ML14132A101
| ML14132A101 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/02/2010 |
| From: | Baxter D, James Buchanan Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML14132A101 (36) | |
Text
Entrainment Monitoring At Sequoyah Nuclear Plant 2004 by Dennis S. Baxter and Johnny P. Buchanan October 2006 Final Revised August 2, 2010
Revisions to Report In the Executive Summary and Introduction sections, a clerical error was discovered in the sentence stating that During operational monitoring at SQN from 1980 through 1985, the average hydraulic entrainment of fish larvae was estimated to be 8.6 percent of those passing the plant. This sentence was revised to correctly state During operational monitoring at SQN from 1981 through 1985, the average entrainment rate of fish larvae was estimated to be 2.8 percent of those passing the plant. Average hydraulic entrainment for the same period was 8.6 percent and was mistakenly substituted as the value for larval entrainment and the operational monitoring period was intended to begin in 1981 instead of 1980.
Additionally, the third column of Table 5 was revised to reflect the preferred method of calculating Average Seasonal Density. The revised method sums the densities (number per 1000 m3) for each family for all sample periods and divides by the total number of sample periods. The previous method calculated the average seasonal densities for intake and reservoir samples using the same method, but then added the two average densities and divided by two to obtain average seasonal density for all larvae. The revised method is more accurate as it reflects the difference in volumes of water filtered between intake and reservoir samples.
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TABLE OF CONTENTS Page List of Tables ................................................................................................................................. ii List of Figures............................................................................................................................... iii Acronyms ...................................................................................................................................... iv Executive Summary ...................................................................................................................... v Introduction ................................................................................................................................... 1 Reservoir and Plant Operation during 2004 .............................................................................. 1 Chickamauga Reservoir Operation ........................................................................................ 1 Sequoyah Operation ................................................................................................................. 2 Methods.......................................................................................................................................... 2 Sample Collection ..................................................................................................................... 2 Laboratory and Data Analysis..................................................................................................... 2 Laboratory Analysis ................................................................................................................. 2 Data Analysis ............................................................................................................................. 3 Results and Discussion.................................................................................................................. 3 Fish Eggs .................................................................................................................................... 4 Larval Fish................................................................................................................................. 4 Hydraulic Entrainment Estimates .......................................................................................... 5 Fish Egg and Larvae Entrainment Estimates ........................................................................ 5 Discussion with Historical Comparisons ................................................................................... 5 Chickamauga Reservoir Fish Community ............................................................................. 6 Sport Fishing Index .................................................................................................................. 7 Conclusions .................................................................................................................................... 8 Literature Cited ............................................................................................................................ 9 i
LIST OF TABLES Page Table 1. Total Volume of Water Filtered by Sample Period at Sequoyah Nuclear Plant during 2004 to Estimate Entrainment of Fish Eggs and Larvae. 10 Table 2. List of Fish Eggs and Larvae by Family Collected at Sequoyah Nuclear Plant in 2004 Entrainment Samples and Lowest Level of Taxonomic Resolution for each Family. 11 Table 3. Percent Composition of Fish Eggs and Larvae by Family in Entrainment Samples at Sequoyah Nuclear Plant during 2004. 12 Table 4. Peak Densities and Sample Dates by Family for Fish Eggs and Larvae from Intake and Reservoir Entrainment Samples Collected at Sequoyah Nuclear Plant during 2004. 13 Table 5. Average Seasonal Density of Fish Eggs and Larvae in Entrainment Samples at Sequoyah Nuclear Plant during 2004. 14 Table 6. Estimated Daily Hydraulic Entrainment by Sample Period at Sequoyah Nuclear Plant during 2004. 14 Table 7. Seasonal Entrainment Estimates for Numerically Significant Fish Taxa Collected at Sequoyah Nuclear Plant during 2004. 15 Table 8. Historical and Current Entrainment Percentages for Fish Eggs and Larvae at Sequoyah Nuclear Plant during 1981-1985 and 2004. 15 Table 9. Recent (1993-2005) RFAI Scores Collected as Part of the Vital Signs Monitoring Program Upstream and Downstream of Sequoyah Nuclear Plant. 16 ii
LIST OF FIGURES Page Figure 1. Average daily surface elevation (meters above mean sea level) of Chickamauga Reservoir during 2004. 17 Figure 2. Average daily rate of flow in Chickamauga Reservoir during 2003 and 2004. 18 Figure 3. Average daily rate of generation at Sequoyah Nuclear Plant during 2003 and 2004. 19 Figure 4. Average daily rate of hydraulic entrainment at Sequoyah Nuclear Plant during 2003 and 2004. 20 Figure 5. Map of entrainment sample transects in the vicinity of Sequoyah Nuclear Plant during 2004. 21 Figure 6. Densities of sciaenid eggs collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004. 22 Figure 7. Densities of total larval fish collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004. 23 Figure 8. Densities of clupeid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004. 24 Figure 9. Densities of moronid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004. 25 Figure 10. Densities of centrarchid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004. 26 Figure 11. Densities of sciaenid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004. 27 Figure 12. Sport Fishing Index results for Chickamauga Reservoir between 1997 and 2004. 28 iii
Acronyms AMSL Above Mean Sea Level BIP Balanced Indigenous Population CCW Condenser Cooling Water CFS Cubic Feet per Second NPDES National Pollutant Discharge Elimination System RFAI Reservoir Fish Assemblage Index SFI Sport Fishing Index SQN Sequoyah Nuclear Plant TRM Tennessee River Mile TVA Tennessee Valley Authority VS Vital Signs iv
EXECUTIVE
SUMMARY
Sequoyah Nuclear Plants (SQN) current National Pollutant Discharge Elimination System permit number TN0026450 states, For Section 316(b), the permittee shall summarize previous data and indicate whether significant changes have occurred in plant operation, reservoir operations or instream biology that would necessitate significant changes to the variance.
Condenser Cooling Water (CCW) withdrawn from Chickamauga Reservoir potentially affects the fish community by entrainment (small fish and eggs drawn through the intake screens) and impingement (fish trapped against screens by the intake water velocity). Densities of fish in the reservoir near the intake and daily volume of water transported past the SQN were compared to daily CCW demand and densities of fish at the intake skimmer wall to estimate percent entrainment.
During operational monitoring from 1981 through 1985, the entrainment of total fish larvae was estimated to be 2.8 percent of those passing the plant. In order to compare the current larval fish assemblage and rate of entrainment with data collected during historical monitoring, ichthyoplankton sampling was conducted during May through July 2004. Clupeids (primarily gizzard and threadfin shad) were the dominant taxon collected in entrainment sampling and estimated entrainment was 15.4 percent. Freshwater drum larval entrainment was estimated to be 45.4 percent, the highest for any of the significant taxa. Overall larval entrainment was estimated to be 15.6 percent during 2004.
Entrainment estimates for total larvae in 2004 were higher than those from historical samples colleted during 1981 through 1985. Historical fluctuations in rates of entrainment and recent Reservoir Fish Assemblage Index evaluations indicate the Chickamauga Reservoir near SQN supports a balanced and diverse indigenous fish community with no significant impacts observed from current plant operation.
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Introduction Section 316(a) of the Clean Water Act allows point-source dischargers of heated water to obtain a variance from state water quality standards if the point-source can demonstrate maintenance of balanced indigenous populations (BIP) of aquatic life. Compliance requires permittee to characterize the aquatic community in the vicinity of the intake structure prior to operation; monitoring during normal operation to assess impacts; and periodically review current operational demands, reservoir operation, and condition of the aquatic community to ensure no significant changes have occurred. Two potential impacts associated with cooling water intake structures are impingement and entrainment. Impingement occurs when aquatic organisms are trapped against the intake structure (traveling screens) by the withdrawal of cooling water and entrainment occurs when organisms are drawn through the intake structure into the plant cooling system.
Sequoyah Nuclear Plants (SQN) current National Pollutant Discharge Elimination System (NPDES) permit number TN0026450 states, For Section 316(b), the permittee shall summarize previous data and indicate whether significant changes have occurred in plant operation, reservoir operations or instream biology that would necessitate significant changes to the variance. In 1991, the Tennessee Valley Authority (TVA) implemented changes in TVA reservoir operations to maintain minimum flows below dams at critical times and locations.
These changes were the result of the Tennessee River and Reservoir System Operation and Planning Review (TVA 1991). Other changes included increasing dissolved oxygen below 16 dams by aerating releases, and to delay unrestricted summer drawdown until August 1 on ten tributary reservoirs. Further changes in reservoir operation policy were implemented in 2005 as a result of TVAs Reservoir Operations Study and Environmental Impact Statement (TVA 2004).
During operational monitoring at SQN from 1981 through 1985, the average hydraulic entrainment was estimated to be 8.6 percent. During this period, the average entrainment of total fish larvae was estimated to be 2.8 percent of those passing the plant. In order to compare current level of larval fish and hydraulic entrainment with data collected during operational monitoring, ichthyoplankton sampling was conducted during April through July 2004. The purpose of this document is to summarize and provide Tennessee Department of Environment and Conservation the results and comparisons between current and historical entrainment monitoring data.
RESERVOIR AND PLANT OPERATION DURING 2004 Chickamauga Reservoir Operation Surface elevation of Chickamauga Reservoir and river flow past SQN is dependent on the rate water is released through Watts Bar and Chickamauga Dams. TVAs integrated approach to Chickamauga Reservoir operation includes winter drawdown for flood control, minimum summer pools, and hydroelectric power generation. In 2004, average daily surface elevation of Chickamauga forebay ranged from 206.0 m above mean sea level (AMSL) to 209.5 m AMSL (Figure 1). Daily river flow past SQN ranged from 159 m3/s to 2634 m3/s in 2004 (Figure 2).
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On May 18, 2004, the daily average release from Chickamauga Hydro was zero cubic feet per second (cfs) while the release from Watts Bar Hydro was 7100 cfs. This unusual situation resulted in essentially zero or negative flow past SQN.
Sequoyah Operation SQN Units 1 and 2 were both in operation during the 2004 entrainment sampling (Figure 3). The combined generation rate for Units 1 and 2 averaged 2081 megawatts in 2004. The average daily withdrawal rate (hydraulic entrainment) of CCW from Chickamauga Reservoir during 2003 and 2004 was 86 m3/s (Figure 4). However, CCW demand during entrainment sampling (April 27 through July 12, 2004) reflected normal operation, averaging 91 m3/s.
Methods Sample Collection Larval sampling began on April 20 and continued through July 12, 2004. Ichthyoplankton samples provided temporal abundance of larval fish and eggs at five stations along a transect perpendicular to river flow just upstream of the plant intake channel at Tennessee River Mile (TRM) 485 (Figure 5). Seven samples were collected weekly during both day and night.
Samples consisted of one full-stratum sample from both left and right overbanks, three samples from the mid-channel area with one taken from surface to mid-depth, one from mid-depth to bottom and one towed near bottom for the duration of the sample. In addition, two replicate, 20-minute full-stratum samples were collected along the intake skimmer wall.
Samples were collected with a beam net (0.5 m square, 1.8 m long, with 505 micron nitex mesh netting) towed upstream at a speed of 1.0 m/s for ten minutes. The volume of water filtered through the net was measured with a large-vaned General Oceanics flowmeter. Approximately 150 m3 of water were filtered per ten minute sample. Intake samples were collected by lowering the net to the bottom and gradually raising the net during the 20 minutes to the depth of the skimmer wall (approximately 16-17 meters). Approximately 40-50 m3 of water were filtered per intake sample. Water temperature was recorded using a mercury thermometer calibrated to the tenth degree Celsius.
Laboratory and Data Analysis Laboratory Analysis Larval fish and eggs were removed from the samples, identified to the lowest possible taxon, counted and measured to the nearest millimeter total length following procedures outlined in NROPS-FO-BR-24.1 (TVA 1983). Taxonomic decisions were based on TVAs Preliminary Guide to the Identification of Larval Fishes in the Tennessee River, (Hogue et al., 1976) and other pertinent literature.
The term unidentifiable larvae applies to specimens too damaged or mutilated to identify, while unspecifiable before a taxon implies a level of taxonomic resolution (e.g., unspecifiable catostomids designates larvae within the family Catostomidae that currently cannot be identified to a lower taxon). The category unidentifiable eggs applies to specimens that cannot 2
be identified due to damage or lack of taxonomic knowledge. Taxonomic refinement is a function of specimen size and developmental stage. Throughout this report, the designation unspecifiable clupeids refers to clupeids less than 20 mm in total length and could include Dorosoma cepedianum (gizzard shad), D. petenense (threadfin shad), and/or Alosa chrysochloris (skipjack herring). Any clupeid specimens identified to species level represent postlarvae 20 mm or longer in total length.
Developmental stage of moronids also determines level of taxonomic resolution. Morone saxatilis (striped bass) hatch at a larger size than either M. chrysops (white bass) or M.
mississippiensis (yellow bass). Although it is currently impossible to distinguish between larvae of the latter two species, M. saxatilis can be eliminated as a possibility based on developmental characteristics of specimens 6 mm or less in total length (hence, the taxonomic designation Morone, not saxatilis). Specimens identified as Morone spp. are greater than 6 mm total length.
Data Analysis Temporal occurrence and relative abundance of eggs and larvae by taxon are presented and discussed for the entire monitoring period. Densities of fish eggs and larvae are expressed as numbers per 1000 m3 of water sampled.
Estimated entrainment of fish eggs and larvae at SQN was calculated by the following method:
densities of eggs and larvae transported past the plant were estimated for each sample period by averaging densities (all stations) of eggs and larvae from TRM 485 and multiplying by the corresponding 24-hour flow past the plant. Percentage of transported ichthyofauna entrained by the plant was estimated from the formula:
E = 100 Di Qi Dr Qr where Di = mean density (N/1000 m3) of eggs or larvae in intake samples; Dr = mean density (N/1000 m3) of eggs or larvae in river (TRM 485 transect);
Qi = plant intake water demand (m3/d);
Qr = river flow (m3/d).
Results and Discussion During twelve sample periods in 2004, the average volume of water filtered each period was 232.7 m3 for intake samples and 876.6 m3 for reservoir samples (Table 1). A list of families of fish eggs and larvae collected during 2004 including the lowest level of taxonomic resolution is presented in Table 2.
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Fish Eggs Freshwater drum eggs comprised 98.8 percent of the total fish eggs and were collected during all twelve sample periods (Table 3), demonstrating the extended spawning season for this species.
Densities peaked on May 25 at 24,367/1000 m3 in reservoir samples and on June 2 at 1,594/1000 m3 in samples collected near the intake (Table 4) (Figure 6). Average seasonal densities for drum eggs were 549 and 652/1000 m3 in the intake and reservoir samples respectively (Table 5).
Larval Fish Relative abundance for all taxa of larval fish collected during the twelve weekly sample periods of 2004 (Table 3) was dominated by clupeids (87.9%), Morone (5.5%), freshwater drum (3.2%)
and centrarchids (3.1%). Total number of larvae collected for the four dominant taxa was 51,350 and total collected for all taxa was 52,881. A comparison of densities of total fish larvae by sample period between intake and reservoir samples is presented in Figure 7.
Peak densities of clupeid larvae (primarily gizzard and threadfin shad) occurred on April 27 in reservoir samples (20,570/1000 m3) and on May 3 in intake samples (15,464/1000 m3) (Table 4).
Following the high densities in late April and early May, clupeid densities decreased dramatically through the remainder of the sampling period with a slight increase observed during early June (Figure 8). Average seasonal density for clupeids was 2,249/1000 m3 for intake and 3,465/1000m3 for reservoir samples (Table 5).
Larval Morone were collected from the first sample period (April 20) through June 9, 2004.
Densities of Morone (white and yellow bass) larvae also peaked on April 27 (Figure 9) at 1,558 and 277/1000m3 in the reservoir and intake samples respectively. Average seasonal densities of larval Morone were 52/1000 m3 in intake samples and 247/1000 m3 in reservoir samples (Table 5).
Centrarchid (Lepomis and Pomoxis) larvae were first collected on April 27 and were present in samples throughout the remainder of the sampling season (Figure 10). Peak densities of 897/1000 m3 occurred in the reservoir samples on June 2 and 1,027/1000 m3 occurred on June 15 in the intake samples (Table 4). Centrarchid larvae exhibited similar average seasonal densities in both intake (131/1000 m3) and reservoir samples (128/1000 m3).
Freshwater drum larvae were first collected on April 27 and were present in samples throughout the remainder of the sampling season. Densities peaked on May 18 at 717/1000 m3 in the intake samples and on June 9 at 379/1000 m3 in reservoir samples (Table 4). Average seasonal densities were 200/1000m3 in intake and 104/1000 m3 in reservoir samples (Table 5).
Average seasonal densities for all taxa collected are presented in Table 5.
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Hydraulic Entrainment Estimates Hydraulic entrainment by SQN during the twelve sampling periods in 2004 averaged 24.2 percent with a range of 7.4 to 111.1 percent (Table 6). The peak hydraulic entrainment occurred on May 18 and the lowest was recorded on June 30. The entrainment estimate of 111.1 percent on May 18 was a result of zero release at Chickamauga Dam and 7,100 cfs average release from Watts Bar Dam.
Fish Egg and Larvae Entrainment Estimates Estimated total transport of fish eggs (98.8% drum eggs) past SQN during 12 sample periods in 2004 was 5.4 billion. The seasonal entrainment estimate for drum (Sciaenid) eggs was 11.2 percent (Table 7).
Estimated total transport of fish larvae past SQN during 12 sample periods in 2004 was 9.8 billion. Clupeid larvae comprised 87.9 percent of this total and were entrained at a rate of 15.4 percent of the total passing the plant. The overall estimated rate of entrainment for total fish larvae was 15.6 percent, obviously driven by clupeids as the most dominant taxon. Average seasonal densities of clupeids in intake vs. reservoir samples were 2,249 and 3,465/1000 m3 respectively (Table 5).
Estimated entrainment of freshwater drum larvae was 45.4 percent. The two highest densities of drum larvae were both observed in intake samples on May 18 and on June 02. The peak density of 717/1000 m3 at the intake on May 18 occurred coincidentally when the hydraulic entrainment estimate also peaked at 111.1 percent. Overall, densities of freshwater drum larvae were higher in intake samples than channel samples during 8 out of 12 sample periods (Figure 11).
The entrainment estimate for Centrarchids (primarily sunfish and crappie larvae) was 24.2 percent of those passing the plant. Average seasonal density was similar at both intake (131/1000 m3) and reservoir (128/1000 m3) samples (Table 5).
Morone larvae were the only other significant taxon with estimated entrainment over one percent (Table 5). An estimated five percent of Morone larvae passing SQN during 2004 were entrained.
Cyprinid (minnows) larvae were collected in very low numbers evidenced by seasonal densities of 7 and 2/1000 m3 in intake and reservoir samples respectively. Higher densities in intake samples resulted in an estimate of 72.6 percent entrainment for this taxon (Table 6).
DISCUSSION WITH HISTORICAL COMPARISONS Sample methods used to collect fish eggs and larvae during 2004 were only slightly different than those used in 1985 (TVA 1986 and TVA 1987). Seasonal mean hydraulic entrainment was 12.2 percent in 1985 compared to 24.2 percent in 2004. Higher hydraulic entrainment was likely the result of lower reservoir flow rate caused by lower than average runoff from rainfall. This also influenced the total entrainment rate of 15.6 percent for larval fish which was the highest ever recorded.
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Estimated entrainment of freshwater drum eggs was 11.2 percent in 2004 compared to 16.6 percent in 1985. Drum larval entrainment was estimated at 30.2 percent in 1985 compared to 45.4 percent in 2004. Considering that hydraulic entrainment doubled from 1985 to 2004, this increased rate of entrainment estimated for drum larvae could be expected. Table 8 compares historical fish egg and larval entrainment estimates between 1981 through 1985 with the recent estimates during 2004. Historical data led to the conclusion that significant spawning by freshwater drum occurs in the vicinity of, or slightly downstream of SQN, producing eggs and larvae that are not subjected to plant entrainment. Even though seasonal larval drum entrainment was abnormally high (45.4%) during 2004, it was primarily attributed to the May 18 sample period when the peak density occurred simultaneously with peak hydraulic entrainment (111 %).
Chickamauga Reservoir Fish Community Industries responsible for point-source discharges of heated water can obtain a variance from state water quality standards if the industry can demonstrate compliance with thermal criteria by documenting the maintenance of BIP of aquatic life in the vicinity of its discharge. SQNs current NPDES permit number TN0026450 states, For Section 316(a), the permittee shall summarize previous data and indicate whether significant changes have occurred in plant operation, reservoir operations or in stream biology that would necessitate significant changes to the permitted variance. The permittee shall use the Reservoir Fish Assemblage Index (RFAI) to assess Chickamauga Reservoir fish community health. Any apparent declines in the fish community health will be further investigated to discover whether the decline is a valid conclusion and if the decline is real and to identify possible sources for the fish community decline. As part of the identification of potential sources for the decline, the instream effects of the discharges made under this permit will be investigated (TDEC 2000). In response to this requirement, TVAs Vital Signs (VS) monitoring program (Dycus and Meinert 1993) will be used to evaluate areas of Chickamauga Reservoir upstream and downstream of SQN discharge.
Reservoirs are typically divided into three zones for VS Monitoring - inflow, transition and forebay. The inflow zone is generally in the upper reaches of the reservoir and is riverine in nature; the transition zone or mid-reservoir is the area where water velocity decreases due to increased cross-sectional area, and the forebay is the lacustrine area near the dam. The Chickamauga Reservoir inflow zone sample site is located at TRM 529.0; the transition zone sampling site is located at TRM 490.5 and the forebay zone sampling site is located at TRM 472.3. The VS transition zone, which is located approximately 7.2 river miles upstream of the SQN discharge (TRM 483.3), will be used to provide upstream data for the 316(a) thermal variance studies performed in sample years between 1993 and 2005. An additional transition station was later added downstream of the SQN discharge to more closely monitor Chickamauga Reservoir aquatic communities in close proximity to the SQN thermal effluent. This station is located at TRM 482.0 and will be used for downstream comparisons of aquatic communities for the 1999 through 2005 sample seasons. The forebay zone, will serve as the downstream station for 1993 through 1995 and 1997 sample seasons.
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Sport Fishing Index In the past, the Sport Fishing Index (SFI) was used in support of a thermal variance request at SQN (TVA 1996). The SFI was developed to quantify sport fishing quality for individual sport fish species. The SFI provides biologists with a reference point to measure the quality of a sport fishery. Comparison of the population sampling parameters and creel results for a particular sport fish species with expectations of these parameters from a high quality fishery (reference conditions) allows for the determination of fishing quality. Indices have been developed for black bass (largemouth, smallmouth and spotted bass), sauger, striped bass, bluegill, and channel catfish. Each SFI relies on measurements of quantity and quality aspects of angler success and fish population characteristics.
In recent years, SFI information has been used to describe the quality of the resident fishery in conjunction with compliance monitoring, thermal variance requests, and other regulatory issues at TVA nuclear plants in Tennessee. Similar NPDES compliance monitoring programs using the methodologies described above are also being performed at Browns Ferry Nuclear, Colbert and Widows Creek Fossil Plants in Alabama.
The TVA Spring Sport Fish Survey is conducted to evaluate the sport fish population of TVA Reservoirs. The results of the survey are used by state agencies to protect, improve and assess the quality of sport fisheries. Predominant habitat types in the reservoir are surveyed to determine sport fish abundance. In addition to accommodating TVA and state databases, this surveying method aligns with TVA Watershed Team and TVAs Reservoir Operations Study objectives. Sample sites are selected using the shoreline habitat characteristics employed by the Watershed Teams. The survey predominantly targets three species of black bass (largemouth, smallmouth, and spotted bass) and black and white crappie. These species are the predominant sport fish sought after by fisherman.
In the autumn of 2004, Chickamauga Reservoirs sport fish population received similar RFAI scores (Table 9) compared to the eight year average (TVA 2006). Largemouth bass, smallmouth bass, spotted bass, crappie, bluegill, and channel catfish received higher scores than their seven year averages (Figure 12). Channel catfish, largemouth bass, and bluegill received their highest SFI scores to date. Crappie and black bass received lower scores in 2004 compared to scores in 2003. This quality assessment is not necessarily indicative of a trend and historical data indicate that SFI scores typically vary among years. However if future scores would continue to decline, further investigation would be warranted.
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CONCLUSIONS Both historical data and the 2004 sampling results demonstrate the significant variability in the occurrence and spatial-temporal distribution of larval fish in Chickamauga Reservoir near SQN.
This variability translates into significant fluctuation in the entrainment rates associated with plant operation. Factors contributing to these fluctuations include:
- Proximity of intake to spawning and nursery areas
- Seasonality and period of occurrence
- Vertical distribution/movement
- Cross-sectional or horizontal distribution
- Diel distribution
- Life-stage/swimming ability
- Growth rate
- Physical parameters and operation of Chickamauga Reservoir in the vicinity of SQN In calculating entrainment estimates, one or two species usually comprise a high percentage of the total composition, as is the case with clupeids and freshwater drum in the vicinity of SQN.
Freshwater drum spawn in open water while shad spawn near shore and each female produces thousands of eggs, creating areas in the reservoir with high densities of fish eggs and early larvae. As these high density pulses of eggs and larvae drift downstream, their occurrence within a sampling area (either near the plant intake or in the open reservoir) may significantly affect individual entrainment estimates.
The 2004 316(b) data and recent fish community assessments in Chickamauga Reservoir near SQN show no significant impacts from current operation of SQN on the fish community near the plant. Furthermore, current 316(b) data support conclusions presented in the 1986 historical assessments. Results demonstrate annual variations in the relative abundance and spatial-temporal distribution of fish and fluctuations in reservoir flow are common in the vicinity of SQN. Life history aspects and dynamics of drifting larvae and fluctuation in reservoir flow past SQN are significant factors influencing variations observed in the annual entrainment estimates.
These variations in fish density and reservoir flow in the Chickamauga transition zone have apparently had little affect on the fish community. Based on the 2004 316(b) evaluation and the annual RFAI and SFI scores for Chickamauga Reservoir, a viable balanced indigenous fish community is present in Chickamauga Reservoir in the vicinity of SQN.
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LITERATURE CITED Dycus, D. L. and D. L. Meinert. 1993. Reservoir Monitoring, Monitoring and Evaluation of Aquatic Resource Health and Use Suitability in Tennessee Valley Authority Reservoirs.
Tennessee Valley Authority, Water Resources, Chattanooga, Tennessee, TVA/WM-93/15.
Hogue, Jacob J., Jr., R. Wallus, and L. K. Kay. 1976. Preliminary Guide to the Identification of Larval Fishes in the Tennessee River. TVA Tech. Note B19. 67 pp.
Tennessee Department of Environment and Conservation. 2000. Draft NPDES Permit Number TN0026450.
Tennessee Valley Authority. 1983. Aquatic Environmental Conditions in Chickamauga Reservoir during Operation of Sequoyah Nuclear Plant, Second Annual Report (1982).
Knoxville, Tennessee: Division of Air and Water Resources. TVA/ONR/WRF-83.
Tennessee Valley Authority. 1986. Aquatic Environmental Conditions in Chickamauga Reservoir during Operation of Sequoyah Nuclear Plant, Fifth Annual Report (1985).
Knoxville, Tennessee: Division of Air and Water Resources. TVA/ONR/WRF-86/5a.
Tennessee Valley Authority. 1987. Aquatic Environmental Conditions in Chickamauga Reservoir during Operation of Sequoyah Nuclear Plant, Sixth Annual Report (1987).
Knoxville, Tennessee: Division of Air and Water Resources. TVA/ONR/WRF-87/7.
Tennessee Valley Authority. 1991. Tennessee River and Reservoir System Operation and Planning Review Record of Decision; Final Environmental Impact Statement.
TVA/RDG/EQS-91. Knoxville, TN. February 1991.
Tennessee Valley Authority. 1996. A Supplemental 316(a) Demonstration for Alternative Thermal Discharge Limits for Sequoyah Nuclear Plant, Chickamauga Reservoir, Tennessee.
Tennessee Valley Authority, Engineering Laboratory, Norris, TN. WR96-1-45-145. 87 pp.
Tennessee Valley Authority. 2004. Final Programmatic Environmental Impact Statement.
Tennessee Valley Authority Reservoir Operations Study Volume 1-Environmental Impact Statement. February 2004.
Tennessee Valley Authority. 2006. Biological Monitoring of the Tennessee River Near Sequoyah Nuclear Plant Discharge.
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Table 1. Total Volume of Water Filtered by Sample Period at Sequoyah Nuclear Plant during 2004 to Estimate Entrainment of Fish Eggs and Larvae.
2004 Sample Date Intake Reservoir Total m3 m3 m3 Apr 27 216.7 965.5 1182.2 May 4 271.6 1067.7 1339.3 May 10 299.4 833.8 1133.2 May 18 346.1 799.8 1145.9 May 25 276.4 822.1 1098.5 Jun 2 209.6 901.9 1111.5 Jun 9 97.7 939.0 1036.7 Jun 15 189.9 738.5 928.4 Jun 23 254.5 884.1 1138.6 Jun 30 228.0 688.1 916.1 Jul 7 260.4 977.6 1238.0 Jul 12 142.0 901.3 1043.3 Total 2792.3 10519.4 13311.7 Average 232.7 876.6 1109.3 10
Table 2. List of Fish Eggs and Larvae by Family Collected at Sequoyah Nuclear Plant in 2004 Entrainment Samples and Lowest Level of Taxonomic Resolution for each Family.
Scientific Common Lowest Level of Taxonomic Name Name Identification Clupeidae Shad Family - all larvae < 20 mm TL.
Genus or species -larger individuals to Alosa spp.- alewife, skipjack, Dorosoma spp. - gizzard and threadfin shad.
Cyprinidae Minnows and Family - most minnows, shiners, and Carps chubs Genus or species -common carp, golden shiner, and larger individuals to emerald shiner, mimic shiner, Pimephales spp.
Catostomidae Suckers Subfamily - ictiobines (buffalo and carpsuckers)
Genus - Larger individual to buffalo.
Ictaluridae Catfishes Species - Blue, Channel Moronidae Temperate basses Genus -most larval life phases Species - yolk-sac larvae > 5 mm TL (striped bass), larger individuals to white, yellow, and striped bass.
Centrarchidae Sunfishes Genus - crappie, lepomids (sunfishes), and black bass.
Species - larger individuals to largemouth bass.
Sciaenidae Drums Species. freshwater drum Unspecified Identification to family was not possible.
Larvae and Eggs Limiting factors were size, stage of development, and season when egg was collected.
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Table 3. Percent Composition of Fish Eggs and Larvae by Family in Entrainment Samples at Sequoyah Nuclear Plant during 2004.
Intake Reservoir Samples Samples All Samples Eggs Unspecified 0.0 1.9 1.2 Sciaenidae 100.0 98.1 98.8 Larvae Clupeidae 85.2 87.8 87.9 Cyprinidae 0.3 0.1 0.2 Catostomidae T T T Ictaluridae T T T Moronidae 2.0 6.3 5.5 Centrarchidae 5.0 3.3 3.1 Sciaenidae 7.6 2.6 3.2 T - Taxon was collected in samples but composition was less than 0.1%.
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Table 4. Peak Densities and Sample Dates by Family for Fish Eggs and Larvae from Intake and Reservoir Entrainment Samples Collected at Sequoyah Nuclear Plant during 2004.
Peak Density Number/1000 m3 Intake/ Sample Sample Date Skimmer Date Reservoir D=Day Wall D=Day N=Night N=Night EGGS Family Sciaenidae 1,594 June 2 4,433 May 25 LARVAE Family Clupeidae 15,464 May 3 20,570 April 27 Cyprinidae 28 April 27 6 April 27 Catostomidae 0 - 7 June 15 Ictaluridae 0 - 2 June 9 Moronidae 277 April 27 1,558 April 27 Centrarchidae 1,027 June 15 897 June 2 Sciaenidae 717 May 18 379 June 9 13
Table 5. Average Seasonal Density of Fish Eggs and Larvae in Entrainment Samples at Sequoyah Nuclear Plant during 2004.
Intake Reservoir Samples Samples All Samples 1000 m3 1000 m3 1000 m3 Eggs Unspecified 0 12 6 Sciaenidae 549 652 618 Totals: 549 664 627 Larvae Clupeidae 2249 3465 3221 Cyprinidae 7 2 3 Catostomidae 0 T T Ictaluridae 0 T T Moronidae 52 247 204 Centrarchidae 131 128 128 Sciaenidae 200 104 129 Totals: 2639 3946 3685 T - Taxon was collected in samples but density averaged less than 1 individual per 1000 m3.
Table 6. Estimated Daily Hydraulic Entrainment by Sample Period at Sequoyah Nuclear Plant during 2004.
Volume Sample Date Intake Reservoir m3 day m3 day Entrained Qi Qr %
Apr 27 5.90E+06 2.50E+07 23.6%
May 4 6.00E+06 5.50E+07 10.9%
May 10 6.00E+06 5.40E+07 22.2%
May 18 6.00E+06 5.40E+06 111.1%
May 25 6.1.0E+06 2.10E+07 29.0%
Jun 02 6.00E+06 1.80E+07 33.3%
Jun 09 6.00E+06 6.70E+07 9.0%
Jun 15 6.00E+06 4.60E+07 13.0%
Jun 23 6.10E+06 5.90E+07 10.3%
Jun 30 6.10E+06 8.20E+07 7.4%
Jul 07 6.10E+06 5.70E+07 10.7%
Jul 12 6.10E+06 6.20E+07 9.8%
Average 6.03E+06 4.37E+07 24.2%
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15 Table 7. Seasonal Entrainment Estimates for Numerically Significant Fish Taxa Collected at Sequoyah Nuclear Plant during 2004.
Intake Reservoir Number Total Entrained Number Entrainment Per Day Per Day Estimate Taxa Q iX D i Q rX D r %
Eggs Sciaenidae 6.10E+09 5.40E+10 11.2 Totals: 6.10E+09 5.40E+10 11.2 Larvae Clupeidae 1.30E+10 8.60E+10 15.4 Cyprinidae 4.30E+07 5.90E+07 72.6 Catostomidae 0.00E+00 1.40E+07 0.0 Ictaluridae 0.00E+00 6.50E+06 0.0 Moronidae 3.10E+08 6.20E+09 5.0 Centrarchidae 7.70E+08 3.20E+09 24.2 Sciaenidae 1.20E+09 2.60E+09 45.4 Totals: 1.53E+10 9.81E+10 15.6 Table 8. Historical and Current Entrainment Percentages for Fish Eggs and Larvae at Sequoyah Nuclear Plant during 1981-1985 and 2004.
1981 1982 1983 1984 1985 2004 Freshwater Drum Eggs 6.7 41.4 22.6 9.7 16.6 11.2 Larvae Clupeidae 2.1 1.5 2.7 1.8 1.1 15.4 Cyprinidae 4.3 4.2 5.9 2.3 3.1 72.6 Catostomidae 0.0 0.0 6.1 2.6 0.0 0.0 Ictaluridae 8.4 7.7 9.1 45.9 27.8 0.0 Moronidae 1.7 2.7 4.8 2.2 2.46 5.0 Centrarchidae 1.0 1.8 1.1 0.6 0.7 24.2 Percidae 3.6 1.6 10.7 1.6 3.5 0.0 Sciaenidae 5.5 25.6 57.8 22.7 30.2 45.4 Total Larvae 2.3 2.2 4.7 2.3 2.6 15.6 16
Table 9. Recent (1993-2005) RFAI Scores Collected as Part of the Vital Signs Monitoring Program Upstream and Downstream of Sequoyah Nuclear Plant.
Station Reservoir Location 1993 1994 1995 1997 1999 1993- 2000* 2001 2002* 2003 2004 2005 1993-2005 1999 Average Average Upstream Chickamauga TRM 490.5 49 40 46 39 45 44 46 45 51 42 49 48 45 (Good) (Good)
Sequoyah Chickamauga TRM 482.0 41 41 48 46 43 45 41 39 43 Transition (Good) (Good)
Forebay Chickamauga TRM 472.3 44 44 47 39 45 44 45 48 46 43 43 46 45 (Good) (Good)
- The 2000, and 2002, sample years were not part of the VS monitoring program, however the same methodology was applied.
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Meters 205.0 205.5 206.0 206.5 207.0 207.5 208.0 208.5 209.0 209.5 210.0 1-Jan 21-Jan 10-Feb 2-Mar 22-Mar 11-Apr 1-May 21-May 10-Jun 30-Jun 20-Jul 9-Aug 29-Aug 18-Sep 8-Oct 28-Oct 17-Nov 7-Dec 18 27-Dec 16-Jan 5-Feb 25-Feb 16-Mar 5-Apr 25-Apr 15-May 4-Jun 24-Jun 14-Jul 3-Aug 23-Aug 12-Sep Figure 1. Average daily surface elevation (meters above mean sea level) of Chickamauga Reservoir during 2004.
2-Oct 22-Oct 11-Nov 1-Dec 21-Dec
Cubic Meters/Second 0 200 400 600 800 1000 1200 1400 1-Jan 22-Jan 12-Feb 5-Mar 26-Mar 16-Apr 7-May 28-May 18-Jun 9-Jul 30-Jul 20-Aug 10-Sep 1-Oct 22-Oct 19 12-Nov 3-Dec 24-Dec 14-Jan 4-Feb 25-Feb Figure 2. Average daily rate of flow in Chickamauga Reservoir during 2003 and 2004.
17-Mar 7-Apr 28-Apr 19-May 9-Jun 30-Jun 21-Jul 11-Aug 1-Sep 22-Sep 13-Oct 3-Nov 24-Nov 15-Dec
MW 0 500 1000 1500 2000 2500 01/01/2003 02/01/2003 03/01/2003 04/01/2003 05/01/2003 06/01/2003 07/01/2003 08/01/2003 09/01/2003 10/01/2003 11/01/2003 12/01/2003 20 Unit 1 01/01/2004 02/01/2004 Unit 2 03/01/2004 04/01/2004 05/01/2004 Figure 3. Average daily rate of generation at Sequoyah Nuclear Plant during 2003 and 2004.
06/01/2004 07/01/2004 08/01/2004 09/01/2004 10/01/2004 11/01/2004 12/01/2004
Cubic Meters/Second 20 30 40 50 60 70 80 90 1-Jan 21-Jan 10-Feb 2-Mar 22-Mar 11-Apr 1-May 21-May 10-Jun 30-Jun 20-Jul 9-Aug 29-Aug 18-Sep 8-Oct 28-Oct 17-Nov 7-Dec 21 27-Dec 16-Jan 5-Feb 25-Feb 16-Mar 5-Apr 25-Apr 15-May 4-Jun 24-Jun 14-Jul 3-Aug Figure 4. Average daily rate of hydraulic entrainment at Sequoyah Nuclear Plant during 2003 and 2004.
23-Aug 12-Sep 2-Oct 22-Oct 11-Nov 1-Dec 21-Dec
Figure 5. Map of entrainment sample transects in the vicinity of Sequoyah Nuclear Plant during 2004.
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5000 Intake Reservoir 4500 4000 3500 Number / 1000 m3 3000 2500 2000 1500 1000 500 0
27-Apr 3-May 10-May 18-May 25-May 2-Jun 9-Jun 15-Jun 23-Jun 30-Jun 7-Jul 14-Jul Date Figure 6. Densities of sciaenid eggs collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004.
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25000 Intake Reservoir 20000 Number / 1000 m3 15000 10000 5000 0
27-Apr 3-May 10-May 18-May 25-May 2-Jun 9-Jun 15-Jun 23-Jun 30-Jun 7-Jul 14-Jul Date Figure 7. Densities of total larval fish collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004.
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25000 Intake Reservoir 20000 Numbers / 1000 m3 15000 10000 5000 0
27-Apr 3-May 10-May 18-May 25-May 2-Jun 9-Jun 15-Jun 23-Jun 30-Jun 7-Jul 14-Jul Date Figure 8. Densities of clupeid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004.
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1800 Intake Reservoir 1600 1400 1200 3
Number / 1000 m 1000 800 600 400 200 0
27-Apr 3-May 10-May 18-May 25-May 2-Jun 9-Jun 15-Jun 23-Jun 30-Jun 7-Jul 14-Jul Date Figure 9. Densities of moronid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004.
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1200 Intake Reservoir 1000 800 3
Number / 1000 m 600 400 200 0
27-Apr 3-May 10-May 18-May 25-May 2-Jun 9-Jun 15-Jun 23-Jun 30-Jun 7-Jul 14-Jul Date Figure 10. Densities of centrarchid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004.
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800 Intake Reservoir 700 600 500 Number / 1000 m3 400 300 200 100 0
27-Apr 3-May 10-May 18-May 25-May 2-Jun 9-Jun 15-Jun 23-Jun 30-Jun 7-Jul 14-Jul Date Figure 11. Densities of sciaenid larvae collected in intake and reservoir entrainment samples at Sequoyah Nuclear Plant during 2004.
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Chickamauga SFI Scores 1997-2004 60 50 Black bass 40 Largemouth bass Smallmouth bass SFI Score Spotted bass Crappie 30 Sauger Striped bass Bluegill 20 Channel catfish White bass 10 0
1997 1998 1999 2000 2001 2002 2003 2004 Year Figure 12. Sport Fishing Index results for Chickamauga Reservoir between 1997 and 2004.
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