawning habitat would be expected to have little influence on fish reproduction.
Therefore, the chief remaining concerns are that higher temperatures might induce advanced (early) spawning or, at the other extreme, might remain sufficiently high throughout the year that they might inhibit or preclude spawning.
As long as the seasonal temperature I
cycle is not disrupted in waters that receive a thermal discharge, indigenous fish populations would be more likely to spawn early than not to spawn at all.
i Operation of SQN under the proposed 5 C* (9 F') temperature rise limit would not disrupt the normal seasonal temperature cycle in Chickamauga Reservoir and would not sustain temperatures at a level high enough to be likely to repress gonad development or inhibit or preclude spawning.
Therefore, the most likely impact of the proposed limit is the possibility of early spawning. and the related potential impacts.
It is these impacts that are emphasized in this assessment.
Advanced spawning by white crappie, bluegill, and smallmouth bass in elevated thermal regimes has been documented under temperature-controlled conditions in large, outdoor channels (Wrenn and Grannemann, 1980; Heuer et al.,
1983; and Wrenn, 1984).
In thermal
25 regimes 3 to 6 C* (5 to 11 F*) above ambient--encompassing the proposed discharge limit for SQN--spawning was advanced two to three weeks but occurred within the normal spawning temperature ranges reported for these species.
A general, undocumented concern regarding early spawning has been that newly hatched f ry may not survive because an adequate food supply might not yet be available or because the f ry might be exposed to greater extremes of low or high temperatures.
However, results of these experiments with bluegill and smallmouth bass showed that, although spawning can be advanced, similar changes occur simultaneously in the rest of the biological community (including spawning of other fish species).
Therefore, the supply of food organisms was not limiting for growth and survival of newly hatched fry.
Mathur and McCreight (1980) evaluated the ef f ects of the heated discharge (temperature rise of 5.6 to 11.1 C*, 10 to 20 F') f rom the Peach Bottom Nuclear Station on white crappie reproduction in Conowingo Pond (lower Susquehanna River) in Pennsylvania.
They found no evidence of earlier spawning in the thermal plume than in the ambient areas or during operation than before operation of the plant, as determin?d from gonosomatic ratios and larval fish catches.
Also, they noted that white crappie did not reside permanently in the thermal plume and that a discrete population was not acclimated to warmer water for extended periods.
- Likewise, white crappie showed little attraction to the Cumberland Fossil Plant thermal discharge during winter and spring and appeared to avoid the discharge during summer (TVA,1977).
Although the larval fish sampling phase for monitoring SQN was not designed specifically to assess early spawning, results of that monitoring before and during operation of SQN indicate that white crappie have not spawned early under a 3 C*
(5.4 F*) temperature rise limit.
Considering that a 2 C* (3.6 F*) increase in this limit would alter only a zone of the reservoir that is not a primary spawning area for white crappic, advanced spawning by this species would not be expected with a 5 C* (9 F*) limit from November through March.
The earliest date that crappie larvae were collected before the plant began operation (1971-80) was April 23.
During monitoring after the plant began operation, the
26 earliest, collection of crappie larvae was April 13. -1981.-
From 1982 3
through 1985, larvae were not present until the first week in May.
Overall ' the relative abundance of - crappie larvae 'in samples from the vicinity of SQN is low, 0.4-percent of all. larvae collected.
A supplemental study of white crapple reproduction in the l
vicinity of SQN was conducted in 1986.
The low numbers of crappie larvae L
in samples collected in the vicinity of the plant, as well as the concentration of adults usually observed in the larger embayments each spring, suggested that only limited spawning occurs in or along the main ri' channel.
For this study, larval fish sampling transects were es
,hed in the main channel near the SQN dif fusers (TRM 482.6) and
' downstream in the Dallas Bay area (TRM 480.8).
Embayment sampling stations were located downstream f rom SQN in Wolf tever Creek. Sixty-four samples were collected f rom April 29 to May 20.
Although crappie larvae were present at all three locations on all sampling dates, progressively higher densities and smaller mean lengths clearly-demonstrated that the embay'nent was the primary spawning area (Tables 5 and 6).
On May 20, when peak densities occurred, numbers of crappie larvae ranged from 3
3 32/1000 m at the diffuser transect to 414/1000 m in Wolf tever Creek embayment.
Laboratory and site-specific observations on the effect~ of elevated temperature regimes on sauger reproduction are not available.
However, because of the spawning temperatures and time of spawning for this species over its geographical range and because it is a
spring-spawner that requires a rising temperature regime for successful reproduction, advanced spawning by sauger would be possible in a thermal regime 5 C'
(9 F') above ambient.
Reported spawning temperatures and times of spawning vary from 15'C (59'F) in late March (southern latitudes) to 5'C (41*F) in early June (northern latitudes), with the lowest reported spawning temperature f rom North Dakota (Hokanson,1977).
As indicated by - the occurrence of larvae in ichthyoplankton samples, sauger in the Tennessee River system generally spawn f rom late March through mid-April at temperatures ranging f rom 12 to 15'C (54 to 59'F).
At these temperatures, corresponding periods for egg incubation would be about 12 to 8 days, respectively (Smith and Koenst,1975).
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ =
27 o
. Table 5.
Densities and Mean Lengths
- of Crapple Larvae Collected at Three Transects in Chickamauga Reservoir, Spring 1986.
Sarele Dates 1
4/29/06 5/6/86 5/13/86 5/20/86 Transect No./l.000 m3 (nsn) '
No./l.000m3(h)
No./l.000 m3 (h)
No./l.000 m3 (b)
Diffuser 16.6 6.5 15.2 5.5 19.9 5.5 32.1 6.5 l
l Dallas Bay 15.4 7.4 30.9 5.6 48.5 5.4 56.1 5.8 Wolftever Embayment 64.0 6.2 126.5 5.5 155.2 5.7 414.2 5.5 8 Mean length = ML l
i.l 28 l
Table 6.
Estlu ted Fish Impingement at Sequoyais Nuclear Plant.
a Connon Name 1981 1982 1983 1964 1985 Paddlefish 0
7 0
0 0
Lamprey 0
0 37 0
0 Chestnut lanprey 29 0
0 0
7 Shad, herring 0
0 183 0
0 Skipjack herring 73 149 270 1,221 1,089 Unidentified shad 0
0 0
70 0
Gizzard shed
-453 9,967 2,365 1,502 1,499 Threadfin shad 56,582 15,829 4,687 29,221 14,862 Rainbow trout 0
0 0
7 0
Mooneye 37 60 15 14 15 Minnow, carp 0
7 0
0 0
Carp 0
0 7
0 0
Silver chub 102 30 0
0 0
River chub 7
0 0
0 0
Golden shiner 153 15 15 7
0 Emerald shiner 22 7
22 7
7 Common shiner 0
0 0
0 15 Spotfin shiner 0
0 0
14 0
Mimic shiner 0
0 15 35 0
Bluntnose minnow 22 2 V.
37 126 0
Bullhead minnow 110 1%S 241 288 6 36 Spotted ocker 7
0 0
0 0
Golden redhorse 0
0 7
0 0
Blue catfish 102 127 146 175 102 Black bullhead 0
7 0
0 0
Yellow bullhead 7
7 7
0 0
Brown bullhead 0
0 0
0 7
Channel catfish 387 179 387 358 212 Flathead catfish 58 97 22 84 22 Mosquitoffsh 7
0 0
0 0
Unidentified temperate bass 0
0 0
0 7
White bass 51 782 95 267 44 Yellow bass 212 1,B62 350 821 1,214 Striped bass 0
0 0
7 0
Rock bass 0
0 0
0 7
Unidentified sunfish 0
37 0
0 7
Warmouth 153 45 37 56 37 Redbreast sunfish 51 97 7
84 22 Green sunfish 2,759 74 22 35 37 Bluegill 4,672 3,553 2,613 2,365 1,426 Longear sunfish 110 0
7 21 7
Rodear sunfish 256 216 73 161 66 Spotted bass 117 670 22 49 15 Largemouth bass 44 67 29 21 44
h 29 Table 6 (Continued) w a
L Comon Name 1981 1982 1985 1984 1985 White crapple 190 97 159 35 22 Yellow perch 445.
387 190
~140 66 Logperch 22 268 15 84 0
Sauger 22 7
7 0
0 Freshwater drum 2,759 5,706 2,891
.5,482 1,287
- Banded sculpin 0
0 0
7
.O Mixed unidentified minnows 0
0 0
21 0
Total
.70,022 40,947 14,958.
40,789 22,779
- Based on 212 days of Impingement as compared to 565 days for previous years.
~30 The general lack of gravel. substrate and the excessive water depths in the vicinity-of SQN. would preclude this zone' as a prime spawning area for sauger, regardless of the' thermal regime.
The a
1 concentrations of adults that' occur in the tailwater zone of Watts Bar Dam f rom December through, April of each year, just before the spawning period, and the low numbers of sauger larvae collected in the vicinity of SQN (in 1984, for example, only one sauger larva was collectvd) indicate
.that primary spawning areas are well upstream from SQN.
Gill ' net sampling since 1985, conducted as part of the revised aquatic monitoring program, has indicated that the Hunter Shoals area (TRM 521), 35 miles upstream.from SQN, is the primary sauger spawning location in Chickamauga Reservoir.
Extensive searching has failed to locate any other spawning areas in Chickamauga Reservoir.
Another potential impact of thennal discharges on percid reproduction has been-postulated in relation to a
chill-period requirement for gamete maturation in yellow perch.
Under laboratory conditions, Jones et al. (1977) reported that egg maturation of ' yellow perch was depressed severely if exposure to temperatures of 4 to 6*C
-(39 to 43'F) was less than 120 days.
Results from a laboratcry study (Barans and Tubb,1973) showed preferred winter temperatures to be 12 to 16'C (54 to 61*F) for this species.
Therefore, it could be concluded from -these laboratory results that yellow perch would be attracted to a thermal-discharge, which would limit or preclude exposure to the required chill period and adversely affect reproduction.
However, there are questions about the ecological relevance of a chill period at the level and duration reported from the laboratory study of yellow perch reproduction.
Although temperature requirements for sauger, walleye, and yellow perch are similar, no similar requirement of a chill period for gamete maturation has been reported for sauger or l
walleye.
Chickamauga Reservoir has an expanding yellow perch population; however, its ambient temperature cycle shows that temperatures below 6'C (43*F)~ are not likely to persist more than 80 days.
The same is true in other southern reservoirs that have yellow perch populations.
Clugston et al. (1978) reported that winter temperatures in Keowee Reservoir, i
31 South Carolina, seldom dropped below 8'C (46*F); nevertheless, yellow perch spawned successfully (at 10*C, 50*F, the same as for northern populations) and maturity indices for females were essentially the same e
as for those in northern states.
Spawning did occur about two months earlier in South Carolina than in northern waters.
Creel surveys and gill net samples show that neither yellow perch nor sauger have congregated in the SQN thermal discharge during winter.
Results rof telemetry studies in Mir.nesota showed that the mean winter temperature selected by yellow perch in the vicinity of a thermal discharge (temperature rise 15 C*,
27 F*) was 6.3*C (43*F) (Ross and Siniff, 1982).
Response to temperature varied greatly among individual fish, and they selected significantly lower temperatures in the field than those reported in laboratory experiments. The researchers concluded that f actors other than, or in addition to, temperature substantially influenced yellow perch spatial distribution in the field.
Because of the wide distribution of threadfin shad in areas of Chickamauga Reservoir with acceptable spawning habitat, the thermal discharge f rom SQN would not be expected to have an adverse impact on reproduction of this species.
Although threadfin shad undergo rapid ovarian development and have been observed spawning at temperatures as low as 15'C-(59'F) (Lambou, 1965), peak spawning normally occurs at 20 to 24*C (68 to 75'F)
(Swingle, 1969).
The ambient temperature of Chickamauga Reservoir is usually about 10 to 14*C (50 to 57*F) at the end of March (Figure 2); therefore, the proposed 5 C' (9 F*) temperature rise limit for November through March would provide only marginal spawning l
conditions for this species even in the warmest Zone of the thermal plume.
Although it is not possible to separate gizzard and threadfin shad larvae in the early stages (less than 20-m long), shad larvae of either species have not been collected in the vicinity of SQN until late May.
Fish Concentration in the Thermal Plume Within the context of the general concern expressed by TDWPC and J
TWRA regarding fish concentrating in the SQN thermal discharge, the 1
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33 following. points.'of particular concern will be addressed, with emphasis -
on the representative important species:
impingement, fishing pressure.
p and. predation,. disease, and fish sampling methods.
By definition, the SQN thermal discharge plume includes the approved mixing zone as well as n
any additional areas of the reservoir outside of the mixing zone (normally downstream) in which temperatures are altered by the SQN discharge.
As explained in the hydrothermal section of this report, under ' worst-case conditions ' hourly temperature rises within the mixing i
zone ' would exceed the nresent 3 C*
(5.4 F*) limit 21 percent, of. the Natural. mixing ' aused.by changes in river flow that occur over a time.
c day would limit temperature rises downstream from - the mixing zone to about '4 C'.(7: F*).
Because of the depth (15 meters,. 50 feet) of water in which the discharge dif fusers are located, vertical temperature gradients occur within the mixing zone, such that a 5 C* (9 F*) temperature rise at the. surface usually would not be realized throughout the ' mixing zone.
Therefore, we believe that under the increased temperature rise -limit proposed for. November through March, the actual f requency and duration of a' 5 C* (9 F*) temperature rise would be limited, and the volume and area of the-reservoir affected by such a temperature rise would also be limited.
Impingement The~ prrpensity of threadfin shad to concentrate in large numbers in thermal discharges during winter (Dryer and Benson, 1956; Adair and Demont,1971; Barkley and Perrin,1971; and Wrenn,1975) and to comprise
-the majority of fish impinged on power plant intake screens has been well documen'gd (Griffith, 1978).
However, treither the literature nor TVA's
. monitoring at various fossil and nuclear power plants provides evidence to link concentrations of. threadfin shad (or any other fish species) in the' thermal discharge with impingement.
Although both phenomena are related to water. temperature, the temperature and physiological i
relationships responsible for concentration are opposite of those responsible for impingement.
Higher impingement rates for threadfin shad during late winter, usually January and February at most power plants in
J 34 4
the Southeast,= have been associated 'with cumulative low-temperature j
stress that may begin in late November.
Concentration in the thermal discharge plume results from the ability of this species to locate and
~
L migrate into this
- zone, via thermoregulatory behavior, before its swimming ability is. impaired at temperatures below 9'C (48'F) (Grif fith v.d Tomljanovich, 1976; Grif fith. 1978).
Therefore.- because of the-absence of an upstream thermal gradient, higher impingement levels in Januiry or February would _not likely be caused by large numbers of threadfin shad c ving downstream in an attempt to locate the SQN thermal discharge.
Also, for fish that are acclimated to the thermal discharge, there is no physiological basis for them to move upstream through colder temperatures and concentrate near the SQN intake where they could be susceptible to impingement.
Although at SQN, impingement of all fish species is quite low throughout the year, the impingement that does take place occurs mostly during January.
No sauger were collected from the intake screens during the last two years of sampling,1984 and 1985.
Previously, the combined total estimated impingement of sauger from 1981 through.1983 was 36 fish (Table 6).
Impingement esti: nates for white crappie were - similar; 5 were sampled in 1984, yielding a total annual estimate of 35 impinged. Annual impingement of threadfin shad since plant operation began has ranged from about 4,000 (1983) to 57,000 (1981).
This is in contrast to 240,000 impinged at Kingston Fossil Plant (Watts Bar Reservoir) from November through April (McLean et al.,1979) and one million per day at Arkansas Nuclear One (Texas Instruments, Inc., 1976).
McLean et al., estimated that the 240,000 threadfin shad impinged at Kingston Fossil Plant represented about 2 percent of the Watts Bar Reservoir population, and they could determine no adverse ecological impact.
They concluded that the majority of threadfin shad, had they not been impinged, would have died f rom cold stress, because the ambient temperature was below 4'C
- (39'F).
l TVA assumes that some threadfin shad are seasonally attracted to the SQN thermal discharge, and TVA has recently attempted to estimate the numbers that may be present.
As indicated by the open-water location of I
J
35 the mixing zone, the relatively low temperature rise (usually less than 3 C*,
5.4 F*),
and the general lack of a concentrated winter sport fishery in this area, numbers of threadfin shad in the SON thermal discharge probably have not approached the concentrations observed at other TVA thermal discharges that are confined in basins or canals where the temperature rise is greater than 5 C*
(9 F').
Regardless of the number of thr2adfin shad that may be present in the SQN thermal discharge or attracted to it, in light of the fact that no attractive thermal gradient exists in the intake channel increasing the temperature rise limit to 5 C' (9 F') would not likely cause an increase in numbers of threadfin shad impinged upstream at the cooling water intake.
Fishing Pressure and Predation l
This demonstration considers the potential adverse effects of l
fishing pressure primarily in relation to the game species, sauger and white crappie, and considers the effects of predation primarily in relation to threadfin shad.
Historically, fish have commonly concentrated in thermal discharge canals or basins of TVA power plants, especially fossil-fueled plants.
Initial studies at these locations were limited to intermittent l
surveys, but they indicated a seasonal concentration of various species, intensive seasonal fishing pressure, and no mass mortalities f rom the ef fects of temperature dif ferences (Dryer and Benson,1956; TVA,1969 and 1973).
Later studies were more comprehensive, especially the 316(a) demonstrations condu:ted at fossil plants for permitting under the National Pollutant Discharge Elimination System (NPDES);
- overall, however, the conclusions of these studies were similar to those of previous studits.
No adverse impacts to reservoir fish populations were evident.
Winter concentrations of both gizzard and threadfin shad were common.
Dryer and Benson (1956) reported that the abundance of sauger and skipjack herring in the heated discharge f rom Johnsonville Fossil Plant (temperature rise more than 5 C', 9 F') on Kentucky Reservoir was directly related to numbers of threadfin shad during winter months.
I 36 During a 2-year investigation of the Colbert Fossil Plant discharge basin and, channel on Pickwick Reservoir, sauger, walleye, and skipjack herring also. occurred in conjunction with gizzard and threadfin shad concentrations in winter- (Wrenn, 1975).
Sauger and walleye were absent I
from the Colbert ' discharge channel in - summer but reappeared there in 1
November in phase with their usual appearance in tailwater areas below f
TVA dams.
Moderate to heavy fishing pressure has occurred at both of these plants, but it has been practically impossible to evaluate the 1
effect of harvest on the total reservoir populations of sauger or walleye.
There has been no attempt to determine the effect of predation on ' threadfin shad at these locations relative to the total population
-dynamics of.this species in the reservoir.
As noted previously, no concentration of fish or concentrated -
fishing pressure has b Wn. observed in the SQN thermal plume during winter.
The absence. of a concentration of predatory game fish may be associated with the absence of a concentration of prey fish such as threadfin shad.
The supplemental creel survey conducted since 1982 in the vicinity of SQN (TRM 482.0-TRM 485.6; SQN mixing zone, TRM 483.4-TRM 483.6), although not. designed to test the effect of fishing pressure within or outside of the mixing zone, has shown:
(1) blue and channel catfish are the primary species caught within the mixing zone or nearest.
the discharge diffusers during summer and to a lesser extent during winter, (2) most crappie are caught upstream from SQN near Skull Island, (3) bass fishermen generally are scattered within the whole area, and (4) there are reports.of a few sauger having been caught in the area but none have actually been observed in the creel survey.
1 The impact of fishing pressure, or more appropriately fish harvest, on the populations of various species in Chickamauga Reservoir is a complex issue that will require additional consideration in the future by TWRA and TVA.
Because of the temperature and habitat conditions at SQN, however, and as a result of previous observations at existing thermal discharges where the temperature rise is greater than 5 C' (9 F'), no adverse impact relative to fishing pressure on sauger, white crappie, or other species would be expected under the proposed 5 C' i
iq m
R
-(9; F') winter discharge limit.
Even if fish and fishing pressure were concentrated in-the thermal discharge, it would seem contradictory to s.ngle - cut fishing: pressure at'a thermal discharge as an adverse impact o
in view of the fact that the concentration of' fish and. fishermen in 3
tailwater areas z is generally recognized as desirable and in view of the f act that : both TVA.'and TWRA promote and endorse various fish attractor-projects.
Disease Fish disease. includes all health conditions' caused by pathogens
-(parasites, bacteria, and ' viruses) and adverse water quality conditions-(such as ' chlorine, dissolved gas supersaturation, and pesticides).
L Although' pathogenic organisms are present in all' water bodies, pathogenic disease is infrequently detected in wild fish and rarely causes mass mortalities (Strange, 1983).
Therefore, water quality is usually' the most important factor relative to-health of wild fish.
Condenser cooling water discharges from power plants, regardless of the temperature rise, have not caused significant problems _ of fish disease, as shown. by studies reported in the two national symposia c on therral. ecology.
An incidental occurrence 'of gas-bubble ' disease ' f rom supersaturation of dissolved gas (primarily nitrogen) in the discharge canal of Marshall Steam Station (temperature rise, 9.8 to 12 C',17.6 to 21.6' F') ' was reported by Adair and Mtins (1974).
However, Otto (1976) reported that gas-bubble disease did not occur at the Zion Station (temperature rise, 8 C',14 F') on Lake Michigan.
Eure and Esch (1974) noted a higher loading of helminth parasites in largemouth bass in the-
- heated zone of Par Pond (temperature rise greater than 10 C*,18 F'), and one species of trematode was higher in mosquitofish in this waterbody (Aho et al., 1976).
Naither of these studies indicated that~ differences in parasite levels caused significant adverse effects to the fish populations.
Evaluation of thermal effluent from Connecticut Yankee Plant (27 months monitoring before operation and 21 months during operation) showed no adverse effects on water quality or microbiology in the thermal plume (temperature rise in warmest zone of plume, 11 C',
20 F') (Rankins et al., 1974).
38 The. proposed increases in the temperature rise limit would have little effect on winter DC levels and might improve conditions near the bottom during the summer.
There are no reports of heated discharges from power - plants causing significant reductions in dissolved oxygen (00) levels in effluents.
As noted in this discussion, gas supersaturation is more - likely to te an issue.. Although low DO has occurred at SQN, this problem originates in upstream reservoirs and is associated with summertime thermal stratification rather than discharges of heated water.
Because of the fully mixed or isothermal conditions that prevail from November.through March in Chickamauga Reservoir, as well as the high rate of water exchange in this system (as discussed in the hydrothermodynamic section), low D0 has not occurred during that period under the present 3 C' (5.4 F') temperature rise limit. - The proposed increase in that-limit to 5 C' (9 F') would result in a loss of less than 0.4 mg/L 00 under average winter conditions, when D0 averages' about 9.3 mg/L.
- Outbreaks of f P disease have not been observed in conjunction with operation of SQN under a 3 C' (5.4 F') temperature rise limit, and none would be expected under the proposed 5 C' (9 F*) limit.
TVA monitored fish disease in thermal discharges in conjunction with 316(a) demonstrations for fossil-fueled plants and determined no adverse effects to fish f requenting thne discharges.
Also, during the series of tests conducted in outdoor channels (temperature rise 3 to 9 C', 5.4 to 16 F')
at TVA's Aquatic Research Laboratory (formerly the Browns Ferry Biothermal Research Station), no adverse effects of temperature on disease or water quality were observed.
Samplino Methods During preliminary discussions concerning this demonstration, TWRA and TDWPC expressed questions or concerns about whether the fish sampling methods used in the NPDES monitoring program for SQN were adequate to address the issues of fish concentration in the thermal plume and assessment of reservoirwide populations.
These issues are related; therefore, they are addressed concurrently.
39 The use of gill net sampling and cove rotenone sampling for estimating reservoir fish stocks was questioned in relation to impingement assessment and t; differentiating adverse impacts of SQN from other point or nonpoint sources.
As noted in the NPDES biomonitoring reports, selectivity of fish capture (by size, species, etc.) by both sampling methods places obvious limitations on the application of the data for precise population estimates.
Both methods essentially provide a measure of relative abundance.
However, the purpose for including each of these methods in the monitoring program was different.
Gill net sampling (one station 0.3 to 0.4 km downstream from the approved mixing zone, and control stations upstream and well downstream) was used to monitor near-field ef fects or changes f rom the thermal discharge.
Cove rotenone sampling and the reservoirwide creel surveys were used to monitor f ar-field conditions relative to the potential combined ef fects of plant operation (thermal, entrainment, impingement, and water quality).
Because of the high natural variability in size (by number or biomass) of reservoir fish stocks as well as the limitations imposed by sampling methods, TVA generally recognized that only major changes or impacts could be detected.
As concluded in the last two broad-coverage monitoring reports (TVA, 1985b; 1986), monitoring results (10 years before operation and 5 years during operation) have not identified significant adverse changes in fish stocks in Chickamauga Reservoir related to operation of SQN.
However, it may be assumed that, had major adverse changes occurred, it may have been difficult to identify the source without followup investigations.
Targeted monitoring studies have been initiated to evaluate the population status of individual, important fish species.
Other types of rish sampling gear and other sampling plans could be used to monitor fish populations in Chickamauga Reservoir.
Generally, each type of gear has some inherent selectivity as to the size or species of fish captured.
Although one type of gear may yield a larger sample of one or more species compared to another type, both can provide a measure of relative atandance that can be used to assess the population of those species for example, large Wisconsin-type trap nets.as well as gill
(
i 40 i
nets were used in moC toring before operation of SQN (TVA, 1978).
l Although trap nets yielded a larger number of white crappie than gill nets, both types of gear provided a relative abundance value.
Both trap net and gill net catches indicated a declining trend for this species f rom 1973 ' through 1978.
However, due in part to the variability in the total number of trap net lifts per quarter and in the interval of time between lifts, trap nets provided an inconsistent assessment of seasonal distribution for white crappie.
Therefore, gill net sampling, which had a consistent unit of effort and a greater number of observations within any given quarter, was selected as the most appropriate technique for evaluating seasonal distribution of white crappie and other species relative to operation of SQN.
In conjunction with the concern about unknown impacts of l
concentrating large numbers of fish in the SQN thermal plume or mixing
- zone, specific questions were asked about the use of hydroacoustic sampling.
Although hydroacoustic fish sampling is not a new technique, its capabilities have greatly expanded by recent innovations in equipment design and computer development.
This sampling technique is especially useful for quantifying numbers or biomass of pelagic species in deep waters.
However, because this technique identifies fish only by length, conventional methods of fish capture are required to verify species composition and to establish length and weight relationships for use in estimating biomass.
Another limitation of this sampling technique is its inability to detect fish near the surf ace and bottom areas.
Typically, optimum sampling conditions require transducer placement 1 meter below the surface, and there is also a bottom window (which blanks out returning signals) of 1 meter.
Fish cannot be detected in these two critical areas.
TVA began reservoirwide hydroacoustic sampling on Cnickamauga Reservoir in August 1987, and subsequent surveys were made in March and August 1988 and in February 1989.
A special survey was conducted in the vicinity of SQN on January 12,
- 1989, when both units were operating near peak load (2,089 MWe).
One unit (1,192 MWe) was generating during the February
41 1989 survey.
An additional variable during the January and February 1989 surveys was riverflow.
Floodgates were opened during the January survey, and the flow past SQN was about 60,000 cf s, compared to - a flow of 10,200 cf s through Chickamauga Dam during the March 1988 survey.
Although concurrent trawl sampling was not conducted for verification, results of the January and February surveys indicated higher target densities in the transect! downstream f rom the underwater dam and the SQN dif f users. compared to target densities immediately upstream, especially during January (Table 7).
In this case, fish may have been attracted to both thermal and nonthermal conditions in this area. Target densities in the February 1989 survey (full operation of one unit at SQN), as c. whole, were similar to those observed during March 1988 when the plant was not online.
Although hydroacoustic sampling may eventually provide a better l
quantitative estimate of fish concentration in the SQN thermal discharge than present
- methods, observations to date indicate that large concentrations of game and prey fish species have not occurred in winter.
On the other hand, known winter concentrations of fish at power plants within and outside the TVA system have seldom caused adverse impacts.
Winter concentration of fish in thermal discharges has been a common phenomenon, but definitive studies at various locations since the mid-1970s (including use of hydroacoustic surveys and radio telemetry) have shown that discrete populations of fish, especially predatory game species, do not reside continually in these areas and that temperatures selected by fish in these areas are usually intermediate between ambient conditions and the maximum temperature available (Neill and Magnuson, 1974; Minns et al.,1978; Ross and Winter,1981; Ross and Sinif f,1982; and Spigarelli et al., 1982).
Status of Important Species Having met the necessary NPDES permit requirements in 1985, as approved by EPA, TVA terrtinated several aspects of the broad coverage monitoring program that was originally designed to identify adverse 1
42 l
Table 7.
Number of Targets Detected Per Cubic Meter By Transect During Hydroacoustic Surveys Conducted 6n Chickamauga Reservoir Near Sequoyah Nuclear Plant, January 12 and February 7,1989.
j J
Survey Transect 95 Percent Transect Location Temperature Target Density Confidence Number (TRM)
('C)
(No./m3)
Interval January 1989 1
482.4 8.6 45.7 22.6 1A 482.9 11.4 6.6 18 483.3 8.9 32.6 10.5 2
483.4 19.4 10.2 3a 483.6 9.0 39.4 15.4 4b 483.8 7.8 36.0 16.2 4A 484.3 27.4 5.6 5
484.9 7.8 12.3 7.2 6
485.4 7.8 10.7 10.6 February 1989 1
482.4 9.5 10.1 4.2 2
483.4 10.5 13,2 13.9 3a 483.6 21.7 11.0 4D 483.8 6.2 4.6 5
484.9 8.5 7.7 2.8 6
485.4 8.5 3.3 2.0 a Transect located immediately downstream f rom the dif fuser area.
b Transect located immediately downstream f rom the underwater dam.
l 1
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4
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43 changes, both spatial and ' temporal, in water quality and biological communities f rom the operation of SQN (TVA,1986).
Although few changes were identified, a revised monitoring program has been continued since 1986 to address those changes that could potentially be attributable to SQN, as well as other issues of special concern that apply to Chickamauga 6
Reservoir as a whole.
Under this revised program, TVA initisted targeted investigations of population status and dynamics of sauger and white crappie that included additional sampling and data collection as well as further analyses of the existing database.
Annual internal progress reports have been prepared.
The following sections summarize the results through 1988.
White Crappie Since
- 1972, white crappie dominated the creel overall on Chickamauga Reservoir, but largemouth bass or channel catfish harvest (biomass) has been higher since 1982.
Wide fluctuations in estimates-of annual white crappie harvest have been common, and f rom 1982 through 19ES a declining trend was apparent, ranging f rom about 14,000 kg in 1982 to 8,000 kg in 1985.
Catch rates also declined.
During this period and through 1987, trend analysis of the rotenone data showed declining trends in numbers and biomass of both intermediates and adults but not for
. young-of-year white crappie.
Results of TVA's investigations since 1986 indicate that the declining trend for adult white crappie in Chickamauga Reservoir is not a result of unsuccessful spawning, because annual mean densities of larval crappie and numbers and biomass of young-of-year crappie in cove rotenone samples have increased through time.
Three factors have been identified as directly or indirectly affecting the white crappie population:
increased submerged aquatic macrophytes (sevenfold increase in acreage since 1974), competition with sunfish (lepomis) for food and habitat, and high mortality of crappie during their first winter from f ailure to attain sufficient size to switch successfully to a piscivorous-diet.
- Also, increased numbers and biomass of black crappie in creel and rotenone samples indicate that a total shift in dominance may be i
i 44 i
occurring between these two species.
If this occurs, increased numbers and harvest of black crappie may compensate for declining numbers of
{
white crappie.
- However, such declines may be only temporary:
the estimated white crappie harvest exceeded 20,000 kg in 1987 (Table 3).
TVA judges the potential for adverse impacts to white crappie from y
operation of SQN to be minimal.
Saucer Although sauger occur occasionally in rotenone samples, only 1
gill netting and creel surveys are ef fective sampling techteiques for this 1
species because of habitat preference and seasonal distribution.
Although no distinct trends in relative population abundance of this species could be discerned by gill net sampling before 1986, an obvious decline in harvest estimates from creel-surveys in 1979 through 1984 (Table 3) was of special concern to TWRA.
Harvest estimates (biomass) increased-during 1985 and 1986 and slightly declined in 1987.
However, a new method of calculating harvest estimates, initiated by TWRA in 1984, resulted in much higher estimated harvest, even though the actual numbers of-sauger creeled were similar in both study periods.
In cooperation with TWRA, TVA initiated an intensive program in 1986 that included gill net sampling and tagging (mark and recapture) to
~
evaluate further the sauger population in Chickamauga Reservoir.
Results of these investigations have provided important information on population density, distribution and movement, and timing and location of spawning.
Before spawning, sauger congregate below Watts Bar Dam f rom early February until late March.
As water temperature approaches 11'C (52*F), most adult-male sauger move downstream 7 miles to the Hunter Shoals spawning area and remain there until early May.
Females wait until imminently ready to spawn, move onto the spawning area, spawn, and leave the area within a few hours.
Spawning activity is hi:thest at the end of March and continues about two weeks into April, depend ng on water temperature.
After spawning ceases, sauger generally disperse both upstream and downstream.
Annually,15 to 20 percent of the adult sauger move between Chickamauga and adjacent reservoirs.
Considering this level
45 of integration of reservoir sauger populations, it is evident key spawning areas in one reservoir may supply or supplement sauger year classes in other reservoirs.
Estimated numbers of adult sauger migrating to upper Chickamauga Reservoir declined from about 18,000 fish in 1986 to less than 1,300 fish e
. an 1988.
Total harvest rates remained stable over the 1986-88 period (5 to 8 percent), indicating that fishing pressure is not a significant cause of decreasing sauger abundance.
The main reasons for declining abundance from 1986 through 1988 were the weakness of the 1985 and 1986 year classes and the normal high mortality of older age classes.
Water temperature, especially a gradual rise, was the only condition correlated with progression of spawning maturity and time of
{
spawning.
The operation schedule of Watts Bar Dam is an important influencing f actor on water temperatures in the sauger spawning area of upper Chickamauga Reservoir.
Consistent releases f rom the dam result in less variation in downstream water temperatures.
Fluctuations in releases and downstream ambient water temperature during the 1986 sauger spawning period delayed both sauger maturation and spawning activity to the extent that water temperatures may have reduced gamete viability and egg survival.
Gradual warming during the 1987 spawning season produced more sustained spawning activity at lower temperatures.
Because yearling sauger are generally not collected during winter and spring sampling in reservoir headwaters,
- however, the first definitive information on success of the 1987 sauger spawn will be provided by sampling in 1989 and 1990.
Reduced turbidity is considered unfavorable for reproductive success of sauger and may be the most important f actor af fecting the apparent decline in the sauger population in Chickamauga Reservoir.
However, the effect of high turbidity could not be evaluated as a factor influencing spawning success because the severe drought during the three years of study resulted in consistently low turbidity.
Also, other TVA studies indicate that the drought in the 1980s affected sauger densities or reproductive success in other locations, especially in the Clinch River arm of Watts Bar Reservoir and in Fort Loudoun and Wheeler Reservoirs.
1 i
46 Although~ the most recent ' harvest' estimates based:.on creel surveys are-not consistent' withL the mark-and-recapture, population estimates for ; adult sauger, results. of-. : the revised 1 monitoring ' program' definitely -indicate that the 'sauger population is >well' below historical-l levels.
Winter thermal ' discharge from SQN is not considered: to. be' a-factor Nthis decline.
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47 HYDROTHERMAL ASPECTS OF CHICKAMAUGA RESERVOIR The natural hydrothermal conditions of Chickamauga Reservoir from November through March are characterized by descriptions of reservoir geometry, river flow, and water temperature.
The potential o
effects of an alternative wintertime thermal rise limit were evaluated by use of simulation models and historical monitoring data for river flow and temperature.
Natural Hydrothermodynamics of Chickamauga Reservoir Chickamauga Reservoir Geometry Reservoi r Elevations--From November through Ma rch,
reservoir levels are normally at winter or low pool elevations, near 675 feet ms1.
Figure 3 shows the operating guide curve for Chickamauga Reservoir.
During November, the reservoir is drawn down for flood control, in anticipation of winter runof f.
By mid-November the reservoir elevation l
is in the usual winter fluctuation range, with 675 feet ms1 targeted from January 1 through April 1.
l Longitudinal Geometry--Chickamauga Reservoir extends 58.9 miles (94.8 km) f rom Chickamauga Dam (TRM 471.0) to Watts Bar Dam (TRM 529.9).
The SQN intake is located at TRM 484.5 (right bank).
The depth of the main channel shown in profile in Figure 4A increases between Watts Bar Dam and SQN, where the maximum channel depth is approximately 50 feet at low pool.
From SQN, the main channel depth at low pool increases to a maximum of 65 feet at Chickamauga Dam.
Reservoir width follows a
similar pattern of downstream increase.
The reservoir is narrow and riverine with occasional embayments from Watts Bar Dam to the vicinity of Hiwassee River embayment (TRM 500). The reservoir width and cross-sectional area increase between the Hiwassee River embayment and Chickamauga Dam.
In this reach, the reservoir includes shallow overbank areas with depths of 5 to 8 feet.
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A.
Chickamauga Reservoir Profile TENNESSEE RIVER MILE 470 480 490 SUMMER POOL 510 520 530 I
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lI py 207-680 -
o-hWAT T PERATURE 204 -
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h E 201-E660 UNDERWATER h650 o
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630 NU LEAR 18 9 -
620 HiWASSEE WAT BAR CON L ENCE 610 SEQUOYAH NUCLEAR PLANT B.
Longitudinal Volume Distribution From Watts Bar Dam CHlCKAMAUGA DAM 700 -
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20 TRM 484.5
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.C INTAKE
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Figure 4.
Chickamauga Reservoir Depth Profile and Longitudinal Volume I
Distribution.
l 50 SQN is located ~ within the segment of reservoir -having both a deep main
]
channel and shallow overbank areas.
The downstream portion of l
Chickamauga Reservoir is deep and relatively wide with significant
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overbank areas.
The cross-sectional area above the Hiwassee River embayment is comparatively small, gradually increasing downstream towards SQN and
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further increasing towards Chickamauga Dam (Figure 4B).
The different cross-sectional areas affect flow velocities and patterns at these j
reservoir locations.
The upstream portion of the reservoir has higher velocities, which provide a great deal of turbulence and usually result in full mixing.
Velocities in the downstream portion of Chickamauga Reservoir are lower. because the cross-sectional area is greater.
Turbulent mixing decreeses as velocity decreases.
However, slightly higher reservoir velocities in the winter, caused by low pool elevation, higher average flows, and normal cooling conditions, promote full mixing from November through March.
Shallow Regions--The shallow portions of Chickamauga Reservoir can be divided into embayment areas partially isolated f rom the main reservoir, shallow areas near shore along the main channel in the riverine reaches, and overbank areas along the main channel.
Embayments are often quite
- shallow, with mean depths of 3 to 6 feet, and ' are relatively isolated f rom the main channel flow.
When fully mixed, embayments can cool rapidly in response to changing weather because of their large surf ace area relative to their volume (low mean depth).
Embayments downstream f rom SQN may also contain slightly cooler water from runoff that has not been affected by the thermal discharge.
The shallow areas near the main channel in the riverine reaches are directly influenced by the main channel flows and temperatures.
Overbank areas, such as those between the Hiwassee River embayment and Chickamauga Dam (both upstream and downstream of SQN) behave in a manner intermediate between embayments and main channel bank areas.
Flow may be much lower in these overbank areas than in the main
51 channel, allowing the temperature response to approach that of isolated embayments.
When the reservoir is fully mixed from November through March, temperatures in shallow areas are very similar to those in the main channel, although the shallower areas may respond n'o re quickly to changing weather.
River Flow and Residence Times Historical Reservoir Operations--Insta ntaneous river flows in the vicinity of SQN oepend upon previous discharges fron Watts Bar Dam (TRM 529.9), 45.4 miles upstream, and f rom Chickamauga Dam (TRM 471),
12.5 miles downstream.
The dams are normally operated for peaking power, and releases are reduced during the early morning hours when power demand is low.
The 1976-88 annual average release at Chickamauga Dam was 29,787 cfs.
Reservoir inflows from the Hiwassee River are of secondary importance, because the mean annual flow was 4,719 cf s for 32 years of record.
Because flows through Chickamauga Reservoir af fect the mixing and travel time through various reservoir segments, flow conditions must be considered in evaluations of temperature patterns in the vicinity of SQN.
A 1-dimensional, unsteady state, numerical flow-routing model (Ferrick and Waldrop,1977) was used to determine hourly flows at SQN on the basis of hourly discharges f rom Watts Bar and Chicksmauga Dams for 1976-88 (Table 8).
Table 8.
Monthly River Flows at Sequoyah Nuclear Plant, 1976-88.
Average Monthly Flow Cumulative Minimum Maximum Flow Years Flow Year Flow Year Month (cfs)
(cfs)
(cfs)
Nov 25,100 1976-88 15,400 1978 55,800 1979 Dec 32,700 1976-88 12,800 1987 69,700 1977 Jan 36,000 1976-88 15,900 1981 63,900 1979 Feb 34,000 1976-88 22,300 1977 73,200 1982 Mar 30,700 1976-88 11,900 1988 72,200 1979
52 Residence, times from SQN to Chickamauga~ Dam were estimated by
. displacing the cumulative volume.of water contained in the reservoir at low wi'nter pool elevation.
This volume was divided by the historical flows to provide residence times in days (Table 9).
Table 9. ~ Monthly Average Travel Times.in Chickamauga Reservoir E
'From Sequoyah Nuclear Plant to Chickamauga Dam.
Monthly Average Residence Time. Days Month Cumulative Maximum Minimum Nov 3
5 1
Dec
.2 6
1 Jan 2
5 1
Feb 2
3 1
Mar 2
6 1
Under average flow conditions, water in Chickamauga Reservoir downstream from SQN is displaced in about two days.
At the lowest monthly flows in the. historical record, residence time varied f rom three to six days. Any effect of SQN operations from November through March passes out of Chickamauga Reservoir well before the summer.
River flows near SQN vary significantly during the course of a day as a result of peaking operations at the upstream and downstream dams.
Figures SA and SB show typical flows at SQN during months of low and average river flow.
Hydro operation on a given day consists of zero release from the dams during the night.
When the demand for electricity picks up, releases f rom the dams are used to meet peak demand periods.
The dams release in increments of about 8,000 to 10,000 cfs in the normal range of ef ficient operation; therefore, flows during 'the day can range from 8,000 cfs to about 40,000 cfs at full hydro output.
Spilling conditions during extremely wet years can cause higher flows.
The daily fluctuations in dam releases can also cause reverse flows (sloshing) at SQN when releases are stopped at night.
Appendix A shows a breakdown of hourly flows from November 1976 to March 1989. The minimum daily average flow at - SQN for November through March has been between 5,100 and 6.300 cfs for 1976-89, based on the present minimum average daily flow l
constraint of 6,000 cfs from Chickamauga Dam.
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54 Potential Chances in Reservoir Operations--TVA is conducting a Tennessee River and Reservoir System Operation and Planning' Review, primarily to ' determine whether and what changes could or should be made to reservoir operations.
Greater minimum triuutary dam release flows and higher tributary _ lake levels are being considered as well as changes to i
4 releases f rom mainstream dams.
Changes in reservoir operations could affect the November - through March period and the historical flow data used in the evaluation (Miller and Parsly,1989).
Potential minimum release flows would probably not sffect releases at Watts Bar and Chickamauga Dams from November through March.
A review of the modeling data from reservoir operation simulations showed essentially no effect of minimum release scenarios compared to the present (base case) operation.
Most of the minimum flows were modeled at weekly intervals.
Variations within the week may be similar to those that now occur.
Keeping tributary reservoirs at higher pool levels into the summer would affect flows at SQN from November through March.
In:
general, dam releases would be slightly higher in November and December, about the same in January and February, and lightly less _in March.
Figure 6 shows a flow duration curve for March at Chickamauga Dam for modeling simulations that compared present operation (BASES) with the JULY 29 lake level case.
The JULY 29 simulation case targeted lake levels to a selected value until July 29.
Lower flow occurrences increased by up to 7 percent during March when aggressive reservoir filling occurred.
Potential changes in reservoir operation policy (TVA, 1989) will be made available for public review and more study before adoption.
The effect of potential reservoir operation changes on the thermal conditions at SQN is discussed 'in a later section of the report.
These potential changes, should they occur, would not be expected to alter the conclusions of this 316(a) demonstration.
Observed Natural Water Temperature Patterns The temperature patterns observed in Chickamauga Reservoir are
(
constantly changing in response to varying flow and meteorological l
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56 conditions. ' Records of winter water temperature patterns are based on data from the SQN thermal monitoring network.
W Time Scales and Magnitudes of' Variation--Chickamauga Reservoir undergoes the annual cycle of temperature change typical of controlled i
reservoirs of medium depth.
Figure 7 shows a typical annual cycle of water temperatures (for 1984) at the SQN intake.
The overa11' magnitude of the seasonal variation is remarkably
- constant, with winter temperatures typically between 1 and B*C (34 and 46*F), and summer temperatures approaching 29 to 31*C (84 to 88'F).
- Thus, water temperatures vary seasonally about 30 C' (54 F').
From November through March, water temperatures range f rom 1 to 21*C (34 to.70*F), as shown in Figure 2.
Upon closer examination, the seasonal pattern can be described as a sequence of warming and cooling periods caused by changing meteorological conditions.
Water temperature fluctuations are not as large as the air temperature fluctuations, but water temperatures in the entire reservoir commonly change by 3 C* (5 F')
in 10 days.
These transient fluctuations are generally larger.in spring.
Any changes that af fect water temperatures f rom November through March would not impact the annual cycle of water temperatures in other months because of the short residence time in the reservoir.
Daily variations in water temperatures upstream f rom SQN are small because the reservoir is fully mixed from November through March.
' Figure 8 shows hourly data upstream at the 5-foot depth.
Extreme meteorological conditions of heating or cooling can sometimes change temperatures as much as 2 C' (4 5') within a day; however, these extreme conditions are rare. Most daily variitions are less than 1 C' (2 F*).
Temperature Patterns in the Main Channel--The main channel in the upstream, riverine portion of Chickamauga Reservoir is fully mixed during fall, winter, and early spring; therefore, diurnal fluctuations are relatively small.
- However, rapid changes in meteorological l
conditions can cause significant fluctuations in water temperature.
In I
the downstream portion of the reservoir, near Chickamauga Dam, water Io
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59 depths at low pool are near 65 feet, and the large cross-sectional areas result in low velocities and limited turbulent mixing.
Because of low f
6 air and water temperatures and high flows, however, this downstream portion of the reservoir experiences little or no thermal stratification a
in winter.
Temperature Patterns in Shallow Regions--The temperature patterns are quite similar in the overbank and main channel areas, despite differences in depth and flow-induced mixing.
Any dif f erences are largely confined to the near-surf ace layer and to periods of rapid warming or cooling.
Cooling is more rapid in the overbank areas, but temperatures slowly converge following a cooling event because the surf ace heat exchange in both nain chanr,el and overbank areas respond to common meteorological conditions.
Fully Mixed Conditions at SON--Daily average reservoir temperatures at the SQN intake, presented in Figure 2,
are used to characterize the variation of surface and bottom temperatures.
During November and
- December, convection cooling occurs because air temperatures are lower than water temperatures.
During
- January, temperatures are usually f airly stable.
In February and March, warmer air temperatures and solar radiation begin heating the reservoir.
High flow: and low pool elevations in the reservoir during the winter and early spring usually mean full mixing and uniform temperatures throughout the entire depth of the reservoir.
Figure 2 shows that only near the end of March do surf ace temperatures begin to be slightly warmer than bottom temperatures.
Chances in Temperature Patterns Resulting From Potential Changes in Reservoir Operations--The minimum dam release and higher lake level alternatives ar6 not expected to significantly alter temperature patterns in Chickamauga Reservoir in November through March.
Bdcause minimum release alternatives do not significantly affect flows in November through March, temperature patterns are not expected to change.
Higher j
60 lake level alternatives would mainly affect tefnperatures in the mainstem reservoirs in the sunrner period, but there may be a tendency toward cooler November temperatures.
Any potential delay in reservoir turnover would occur before November.
Lower flows in February and March may cause a slight increase in stratification during surface heating periods (Hauser et al., 1989).
Hydrothermodynamics of Chickamauga Reservoir Under Proposed Winter Temperature Rise Limit The ef fect of the proposed winter thermal limit for the SQN discharge into Chickamauga Reservoir was studied by use of simulation models and available historical data.
Thirteen years of historic river flows and ambient temperatures were used. This period of record contains both normal and extreme temperature and flow conditions and should be representative.
For a conservative evaluation, SQN was assumed to operate at maximum 2-unit loads for the entire study period, with no consideration given for refueling or maintenance outages.
A computer model was used to simulate the ef fects of dif fuser mixing of the heated discharge in the mixing zone for November through March from 1976 through 1989.
The computer model used in this study is now used for demonstrating compliance with thermal discharge limits at SQN and includes upgrades made as a result of operational experience.
Further information concerning the model can be found in McIntosh et al.,1983.
An analytical model of the surf ace heat exchange was used to determine heat loss from the thermal plume downstream from the mixing zone.
Description of Model for Diffuser Mixing The computer model simulates the diffuser-induced mixing downstream f rom SON near the 5-foot compliance depth.
The plant-induced temperature rise is defined as the difference between the diffuser-induced mixed river temperature downstream from the thermal discharge and the ambient temperature measured at the upstream intake.
Initial diffuser-induced mixing occurs rapidly in the mixing zone; model-predicted temperatures occur within 500 feet downstream f rom the
1 l
r 61
-diffaser.
The defined mixing zone for SQN extends 1,500 feet downstream f rom the dif fusers.
Natural mixing and surf ace heat loss downstream f rom g.
this point 'will be discussed in a later section.
The computer model of dif fuser ' mixing requires four inputs:
dif fuser dischargr
- mperature, N
' dif fuser discharge flowrate, ambient river temperature, and o.nbient river flowrate.
Discharge temperatures were based on a maximum net plant production of 2,560 MW of electric power with an associated waste heat output of 16.4x10' Btu /hr.
Anticipated worst-case maximum plant operation f rom November through March, with four CCW pumps. in operation, would result in a plant discharge flowrate of about 2,000 cu.
The resulting condenser temperature rise at maximum heat output is 20 C' (36 F*).
The condenser temperature rise was added to the ambient upstream teme*<4ture at the intake depth to obtain a discharge temperature fw thermal plume modeling.
The simulation model evaluates the olant-induced temperature rise with the assumption that the plant is operated entirely on river cooling.
Reduction of thermal discharge from use of cooling towm was, therefore, not considered.
Ambient river temperatures were obtained from monitors at
' Station 9 for the winters of 1976-77 through 1979-80 and at Station 13 for the winters of 1980-81 through 1988-09 (Figure 9).
Station 9, the ambient monitor used until 1930, was located at TRM 485.2.
Station 13, the present ambient monitoring station, is located on the intake skimmer wall at TRM 484.5.
River flowrates primarily depend on dam releases at Watts Bar and Chickamauga hydroelectric plants.
Data for hourly dam releases for the 13 winter periods studied were used to run a finite-difference, unsteady flow model to evaluate the instantaneous river flows at SQN.
The hourly flows at SQN are shown in Atpendix A.
Results of the Diffeser hixing Model Results of the simulation model are summarized on a monthly basis.
Examples of average and low river flow during winter months are shown in Figures 10 and 11.
Graph A on these figures shows the upstream
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-588 1 2 3 4 5 6 7 8 5 1811121314151617181S2821222324252627282S3831 ENG LAB 88/8S/89 JANUARY 1981 (DAYS)
Figure 10. Sequoyah Nuclear Plant Temperature Rise Simulations for January 1981.
64 A. UPST8 TEAM AND DUWNSTREAM HMPERATURES i.. i.
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Figure II.
Sequoyah Nuclear Plant Temperature Rise Simulations for February 1980.
ii 65-temperature measured at the 5-foot - depth and downstream temperature modeled at the 5 foot depth.
Graph B shows the modeled temperature rise.
0
. Graph C shows the modeled rate of temperature chang, and Graph D shows river 1 flows. at SQN simulated by the routing model.
The computed h
downstream temperature,. temperature ' rise, and rate of temperature change l
are determined for the point where the dif fuser-induced mixing ends, normally within 500 feet of the diffuser.
On a daily basis, river flow!
vary from short periods of reverse flow (less than.10,000 cfs) during the night to 20,000 : to 40,000 cf s during -the day.
Higher temperature rises occur.when river flows drop below 26,000 cfs.
Computed rates of temperature change are sometimes outside the defined 2 C*
(3.6 F')
limit.
These occurrences are based on instantaneous readings and are not indicative of real-time results.
Compliance with the present rate of temperature change is based on an average of instantaneous readings taken every 15 minutes.
These readings are then averaged over an hour to determine a'more realistic measure of compliance with the rate of change limit.
Appendix B summarizes each of the 13 winters studied.
Maximum SQN operation would exceed the present temperature rise limit an average of. 27 percent of the time on an hourly basis. The majority of the higher temperature rises would be less than 4 C' (7 F').
Temperature rises higher than 4 C* (7 F*) would occur about 4 percent of the time.
The most extreme winter was in 1980-81, when temperature rises would have exceeded 3 C'
(5.4 F') 63.6 percent of the time.
Nearly all the r-temperature rises in 1980-81 were below 4.5 C' (8 F').
Most, if not all, of the higher hourly temperature rises occur during periods of low releases from the upstream and downstream dams. On a daily basis, higher flow releases usually cause the daily average
. downstream temperature to be much lower.
Reservoir temperature rises downstream from SQN will be an average of temperature rises in the mixing zone-as river flows vary over the day and produce natural mixing.
From a biological standpoint, the best way to consider the effects downstream from SQN is to look at 24-hour averages of the temperature rise.
Appendix C shows 24-hour average temperature rises simulated by the
g 5
m
- f. 6
~ dif f user-mixing model.- When averaged over the day,- the higher hourly
. temperature rises discussed previously bring downstream temperature rises i
to less than 4 C' (7 F*).
Temperature rises based on 24-hour averages e
would be above the present 3 C' (5.4 F') limit 'about 20 percent of the time.
Based on EPA recommendations for applying temperature criteria,-
which are based on maximum weekly average temperature, even the 24-hour average temperature ~ rise is a
conservative approach relative to evaluating possible effects on fish reproduction or winter survival.
The effect of potential changes in reservoir system operation policy could affect river flows past SQN from November through March. As indicated earlier, reservoir system modeling simulations have shown that l
lower flow occurrences (between 25,000 and 10,000 cfs) increased mainly in Ma rc h.
Worst-case SQN two-unit operation can exceed the present temperature rise limit whenever river flows past SQN fall below about i
26,000 cfs.
Therefore, the frequency of temperature rises abeve the j
present limit would not increase significantly.
The magnitude of the I
temperature rises would be higher, with no increase larger than about 1 C* (2 F').
Potential changes in reservoir system operation would not
{
cause temperatur6 rises higher than 5 C* (9 F').
)
The modeled' temperature rises represent conditions at the 5-foot compliance depth within the mixing zone.
The vertical profile of temperatures depends on river flow conditions and ambient -water.
temperatures.
At higher river flows, the thermal plume approaches full mixing by the end of the mixing zone.
At lower flows, less mixing causes
)
higher temperature rises.
The vertical profile of the plume under low flow conditions concentrates the higher temperatures in approximately the top one-third of the reservoir depth (Roberts, 1979a and 1979b).
Conditions closer. to the ambient temperature can be found at lower depths.
Therefore, compensating effects occur.
At higher flows, the
]
temperature rise affects more of the reservoir depth but at a lower temperature; and at low flows, higher temperatures result but only occupy I
the upper layer of the reservoir.
j l
'I
67 Effects of the Proposed Winter Temperature Rise Limit on Chickamauga Reservoir Downstream from the Mixino Zone l
[
L Two mechanisms will affect water temperatures as the thermal discharge moves downstream.
As discussed above, natural mixing in the I
reservoir, which occurs over a day as river flows vary as a result of hydro peaking operations, causes downstream temperature rises better represented by 24-hour averages.
Surf ace heat exchange will also cool or heat the surface layer.
Surface cooling and heating of a water body is determined by meteorological conditions and water surface temperatures.
The theoretical equilibrium temperature can be used to estimate surf ace heat exchange. This is the temperature to which a body of water would eventually stabilize if exposed to constant meteorological conditions. A body of water not at the equilibrium temperature will approach that temperature at a rate proportional to the dif ference between the actual surf ace water temperature and the equilibrium temperature, and to a rate constant, the heat transf er coef ficient (a function of meteorological conditions).
l Monthly average equilibrium temperatures were obtained for each month of the year f rom available weather data taken at the National Weather Service Station in Chattanooga, Tennessee.
The values for ambient water temperature and equilibrium temperature used in this evaluation are given in Table 10.
Table 10. Surface Heat Transfer Data for the Ef fect of Sequoyah Nuc' ear Plant on Chickamauga Reservoir.
Ambient Water Equilibrium Month Temperature Temperature
(*C)
(*F)
('C)
(*F)
November 15.0 59.0 12.0 53.6 December 9.5 49.1 5.8 42.4 January 5.4 41.7 2.6 36.7 February 5.6 42.1 7.3 45.1 March 9.7 49.5 13.6 56.5
i 68-(
-During an -average November and
- December, the-equilibrium l
temperature is below the ambient water temperat'ure, and meteorological L
-conditions cause significant cooling of the water.
This cooling continues to a. lesser extent in Janbary.
In February, the equilibrium temperature is slightly higher than the = ambient temperature, indicating that heating has begun.
In Ma rch, the equilibrium temperature is-l
'significantly higher than ambient water temperature., indicating that normal spring heating has intensified.
An exponentially decaying heat transfer equation at steady-state rates. of heat and water flow (Eddinger and Geyer,1965; Fischer et al.,-
t 1979) was used to estimate the downstream distance required for the I
surface layer of the thermal plume to return to the present temperature rise limit of 3 C* (5.4 F*).
The initial plume, temperature (temperature j
when the thermal plume reaches the water surface or when the vertical
)
momentum of the plume ~ is exhausted) was determined for ambient reservoir flow and temperature by the dif fuser-mixing model described above'.
The spatial temperature variation of the thermal plume was determined for various reservoir flowrates, based on full SQN operating conditions and average upstream ambient reservoir temperature.
With constant. reservoir flow rates up to 20,000 cfs, the distance that the thermal plume travels until its temperature cools 3 C* (5.4 F*) is less than 4.4 miles for the cooling months of November, December, and January.
When meteorological conditions in February start heating the-reservoir surface, the influence of the thermal plume can extend as far as Chickamauga Dam.
In March, significant natural surface heating causes surface temperatures to increase.
.1
69 THERMAL LIMIT COMPLIANCE VERIFICATION TECHN100ES The present method of verifying compliance with the temperature rise limit is based on a combination of measurements and modeling techniques.
Measurements and modeling calculations are completed every 15 minutes for a
quasi-continuous, real-time verification.
Five 15-minute values are used to determine hourly average downstream mixed temperature and temperature rise.
Currently, the hourly average temperature is compared with the NPDES temperature rise limit.
The same method of verifying and reporting compliance based on the thermal computed compliance system is recommended for the alternative temperature rise limit.
The existing hourly interval for temperature reporting and compliance was established when EPA approved TVA's recommended temperature monitoring plan.
At the time this plan was submitted, there were no EPA recommendations on the f requency of temperature measurement.
EPA's subsequent temperature criteria recommendations (1976-77), that were directed to seasonal conditions to protect fish
- growth, reproduction, and winter survival, were based on maximum weekly average temp 9ratures and a short-term (24-hour) temperature maximum to prevent potentially lethal conditions.
Thus, the required minimum f requency of temperature measurement that would be biologically significant is daily.
l Although TVA is not requesting that the existing hourly compliance interval be changed at this time, it should be noted that this interval is extremely conservative relative to protecting fish reproduction and winter survival.
As discussed previously, the existing temperature rise limit in the Tennessee temperature criteria (standards) was established to set seasonal limits, except for the summer period; and therefore, it should not be appliet an instantaneous maximum.
1 A continuing )rogram for verifying the SQN thermal computed compliance system (Ostrowski and Shiao, 1987) was sent to Tennessee in 1987.
Upon approval by Tennessee, this program will be used to document the modeling evaluations presented in this report.
Field surveys at various river flows during f all, winter, and spring will be conducted to verify the modeled results.
I
70 ECONOMIC EVALUATION OF ALTERNATIVE THERMAL LIMIT The present temperature rise limit on SQN can impose significant o
operational costs.
The following is an evaluation of the cost associated with operating the plant under the current temperature limits vs the cost a
that will be incurred with a higher temperature rise limit during the winter operation from November 1 through March 31.
The evaluation addresses the cost of repairing the existing cooling tower ice damage; subsequent maintenance costs; and the cost of changing hydro operations, using cooling towers, and reducing plant load to meet the limit.
l I
Coolina Tower Operation and Repair Costs If the current 3 C'
(5.4 F') temperature limit remains in ef fect, TVA must either modify the cooling towers to be more resistant to ice damage; or repair the current tower damage, be ready to run the plant in closed mode if potential icing conditions are forecasted, and repair the resulting damage each spring to meet summer operation requirements.
The cost to modify the towers will be $16-20 million. The cost to repair the towers will vary considerably depending on the extent of the damage incurred.
The 1984 ice damage cost approximately 50.5 million to repair and the 1985 damage will cost nearly $1.5 million to repair.
Such cost would be incurred on an annual basis.
Economics of Meeting the Temperature Rise Limit Based on Available Historical Record The historical data set used to determine the ef fects of the thermal discharge on Chickamauga Reservoir was used to determine the economic cost of meeting the temperature rise limit.
Additional air temperature data was obtained from the National Weather Service Station in Chattanooga for determining potential freezing conditions.
Simulations were made based on assumed full plant operation for the entire period.
i 1
71 Operational decisions for running the plant and reservoir system were based 'on knowing the actual conditions for the next day. -Based on known-forecast,.TVA. would use the _following order to determine cl alternatives for ; meeting the. thermal limit.
If it. appeared that' SQN would violate the thermal limit the following sequence of actions would -
'be taken.
1.
Peaking operations at the upstream and downstream dams would be curtailed and releases would be distributed (or daily averaged) over the day.
2.
If the limit was not met, cooling towers would be used if the h
air temperature was above O'C (32*F) for the entire day.
3.
If the air temperature was forecast to be less than O'C at any time, load reductions would be used to meet the limit.
The costs associated with using this stepwise approach. of curtailed hydro operations, use of cooling towers, and reduced plant load were ' calculated for the period f rom November 1976 through March 1988 (Table 11).
Table 11. Average Annual Costs of Meeting Current Temperature Rise Limit Based on Available Historical Record.
Hydro Operations Coolino Tower Load Reductions
$101,000
$94,000
$440,000 inis period of time was selected because it provided actual meteorological and river temperature data that could be applied to the operation of SQN.
Under those environmental conditions a determination was made as to when modified hydro operations, cooling tower use, and plant load reductions would be needed to meet the temperature rise limit.
Using that information, future power costs were used to calculate costs for meeting the limit.
The need for each level of action was determined and costs for each level were calculated.
A worst case scenario' would involve a stepwise progression of the actions and the
. costs would be cumulative.
Usina 1990 future power costs and $7/MWH for SON costs and 1995 future costs and $8/MWH for SON costs an average l
l
72
' vearly cost' of - 1635.000 ' for meetino the current' temperature rise limit o
was derived.
b Economics of Meetino the Proposed Temperature Rise Limit C
Under the proposed temperature rise limit TVA would be able to meet the limit without the use of cooling towers or plant load reductions'
- and the costs of those actions would be avoided. This would represent'an.
~
average annual-- savings of $534,000 during the period f rom 1990 _through 1995.
In addition, the ' need to upgrade the cooling towers to improve their-ability to resist ice damage would be eliminated as-would the-
' incremental costs for the annual ice damage repairs.
i l
l
73 REFERENCES Adair, W. D. and D. J. DeMont.
1971.
Fish, p. 50-58.
in,R. W. Koss (ed.)
" Environmental Responses to Thermal Discharges From Marshall Steam Station, Lake Noman, North Carolina."
Interim f!ept. by Dept. Geology and Environ. Engr.
The Johns Hopkins Univ., Baltimore. Maryland.
Adair, W. D. and J. J. Hains.
1974.
" Saturation Values of Dissolved Gases ~ Associated With the Occurrence of Gas-Bubble Disease in Fish in a Heated Ef fluent."
Jn_:
Thermal Ecol., J. W. Gibbons and R.
R.
Sharitz, ecs., pp. 59-78.
Dept. of Energy Symposium Series (CONF-73050), National Tech. Inform. Serv., Springfield, Virginia.
Aho, J. M., J. W. Gibbons, and G. W. Esch. 1976.
"Relationsh1p Between Thermal Loading and Parasitism in the Mosquitofish."
In,:
Thermal Ecol. II, G.
W.
Esch and R.
W. McFarlane, eds., pp.
213-218.
Dept. of Energy Symp. Series (CONF-75025), National Tech. Inform. Serv., Springfield, Virginia.
Barans, C. A. and R. A. Tubb.
1973.
" Temperatures Selected Seasonally by Four Fishes From Western Lake Erie."
J. Fish. Res. Board. Can.
30(11):1967-1703.
Barkley, S. W. and C. Perrin.
1971.
"The Effects of the Lake Catherine Steam Electric Plant Effluent on the Distribution of Fishes in the Receiving Embayment."
Twenty-fif th Ann. Conf. Southeast.
Assoc. Game and Fish Com., Proc. p. 384-392.
Brungs, W. A. and B. R. Jones.
1977.
" Temperature Criteria for Freshwater Fish:
Protocol and Procedures."
United States l
Environmental Protection
- Agency, Duluth, Minnesota.
EPA-600/3-77-061.
130 pp.
Carlander, K. D.
1977.
Handbook of Freshwater Fishery Bioloov, Volume 2.
Iowa State Univ. Press, Ames, Iowa.
Clugston, J. P.,
J. L. Oliver, and R. Ruelle.
1978.
" Reproduction, Growth and Standing Crops of Yellow Perch in Southern Reservoirs." Am. Fish. Soc. Spec. Publ.
11:89-99.
Coutant, C. C.
1975.
" Temperature Selection by Fish--a factor in Power-Plant Impact Assessments."
In,:
Environmental Effects of Cooling Systems at Nuclear Power Plants.
pp. 575-597.
Int.
Natl. Atomic Energy Agency, Vienna.
Dryer, W. and N. G. Benson. 1956.
" Observations on the Influence of the Nev Johnsonville Steam Plant on Fish and Plankton Populations."
Tenth Ann. Conf. Southeast Assoc. Game and Fish Comm. Proc. p. 85-90.
74 Eddinger, John E., and John C. Geyer.
1965.
" Heat Exchange in the
~
l' Environment,"
Publications No.65-902, Edison Electric Institute, New York, New. York, s
Eure, H. E. and G. W. Esch. 1974.
" Effects of-Thermal Effluent on the Population Dynamics of Helminth Parasites in largemouth Bass."
in:
Thermel Ecol.,
J.
W.
Gibbons and R.
R.
Sharitz, eds.,
n w
pp. 207-215.
Dept. of Energy Symposium Series (CONF-73650),
4 National Tech. Inform. Serv., Springfield, Virginia.
Ferrick, M. G., and W. R. Waldrop. 1977.
"Two Techniques for Flow Routing With Application to Wheeler Reservoir," Report No. 3-519 T !A Division of Water Management, Water Systems Development Branct,
Norris, Tennessee.
Fischer, Hugo B., et al. 1979. Mixina i, Inland and Coastal Waters, j
Academic Press, New York, New York.
l I
Griffith, J. S.
1978.
"Ef fects of Low Temperatures on the Behavior and i
Survival of Threadfin Shad. Dorosoma petenense."
Trans. Amer.
Fish. Soc. 107(1):63-70.
Grif fith, J. S. and D. A. Tomljanovich. 1976.
" Susceptibility of Threadfin Shad to Impingement."
Proc. Annual Conf. Southeast.
Assoc.
Game and Fish Comm. 29:223-234.
Hart, J. S.
1952.
" Geographic Variations of Some Physiological and Morphological Characters in Certain Freshwater Fish."
Univ.
Toronto Biol. Ser., No. 60. 70 p.
Hauser, G.
E., M.=C. Shiao, and M. D. Bender. 1989.
"Modeled Effects of Extended Pool Level Operations on Water Quality," TVA Engineering Laboratory Report No. WR28-2-590-148, Norris, Tennessee.
Heuer, J. H.
1983.
" Browns Ferry Biothermal Research Series VI.
Effects of Temperature on White Crappie and Periphyton and Zooplankton Communities in Large Experimental Ecosystems."
TVA, Division of Air and Water Resources, 58 p.
Hokanson, K.E.F.
1977.
" Temperature Requirements of Some Percids and Adaptations to the Seasonal Temperature Cycle." Jour. Fish. Res.
Bd. Canada, 34:1524-1550.
Horning, W. B. and R. E. Pearson. 1973.
" Growth Temperature Requirements and Lower Lethal Temperatures for Juvenile Smallmouth Bass."
Jour. Fish. Res. Bd. Canada, 30(8):1226-1230.
Houser, A. and H. Bryant. 1967.
" Sampling Reservoir Fish Population Using Midwater Trawls."
in:
Reservoir Fishery Resource Symposium, G.
E. Hall, ed., pp. 391-404. Amer. Fish. Soc.
75 Houser, A. and H. E. Bryant. 1967.
" Sampling Reservoir Fish Populations Using Midwater Trawls,"
- p. 391-404.
Reservoir. Fishery Resources Symposium, Proc. So. Div. Amer. Fish. Soc.
I b
Jones, B. R., K.E.F. Hokanson, and J. H. McCormick.
1977.
" Winter
{
Temperature Requirements for Maturation and Spawning of Yellow j
Perch."
In:
M.
- Marios, ed.,
Towards a Plan of Actions for' Mankind.
Proc. World Conf., Vol.
3.
Biological Balance and Thermal Modifications. Permagon Press. New York.
Kendall, R. L. (ed.).
1978.
"A Symposium on Selected Cool Water Fishes of North. America."
Special Publ.
No.
11, Amer.
Fish.
S o c..,
Washington, D.C.
437 pp.
Lambou, V. W.
1965.
" Observations on Size Distribution and Spawning Behavior of Threadfin Shad."
Trans.
Amer.
Fish.
Soc.
94(4):385-386.
Mathur, D. and P. L. McCreight.
1980.
" Effects of Heated Effluent on the Reproductive Biology of White Crappie, in Conowingo Pond, Pennsylvania." Arch. Hydrobiologia.
88:491-499.
i Mathur, D., R. M. Schutsky, E. J. Purdy, Jr., and C. A. Silver. 1981.
" Similarities in Acute Temperature Preferences of Freshwater Fishes." Trans. Amer. Fish. Soc.
110:1-13.
Mclean, R.
B., J. S. Grif fith, M. V. McGee, and R. Pasch.
1979.
"Threadfin Shad Impingement:
Effect of Cold Stress on a
Reservoir Community."
ORNL Environ. Sci. Div. Publ.
No. 1198, Oak Ridge, Tennessee.
McIntosh, D.
A., B. E. Johnson, and E. B. Speaks, " Validation of Computerized Thermal Compliance and Plume Development at Sequoyah Nuclear. Plant," TVA Division of Air and Water Resources, Water Systems Development Branch Report No. WR28-1 115,
- Norris, Tennessee.
Miller, Barbara A., and James Parsly. 1989.
" Reservoir Operation and Planning Review:
Weekly Scheduling Model Analyses of Minimum Flow Releases and Recreation Levels," TVA Engineering Laboratory, Report No. WR28-1-500-165, Norris, Tennessee.
Minns, C.
K., J.R.M. Kelso, and W. Hyatt. 1978.
" Spatial Distribution of Near Shore Fish in the Vicinity of Two Thermal Generating Stations Nanticoke and Douglas Point, on the Great Lakes."
J. Fish. Board Can. 35:895-892.
Neill, W. H. and J. J. Magnuson. 1974.
"Distributional Ecology and Behavioral Thermoregulation of Fishes in Relation to Heated Effluent From a Power Plant at Lake Monona, Wisconsin."
Trans. Amer. Fish. Soc. 103(4):663-710.
E 76 Ostrowski, Peter, and Ming Shiao. 1987.
" Quality Progr4 ci for Verification
' of Sequoyah Nuclear Plant Thermal Computed-C )mpliance System,"-
TVA Engineering Laboratory, Report No. WR28-3-4 5-134, Norris, Tennessee.
i Otto, R. G. -1976.
" Thermal Effluents, Fish, and Gas-Bubble Disease in l
Southwestern Lake Michigan."
3:
Thermal Ecol. II, G. W. Esch c
and.
R.
W.
McFarlane, eds.,- pp.
121-129.
Dept.~ of Energy Symposium Ser.
(CONF-75025),
National Tech.
Inform.
Serv.,
Springfield, Virginia.
I:
Rankins, J.
S., and J. D. Buck, and J. W. Foerster. 1974.
" Thermal Effects on the Microbiology and Chemistry of-the Connecticut River - A Summary."
M:
Thermal Ecology, J.
W.
Gibbons and R. R.
Sharitz, eds., pp. 350-355.
Dept. of Energy Symposium Series (CONF-73050), National Tech. Inform. Serv., Springfield, Virginia.
i Roberts, Philip, J. W.
1979A.
"Line Plume and Ocean Outfall Dispersion."
)
ASCE, Journal of the Hyd raulics Division, Vol. 105, No. HY4, pp. 313-331.
Roberts, Philip, J. W.
1979B.
"Two-Dimensional Flow Field of Multiport Diffuser."
ASCE, Journal of the Hydraulics Division, Vol. 105, No. HYS, pp. 607-611.
Ross, M. J. and D. B. Siniff. 1982.
" Temperatures Selected in a Power Plant Thermal Effluent by Adult Yellow Perch in Winter." Can. J.
Fish. Aauat. Sci.
39:346-349.
Ross, M. J. End J. D. Winter.
1981.
" Winter Movements of Four Fi!,h Species Near a Thermal Plume in Northern Minnesota."
Trans.
Amer. Fish. Soc. 110:14-18.
Saylor, C.
F.,
E. M. Scott, Jr., and D. A. Tomljanovich. 1983.
"An Investigation of Sauger Spawning in the Vicinity of the Clinch River Breeder Reactor Plant."
TVA Tech. Rept. TVA/0NR/WRF-83/1, 38 p.
Schlick, R. O.
1976.
" Management for Walleye or Sauger, South Basin, Lake Winnipeg." Amer. Fish. Soc. Spec. Publ. 11:266-269.
Smith, L. L. and W. M. Koenst. 1975.
" Temperature Effects on Eggs and Fry of Percoid Fishes."
- EPA, Ecological Res.
Ser.
EPA-660/3-75-017. Supt. of Documents, Washington, D.C.
Spigarelli, S.
A., R. M. Goldstein, W. Prepejchal, and M. M. Thommes.
1982.
" Fish Abundance and Distribution Near Three Heated Effluents to take Michigan."
Can.
J.
Fish.
Aquat.
Sci.
39:305-315.
77
-Strange, R._J.
1983.
" Field Examination of Fish." In:
Fisheries Techniques, L.
A. Nielsen and D.
L.
Johnson, eds., Amer. Fish.
Soc., Bethesda, Maryland.
Swingle. H. A.
1969.
" Production of Threadfin Shad, Dorosoma oetenense
-(Gunther)."
Proc. Ann. Conf. Southeast. Assoc. Game and Fish.
Comm. 23:407-421.
g Tennessee Valley Authority. 1969.
Division of Forestry Development.
" Fish and Fishing Around TVA Steam Plants."
Leaflet No. F70FR1.
n.p.
Tennessee Valley Authority. 1913.
Division of Forestry, Fisheries, and Wildlife Development. Annual Report.
n.p.
Tennessee Valley Authority. 1977.
" Effects of Thermal Discharges From Cumberland Steam Plant on the Fish Populations of Barkley Reservoir,"
Vol.
4.
Division of
- Forestry, Fisheries, and Wildlife Development. Norris, Tennessee.
Tennessee Valley Authority. 1978.
"Preoperational Fisheries Report for the Sequoyah Nuclear Plant."
179 p.
Division of. Air and Water l-Resources, Knoxville, Tennessee.
Tennessee Valley Authority. 1983.
"A Supplemental 316(a) Demonstration for Alternative Thermal Discharge Limits for Browns Ferry Nuclear Plant, Wheeler Reservoir, Alabama."
Tennessee Valley Authority. 1985a.
"Preoperational Assessment of Water Quality and Biological Resources of Guntersville Reservoir in the Vicinity of Bellefonte Nuclear Plant, 1974 Through 1984." ONRED, Division of Air and Water Resources.
Tennessee Valley Authority.
1985b.
" Aquatic Environmental Conditions in Chickamauga Reservoir During Operation of Sequoyah Nuclear Plant,"
Fourth Ann.
Rept.
(1984).
Knoxville, Tennessee.
Division of Air and Water Resources.
Tennessee Valley Authority.
1986.
" Aquatic Environmental Conditions in Chickamauga Reservoir During Operation of Sequoyah Nuclear Plant,"
Fifth Annual Rept.
(1985).
Knoxville, Tennessee.
Division of Air and Water Resources.
Texas Instruments, Inc. 1976.
" Biological Evaluation of Air Curtain at Arkansas ' Nuclear One--Unit 1."
Report to Arkansas Power and Light Co., Little Rock, Arkansas.
112 p.
U.S. Environmental Protection Agency. 1976.
" Quality Criteria for Water."
Office of Water and Hazardous Materials, Washington, D.C.,
EPA 440/9-76-023, 501 p.
i
78 Vasey, F.- W.
1972.
"The Early Life History of White Crappies in Table Rock Reservoir."
D-J
- Project, F1-R-22.
Missouri Dept. of Conservation.
l1 Wrenn, W. B.
1975.- " Seasonal Occurrence and Diversity of Fish in a L
)'
Heated Discharge
- Channel, Tennessee River."
Proc.
of the Southeastern Assoc. of Game and Fish Comm.
29;235-247.
Wrenn, W. B. and K. L. Grannemann. 1980.
" Effects of Temperature on l
Bluegill Reproduction and Young-of-the-Year Standing Stocks in Experimental Ecosystems."
J_n,:
Microcosms in Ecological l
)
- Research, J. P.
Giesy, ed., Department of Energy Symp. Ser. 52 (CONF-781101), NTIS, 703-714 pp.
Springfield, Virginia.
Wrenn, W. B.
1980.
" Effects of Elevated Temperature on Growth and Survival of Smallmouth Bass."
Trans.
Amer.
Fish.
Soc.
109:617-625.
<Wrenn, W. B.
1984.
"Smallmouth Bass Reproduction in Elevated Temperature Regimes at the Species Native Southern Limit."
Trans. Amer.
j Fish. Soc. 113:295-303.
79 Appendix A Frequency of Hourly River Flow at Sequoyah Nuclear Plant for the Winters 1976-1989 3
Flowrote (x 10 )
<0 0-9.9 10-19.9 20-29.9 30-39.9 40-49.9 50-59.9 60-69.9 70-79.9 80-89.9 >90 NOV 1975 3
25 91 2 54 356 11 0
0 0
0 0
DEC 1976 0
4 20 81 235 404 0
0 0
0 0
JAN 1977 2
2 12 87 242 301 98 0
0 0
0 FE8 1977 36 87 139 196 185 29 0
0 0
0 0
MAR 1977 17 61 105 210 255 96 0
0 0
0 0
Subtotal 58 179 367 808 1273 841 98 0
0 0
0 Sub 5 1.6 4.9 10.1 22.3 35.1 23.2 2.7 0.0 0.0 0.0 0.0 NOV 1977 2
18 24 45 87 27 209 109 161 58 0
DEC 1977 0
0 0
0 0
0 58 325 311 50 0
JAN 1978 0
0 0
3 30 47 426 33 74 43 88 FE8 1978 0
0 4
35 202 228 116 56 18 13 0
MAR 1978 11 15 47 187 294 190 0
0 0
0 0
Subtotal 13 33 75 270 613 492 B09 503 584 144 88 Sub 5
.4
.9 2.1 7.5 16.9 13.6 22.3 13.9 16.1 4.0 2.4 NOV 1978 131 151 133 154 139 12 0
0 0
0 0
DEC 1978 18 51 67 110 288 200 0
0 0
0 0
JAN 1979 0
0 0
3 2a 148 182 85 179 73 46 FEB 1979 0
3 16 77 194 239 46 39 23 5
50 MAR 1979 0
0 2
10 166 171 17 4
47 26 301 Subtotal 149 205 218 564 815 770 245 128 249 104 377 Sub 5 4.1 5.7 6.0 10.0 22.5 21.2 6.8 3.5 6.9 2.9 10.4 NOV 1979 0
0 0
2 8
115 356 239 0
0 0
DEC 1979 0
0 13 27 202 252 250 0
0 0
0 JAN 1980 0
0 0
19 131 306 102 134 52 0
0 FEB 1980 27 23 72 150 314 150 0
0 0
0 0
MAR 1980 7
12 37 100 IB6 98 40 2
44 132 B6 Subtotal 34 35 122 278 841 901 748 375 96 132 86 Sub %
.9 1.0 3.3 7.6 23.1 24.7 20.5 10.3 2.6 3.6 2.4 NOV 1980 67 105 164 238 144 2
0 0
0 0
0 DEC 1980 52 109 249 267 67 0
0 0
0 0
0 JAN 1981 78 150 2 54 184 93 5
0 0
0 0
0 FED 1981 65 75 117 162 202 51 0
0 0
0 0
MAR 1981 175 175 160 158 66 10 0
0 0
0 0
Subtotal 437 614 924 1009 572 68 0
0 0
0 0
Sub 5 12.1 16.9 25.5 27.8 15.8 1.9 0.0 0.0 0.0 0.0 0.0
80-Appendix A (Continued) 3 Flowrate (x 10 )
<0 0-9.9 10-19.9 20-25.9 30-39.9 40-49.9 50-59.9 6049.9 70-79.9 80-89.9.>,90 1
.NOV 1981 70' 136 240 173 100 1
0-0 0
0 0
DEC 1981 36 72 s50 216 243 27 0
0 0
0 0
JAN 1982 0
1 3
4 70 145 45 331 142 3
0 l
FE8 1982 0
0 0
0 0-37 110 48 184 276 17 i
MAR 1982 3
11 23 41 119 223 302 22 0
0' 0
Subtotal 109 220 416 4 34 532 433 457~
401 326 279 17 i
Sub 5 3.0 6.1 11.5 12.0 14.7 11.9 12.6 11.1 9.0
'7.7
.5 l
NOV 1982 1
11 75 166 355 112 0
0 0
0 0
'DEC 1982 0
0 0
0 0
41 205 279 219 0
0 JAN 1983 0
0 1
40 266 361 76 0
0 0
0 FEB 1983 0
0 9
44 123 355 141 0
0 0
0 MAR 1983 0
131 252 265 96 0
0 0
0 0
0 Subtotal i
142 337 515 840 869 422 279 219 0
0 Sub %
.0 3.9 9.5 14.2 23.2 24.0 11.6 7.7 6.0 0.0 0.0 NOV 1983 1
73 155 256 252 3
0 0
0 0
0 DEC 1983 0
0 0
5 93 376 221 49 0
0 0
JAN 1984 0
9 65 175 284 193 18 0
0 0
0 FE8 1984 0
'O 131 130 178 186 71 0
0 0
0 MAR 1984 0-0 49 138 229 167 161 0
0 0
0 Subtotal I
82 400 684 1036 925 471 49 0
0 0
Sub %
.0 2.2 11.0 18.8 28.4 25.4 12.9 1.3 0.0 0.0 0.0 NOV 1984 29 63 123 168 330 7
0 0
0 0
0 DEC 1984 43 53 117 217 235 79 0
0 0
0 0
JAN 1985 32 84 126 190 199 113 0
0 0
0 0
FEB 1985 11 20 33 58 256 195 32 67 0
0 0
MAR 1985 1
253 177 160 121 32 0
0 0
0 0
Subtotal ll6 473 576 793 1841 426 32 67 0
0 0
Sub %
3.2 13.1 15.9 21.9 31.5 11.8
.9 1.8 0.0 0.0 0.0 NOV 1985 64 85 130 317 124 0
0 0
0 0
0 DEC 1985 29 55 108 189 266 96 1
0 0
0 0
JAN 1986 88 153 195 195 85 28 0
0 0
0 0
FEB 1986 48 76 152 151 158 86 0
0 0
0 0
MAR 1986 90 109 163 228 147 7
0 0
0 0
0 Subtotal 319' 478 748 1081 780 217 1
0 0
0 0
Sub %
8.8 13.2 20.6 29.8 21.5 6.0
.0 0.0 0.0 0.0 0.0
7<,
81 Appendix A (Continued) 3 Flowrote (x 10 )
+
4 0-9.9 10-19.9 20-29.9 30-39.9 40-49.9 50-59.9 60-69,9 79.9 80-89.9 >90
- NOV 1986 38. - 31 117 215 273 46 0
0 0
0 0
DEC 1986 0
0 3
49 322 370 0
0 0
0 0
JAN 1987 13 26 57 151 248 249 0
0 0
0 0
FEB 1987 10.
14 29 85 211 260 23 2
1 13 24
' MAR 1987.
27 24 70 108 130 106 165 86 15 13 0
Subtotal 88 95 276 608 1884 1031 188 h8 16 26 24 Sub 5 2.4 2.6 7.6 16.8 32.7 28.4 5.2 2.4
.4
.7
.7
.NOV 1987 108 126 169 206 95 16 0
0 0
0 0
DEC 1987 143 171 191 174 62 3
0 0
0
,0 0
JAN 1988 78 82
'102 161 211 66 44 0
0 0
0 FEB 1988 48 69 129 220 200 30 0
0 0
0 0
MAR 1988 152 229 170
. 89 60 44 0
0 0
0 0
Subtotal 529 677 768 850 628 159 44 0
0 0
'0
'Sub 5 14.5 18.6 20.9 23.3 17.2 4.4 1.2 0.0 0.0 0.0 0.0 NOV 1988 79 82 123 259 176 1
0 0
0 0
0 DEC 1988 75 124 159 172 138 55 0
0 0
0 0
JAN 1989
.0 18 65 68 230 172 20 23 148 0
0 FEB 1989 1
31 51 56 126 206 200 1
0 0
0 MAR 1989 21 18 37 100 214 125 til 55 65 0
0 Subtotal 176 2i3 435 655 884 557 331-79 213 0
0 Seb 5 4.9 7.6 12.1 18.2 24.5 15.5 9.2 2.2 5.9 0.0 0.0 FOR ALL YEARS FROM 1976 THROUGH 1989 Total Hrs. 2030 3506 5655 8349 11139 7689 3846 1969 1703 685 592 Avg 5 4.3 7.4 12.0 17.7 23.6 16.3 8.2 4.2 3.6 1.5 1.3 re i
,i
82l Appendix B Frequt7cy of Hourly' Temperature Rise.at Sequoyah Nuclear Plant for the Winters 1976-1989.
9 Temperature Rise (C')
<3.0 3.0-3.4 3.5-3.9 4.0-4.4 4.5-4.9
>5 Hours NOV 1976 535 127 57 0
0 0
DEC 1976 697
.18 25 4
0 0
JAN 1977 722 7
3 8
4 0
l FEB 1977 377 51-82 126 36 0
MAR 1977 523 94 123 4
0 0
Subtotal 2854 297 290 142 40 0
Sub %
78.8 8.2 8.0 3.9 1.1 0.0 NOV 1977 664 55 0
0 0
0 DEC 1977..
744 0
0 0
0 0
.JAN11978 744 0-0 0
0 0
FE8 1978-661 6
3 2
0 0
' MAR 1978 618 69 50 7
0 0
==
L Subtotal 3431 130 53 9
0 0
l Sub %
94.7 3.6
- 1. 5
.2 0.0 0.0 l
NOV 1978 321 372 26 0
0 0
DEC 1978 573 87 83 1
0 0
JAN 1979
.744 0-0 0
0 0
l FE8 1979 641 14 10 7
0 0
l MAR 1979 740 4
0 0
0 0
Subtotal 3019 477 119 8
0 0
Sub %
83.3 13.2 3.3
.2 0.0 0.0 NOV 1979 719 0
0 0
0 0
i DEC 1979 727 4
13 0
0 0
JAN 1980 740 4
0 0
0 0
FEB 1980 547 26 70 53 0
0 MAR 1980 664 30 37 13 0
0
}
Subtotal 3397 64 120 66 0
0 Sub %
93.1 1.8 3.3 1.8 0.0 0.0
)
83 Appendix B'(Continued).
Temperature Rise (C')
7
<3.0-3.0-3.4 3.5-3.9-4.0-4.4 4.5-4.9 o
. >5 Hours
- NOV 1980 286 265 168 0
0 0
DEC 1980 225.
114 319
-86 0
0' JAN 1?B1 217 52 105 365-5 0
FEB 1981 381 42 105 143 1
0 MAR 1981 211
~159 347 27 0
0 Subtotal-1320 632 1044 621 6
0 Sub 5 36.4-17.4 28.8 17.1 2
0.0 NOV 1981 248 385 86 0
0 0
DEC 1981 427; 90~
204 23 0
0 JAN 1982 740 0
1 3
0 0
FEB.1982 672
.0 0
0 0
0
. MAR 1982 693 31 20 0
0 0
_-------- =
Subtotal-2780 506 311 26 0
0 Sub %
76.7 14.0.
B.6 7
0.0 0.0 NOV 1982.
571
'143 5
0 0
0-DEC 1982 744 0
0' O
O O
'J AN.1983 741 0
3 0
0 0
'FEB 1983 653 15 4
0 0
0 MAR 1983 344 165 235 0
0
_------------------------------------------------------0-----------
Subtotal 3053 323 247 0
0 0
Sub %
84.3 8.9 6.8 0.0 0.0 0.0 NOV 1983 411 286 22 0
0 0
DEC 1983 744 0
0 0
0 0
JAN.1984 623 44 50 27 0
0 FEB 1984 531 70 95 0
0 0
MAR 1984 656 75 13 0
0 0
.=-----------
Subtotal 2965 475 180 27 0
0 Sub %
81.3 13.0 4.9
.7 0.0 0.0 NOV 1984 455 215 49 0
0 0
DEC 1984 463 88 192 1
0 0
JAN 1985 440 56 114 1 31 3
0 FEB 1985 597' 13 49 13 0
0 MAR 1985 274 221 248 1
0 0
Subtotal 2229 593 652 146 3
0 Sub %
61,5 16.4 18.0 4.0
.1 0.0
84
-Appendix B (Continued)
Temperature Rise (C')
<3.0 3.0-3.4 3.5-3.9 4.0-4.4 4.5-4.9
>5 o
Hours NOV 1985 41 6 303 0
0 0
0 DEC 1985 506 101 102 35 0 JAN 1986 246 82 258 158 0
0 FEB 1986 360 66 191 55 0
0 MAR 1986 437 161 146 0
0 0
Subtotal-1965 713 6B7 248 0
0 Sub %
54.2 19.7 19.2 6.8 0.0 0.0 l
l
'NOV 1986 598 121 0
0 0
0 DEC 1986 736 8
0 0
0 0
i JAN 1987 634 44 66 0
0 0
FEB 1987 612 27 33 0-0 0
MAR 1987 663 81 0
0 0
0 1
Subtotal 3243 281 99 0
0 0
Sub %
89.5 7.8 2.7 0.0 0.0 0.0 NOV -1987 580 46 93 0
0 0
DEC 1987 164 109 471 0-0 0
JAN 1988 439 40 136 129 0
0 FEB 1988 390 58 148 100 0
0 MAR 1988 184 256 300 4
0 0
L
.....--------------------------------------------------------------- 0 Subtotal 1757 509 1148 233 0
Sub %
-48.2 14.0 31.5 6.4 0.0 0.0 NOV 1988 362 329 29 0
0 0
DEC 1988 300 79 307 37 0
0 JAN 1989 633 34 66 11 0
0 FEB 1989 578 19 75 0
0 0
MAR 1989 647 56 41 0
0 0
0 Subtotal 2520 517 51 8 48 0
Sub %
69.9 14.3 14.4 1.3 0.0 0.0 FOR ALL YEARS FROM 1976 THROUGH 1989 Avg total 34533 5517 5478 1574 49 0
Avg 73.2 11.7 11.6 3.3
.1 0.0 l
l l
i 1
85 Appendix C b
Frequency-of 24-Hour Average Temperature Rises at Sequoyah Nuclear Plant a;
for the Winters 1976-1989.
1 Temperature Rise (C*)
<3.0
.3.0-3.4 3.5-3.9 4.0-4.4 4.5-4.9
>5 Hours NOV 1976 641 78 0
0 0
0 DEC 1976 744 0
0 0
0
.0
- JAN 1977 744 0
0 0
0 0
FEB 1977 538 134 0
0 0
0 MAR 1977 674 48 22 0
0-Subtotal 3341 260 22 0
0 0
Sub %
92.2 7.2
.6 0.0 0.0 0.0 NOV 1977.
675 44 0
0 0
0 DEC 1977 744 0
0 0
0 0
JAN 1978 744 0
0 0
0 0
FEB 1978 :
672 0
0 0
0 0
MAR 1978 720 24 0
0 0
0 Subtotal 3555 68 0
0 0
0 Sub %
98.1 1.9 0.0 0.0 0.0 0.0 NOV 1978 565 154 0
0 0
0 DEC 1978 718 26 0
0 0
0 JAN 1979 744 0
0 0
0 0
FEB 1979 672 0
0 0
0 0
MAR 1979 744 0
0 0
0 0
Subtotal 5443 180 0
0 0
0 Sub %
95.0 5.0 0.0 0.0 0.0 0.0 NOV 1979 719 0
0 0
0 0
DEC 1979 744 0
0 0
0 0
JAN 1980 744 0
0 0
0 0
FEB 1980 669 27 0
0 0
0 MAR 1980 727-17 0
0 0
0 Subtotal 3603 44 0
0 0
0 Sub %
98.8 1.2 0.0 0.0 0.0 0.0
/
_____.____m.-_
y,e
- s
_gg.
t-i,
c.
Appendix C (Continued)
Temperature Rise (C')
<3.0 3.0-3.4 3.5-3.9 4.0-4.4 4.5-4.9
>5 d
. Hours s
NOV 1980 335 356 28 0
0 0
DEC 1980 174 460 110 0
0 0
JAN 1981 58 419 257 10 0
0 FEB 1981 514 94 61 3
0 0
MAR 1981 118 533 93 0
0 0
Subtotal 1199 1862 549 13 0
0 Sub %
33.1 51 4 15.2
.4 0.0 0.0 NOV 1981 291 428 0
0-0 0
DEC 1981-577 159 8
0 0
0 JAN 1982 144
'O 0
0 0
0 FE8 1982 672 0
0 0
0 0
MAR 1982 744 0
0 0
0 0
Subtotal 3028 587 8
0 0
0 Sub %
83.6 16.2
.2 0.0 0.0 0.0
'NOV 1982 719 0
0 0
0 0
DEC 1982 744 0
0 0
0 0
JAN 1983 744 0
0 0
0 0
FE8~1983 672 0
0 0
0 0
MAR 1983 369 187 188 0
0 0
-Subtotal 3248 187 188 0
0 0
Sub %
89.6 5.2 5.2 0.0 0.0 0.0 NOV 1983 538 1 81 0
0 0
0 DEC 1983 744 0
0 0
0 0
JAN 1984 725 13 6
0 0
0 FEB 1984 579 35 82 0
0 0
MAR 1984 744 0
0 0
0 0
l q
I Subtotal 3330 229 88 0
0 0
Sub %
91.3 6.3 2.4 0.0 0.0 0.0 NOV 1984 590 129 0
0 0
0-DEC 1984 575 160 9
0 0
0 JAN 1985 522 140 60 22 0
0 FE81985 659 13-0 0
0 0
MAR 1985 388 290 66 0
0 0
__---_____--______-__________-___________-,--____-________ 0 0
Subtotal 2734 732 135 22 Sub %
75.5 20.2 3.7
.6 0.0 0.0
87 Appendix C (Continued)
Temperature Rise-(C')
<3.0 3.0-3.4 3.5-3.9 4.0-4.4 4.5-4.9 15 G
y Hours NOV 1985 546 173 0
0 0
0 DEC 1985 596 127 21 0
0 0
JAN 1986 256 291-187 0
0 0
FE8 1986 -
399 103 170-0 0
'O MAR 1986 535 182 27 0.
0 Subtotal 2342 876 405 0
0 0
Sub %
64.6 24.2 11.2 0.0 0.0 0.0 NOV 1986' 719 0
0-0 0
0 DEC 1986 744 0
'O O
O O
JAN 1987 727
'17 0
0 0
0
'FE8 1987 654 18 0
0 0
0 MAR 1987 744 0
0 0
0
_____________________________________________________________________0 Subtotal.
3586 35 0
0-0 0
Sub %
99.0 1.0 0.0 0.0 0.0 0.0 NOV 1987 592 64.
63 0
0 0
DEC 1987 170 223 351 0
0 0
JAN.1988 492 116 136 0
0 0
FE81988 490 141 65 0
0 0
MAR 1988 162 d64 218 0
0
_____________________________________________________________________0 Subtotal 1906 908 833 0
0 0
Sub %
52.3 24.9 22.8 0.0 0.0 10.0~
. NOV 1988 414 306 0
0 0
0 DEC 1988 379 138 206 0
0 0
JAN 1989 674 27 43 0
0 0
FE8 1989 607 40 25 0
0 0
MAR 1989 725 19 0
0 0
0 Subtotal 2799 530 274 0
0 0
Sub %
77.7 14.7 7.6 0.0 0.0 0.0 FOR ALL YEARS FROM 1976 THROUGH 1989
' Subtotal 38116 6498 2502 35 0
0 Sub %
60.8 13.8 5.3
.1 0.0 0.0 i
-- ~~~~ _- - _
.