ML19007A331

Peach Bottom Atomic Power Station - Final Report for Post-EPU Thermal and Biological Monitoring

ML19007A331
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Site:	Peach Bottom
Issue date:	02/28/2017
From:	ERM, Exelon Generation Co, Normandeau Associates
To:	Office of Nuclear Reactor Regulation
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ML19008A020	List: ML19007A326 ML19007A327 ML19007A328 ML19007A330 ML19007A331 ML19007A334 ML19007A335 ML19007A340
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January 7, 2019 U.S. Nuclear Regulatory Commission ENCLOSURE12 12_NAl-ERM_2017.pdf

[NAI and ERM] Normandeau Associates, Inc. and Environmental Resource Management.

2017. "Final Report for Post-EPU Thermal and Biological Monitoring Peach Bottom Atomic Power Station." Prepared for Exelon Generation.

February 2017. ---------------

FINAL REPORT FOR POST-EPU THERMAL AND BIOLOGICAL MONITORING PEACH BOTTOM ATOMIC POWER STATION Exelon Generation

,, February 2017 FINAL REPORT FOR POST-EPU THERMAL AND BIOLOGICAL MONITORING PEACH BOTTOM ATOMIC POWER STATION Prepared for: Exelon Generation

... Prepared by: Normandeau Associates, Inc. and ERM, Inc. February 2017 PBAPS Post-EPU Study Executive Summary .........................................................................................

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1 1 Introduction

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3 2 Background

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5 2. 1 The Peach Bottom Atomic Power Station ..................................

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5 2.2 Conowingo Pond .................

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5 2. 3 Biota of Conowingo Pond ...............

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6 2.4 Summary of 2014 316(a) Demonstration Study ...........................................................

6 3 Temperature Monitoring Program .......................................

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9 3.1 Characteristics of the 2016 Post-EPU Study Year. .......................................................

9 3.2 Thermal Plume Monitoring

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10 4 Biological Station Temperature Monitoring

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..... 33 5 Dissolved Oxygen Monitoring

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............. 49 6 Biological Monitoring and Assessment

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57 6. 1 Introduction

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57 6. 2 Benthic Macroinvertebrate Community

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.... 57 6.3 Fish Community

.......................................................................................................... 82 7 Juvenile American Shad Migration

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131 7. 1 Analysis .....................

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................................ 131 7.2 Summary and Conclusions

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... 132 8 Gizzard Shad Seasonal Distribution .

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.... 140 8. 1 Analysis ....................................................................................................................

140 8. 2 Summary and Conclusions

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141 9 Conclusions

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143 1 O Literature Cited ...............

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... 146 11 Appendices

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149 PBAPS Post-EPU Study 11. 1 PBAPS Post-EPU Study Plan ..............................

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149 11. 2 Chronology of Gizzard Shad Population Expansion

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149 ii PBAPS Post-EPU Study List of Figures Figure 3-1 Location of 2016 temperature monitoring stations ....................................................

12 Figure 3-2 Location of 2016 intake and discharge canal temperature monitoring stations .........

12 Figure 3-3 Excerpt from the NPDES Permit, Part C describing the cooling tower operating schedule ...................................................................................................................................

13 Figure 3-4 Summer 2016 cooling tower operations

................................................................... 14 Figure 3-5 Temperatures in the discharge canal and at Monitoring Station 214 ........................

18 Figure 3-6 Summer 2016 temperatures presented as increases above intake temperature

...... 19 Figure 3-7 End of canal and 214 temperatures during startup of the first cooling tower .............

22 Figure 3-8 End of canal and 214 temperatures during the transitions from two to three to two cooling towers ...........................................................................................................................

22 Figure 3-9 End of canal and 214 temperatures during shutdown of all three towers ..................

23 Figure 3-10 Monitoring stations used for the model verification

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26 Figure 3-11 Comparisons of modeled and observed temperature increases at 214 ..................

28 Figure 3-12 Comparisons of modeled and observed temperature increases at 215 ..................

29 Figure 3-13 Comparisons of modeled and observed temperature increases at 189 ..................

30 Figure 3-14 Comparisons of modeled and observed temperature increases at 301S ................

31 Figure 4-1. Location of biological water temperature collection stations ....................................

35 Figure 4-2. Daily mean water temperature measured at PBAPS Intake, 2010-2016

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36 Figure 4-3. Daily mean water temperature measured at Station 221 in 2016 ............................

36 Figure 4-4. Daily mean water temperature measured at Station 208, 2010-2016

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37 Figure 4-5. Daily mean water temperature measured at Station 214, 2010-2016

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37 Figure 4-6. Daily mean water temperature measured at Station 215, 2010-2016

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38 Figure 4-7. Daily mean water temperature measured at Station 189, 2010-2016

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38 Figure 4-8. Daily mean water temperature measured at Station 190, 2010-2016

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39 Figure 4-9. Daily mean water temperature measured at Station 216, 2010-2016

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39 Figure 4-10. Daily mean water temperature measured at Station 217, 2010-2016

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.40 Figure 4-11. Daily maximum instantaneous water temperature measured at PBAPS Intake, 2010-2016 ................

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40 Figure 4-12. Daily maximum instantaneous water temperature measured at Station 221 in 2016 . ...............

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41 Figure 4-13. Daily maximum instantaneous water temperature measured at Station 208, 2010-2016 ..........................................................................................................................................

41 iii PBAPS Post-EPU Study Figure 4-14. Daily maximum instantaneous water temperature measured at Station 214, 2010-2016 ..........................................................................................................................................

42 Figure 4-15. Daily maximum instantaneous water temperature measured at Station 215, 2010-2016 ..........................................................................................................................................

42 Figure 4-16. Daily maximum instantaneous water temperature measured at Station 189, 2010-2016 ..........................................................................................................................................

43 Figure 4-17. Daily maximum instantaneous water temperature measured at Station 190, 2010-2016 ..................

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43 Figure 4-18. Daily maximum instantaneous water temperature measured at Station 216, 2010-2016 ..........................................................................................................................................

44 Figure 4-19. Daily maximum instantaneous water temperature measured at Station 217, 2010-2016 ..................................................................................................

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44 Figure 5-1. Dissolved Oxygen monitoring locations in Conowingo Pond during 2016 ...............

52 Figure 5-2. Hourly dissolved oxygen measurements at Station 189, June through September 2016 ................

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54 Figure 5-3. Hourly dissolved oxygen measurements at Station 215, June through September 2016 ..................................................................................................

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55 Figure 5-4. Hourly dissolved oxygen measurements at Station 208, June through September 2016 ..........................................................................................................................................

56 Figure 6-1. Location of benthic macroinvertebrate collection stations ........................................

64 Figure 6-2 Location of seine collection stations .........................................................................

65 Figure 6-3. Location of electrofishing collection stations ...............

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.............................. 66 Figure 6-4. Bar chart showing the IBI scores for each station by month, May through September 2016 .......................................................................................................................

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75 Figure 6-5. Box plot of May IBI scores for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal.

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76 Figure 6-6. Box plot of June IBI scores for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal.

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76 Figure 6-7. Box plot of July IBI scores for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal.

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77 Figure 6-8. Box plot of August IBI scores for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal.

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77 Figure 6-9. Box plot of September IBI scores for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal.

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78 iv PBAPS Post-EPU Study Figure 6-10. Relation of mean water temperature measured during the month of benthos collection to the corresponding 181 Score for that month for post-EPU (left panel) and pre-EPU (right panel) monitoring, May through September 2010-2016

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78 Figure 6-11. Box plot of Total Richness for all stations during pre-EPU (2010-2013) and EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal

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79 Figure 6-12. Box plot of EPT Richness for all stations during pre-EPU (2010-2013) and EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal.

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79 Figure 6-13. Box plot of Ephemeroptera Richness for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal.

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80 Figure 6-14. Box plot of Trichoptera Richness for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal.

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... 80 Figure 6-15. Box plot of Beck's Index for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal. ........................................................................................

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81 Figure 6-16. Box plot of Shannon Diversity for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal.

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...... 81 Figure 6-17. Box plot of square root transformed CPUE (no./0.5hr) for all electrofishing stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) .............................................

103 Figure 6-18. Box plot of total species for all electrofishing stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) .............................

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103 Figure 6-19. Box plot of total RIS for all electrofishing stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) ....................................................................

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104 Figure 6-20. Box plot of Shannon Diversity for all electrofishing stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) ..................................................................................

104 Figure 6-21. Box plot of CPUE for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) .........................................................

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105 Figure 6-22. Box plot of total species for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) ........................................................................................

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105 Figure 6-23. Box plot of total RIS for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) ..........................

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..................... 106 Figure 6-24. Box plot of Shannon Diversity for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016) ..........................................................................................

106 v PBAPS Post-EPU Study Figure 6-25. Length-frequency distribution of Bluegill collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

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111 Figure 6-26. Length-frequency distribution of Bluntnose Minnow collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

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111 Figure 6-27. Length-frequency distribution of Channel Catfish collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

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112 Figure 6-28. Length-frequency distribution of Gizzard Shad collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

.... 112 Figure 6-29. Length-frequency distribution of Largemouth Bass collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

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113 Figure 6-30. Length-frequency distribution of Chesapeake Logperch collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

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113 Figure 6-31. Length-frequency distribution of Smallmouth Bass collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

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114 Figure 6-32. Length-frequency distribution of Spotfin Shiner collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

.... 114 Figure 6-33. Length-frequency distribution of Walleye collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations

..................... 115 Figure 6-34. Box plot of Bluegill relative weight by station during pre-EPU and post-EPU monitoring, May through September

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117 Figure 6-35. Box plot of Largemouth Bass relative weight by station during pre-EPU and post-EPU monitoring, May through September

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......................................................... 118 Figure 6-36. Box plot of Channel Catfish relative weight by station during pre-EPU and post-EPU monitoring, May through September

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119 vi PBAPS Post-EPU Study Figure 6-37. Box plot of Smallmouth Bass relative weight by station during pre-EPU and post-EPU monitoring, May through September

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120 Figure 6-38. Square root transformed mean CPUE for Bluegill collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016 ..................................

123 Figure 6-39. Square root transformed mean CPUE for Smallmouth Bass collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016 ..............................

124 Figure 6-40. Square root transformed mean CPUE for Spotfin Shiner collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016 ..................................

124 Figure 6-41. Square root transformed mean CPUE for Bluntnose Minnow collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016 .....................

125 Figure 6-42. Square root transformed mean CPUE for Chesapeake Logperch collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016 .....................

125 Figure 6-43. Square root transformed mean CPUE(no/0.5hr) for Gizzard Shad collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016 .. 126 Figure 6-44. Square root transformed mean CPUE(no/0.5hr) for White Crappie collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016 .. 127 Figure 6-45. Square root transformed mean CPUE(no/0.5hr) for Smallmouth Bass collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016 ...........................

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127 Figure 6-46. Square root transformed mean CPUE(no/0.5hr) for Bluegill collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016 .......... 128 Figure 6-47. Square root transformed mean CPUE(no/0.5hr) for Channel Catfish collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016 . ...............................................................................................................................................

128 Figure 6-48. Square root transformed mean CPUE(no/0.5hr) for Chesapeake Logperch collected using a boat electrofisher in Conowingo Pond, June-October 1996-2013 and May-September 2016 ........................................................................................

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129 Figure 6-49. Square root transformed mean CPUE(no/0.5hr) for Walleye collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016 ..........

129 Figure 7-1. Predicted thermal plume at surface, 5ft, 10ft, and 15ft during MRPSF pumping .... 136 Figure 7-2. Predicted thermal plume at surface, 5ft, 10ft, and 15ft during MRPSF pumping .... 138 vii PBAPS Post-EPU Study List of Tables Table 3-1 Monthly average Susquehanna River flows: Historical, Demonstration Study, and Post-EPU Study years ..........

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9 Table 3-2 Monthly average Susquehanna River temperatures:

Historical, Demonstration Study, and Post-EPU Study years ........................................................................................................

1 O Table 3-3 Frequency of occurrence of combinations of low Susquehanna River flows and high Susquehanna River temperatures

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10 Table 3-4 Cooling tower start-up and shutdown dates ...............................................................

14 Table 3-5 Temperature increases from the intake to the head of canal for 2016 .......................

19 Table 3-6 Temperature reduction as a function of number of cooling towers in operation at downstream stations .................................................................................................................

20 Table 3-7 End of canal and 214 daily average, minimum, and maximum temperatures relative to intake temperatures during startup of the first cooling tower ......................................................

23 Table 3-8 End of canal and 214 daily average, minimum, and maximum temperatures during transitions from two to three then back to two cooling towers in operation

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24 Table 3-9 End of canal and 214 daily average, minimum, and maximum temperatures during shutdown of all three towers ......................................................................................................

24 Table 3-10 Travel time to reach the monitoring stations ............................................................

25 Table 4-1. Monthly mean water temperature measured at the biological monitoring locations and PBAPS intake, May through September, 2010-2013, and 2016 ...............................................

.45 Table 4-2. Summary of instantaneous maximum and daily mean water temperature data for multiple locations within Conowingo Pond in 2016 ....................................................................

46 Table 4-3. Summary of instantaneous maximum and daily mean water temperature data for multiple locations within Conowingo Pond in 2010 ...................................................................

.46 Table 4-4. Summary of instantaneous maximum and daily mean water temperature data for multiple locations within Conowingo Pond in 2011 ...................................................................

.47 Table 4-5. Summary of instantaneous maximum and mean water temperature data for multiple locations within Conowingo Pond in 2012 ................................................................................

.47 Table 4-6. Summary of instantaneous maximum and mean water temperature data for multiple locations within Conowingo Pond in 2013 ................................................................................

.48 Table 5-1. Descriptive statistics for dissolved oxygen monitoring in Conowingo Pond, June through September 2016 ..........................................................................................................

53 Table 6-1. Description of seine, benthos, electrofishing, and water temperature stations in Conowingo Pond (negative values indicate distance upstream from the discharge canal) ........ 67 Table 6-2. Descriptions of benthic macroinvertebrate community metrics ................

................. 68 viii PBAPS Post-EPU Study Table 6-3 Average habitat assessment scores for the seven benthic macroinvertebrate collection locations, May through September 2016 ...................................................................

68 Table 6-4. Total number of benthic macroinvertebrates collected at each station in Conowingo Pond from May through September 2016 ..................................................................................

69 Table 6-5. Percent composition of common benthic macroinvertebrates

(>1 % of total organisms) collected from Conowingo Pond, May through September 2016 .............................

71 Table 6-6. Percent composition of common benthic macroinvertebrates

{>1%) collected from Conowingo Pond, May through September 2010-2013

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72 Table 6-7. Total Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016 ......................................................................

73 Table 6-8. EPT Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016 ......................................................................

73 Table 6-9. Ephemeroptera Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016 ...................................................

73 Table 6-10. Trichoptera Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016 ...................................................

74 Table 6-11. Modified Beck's Index values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016 ...................................................

74 Table 6-12. Shannon Diversity values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016 ...................................................

74 Table 6-13. List of common and scientific names of fishes collected in Conowingo Pond, May through September 2016 ..........................................................................................................

84 Table 6-14. Total number of fish collected with boat electrofisher from Conowingo Pond, May through September 2016 ..........................................................................................................

85 Table 6-15. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, May 2016 ........................................................................................................................

86 Table 6-16. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, June 2016 .......................................................................................................................

87 Table 6-17. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, July 2016 ........................................................................................................................

88 Table 6-18. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, August 2016 ...................................................................................................................

89 Table 6-19. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, September 2016 .............................................................................................................

90 Table 6-20. Total number of fish collected in seine collections from Conowingo Pond, May through September 2016 ..........................................................................................................

91 ix PBAPS Post-EPU Study Table 6-21. Total number (CPUE) of fish collected with seine from Conowingo Pond, May 2016 . ........................................................................

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92 Table 6-22. Total number (CPUE) of fish collected with seine from Conowingo Pond, June 2016 . ..............................

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93 Table 6-23. Total number (CPUE) of fish collected with seine from Conowingo Pond , July 2016 . ......................................................

........................................................................................... 94 Table 6-24. Total number (CPUE) of fish collected with seine from Conowingo Pond, August 2016 .....................

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95 Table 6-25. Total number (CPUE) of fish collected with seine from Conowingo Pond, September 2016 .........................

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96 Table 6-26. CPUE of fish by month for electrofishing collection locations in Conowingo Pond, May through September 2016 .........................

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100 Table 6-27. Total RIS by month for electrofishing collection locations in Conowingo Pond, May through September 2016 ..............................................................................................

.......... 100 Table 6-28. Total Species by month for electrofishing collection locations in Conowingo Pond, May through September 2016 ..............................

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100 Table 6-29. Shannon Diversity by month for electrofishing collection locations in Conowingo Pond, May through September 2016 ......................

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101 Table 6-30. CPUE of fish by month for seine collection locations in Conowingo Pond, May through September 2016 ...............................................

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101 Table 6-31. Total RIS by month for seine collection locations in Conowingo Pond, May through September 2016 ................................................

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101 Table 6-32. Total Species by month for seine collection locations in Conowingo Pond, May through September 2016 .....................................................................

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102 Table 6-33. Shannon Diversity by month for seine collection locations in Conowingo Pond, May through September 2016 ..................................

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102 Table 6-34. Descriptive statistics for total length of RIS collected in Conowingo Pond ............

110 Table 6-35. Descriptive statistics for Bluegill relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September ....................................... 117 Table 6-36. Descriptive statistics for Largemouth Bass relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September

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118 Table 6-37. Descriptive statistics for Channel Catfish relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September

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119 Table 6-38. Descriptive statistics for Smallmouth Bass relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September

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.......... 120 Table 6-39. Total number of each species with DEL Ts for all sample locations in Conowingo Pond, May through September 2016 .......................................................................................

122 x PBAPS Post-EPU Study Table 6-40. Types of external anomalies observed by species for fish collected in Conowingo Pond, May through September 2016 .......................................................................................

122 Table 7-1. Juvenile American Shad Outmigration Data for Holtwood Lift Net, PBAPS travelling screens, and Conowingo Dam Strainer, September 11 through December 12, 2004 through 2009 ..............

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134 Table 7-2. Joint probability occurrence

(%) of average daily water temperature and river flows measured at Holtwood Dam in October and November, 1956-2012. October -November are emigration periods of juvenile American Shad in lower Susquehanna River ...........................

135 xi PBAPS Post-EPU Study Executive Summary The Post-EPU Thermal and Biological Study (Post-EPU Study) supports the monitoring requirements set forth in the Station's NPDES Permit. The study evaluated increases in water temperature after implementation of the extended power uprate (EPU) and assessed the resulting effects on the biological community.

Field studies included water temperature and dissolved oxygen monitoring, benthic macroinvertebrate sampling, and fish community surveys in thermally and non-thermally affected areas of Conowingo Pond. The study also included desktop evaluations of juvenile American Shad migration past the PBAPS thermal plume and the seasonal distribution of Gizzard Shad in Conowingo Pond relative to the PBAPS thermal discharge.

The Post-EPU Study is the follow-up to the four-year 316(a) Demonstration Study (Pre-EPU Demonstration Study) completed in 2013. The Pre-EPU Demonstration Study concluded that under pre-EPU operations, a balanced, indigenous community (BIC) existed in Conowingo Pond. Modeling and analysis performed during the Pre-EPU Demonstration Study concluded that after EPU implementation with cooling towers operating, a BIC would continue to be maintained.

The Pre-EPU Demonstration Study also recommended that thermal and biological monitoring be continued to evaluate post-EPU conditions against predictions made during the Pre-EPU Demonstration Study. Susquehanna River flows and temperatures during the 2016 study period were at extreme levels (i.e., low flows in combination with high ambient water temperatures) and were thus ideal for direct measurement of temperature increases.

Comparisons showed that predicted temperature increases provided an upper bound to those observed in the field. Field observations also showed that the average post-EPU condenser temperature rise was less than the assumed value (i.e., 22.1°F actual compared with 22.4°F modeled).

Observations also showed that each cooling tower performed better than expected (2.2°F temperature reduction per tower instead of the modeled value of 1.6°F). Overall, field observations show that cooling tower operation as specified in the current NPDES permit effectively mitigates the post-EPU increase in thermal load. Water temperature observations at the biological monitoring locations were generally consistent with pre-EPU observations.

Monitoring of dissolved oxygen (DO) concentrations indicated that DO was protective of the aquatic community and DO concentrations would not block fish migration past PBAPS. Evaluation of the Pre-EPU Demonstration Study model output indicated that a BIC would be maintained after the implementation of the EPU. Post-EPU monitoring indicated that the measurable spatial and temporal impacts of the thermal plume to the biota of Conowingo Pond were similar to those observed during pre-EPU sampling, as expected.

Similar to pre-EPU study results, the temporal patterns of fish avoidance and decline in benthos diversity were related to high water temperatures.

1 PBAPS Post-EPU Study Both the fish and benthic macroinvertebrate community composition and relative abundance were similar to those observed during Pre-EPU monitoring.

Indices used to describe the community structure of the biological community showed that thermally influenced and thermally influenced stations were similar biologically during pre-and post-EPU monitoring.

Field observations showed that, as expected, a BIC has been maintained during post-EPU conditions with cooling tower mitigation.

The time-varying hydrothermal model used for the temperature predictions was subsequently used to predict the areas in Conowingo Pond with water temperatures that would impede juvenile American Shad emigration.

The analysis indicated that virtually the entire Pond is available for juvenile American Shad emigration with no potential for thermal blockage.

In Conowingo Pond, Gizzard Shad tolerate temperatures

< 2.2 °C {< 36.0 °F) and do not appear to need a "thermal refuge" to sustain the population.

The winter electrofishing catch supports a conclusion that the PBAPS thermal plume is not interfering with the fall outmigration of Gizzard Shad or attracting excessively large numbers of this species during the winter months. 2 PBAPS Post-EPU Study 1 Introduction Exelon Generation, LLC's (Exelon) Peach Bottom Atomic Power Station (PBAPS) is a power generating facility located in York County, Pennsylvania.

The Station operates under National Pollutant Discharge Elimination System (NPDES) Permit No. PA0009733 and a Federal Clean Water Act (CWA) §316(a) variance for its thermal discharge to Conowingo Pond. This study supports the monitoring requirements set forth in the NPDES Permit under Part C, Alternate Thermal Limitations.

The purpose of this study is to evaluate the increase in water temperature after implementation of the Extended Power Uprate (EPU) and to determine potential changes to the thermal plume and its effects on the biological community.

After completion and acceptance of the pre-EPU 316(a) Demonstration Study (Normandeau and ERM 2014), Exelon developed a Post-EPU Study Plan that outlined the technical requirements necessary to confirm results of the Pre-EPU Demonstration Study. The Plan was subsequently reviewed and revised in coordination with the Pennsylvania Department of Environmental Protection (PADEP). The final, approved Study Plan was submitted to PADEP on April 25, 2016. The sampling program was initiated shortly thereafter.

The goal of the Post-EPU Study is to use physical and biological field data to confirm predicted biological outcomes and to validate model assumptions and results from the pre-EPU 316(a) Demonstration Study. The 2016 physical and biological field dataset are similar to the datasets used for the pre-EPU 316(a) Demonstration Study. The 2016 dataset is focused on critical areas and issues that were identified in the Pre-EPU Demonstration Study. In addition to the biological and temperature monitoring, the Post-EPU Study Plan included continuous dissolved oxygen monitoring, a desktop study to evaluate juvenile American Shad migration past the PBAPS thermal plume, and a desktop study to address concerns over Gizzard Shad seasonal distribution in Conowingo Pond relative to the PBAPS thermal discharge.

This Post-EPU Study is the follow-up to the four-year pre-EPU 316(a) Demonstration Study as described in the Post-EPU Study Plan (Normandeau and ERM 2016). In the pre-EPU 316(a) Demonstration Study, an extensive set of physical and biological field data were collected and analyzed to show the effects of PBAPS's thermal discharge.

To estimate the impacts of increased heat loads to Conowingo Pond when each of the two generating units was equipped for EPU operations, a three-dimensional hydrothermal model was used to simulate the extent of the thermal plume for average and extreme ambient conditions with EPU operating conditions.

The model also has the capability to simulate temperature in Conowingo Pond during the operation of one, two or three of the cooling towers located along the PBAPS discharge canal. The approved NPDES permit for EPU operation required a summertime cooling tower operating schedule that balanced the additional heat load from the EPU against the heat reduction from the operation of the cooling towers. The cooling tower operating schedule also specified use of cooling towers during episodic, naturally-occurring high river temperature events. The main components of the present study include water temperature monitoring, dissolved oxygen monitoring, and biological sampling of shore zone benthic macroinvertebrates and the 3 PBAPS Post-EPU Study resident fish community in Conowingo Pond. Field data collection was completed for the months of May through September, the main period for fish reproduction and growth, as well as the period with the highest ambient and discharge water temperatures.

Section 2 of this report provides background information about previous thermal and biological studies conducted relative to PBAPS. Sections 3 through 6 discuss water temperature, biological, and dissolved oxygen monitoring results and analysis.

Sections 7 and 8 provide information related to juvenile American Shad migration and seasonal distribution of Gizzard Shad in Conowingo Pond relative to PBAPS's thermal plume. 4 PBAPS Post-EPU Study 2 Background This section summarizes important background information on the Station (including the EPU and cooling tower operations), Conowingo Pond's physical features and biota, and the main conclusions from the pre-EPU 316(a) Demonstration Study. 2. 1 The Peach Bottom Atomic Power Station Exelon operates two nuclear reactors at the Peach Bottom site. Unit 2 began commercial operation in June 1974; Unit 3 entered commercial service in December 1974 1* PBAPS withdraws water for condenser cooling from Conowingo Pond (Pond) through an intake structure using six circulating water pumps (three per unit, 557 cubic feet per second (cfs) per pump) and for service water needs using six service water pumps (three per unit, 31.2 cfs per pump). After passing through the plant, water exits at the head of the 4,700-ft long discharge canal into Conowingo Pond. The discharge structure is designed for rapid mixing of the heated effluent into ambient Conowingo Pond water and an immediate reduction in temperature.

Three cooling towers are located along the canal, each of which is capable of reducing the temperature by approximately 1.6 to 2.2°F, depending on meteorological conditions, especially humidity and wind speed. The design temperature rise across the condensers is 22°F and across the service water system is 10.7°F. As noted in the Pre-EPU Demonstration Study, the actual temperature rise for the combined condenser and service water flow as observed in the study averaged 19.4°F at the head of the discharge canal during the two warmest months of the year, July and August. Exelon began uprating Unit 2 in 2014 and Unit 3 in 2015, with the uprate for each Unit fully implemented about one year later (2015 and 2016, respectively).

Variable cooling tower operation, discussed later in this report, began in the summer of 2015. The additional waste heat added when both uprated reactors are operating results in a 3°F increase in the temperature rise. 2.2 Conowingo Pond Conowingo Pond, the lowermost of four hydroelectric impoundments on the lower Susquehanna River, was formed in 1928 by construction of Conowingo Hydroelectric Station at River Mile 10 (RM 10). Conowingo Hydroelectric Station is a modified run-of-river facility with limited storage for peaking hydropower generation.

Conowingo Pond is bounded upstream by Holtwood Dam (RM 24) built in 1914. PBAPS at RM 17 is about equidistant between the two dams. Conowingo Pond has a surface area of about 9,000 acres and is about 14 miles long and averages 1 mile wide. The elevation at normal full Pond is 108.5 ft and the elevation is normally 1 Unit1 was a small experimental reactor shut down in 1974. 5 PBAPS Post-EPU Study maintained at 106.5 ft or higher for recreational use on weekends between Memorial Day and Labor Day and at levels no less than 104.5 ft at other times for operation of PBAPS. Long-term monitoring that began around 1960 has shown that the Pond is not thermally stratified but that at summer water temperatures and low Susquehanna River (<12,000 cfs), dissolved oxygen stratification can occur in deeper areas of the Pond. Since monitoring dates PBAPS operations, dissolved oxygen stratification is a natural phenomenon, common for this type of waterbody.

The circulation in the Pond is influenced by outflows and inflows that can occur on a daily or hourly basis from controlled inflows of up to 32,000 cfs from Holtwood Hydroelectric Dam and up to 32,000 cfs (during generation) from Muddy Run Pumped Storage Facility (MRPSF) at RM 22. Controlled outflows of up to 85,000 cfs occur at Conowingo Hydroelectric Station and of up to 28,000 cfs (during pumping) at Muddy Run. 2.3 Biota of Conowingo Pond The biota of Conowingo Pond has been studied intensely for many years. Long-term thermal and biological monitoring studies have been completed in Conowingo Pond since 1966, both prior to operation of PBAPS in 197 4 and in the subsequent operational period. Sampling has been performed upstream and downstream from PBAPS and in areas within the heated plume. The numerous long-term studies documented species composition, relative abundance and distribution of fishes within Conowingo Pond. The most recent thermal studies in the form of a pre-EPU 316(a) Demonstration Study were completed from 2010 to 2013. These studies included temperature monitoring and extensive fish community monitoring in Conowingo Pond. Since 1966, approximately 60 species have been captured in the Pond and the tributary streams. 2.4 Summary of 2014 316(a) Demonstration Study The pre-EPU 316(a) Demonstration Study served multiple purposes:

• *

• to study an alternative thermal effluent limitations under §316(a) of the CWA; to evaluate changes in the thermal plume created by operation of up to three helper cooling towers, and to predict changes to the thermal plume associated with planned uprates to Units 2 and 3 and to design the cooling tower protocol.

2.4.1 316(a) Demonstration Study Description The Pre-EPU Demonstration Study was completed with extensive coordination with PADEP. The main components of the study were temperature monitoring, hydrothermal modeling, sampling of macroinvertebrates and of the resident fish community, and integrated analysis of the temperature and biological data. Each component was used to make an independent 6

PBAPS Post-EPU Study assessment of the PBAPS thermal discharge and to evaluate the applicability of a thermal variance.

Monitoring and sampling were performed April through October, the main period of fish reproduction and growth as well as highest ambient and discharge water temperatures.

Data collection began in 2010 and continued through 2013. No towers were operated during the summer of 2010, one tower was operated in 2011, two towers in 2012, and three towers in 2013. The resulting datasets provided all the information necessary to evaluate the temperature reduction effects of cooling tower operation.

2.4.2 316(a) Demonstration Study Results Temperature Monitoring The towers performed as designed; each tower cooled the discharge by about an additional 1.6°F, measured from the head to the end of the discharge canal.

• Operation of the towers reduced water temperatures in Conowingo Pond by consistent and measurable amounts within 1.2 miles of the discharge and near the western shoreline and by smaller amounts beyond 1.2 miles. Benthic Macroinvertebrate Community

• The composition and relative abundance of the benthic community was similar during all 4 years of the study.

• Temporary impact, in terms of lower 181 scores, was observed at Stations 214 and 215 in July and August after a sustained period of high water temperatures, but was followed by recovery.

• Benthic community changes resulting from the thermal plume are localized and temporary and limited to a small proportion of the available shallow shoreline habitat within Conowingo Pond.

• There was no observed impact to the benthic community at the three influenced Stations (189, 216 and 217) that are 1.3 miles or more downstream from the discharge canal. Fish Community

• Inter-annual variation in relative abundance of the Representative Important Species (RIS) and other species did not appear to be related to differences in water temperature resulting from cooling tower operation.

• Metrics used to describe fish community structure show no clear differences in the fish community between thermally influenced and non-thermally influenced locations.

Limited avoidance by selected species was observed at Stations 161, 214, and 215 which are closest to the end of the discharge canal, during the periods of highest water temperature in July and/or August. Little or no habitat avoidance occurs in May and early June, the peak spawning period for most fishes in Conowingo Pond. 7 PBAPS Post-EPU Study The observed fish avoidance for select species occurred mostly in July and August when either the species move out of the area or for most RIS, have completed spawning activity.

• Relative abundance of most RIS from 2010 through 2013 was within the range of values observed previously in Conowingo Pond. Hydrothermal Model The model accurately reproduced the hydrodynamics and thermal structure of the Pond relative to the PBAPS thermal plume and other dynamic input parameters.

The agreement of modeled and observed temperatures over the range of conditions that occurred in 2010, 2011 and 2012 allows the model to predict the thermal structure in the pond for other-than-observed conditions and to establish the cooling tower operating schedule shown in the NPDES Permit, Part C. EPU modeling results for the typical summer condition show that areas of potential fish avoidance would be small, localized, and temporary in nature. Most of the potential avoidance areas for the typical summer condition modeling scenario would occur at the water surface near to the west shoreline immediately downstream from the discharge canal.

• EPU modeling results for the extreme summer condition show that areas of potential fish avoidance would be sizable for several species with most of the elevated water temperatures and avoidance areas at the surface or in the immediate vicinity of the discharge canal.

• Cross-sections of the thermal plume for both modeling scenarios indicated that sufficient areas of the channel would be available at water temperatures less than the avoidance temperatures for the RIS and will allow for their movement within the Pond. 2.4.3 316(a) Demonstration Study Overall Conclusions The Pre-EPU Demonstration Study concluded that under pre-EPU operations, a balanced, indigenous community (BIC) in Conowingo Pond existed. Modeling and analysis performed during the Pre-EPU Demonstration Study also concluded that after EPU implementation with cooling towers operating using the agreed schedule, a BIC would continue to be maintained.

The Pre-EPU Demonstration Study also suggested that thermal and biological monitoring after EPU implementation should be continued to evaluate post-EPU conditions against predictions made during the Pre-EPU Demonstration Study. 8 PBAPS Post-EPU Study 3 Temperature Monitoring Program This section of the report presents the results of the 2016 thermal plume monitoring organized by deliverables listed in the Post-EPU Study Plan. For the thermal plume monitoring, the deliverables are:

• Temperature data in electronic format

• Duration and frequency of high temperatures

• Temperature changes due to cooling tower operations

• Transition period temperatures Model verification The Susquehanna River flows and temperatures that occurred in 2016 are important in understanding the temperature and biological data presented in this study. The 2016 flows and temperatures are discussed below relative to those observed during the four year Pre-EPU Demonstration Study, historical values, and values used to model post-EPU conditions.

3. 1 Characteristics of the 2016 Post-EPU Study Year Table 3-1 shows monthly average 2016 Susquehanna River flows compared to the long-term mean and the four years of the Pre-EPU Demonstration Study. Shaded cells are those flows below the long-term mean. The table shows that the years 2010, 2012 and 2016 stand out as low flow years. July and September are important because those flows are very near or below the 7000 cfs flow chosen for the "extreme" scenario modeled for the Pre-EPU Demonstration Study. Table 3-1 Monthly average Susquehanna River flows: Historical, Demonstration Study, and Post-EPU Study years. Month Average Susquehanna River flow, cfs 1932-2011 2010 2011 2012 2013 2016 April 78,600 46,385 149,867 23,704 53,462 33,210 May 48,500 34,392 110,399 52,547 29,717 34,010 June 28,900 17,508 35,079 29,693 31,949 15,640 July 16,200 10,060 13,202 8,730 37,117 6,947 August 12,700 8,808 17,797 10,275 15,692 9,857 September 15,800 6,142 141,479 11,222 12,266 5,506 October 18,800 40,228 80,023 18,378 18,853 13,821 ----Table 3-2 is shows monthly average temperatures in a similar format, but in this table the shaded months identify temperatures greater than the long-term mean. Like many of the months in the Demonstration Study, 2016 is also characterized by warm temperatures.

September 2016 is unusual -not only are temperatures more than 5°F higher than all Septembers shown in the table, September 2016 most resembles temperatures typically seen in August. 9 PBAPS Post-EPU Study Overall, 2016 resembles 2010; both are warmer and dryer than most years. September 2016 is unique, characterized by very low flows and unusually high temperatures.

Table 3-2 Monthly average Susquehanna River temperatures:

Historical, Demonstration Study, and Post-EPU Study years. Month Average Susquehanna River temperatures, °F 1999-2013 2010 2011 2012 2013 2016 June 74.8 78.8 76.2 75.0 75.1 77.3 July 81.1 84.0 83.3 83.8 81.2 83.6 August 80.1 82.3 80.1 81.8 77.2 84.4 September 73.1 75.1 68.1 74.2 73.8 80.1 In the Pre-EPU Demonstration Study, the flows and temperatures for the typical and extreme modeling scenarios were based on the 10% and 1 % frequency of occurrence of combinations of low Susquehanna River flows and high Susquehanna River temperatures.

Table 3-3 characterizes July, August and September 2016 in the same fashion. The table shows, of all historical combinations of Susquehanna River flows and temperatures (1956-2012, all months), 97% of the months had either higher flows or lower temperatures than occurred in September 2016, making its combination of flows and temperatures unusual, but less so than the extreme scenario modeled for the Pre-EPU Demonstration Study. Table 3-3 Frequency of occurrence of combinations of low Susquehanna River flows and high Susquehanna River temperatures.

Case Monthly mean intake Monthly mean Susquehanna Fraction of months this temperature, °F River flow, cfs combination is exceeded Extreme Modeling Scenario 86 7000 99% Typical Modeling Scenario 80 13000 90% July 2016 84 7051 98% August 2016 84 9954 97% September 2016 80 5587 97% The fact that 2016 was both a low flow and a high temperature year makes it a unique year in which to collect both temperature and biological data and to measure cooling tower performance and the response of the aquatic communities to near-extreme conditions.

3. 2 Thermal Plume Monitoring The 316(a) Demonstration Study measured temperatures with 0, 1, 2, and 3 towers in operation to determine the rate of cooling in the canal and downstream, modeled 1 % and 10% combinations of flow and ambient temperature to estimate post-EPU downstream temperatures for extreme conditions, and used the model to help design the cooling tower operating schedule published in Part C of the N PDES permit. 10 PBAPS Post-EPU Study The Post-EPU Study used observations to show that the expected downstream cooling occurs and compared modeled and observed temperatures to demonstrate the model correctly predicted temperatures for extreme events ("verification").

The use of cooling towers after implementation of the EPU is based on the concept that a healthy fishery existed in Conowingo Pond prior to EPU implementation and that the same healthy fishery post-EPU will be maintained if the additional heat from the EPU is offset by operation of the cooling towers. This offset can be demonstrated by comparing the temperature increase at the head of canal due to the EPU (3°F) with the temperature decrease from operating two cooling towers, each reducing the temperature by 1.6°F for a total of 3.2°F. 3.2.1 Data Program Monitoring Station Descriptions Temperature monitoring for the Post-EPU Study used a subset of the stations used in the EPU Demonstration Study, as approved by PA DEP in consultation with the US Fish and Wildlife Service. Figure 3-1 shows the location of these monitoring stations.

The location, data, and analysis of the biological monitoring stations are discussed in "Biological Station Temperature Monitoring." Figure 3-2 shows the monitoring stations in the discharge canal. Water Temperature Data All water temperature data have been provided to PA DEP, as required, in a separate spreadsheet and transmittal.

The period of record is May 1 through September 30, 2016; data are measured hourly and retrieved monthly. Loss of Data There were 30 monitoring stations taking data hourly for a total of 110, 160 (= 30 stations x 153 days x 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) possible data points over the five month monitoring period. Nearly all temperature data were recovered and available for analysis as 99% data recovery was achieved.

11

'. I -"r HoftWood Dam 't&t'Ltl"lgCntl Raltn1 Pwlftt Ml J.hn1an 11tand H t / ' PBAPS Post-EPU Study ! ,., \ I -* .J ,. I.-" Rollnel'oMt PHch Bottom Alontlc Power SUitton t Figure 3-1 Location of 2016 temperature monitoring stations.

Conawineo DoOI Figure 3-2 Location of 2016 intake and discharge canal temperature monitoring stations.

12 PBAPS Post-EPU Study 3.2.2 Temperature Data Analvsis There are four analytical deliverables, each of which is discussed below. Duration and Frequencv of High Temperatures Because the Pre-EPU Demonstration Study presents the duration and frequency of high temperatures as part of the analysis of the biological data, the corresponding Post-EPU Study data are reported in Section 6. Temperature Changes Due to Cooling Tower Operations This section of the report quantifies temperature changes during cooling tower operations, first from the head of the discharge canal to the end, then at monitoring stations immediately downstream of the canal. During the post-EPU 2016 study period PBAPS operated at full load with the EPU and the cooling towers operated as set forth in Part C of the NPDES Permit (Figure 3-3). Cooling towers shall be operated for the combined operation of Units 2 and 3 during the period of June 15 through August 31 of each year, according to the sequential order. Average Intake temperatures listed below are based on the priOf two day roUing average using Unit 2 or Unll 3 circulating water intake temperature i nstrumentation:

{1) One lower shall commence operalion on June 15 and shall operate continuously through August 31. Should environmental conditions warrant, the Permttee may request that DEP authorize a delay In commencement ot such tower operation.

(2} A second cooling tower shall commence operation within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of average intake temperatures being equal to or greater than 83"F. Once operation has commenced, the second tower shall operate conUnuoosly through August 31. Should environmental conditions warrant, the Perrnitee may request that DEP authorize the termination of the second tower operation prior to August 31. (3) A third cool i ng tower shall commence operation within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of average intake tempefatures being equal to or greater than 86°F. The tower shall operate continuously for seven days, and shall cease operation on the first day, following the seven days, when the average intake temperature is less than 86"F. Thereafter, the third tower shall commence and cease operations when the conditions set forth herein reoccur. Figure 3-3 Excerpt from the NPDES Permit, Part C describing the cooling tower operating schedule.

In the following discussion, temperatures will generally be presented as temperature differences, e.g., increases over ambient 2 or reductions from the temperature measured at the head of the canal. This approach facilitates year-to-year and model-to-observations comparisons.

2 Ambient is assumed to be equivalent to the temperature measured at the PBAPS intake. 13 PBAPS Post-EPU Study Cooling tower performance, measured by temperature reductions in the canal, is discussed next, followed by a discussion of temperature reductions in Conowingo Pond downstream of the discharge with respect to the number of cooling towers operating.

Figure 3-4 shows the number of towers in operation through the summer of 2016, with start-up and shutdown times highlighted in Table 3-4. This table shows dates beginning five days before start-up of the first tower and ending five days after shutdown of the last tower. Figure 3-5 shows observed temperatures at the intake, head of canal, and end of canal 3 for May through September 2016. Temperatures at Monitoring Station 214 are also shown for reference.

Figure 3-5 shows that there is only a small temperature reduction from the head to the end of canal through June 15th (orange and black lines), but that the temperature reduction increases as each tower starts up (note the separation of orange and black lines). Figure 3-6 shows the same locations but the temperatures in this figure are shown as increases above intake temperature.

A ,_ i2 Cl .!: B 0 0 () c May 01 May 15 I Cooling Tower Operations in 2016 I Jun 01 Jun 15 Jul 01 Jul 15 Aug 01 Aug 15 Date I

• Tower in Operation I Figure 3-4 Summer 2016 cooling tower operations.

Table 3-4 Cooling tower start-up and shutdown dates. Sep 01 Sep 15 Oct 01 Date Cooling Tower A Status Cooling Tower B Status Cooling Tower C Status 6/6/2016 Off Off Off 617/2016 Off Off Off 6/8/2016 Off Off Off 6/9/2016 Off Off Off 3 The end of canal monitoring station is called Outfall 001 in the NPDES Permit. 14 PBAPS Post-EPU Study Date Cooling Tower A Status Cooling Tower B Status Cooling Tower C Status 6/10/2016 Off Off Off 6/11/2016 Off Off On 6/12/2016 Off Off Off 6/13/2016 Off Off Off 6/14/2016 Off Off On 6/15/2016 Off Off On 6/16/2016 Off Off On 6/17/2016 Off Off On 6/18/2016 Off Off On 6/19/2016 Off Off On 6/20/2016 Off Off On 6/21/2016 Off Off On 6/22/2016 Off Off On 6/23/2016 Off Off On 6/24/2016 Off Off On 6/25/2016 Off Off On 6/26/2016 Off Off On 6/27/2016 Off Off On 6/28/2016 Off Off On 6/29/2016 Off Off On 6/30/2016 Off On On 7/1/2016 Off On On 7/2/2016 Off Off On 7/3/2016 Off Off On 7/4/2016 Off Off On 7/5/2016 Off Off On 7/6/2016 Off Off On 7nt2016 Off Off On 7/8/2016 Off Off On 7/9/2016 Off Off On 7/10/2016 Off Off On 7/11/2016 Off Off On 7/12/2016 Off Off On 7/13/2016 Off Off On 7/14/2016 Off -Off On ----------

7/15/2016 Off Off On 7/16/2016 Off Off On 7/17/2016 Off On On 7/18/2016 Off On On 7/19/2016 Off On On 7/20/2016 Off On On 7/21/2016 Off On On 15 PBAPS Post-EPU Study Date Cooling Tower A Status Cooling Tower B Status Cooling Tower C Status 7/22/2016 On On On 7/23/2016 On On On 7/24/2016 On On On 7/25/2016 On On On 7/26/2016 On On On 7/27/2016 On On On 7/28/2016 On On On 7/29/2016 On On On 7/30/2016 On On On 7/31/2016 On Off On 8/1/2016 On Off On 8/2/2016 On Off On 8/3/2016 On Off On 8/4/2016 On Off On 8/5/2016 On Off On 8/6/2016 On Off On 817/2016 On Off On 8/8/2016 On Off On 8/9/2016 On Off On 8/10/2016 On Off On 8/11/2016 On Off On 8/12/2016 On Off On 8/13/2016 On Off On 8/14/2016 On Off On 8/15/2016 On Off On 8/16/2016 On On On 8/17/2016 On On On 8/18/2016 On On On 8/19/2016 On On On 8/20/2016 On On On 8/21/2016 On On On 8/22/2016 On On On 8/23/2016 On On On 8/24/2016 On On On 8/25/2016

--On --On On -* ------------8/26/2016 Off On On 8/27/2016 Off On On 8/28/2016 Off On On 8/29/2016 Off On On 8/30/2016 Off On On 8/31/2016 Off On On 9/1/2016 Off Off Off 16 PBAPS Post-EPU Study Date Cooling Tower A Status Cooling Tower B Status Cooling Tower C Status 9/2/2016 Off Off Off 9/3/2016 Off Off Off 9/4/2016 Off Off Off 9/5/2016 Off Off Off 17 115 110 105 100 95 LL' 90 l!! 65 [ E 80 t!! 75 70 65 60 55 PBAPS Post-EPU Study 2016 Data May01 May 15 Jun 01 Jun 15 Jul 01 Jul 15 Aug 01 Aug 15 Sep 01 Sep 15 Oct 01 Date I -Head of Canal -End or Canal -Stalion 214 -Intake Figure 3-5 Temperatures in the discharge canal and at Monitoring Station 214. 18 26 24 22 20 G:' !!_.. 18 2l 16 -i:5 14 !!! 12 8. E 10 8 6 4 '2 PBAPS Post-EPU Study 2016 Data May 01 May 15 Jun 01 Jun 15 Jul 01 Jul 15 Aug 01 Aug 15 Sep01 Sep15 Ocl01 Date -Head of Canal minus Intake -End of Canal minus Intake -Station 214 minus Intake Figure 3-6 Summer 2016 temperatures presented as increases above intake temperature.

The mean temperature increase from intake to head of canal was 22.1°F which is to be compared to the post-EPU condenser temperature rise of 22.4 °F used in the Pre-EPU Demonstration Study. The condenser temperature rise is an important parameter because it, along with the condenser flow rate, represents the heat released by PBAPS to Conowingo Pond. As was the case for the data taken during the Pre-EPU Demonstration Study, there was some variation in this number in 2016, as shown in Table 3-5, with occasional, short duration exceedances of 22.4°F. Table 3-5 Temperature increases from the intake to the head of canal for 2016 Period Temperature increase (°F) from the intake to head of canal Min Mean Max All Months 18.7 22.1 24.0 April 19.2 21.6 22.7 May 19.3 21.7 22.6 June 18.7 21.9 22.7 July 20.3 22.0 23.4 August 20.6 22.4 23.4 19 PBAPS Post-EPU Study Period Temperature increase (°F) from the intake to head of canal Min I Mean I Max September 19.o I 22.5 I 24.0 In 2016 there was one period with one tower in operation, two periods with two cooling towers in operation, and two periods with three cooling towers in operation.

By analyzing each period separately, cooling tower temperature reductions on a per tower basis can be calculated.

This calculation shows that the value of the per tower temperature decrease in the canal was 2.2°F, which exceeds the 1.6°F found for the 2010 through 2013 Pre-EPU Demonstration Study dataset. The reason for the improvement is believed to be maintenance upgrades performed on the cooling towers. The decrease in temperature in the canal absent cooling towers was 0.2°F, identical to the value found in the Pre-EPU Demonstration Study. As noted in Section 3.4 of the Pre-EPU Demonstration Study (Table 3-5) observed temperature reductions in Conowingo Pond downstream of the discharge canal ranged from 2.1°F to 0.0°F and were highly variable (Section 3.4 "Effectiveness of Cooling Towers in Reducing Downstream Temperatures" in that same report). Similar values and variability were found in the 2016 data period, summarized in Table 3-6 below. Temperature changes at downstream stations due to cooling tower operation are further discussed in "Model Verification," below. Table 3-6 Temperature reduction as a function of number of cooling towers in operation at downstream stations. Monitoring Station Temperature reduction per cooling tower (°F) 1 tower 2 towers 3 towers Average 214 1.2 1.2 1.3 1.2 215 1.2 1.1 1.0 1.1 301S 0.9 0.8 0.8 0.8 189 0.5 0.6 0.6 0.6 Transition Period Temperatures This section of the Post-EPU Study report presents observed temperatures changes in the discharge canal and downstream in Conowingo Pond during cooling tower start-ups and shutdowns.

In general there are six common transitions (three start-ups and three shutdowns) built into the cooling tower operating schedule (Figure 3-3):

• Start-up of the first cooling tower operation on June 15 and shutdown on August 31st Start-up of the second cooling tower when intake temperatures reach 83°F; shutdown on August 31st

• Start-up of the third cooling tower when intake temperatures reach 86°F; operation for at least seven days; shutdown when temperatures are below 86°F (multiple start-ups and shutdowns of the third tower in a single summer are possible).

20 PBAPS Post-EPU Study Examples of all six common transitions occurred in 2016. Figure 3-6 and Table 3-4 show the start-up and shutdown dates for each cooling tower in the summer of 2016. From the table, three periods in 2016 which capture all six common transitions were selected for further analysis:

• Start-up of the first tower in mid-June 2016

• Start-up of the second and third towers, shutdown of the third tower in the second half of July 2016

• Shutdown of all three towers in the second half of August. Temperature reductions and increases associated with these transitions are shown in Figure 3-7, Figure 3-8, and Figure 3-9. The figures show temperature reductions (or increases when a tower shuts down) relative to intake temperatures at the end of the canal, at Monitoring Station 214, and the number of towers in operation (right hand vertical scale). Taken together these figures span a period that begins five days prior to the first transition and ends five days after the last transition.

Each figure focuses on a particular type of transition (e.g., from one to two towers). The noticeable decrease in temperature on June 17 1 h (Figure 3-7) is not related to cooling tower operations, but instead to a sudden reduction in generation that results in the discharge of less waste heat. Although temperature changes at the end of the canal are reasonably clear in all three figures, the changes are less obvious at Monitoring Station 214. Operation of the cooling towers reduce temperatures at Monitoring Station 214 when viewed over a multi-day period, but these changes are obscured when viewed on an hourly basis by fluctuations due the daily cycle of pumpback and generation operations at MRPSF, by heat loss to the atmosphere, and variable entrainment of cooler ambient water. Numerical values of temperature reductions and increases corresponding to the figures are tabulated in Table 3-7, Figure 3-8 and Table 3-9. The simulations conducted for the Pre-EPU Demonstration Study were stationery-state, i.e., all input parameters were held constant except for pumpback and generation at MRPSF. Stationery-state means that a repeating cycle of flows and temperatures in Conowingo Pond was calculated.

The length of the repeating cycle is dictated by the frequency of operations at MRPSF. Cooling tower operations in the model were held constant throughout the simulation periods and for this reason transition period temperatures were not explicitly modeled. The model does compute velocities from which estimates of the travel time to downstream stations can be obtained.

These times are shown in Table 3-10 which shows that travel times are short -less than half an hour to Monitoring Station 214 and less than four hours to Monitoring Station 189. That the hourly observations cannot distinguish the arrival time of cooler water is a consequence of the short travel time.

• 21 LL' ""' CD 24 .... 22 .!!I ..5 20 £ 18 QI 16 ca 4i 14 0:: QI 12 "' ca CD 10 0 .5 8 e 6 CD 4 a. E 2 PBAPS Post-EPU Study ' ---------------------------

JIJ'105 Jun07 Jun09 Jun 11 Jun 13 Date End or Canal Temperature ( F) PB214 Temperature ( F) Jun 15 Jun17 Jun 19 Number of Active Coo'ing Towers Jun21 Figure 3-7 End of canal and 214 temperatures during startup of the first cooling tower. E CD 24 .... 22 .!!I ..5 20 £ 18 CD 16 4i 14 0:: 5l 12 ca CD 10 0 .5 8 e 6 ..3 !!! 4 CD a. 2 E Station Tem eratures durin Coolin Tower TI'ansition Period durin End of Jul Jul15 Jul17 -----------------------------------------.

Jul 19 Jul21 Jul23 Date End of Canal Temperature ( F) PB214 Temperature

(°F) I I Jul25 Jul 27 Jul29 Number of Active Cooling Towers Jul 31 3 I!! Cl 2 .s 8 {.) Q) > ... 0 ... .8 E :::s z 0 3 I!! Cl 2 .s 0 0 0 CD > ti <( 0 ... 11 E :::s z 0 Figure 3-8 End of canal and 214 temperatures during the transitions from two to three to two cooling towers. 22 iL 24 CD ... 22 .fl .5 20 18 CD 16 ... Gi 14 a: Q) 12 II> ... CD 10 0 .5 8 6 ::t '! 4 CD a. E 2 Station Tem eratures durln -----*------.

' I Aug23 Aug25 Aug27 PBAPS Post-EPU Study 00 Date -EndofCanalTemperature('F) --NumberolActiveCoo h ngTowers -Figure 3-9 End of canal and 214 temperatures during shutdown of all three towers. 3 "' .. 2 8 (.) Q) > t: c( "i5 ] E ::t z 0 Table 3-7 End of canal and 214 daily average, minimum, and maximum temperatures relative to intake temperatures during startup of the first cooling tower. Date End of Canal Difference Relative to Intake ("F) PB214 Difference Relative to Intake ("F) Min Mean Max Min Mean Max 6/5/2016 21.3 21.6 21.8 12.1 14.0 15.0 6/6/2016 21.4 21.7 22.0 11.2 14.1 16.0 617/2016 20.3 21.8 23.3 12.4 14.1 15.8 6/8/2016 21.1 21.7 22.0 6.6 13.4 15.2 6/9/2016 21.4 21.6 22.3 11.8 13.6 15.2 6/10/2016 20.7 21.4 21.8 11.0 12.6 14.4 One cooling tower starts up, one now running 6/11/2016 20.5 21.3 21.9 10.5 13.7 15.5 6/12/2016 20.9 21.3 21.6 11.4 13.7 15.2 6/13/2016 20.6 21.2 21.8 10.4 13.7 15.3 6/14/2016 19.1 20.5 21.5 12.4 13.9 15.8 6/15/2016 19.3 19.7 20.0 10.4 12.8 14.5 6/16/2016 17.4 19.8 20.3 10.3 13.4 14.7 6/17/2016 10.8 12.2 16.2 2.1 7.7 11.3 6/18/2016 11.4 15.1 20.6 6.6 9.6 14.0 6/19/2016 16.7 18.8 19.8 9.1 11.8 14.2 6/20/2016 16.9 19.3 20.8 10.1 13.0 15.8 6/21/2016 19.2 19.9 20.5 12.1 13.5 14.8 23 PBAPS Post-EPU Study Table 3-8 End of canal and 214 daily average, minimum, and maximum temperatures during transitions from two to three then back to two cooling towers in operation.

Date End of Canal Difference Relative to Intake (°F) PB214 Difference Relative to Intake (°F) Min Mean Max Min Mean Max 7/15/2016 18.8 19.5 21.2 11.7 13.2 15.0 7/16/2016 18.8 19.7 20.6 11.9 13.2 14.9 One cooling tower starts up, two now running 7/17/2016 15.5 17.8 19.8 9.8 11.5 13.8 7/18/2016 15.6 16.7 17.7 8.7 11.2 13.5 7/19/2016 15.9 16.8 17.2 6.3 11.0 13.1 7/20/2016 14.5 16.6 18.0 6.8 10.7 13.3 7/21/2016 15.0 16.4 17.8 3.9 10.2 14.2 One cooling tower starts up, three now running 7/22/2016 14.3 16.3 18.5 5.8 10.4 14.9 7/23/2016 14.5 15.5 17.0 8.0 10.7 13.2 7/24/2016 14.4 15.3 16.6 8.6 10.9 12.8 7/25/2016 13.6 14.9 18.0 7.8 9.8 14.0 7/26/2016 13.7 14.8 16.5 8.5 10.3 11.8 7/27/2016 13.6 14.5 15.6 7.2 9.7 12.5 7/28/2016 13.8 14.9 15.7 8.2 10.0 12.1 7/29/2016 13.2 15.0 15.7 7.5 9.9 11.6 One cooling tower shuts down, two now running 7/30/2016 15.3 16.6 18.2 8.8 10.9 12.7 7/31/2016 15.9 17.2 17.9 8.7 11.4 12.8 Table 3-9 End of canal and 214 daily average, minimum, and maximum temperatures during shutdown of all three towers. Date End of Canal Difference Relative to Intake (°F) PB214 Difference Relative to Intake (°F) Min Mean Max Min Mean Max 8/23/2016 13.0 14.3 15.1 6.8 9.7 11.9 8/24/2016 13.6 14.8 16.1 6.9 9.6 11.7 One cooling tower shuts down, two now running 8/25/2016 14.5 16.4 18.9 8.7 10.9 12.8 8/26/2016 17.8 18.2 18.8 10.5 12.5 14.1 8/27/2016 16.5 17.5 18.5 9.3 12.0 13.7 8/28/2016 16.5 17.4 18.3 9.6 11.7 13.5 8/29/2016 16.7 17.2 17.8 9.5 11.5 12.8 8/30/2016 15.9 17.1 18.7 9.2 11.9 14.9 8/31/2016 16.4 17.6 18.5 9.5 12.1 14.4 Two cooling towers shut down r none now running 9/1/2016 17.5 21.9 22.7 12.2 14.3 15.7 9/2/2016 21.8 22.3 22.9 12.8 14.4 15.7 9/3/2016 18.8 21.2 22.5 13.2 14.2 15.6 9/4/2016 21.4 22.0 22.6 13.6 14.7 15.9 9/5/2016 21.1 21.9 22.4 13.3 14.6 16.1 9/6/2016 20.4 21.8 22.8 9.1 13.6 16.7 9/7/2016 20.3 21.5 22.6 9.8 13.9 16.8 9/8/2016 20.6 22.2 23.3 12.9 15.1 17.4 24 PBAPS Post-EPU Study Table 3-10 Travel time to reach the monitoring stations Station Incremental distance from the Average velocity from the next Total travel time to reach the next upstream station (mi) upstream station (ft/s) monitoring station (hours) End of canal 0.37 --214 0.28 1.39 0.4 215 0.67 0.78 0.9 189 0.37 0.33 3.9 Model Verification Model verification was performed in two steps: (1) validation of model assumptions and (2) comparison of modeled and observed temperatures.

There were two model assumptions that in combination quantify the amount of heat released to Conowingo Pond: (1) the post-EPU temperature rise from the intake to the head of canal and (2) the performance of the cooling towers. For the post-EPU temperature rise, the model assumed a temperatures rise of 22.4°F from the PBAPS intake to the head of canal. The value of 22.4°F is the sum of the pre-EPU rise of 19.4°F and the post-EPU temperature increase of 3.0°F. The assumed pre-EPU rise of 19.4°F was based on the observed rise for all July's and August's from 201 O to 2013 (typically the warmest months). As shown in Table 3-5, the 2016 values of 22.1°F (entire summer) and 22.2°F (July and August) were measured.

The mean post-EPU temperature rise from the intake to the head of the canal for July and August of 22.2°F is less than the 22.4°F assumed value, thus validating this model assumption.

The second model assumption is the extent to which temperatures in the discharge canal are reduced, both from natural cooling and from operation of the cooling towers. The model assumed natural cooling in the discharge canal (i.e., with no cooling towers operating) to be 0.2°F based on the 2010 -2013 dataset. This same value was measured in 2016. For temperature reduction in the discharge canal, the model assumed 1.6°F for each cooling tower, a value also based on the 2010 -2013 dataset. The observations showed that in 2016, the per tower discharge canal cooling was 2.2°F, greater than that assumed for the typical and extreme modeling scenarios and showing that the value assumed in the modeling was conservative.

For the comparisons of modeled and observed temperature increases at downstream stations, data for the four monitoring stations shown in Figure 3-10 were examined.

These stations were identified in the Pre-EPU Demonstration Study as those which experienced the warmest temperatures, the clearest effects of cooling tower operations and the largest biological impacts. That the warmest temperatures occur at these monitoring stations is a consequence of the fact that the thermal plume generally follows along the western shore. 25 PBAPS Post-EPU Study Figure 3-10 Monitoring stations used for the model verification.

There are hourly observations at each monitoring station for five months in the 2016 dataset available for comparison with the modeled results published in the Pre-EPU Demonstration Study. However the Pre-EPU Demonstration Study only predicts post-EPU temperatures for typical (10%) and extreme (1 %) flow and temperature conditions (see Section 3.1 for definitions).

Among the observations are relatively few instances where the combination of Susquehanna River flows and temperatures approach those used for the typical and extreme condition scenarios.

To verify the model, therefore, it is sufficient to show that all observed temperature increases are no larger than the modeled results. The 2016 observations are shown as the cumulative frequency of exceedance of temperature increases above ambient, expressed as a percentage of all observations in Figure 3-11, Figure 26 PBAPS Post-EPU Study 3-12, Figure 3-13, and Figure 3-14. Model results are shown as the blue band that is bounded at the top by modeled extreme temperature increases and at the bottom by modeled average temperature increases.

These figures show that nearly all of the observed temperature increases are below the modeled values (extreme conditions; right side of each panel). The exceptions are

• for Monitoring Station 214, 3 cooling towers in operation:

1 exceedence out of 456 observations (0.2%)

• for 215, no cooling towers: 5 exceedences out of 1696 observations (0.3%)

• for 215, 1 cooling tower: 1 exceedence out of 816 observations (0.1%)

• for 215, 3 cooling towers, 2 exceedences out of 448 observations (0.4%). These exceedances do no overall functionality of the model in bounding the modeled upper temperatures.

The figures show all the 2016 data, including observations at higher flows and lower temperatures than the flows and temperatures used in the model. These observations are shown on the left side of each panel and typically represent about 10% of the observations.

In the figures, the comparisons are shown by the number of cooling towers operating for each monitoring station. Temperatures decrease as more cooling towers are in operation, as expected, and decrease in the downstream direction, also as expected.

The fact that observed temperature increases fall into or below the modeled values can be taken as evidence that the model results agree well with observed values. 27 PBAPS Post-EPU Study Station: 214 Station: 214 # Towers Active: 1 18 18 t 16 E 16 ... "' ... ... I 14 Jl 12 ! 14 s 12 g I 10 ;; i 10 'ii a: a: 6 l'l t; s 6 !: 8 tl 6 ] e 4 j 2 .. 5 i! 4 .. ,!! 2 0 0 0 10 20 30 40 50 60 70 60 90 100 0 10 20 30 40 50 60 70 80 90 100 Cumulative number d occurrence below .,dlcaled dT C umulative number ol OCC\lrrence betow 11dloated dT Station: 214 # Towers Active: 2 Station: 214 # Towers Active: 3 18 18 .... 16 .... 16 le ... " 14 .. 14 ! 12 ,s; 12 Jl g .. 10 :!i 10 .. a: a: 8 8 -' 6 -' 8 !! !! a 3 il 4 E 4 2 2 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Cumulative number of occurrence below indicated dT Cumulauve number of oo::urrenee below indicated dT Figure 3-11 Comparisons of modeled and observed temperature increases at 214. 28 PBAPS Post-EPU Study Station: 215 #Towers Active: 0 Station: 215 # Towers Active: 1 16 18 I'-16 t 16 ... " u 14 ,; 14 12 .!! ; .5 12 g I 10 i 10 ;; .. a: a: :c 8 : 8 ;: 6 l 6 .. s I! 4 I! 4 2 f i!! 2 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 so 60 70 80 90 100 Cumul1llve number of OCCIO'rence betclw mi.,.led dT Cumulllille number ol ocxurrence below Indicated dT Station: 215 #Towers Active: 2 Station: 215 # Towers Active: 3 18 18 E 16 ... 16 I; ... " i 14 .. 14 ! .Ei 12 .5 12 g .!! .. ! 10 10 .!! 1i ..

• a: a: : 8 : 8 g : IJ .5 6 .5 6 j 4 4 n i!! 2 2 0 0 o w 20 30 40 50 60 ro BO so 100 0 10 20 30 40 50 60 70 80 90 100 Cumulalive number of occurrence befoN indicated dT CumulelM!

number ol a:cumnce be!CNI Indicated dT Figure 3-12 Comparisons of modeled and observed temperature increases at 215. 29 PBAPS Post-EPU Study Station: 189 #Towers Active: O Station: 189 # Towers Active: 1 16 16 E 16 E 16 t;; .... " .. 14 ! .5 12 .!! i 14 .!! 12 i 10 i 10 o; .. a: a: 6 n D .5 6 i 8 6 u .. l! e 4 4 u J 2 f 2 0 0 0 10 20 30 40 so 80 70 80 90 100 0 10 20 30 40 so 60 70 60 90 100 Cumul1ltve number d occurrence befO# in cleated dT Cumulllille number of occuuence below Indicated dT Station: 189 #Towers Active: 2 Station: 189 # Towers Active: 3 16 16 E 16 u. 16 t;; .... " i 14 .. 14 .5 12 12 .!! .!! u 10 .!! 10 l! .;! . a: l: 8 I.: 8 D .5 6 .5i 8 !! !! i 4 2 £ 4 2 2 0 0 0 10 :zo 30 40 so 60 70 80 90 100 Cumulelive number of occurrence betow indicated dT Cumuretive number of occurrence bet°" Indicated dT Figure 3-13 Comparisons of modeled and observed temperature increases at 189. 30 18 E 1e t;; 14 12 l 10 ;; a: l! 6 g s 6 i 4 i 2 0 18 0 PBAPS Post-EPU Study Station: 301S #Towers Active: O Cu mvltlMI nvmbor Gf oc=ren .. betc.11dic:<<ted dT Station: 3015 #Towers Active: 2 0 10 20 JO 40 50 60 70 80 90 100 Cumulative numbet' cf oceutrence bekMt 11dcated dT 18 E 18 .... " ! 14 £ g 12 i 10 a: =: 6 g s 6 . e 4 l 2 0 18 ... 16 .... " " 14 I s .!! 12 i 10 :. l! 6 g s; 6 ] E 4 2 0 Station: 301S # Towers Active: 1 0 10 20 30 40 50 60 70 60 90 100 Cum&Jllllil<e l>ll mber d oocwience below Indicated dT Station: 3015 # Towers Active: 3 0 10 20 30 40 50 60 70 60 90 100 cumu111111e numbet' cl oceurm>ee below ndicated dT Figure 3-14 Comparisons of modeled and observed temperature increases at 301S. 3.2.3 Thermal Plume Monitoring Conclusions The year 2016 featured Susquehanna River flows and temperatures that were at extreme values. For that reason, 2016 was ideally suited as the follow-on study year to the Pre-EPU Demonstration Study because extreme temperatures occurred and temperatures increases due to the EPU, temperature reductions when cooling towers operate, and resulting net temperature increases in Conowingo Pond could be directly measured.

The Pre-EPU Demonstration Study model assumptions were validated as each cooling tower provided more cooling than expected (2.2°F instead of 1.6°F) and the temperature increase from the intake to the head of canal was 22.1°F, less than the assumed post-EPU condenser temperature rise of 22.4°F. The observed temperatures at the warmest, most biologically sensitive monitoring stations were less than modeled temperatures for extreme conditions presented in the 316(a) Demonstration Study. The modeled temperatures had been used in the 31 PBAPS Post-EPU Study Pre-EPU Demonstration Study as the basis for the biological assessment of post-EPU conditions and therefore, were sufficiently conservative.

The field observations show that operation of the cooling towers effectively mitigates the additional heat generated by the EPU during the summer period. 32 PBAPS Post-EPU Study 4 Biological Station Temperature Monitoring The temperature record observed at the biological stations is critical to understanding the influence of the PBAPS thermal plume on the biological community.

Continuous temperature monitoring was completed at all of the benthic macroinvertebrate and fish seining collection stations, and four of the six electrofishing stations (no monitoring at Stations 165 and 187) (Figure 4-1). Monitoring was performed in situ using Onset HOBO Pro v2 Water Temperature Data Loggers. These instruments are accurate to 0.36°F in the range 32°F to 122°F and have a five-minute response time in water. The loggers recorded water temperature every hour and were located on the river bottom in shallow shoreline locations

(<5 ft water depth} where complete mixing of the water column occurs. This analysis characterizes the biological water temperature monitoring stations.

Monitoring locations are divided into those stations that are not influenced by the thermal plume (208, 221, PBAPS Intake} and those stations that are thermally influenced (214, 215, 189, 190, 216, and 217). The PBAPS Intake monitor was installed specifically for this study and is used as an ambient temperature reference.

Note that although Station 208 is located along the east shoreline of the Pond and upstream from the end of the discharge canal, it does experience an increase in water temperature resulting from the PBAPS thermal discharge at low river flows during the summer months. This phenomenon is coincident with River flows less than 12,000 cfs and MRPSF pumpback operations (Normandeau and Gomez and Sullivan Engineers 2012). Thermally affected electrofishing Station 161 is characterized by the monitoring at Station 214 (a seine and benthos station}.

Thus, a separate water temperature monitor was not installed at Station 161. The analysis provided herein includes post-EPU biological water temperature monitoring in 2016 and pre-EPU biological water temperature monitoring from 201 O through 2013. Comparison of water temperature observations at these locations is completed to identify differences in the duration and frequency of elevated water temperatures during each year of monitoring.

Ambient water temperatures measured in Conowingo Pond over the course of the 2016 study period (May 1 to September

30) followed a typical seasonal pattern for the Susquehanna River for most of the monitoring period with warmest temperatures observed during July and August (Figure 4-2) Water temperature during mid-August through September was elevated from the typical seasonal pattern with extraordinarily warm and dry and conditions during September.

Figure 4-2 through Figure 4-19 provide daily mean and daily instantaneous maximum water temperatures for each monitoring location during each year. The highest water temperatures at the biological monitoring stations were observed in July and August at Station 214, which is located along the west shoreline and is the monitoring station closest to the end of the PBAPS discharge canal (Figures 4-4 and 4-13). Water temperatures decreased in a downstream direction at monitoring locations farther downstream from the end of the discharge canal. The lowest ambient water temperatures were observed at Station 221, which is located upstream from the PBAPS intake along the east shoreline (Figure 4-3). Station 221 is located at the 33 PBAPS Post-EPU Study confluence of Fishing Creek with Conowingo Pond. This monitoring location is strongly influenced by Fishing Creek. During periods of low pond elevation (MRPST pumpback or Conowingo Hydroelectric Station generation), this monitor essentially measured Fishing Creek water temperature.

Ambient water temperatures in 2016 were much warmer than previous years from mid-August through the end of September (Figure 4-3). The mean water temperature measured in September 2016 at the PBAPS intake was 5 °F warmer than the highest average termperature measured previously in September at the intake (Table 4-1). Table 4-2 through Table 4-6 provide a summary of the of the number of exceedances (days) of both 80 and 90 °F threshholds for instantaneous maximum and mean daily water temperatures for the monitoring locations during each year of the study. The basis for these two water temperature values is that 80°F corresponds to a normal summer condition and 90°F corresponds to a temperature that does not typically occur under natural conditions in the Pond. The purpose is to provide a comparison of these two temperature points among the monitoring stations.

In 2016, water temperatures were warmer than previous years, with a greater number of days that the ambient water temperatures exceeded 80°F as instantaneous maximum or daily mean (Table 4-2). Similarly, the thermally influenced stations in 2016 had a greater number of days exceeding 90°F as instantaneous or daily mean compared to previous years. Overall, the monitoring data indicate that the warmest water temperatures were observed during a greater number of days in 2016 for all locations, compared to the other years. However, the water temperatures observed in 2010 were also high but the monitoring period was abbreviated (not initiated until July 28) and not directly comparable to other years in terms of absolute number of days exceeding 80 or 90°F. As noted above, the highest water temperatures were observed to occur in July and August in 2010 through 2013 and July through September in 2016. Therefore, analyses of potential thermal effects on benthic macroinvertebrates and fish will focus on these months. However, the cumulative effects of elevated temperatures during the course of the year will also be considered.

These types of cumulative effects, as opposed to just the highest temperatures in July, August, and September may potentially alter the aquatic assemblage, in particular, at the near-field stations (Stations 161, 214 and 215). Cumulative effects of elevated water temperatures will be evaluated for fish by documenting body condition, disease occurrence, length/age structure, and retrospective analysis of relative abundance.

In addition, cumulative effects will be evaluated in comparisons of fish and benthic macroinvertebrate community composition (e.g. species richness, and diversity) between thermally influenced and thermally influenced collection locations.

The final data set was compiled into an Excel spreadsheet and the raw water temperature data and a list of collected daily average, minimum and maximum water temperatures was provided to PADEP in electronic format. 34 PBAPS Post-EPU Study ,,, ,' ... . .. ,, Boat Launch Muddy Creek Muddy Run Station 221 "*Y"°'

• Fishing Creek ' \ l Rollins Point Mt. Johnson Island "' Legttnd . . . Peach Bottom Atomic Power Station B k. R 214 ur m11 un

• 215 * < 189

• 190 9:m

• Broad Creek

• Biological Temperat ure Monitoring Location 0.7'; l.5Mii.. "

GEICO o:JG.S FAO.hl'S.NACAA Gf-.S...

°'-....... '!'

ufn

.... ............

W..Q;S\JMICC,,_.,.

lr ... llol'"*lln*

Peters Creek .zos Peach Bottom Beach Williams Tunnel Frazer Tunnel 217

• Hopkins Cove Conowingo Dam *. ................

.* _ ... Figure 4-1. Location of biological water temperature collection stations.

35 PBAPS Post-EPU Study 100 PBAPS Intake so -1010 -1011 -ZOU -JOU -101 0 40 'll 'IU V15 O/& l;/18 6/'Jll 7/ll 1{14 ar., 8111 1/2" 9/ID .,,, Figure 4-2. Daily mean water temperature measured at PBAPS Intake, 2010-2016.

100 Station221

!lO "" -2010 -2011 -lDIZ -lUJl -29J6 "" VI vu Figure 4-3. Daily mean water temperature measured at Station 221 in 2016. Note: no monitoring occurred during 2010-2013 at this location; location added for 2016 monitoring 36 100 llO i ; ! /0 t j ii i 5(1 411 'o/1 -IDlO -20 11 -}0 11 -JOB -ZO Jb "ill <jflr., PBAPS Post-EPU Study Station208 ll/6 *11* 6/!IJ 1/11 8/'!i R/11 8/1'1 ?/10 ?/J} Figure 4-4. Daily mean water temperature measured at S tation 208, 2010-2016.

100 Statlon214 90 "" -J 01 0 -1011 -2012 -lOll -1 0 16 co W M W -Figure 4-5. Daily mean water temperature measured at Station 214, 2010-2016.

37 PBAPS Post-EPU Study lOO Station215

"" -1010 -1011 -20ll -JOIJ -101& .., Vt " 5 i1' 1 ,/6 *II* WJl 1/11 ,, ,, A/'> H/11 8/19 9/10 9/11 Figure 4-6. Daily mean water temperature measured at Station 215, 2010-2016.

100 Station 189 "" -10IO -1n11 -JOIJ -1011 -Jnt6 40 5/1 5/J.'; l;/f; 6/lll 6(*1 1/11 1/14 H/11 *m Wiii *m Figure 4-7. Daily mean water temperature measured at Station 189, 2010-2016.

38 PBAPS Post-EPU Study 100 Stationl90

-1oio -mtt -mo -wu -10t* 40 Si ll ':J/i!1 6/h ri/UI tJJO 7/1l JfJ4 8/5 e/11 j/l:i 9/10 Figure 4-8. Daily me an water temperature measured at Station 190, 2010-2016.

1 ro Statlon216

"" -10 10 -1011 -lllfl -.IOU _,.,,. 40 !>/l 3/U !>/15 6/6._ll/UI ll/Xl 1/JZ 1/l'I Br.> 8/11 l/l3 /Ill fJ//l Figure 4-9. Daily mean water temperature measured at Station 216, 2010-2016.

39 PBAPS Post-EPU Study 100 Station217

!>II -1010 -1011 -JOU -JOIJ -1016 "" S/1 S/U sm bi* 6/1! "'"' l/U 1/14 ar; '6/1/ 8/19 9/10 9/U Figure 4-10. Daily mean water temperature measured at Station 217, 2010-2016.

100 00 ao !:. i f .. 70 j 1 z "" "" 411 VI -2010 -:IOI! -1012 ->Oil -:016 )/13 5//5 PBAPS Intake li/6 h/ll '"*"' 1/11 1/14 *15 1/11 *fl'I 9/10 *Ill Figure 4-11. Daily maximum instantaneous water temperature measured at PBAPS Intake, 2010-2016.

40 PBAPS Post-EPU Study 100 Station221

-10 10 -JO it -lC tl '*/l \/U 0/15 fij'ti 6/IB 6/:'IJ 7/11 1(14 8/'> ff/17 8/l'J ?/I D 'J/l} Figure 4-12. Daily maximum instantaneous water temperature measured at Station 221in2016.

No monitoring occurred during 2010-2013 at this location; location added far 2016 monitoring 100 Statlon208 *O '/1 S/H (1/fi fl/IS 6/)J 7/tl '1(11 Hf' K/tl R/l'J '1/10 'IJ)I Figure 4-13. Daily maximum instantaneous water temperature measured at Station 208, 2010-2016. 41 i ! "" i 10 !l I Ji .,., 40 -JC J1 0 -10 11 l<J 12 -J0 13 PBAPS Post-EPU Study .,/I V II S/1\ fi/6 ro/18 Gl>JJ 1/l] 1//4 3/'I ft/11 8/1'1 9/10 9/1) Figure 4-14. Daily maximum instantaneous water temperature measured at Station 214, 2010-2016. 11 11 Statlon215 -J nto -Jntl -lOU -lOU* -IOl 6 40 \JI 5/11 b/6 rJ ll 6/'!D 1/11 1/1< 8/'i *117 A/)<) 9/10 9/11 Figure 4-15. Daily maximum instantaneous water temperature measured at Station 215, 2010-2016. 42 PBAPS Post-EPU Study 1 00 Station 189 "" -intn -10 11 -10 11 -J Oi t -1016 "" "'1/l V II '.\/l"i f*/6 6/18 6/.'JJ 7/U 1/14 *r. H/11 8/J<I 9/ID 901 Figure 4-16. Daily maximum instantaneous water temperature measured at Station 189, 2010-2016. l!D Station 190 90 l .. 10 j l ii bO -JD10 -JOtl -2QU -lQll -1016 40 W M -W W M -W Figure 4-17. Daily maximum instantaneous water temperature measured at Station 190, 2010-2016. 43 100 '!!I "" t t ,_ /0 ! I

• GO 40 PBAPS Post-EPU Study Station216 -JCJ\U -]()11 -IOU -l<IU -1'116 _J '>/I 'Ill *16 6/1" 6/"!11 7/11 1(1* or. R/11 R/1'> 9/10 ?/71 Figure 4-18. Daily maximum instantaneous water temperature measured at Station 216, 2010-2016. 100 Station217

"' -10 10 -1011 -1011. -J.Otj ---.-'--_ _.;;.;..JOl;.;;_6 _ _, "". 0 -M W --Figure 4-19. Daily maximum instantaneous water temperature measured at Station 217, 2010-2016. 44 PBAPS Post-EPU Study Table 4-1. Monthly mean water temperature measured at the biological monitoring locations and PBAPS intake, May through September, 2010-2013, and 2016. 2010 214 215 189 190 216 217 221 Intake 208 May N/A N/A N/A N/A N/A N/A N/A N/A N/A Jun N/A N/A N/A N/A N/A N/A N/A N/A N/A Jul 98.0 96.2 N/A N/A N/A N/A N/A 85.4 89.2 Aug 95.3 93.5 89.3 86.9 N/A N/A N/A 82.8 84.8 Sep 85.9 84.3 82.0 80.1 N/A N/A N/A 75.2 76.4 2011 214 215 189 190 216 217 221 Intake 208 May 74.8 73.6 N/A 64.9 N/A N/A N/A 63.0 63.5 Jun 88.5 86.6 82.2 79.1 79.4 78.3 N/A 76.6 77.4 Jul 95.2 93.7 90.2 87.8 88.0 87.2 N/A 83.9 87.0 Aug 91.9 90.5 86.8 84.3 84.5 83.7 N/A 80.5 81.0 Sep 76.0 74.6 72.0 69.6 69.7 68.8 N/A 68.2 68.8 2012 214 215 189 190 216 217 221 Intake 208 May 79.0 78.0 73.0 70.0 70.0 68.0 N/A 72.9 67.9 Jun 86.3 85.0 80.9 78.0 78.3 77.4 N/A 75.1 76.6 Jul 94.5 93.4 90.3 88.4 88.5 87.6 N/A 84.0 87.8 Aug 92.5 91.3 88.2 86.4 86.5 85.8 N/A 82.4 86.6 Sep 83.1 81.4 79.5 78.2 78.3 77.9 N/A 75.1 72.1 2013 214 215 189 190 216 217 221 Intake 208 May 78.4 76.8 72.1 69.0 69.0 68.1 N/A 65.2 66.7 Jun 86.3 85.0 80.7 78.5 78.5 77.8 N/A 75.5 77.8 Jul 91.0 89.9 86.0 83.9 84.0 83.2 N/A 81.5 83.3 Aug 86.8 86.0 83.2 81.1 81.2 80.6 N/A 77.6 79.6 Sep 81.1 80.0 78.1 77.1 77.2 76.8 N/A 73.9 74.3 2016 214 215 189 190 216 217 221 Intake 208 May 76.8 75.2 69.9 66.2 66.2 64.6 61.3 62.5 64.3 Jun 89.8 87.7 84.0 81.6 81.6 80.6 75.1 76.9 80.4 Jul 95.6 93.8 90.8 88.3 88.3 87.1 80.4 83.6 87.6 Aug 95.7 94.0 91.0 88.9 89.0 88.0 75.6 84.4 86.4 Sep 94.4 92.1 89.0 85.4 85.4 83.6 73.3 80.1 80.9 45 PBAPS Post-EPU Study Table 4-2. Summary of instantaneous maximum and daily mean water temperature data for multiple locations within Conowingo Pond in 2016. Number of Days Exceeding Instantaneous Maximum Temperature Mean Temperature Station >80°F >90°F >80°F >90°F 221 a 62 0 25 0 PBAPS Intake 95 0 83 0 208 115 40 101 6 214 132 113 131 108 215 131 105 129 92 189 129 77 125 53 190 119 53 110 17 216 120 51 111 17 217 114 31 107 3 a station was not monitored previously Table 4-3. Summary of instantaneous maximum and daily mean water temperature data for multiple locations within Conowingo Pond in 2010. Number of Days Exceeding Instantaneous Maximum Temperature Mean Temperature Station >80°F >90°F >80°F >90°F 220 34 0 28 0 PBAPS Intake 38 0 29 0 208 so 14 38 2 214 65 46 64 44 215 65 43 62 34 189 51 18 42 10 190 43 10 35 5 216 * * *

• 217 * * * * *stations not monitored in 201 O 46 PBAPS Post-EPU Study Table 4-4. Summary of instantaneous maximum and daily mean water temperature data for multiple locations within Conowingo Pond in 2011. Number of Days Exceeding Instantaneous Maximum Temperature Mean Temperature Station >80"F >90"F >80"F >90"F 220 55 3 38 0 PBAPS Intake 60 1 41 0 208 7S 17 56 10 214 lOS 74 104 70 21S 104 70 102 4S 189 96 32 82 21 190 82 22 72 14 216 87 20 72 15 217 80 16 69 8 Table 4-5. Summary of instantaneous maximum and mean water temperature data for multiple locations within Conowingo Pond in 2012. Number of Days Exceeding Instantaneous Maximum Temperature Mean Temperature Station >80"F >90"F >80"F >90"F 220 76 0 SS 0 PBAPS Intake 77 0 69 0 208 S8 18 48 3 214 127 84 122 73 21S 124 78 117 S4 189 108 43 97 19 190 99 30 84 8 216 99 30 8S 7 217 96 14 84 1 No data recovered for Station 208 from 8/8/12 to 9/6/12 47 PBAPS Post-EPU Study Table 4-6. Summary of instantaneous maximum and mean water temperature data for multiple locations within Conowingo Pond in 2013. Number of Days Exceeding Instantaneous Maximum Temperature Mean Temperature Station >80"F >90"F

>SO"F >90"F 220 43 0 25 0 PBAPS Intake 45 0 29 0 208 82 7 57 0 214 133 40 117 20 215 124 28 106 13 189 106 8 89 5 190 93 5 71 0 216 93 6 71 0 217 82 3 63 1 48 PBAPS Post-EPU Study 5 Dissolved Oxygen Monitoring Introduction Aquatic life in Pennsylvania freshwater waterbodies is protected by dissolved oxygen (DO) criteria, which are found in PA Code Chapter 93.7. The criteria were established to protect aquatic organism from adverse impacts associated with low DO. For warmwater fisheries 0/lfWF) the PA Code criteria for concentration of DO are a minimum 7-day average of 5.5 mg/L and instantaneous minimum of 5.0 mg/L. These criteria were developed to be protective of the entire aquatic community, in particular, all life stages of warmwater fish. The criteria specifically are protective of early life stages of fish, such as embryonic and larval stages, which are generally more sensitive to low DO concentrations than adult life stages (PADEP 2016). Methods Dissolved oxygen monitoring was conducted in shallow shoreline areas along the west shoreline downstream of the PBAPS discharge canal at Stations 215 and 189 and upstream of the PBAPS discharge canal on the east shoreline at Station 208 (Figure 5-1). Monitoring was completed June 1 through September 30, 2016. A HACH HL4 Sande with luminescent dissolved oxygen (LOO) sensor was used to record hourly DO concentrations.

The accuracy of this instrument is +/-0.1 mg/L for DO between 0 and 8 mg/L and +/-0.2 mg/L for DO more than 8 mg/L. This monitoring period was selected to focus on the typical seasonal periods of low-flow and high water temperature that occur in Conowingo Pond which could result in low DO concentrations.

Monitoring at Station 208 was completed to determine whether sufficient DO concentrations were present in waters typically outside of the thermal plume. The objective of this monitoring was to determine if there are periods when there is a low DO barrier spanning the width of the pond during low flows, high water temperatures, and upstream migration of the thermal plume due to MRPSF pumping. These areas are thought to be important to provide a refuge or zone of passage for resident and migratory fish migrating upstream or downstream past the PBAPS. A single monitoring device was installed toward the bottom of the water column at each monitoring location.

Monitors were installed in water with depth less than 10 ft with the intent of monitoring to be near the bottom of the water column. Each monitor was attached to a buoy which was attached by cable to an anchor. Challenges associated with fluctuations in Conowingo Pond water elevation (range between 105 and 109 ft during monitoring period at the Conowingo Dam forebay) occurred during the monitoring period. During several different occasions at low Pond elevation the LOO sensor contacted the bottom which resulted in the sensor being covered in sediment or touching the bottom substrate, and provided erroneous DO data. The hourly DO data sets were reviewed for the entire monitoring period in relation to hourly Conowingo Pond elevation in order to determine whether DO data was representative of actual DO at each monitoring location and obvious erroneous data were removed from the final data set before analysis was completed. In addition, the Sande deployed at Station 208 malfunctioned and was removed for repair from August 23 to 29. 49 PBAPS Post-EPU Study The final data set was compiled into an Excel spreadsheet and the raw DO data and the revised data set along with a list of collected daily mean, minimum, and maximum dissolved oxygen concentrations was provided to PADEP in electronic format. This data set also included hourly Conowingo Pond water surface elevation data measured at the Conowingo Dam forebay. Results The number of valid hourly DO measurements varied among the three stations:

Station 208: 2,338; Station 215: 2,500, and Station 189: 2,537 (Table 5-1). The total number of days that the daily mean DO was less than 5.5 mg/L varied from 3 days at Station 208 to 11 days at Station 215. The 7-day mean DO criterion of 5.5 mg/L was not exceeded at any of the three monitoring locations.

However, at Station 215 there were 26 occurrences of the 7-day mean DO equal to the minimum of 5.5 mg/L. The lowest minimum daily average DO (5.0 mg/L) recorded among the stations was at Stations 208 and 215. The total number of hourly DO measurements less than 5.0 mg/L varied from 18 at Station 189 to 98 at Station 215 with a majority of these measurements occurring during September.

The total number of days that at least one hourly DO measurement was less than 5.0 mg/L (the instantaneous minimum criterion) varied from 9 days at Station 189 to 35 days at Station 215. Figure 5-2 through Figure 5-4 provide a time series of the hourly DO measurements for each monitoring location.

The lowest instantaneous minimum DO measurement was 4.4 mg/L and occurred at all three stations.

Discussion Dissolved oxygen (DO) concentrations in the subsurface waters of Conowingo Pond are important in assessing the potential suitability of fish habitat. Low DO can result in stressful conditions that fish may avoid or could potentially result in higher rates of disease. Dissolved oxygen concentrations were measured in the shallow shoreline areas directly downstream from the PBAPS discharge and at an upstream location and evaluated to determine whether sufficient DO was present within these areas to be protective of aquatic life. This monitoring occurred during the typical seasonal periods of low-flow and high water temperature that occur in Conowingo Pond which could result in low DO concentrations.

DO concentrations were similar among the three stations over the course of the monitoring period. Nearly all measurements were above the instantaneous DO criterion of 5.0 mg/L. Similarly, DO concentrations were always equal to or above the 7-day mean criterion of 5.5 mg/L. The monitoring did not indicate that DO concentrations were low and restrictive to aquatic organism movement or use of shallow shoreline areas within the Pond. In addition, the monitoring at Station 208 indicated that DO concentrations do not cause a low DO barrier that would prevent fish from migrating past PBAPS. Most of the lowest instantaneous DO measurements were recorded in August and September.

This was an extremely low flow period in Conowingo Pond. Although DO concentrations were occasionally below the water quality instantaneous minimum criterion of 5.0 mg/Lit is unlikely that the lowest observed concentration (4.4 mg/L) were injurious or caused stress to fish. Low DO concentration is an environmental stressor that may predispose fish to viral or bacterial 50 PBAPS Post-EPU Study infections.

Section 6.3 of this report discusses disease occurrence in Conowingo Pond fish. The instantaneous criterion for DO is protective of the most sensitive life stages of fish (eggs and larvae); these life stages of fish are not present in August and September.

Thus DO during this time period needs to be protective of only juvenile/adult life stages of fish which can tolerate DO less than 5.0 mg/L for short periods of time without measurable negative effects. Nutrient enrichment of the lower Susquehanna River and Chesapeake Bay from upstream sources is a long-term concern for the health of the aquatic ecosystem.

Increases in nutrients have been linked to increased biomass of aquatic macrophytes, which can lead to wide swings and depressions of DO during the growing season. Aquatic macrophytes produce DO during daytime hours when photosynthesis is occurring, but then use the DO for respiration during the nighttime hours. A large amount of aquatic macrophyte biomass in a water body can lead to DO depression or sag during early morning hours particularly during summer time. This pattern was observed in the current study and occurs throughout the Susquehanna River particularly in portions of the river where macrophytes are abundant (SRBC 2013). Low DO concentrations occur in many portions of the Susquehanna River well upstream of PBAPS and are a result of multiple factors including river flow, nutrient enrichment, and aquatic macrophyte growth and decomposition (PADEP 2012). Conclusions Monitoring during 2016 under the prevailing high water temperature and low flow conditions indicated that sufficient DO concentrations existed in Conowingo Pond with the EPU to protect the aquatic community.

No exceedances of the 7-day average criterion were observed and few exceedances of the instantaneous minimum criterion (1.9% of total measurements) were observed.

The exceedances of the instantaneous minimum criterion were few and did not occur over consecutive hours and were not of extended duration.

The DO concentrations observed during actual EPU conditions in an extreme high temperature and low flow year were protective of the aquatic community.

The monitoring also indicated that DO was sufficiently high as to not block fish migration past PBAPS. DO concentrations were sufficient to maintain fish habitat and did not indicate the monitored locations would be unavailable for use by fish or other aquatic organisms.

51 PBAPS Post-EPU Study Boat Launch Muddy Creek Muddy Run Station f .. ftllt**I., Fishing Creek l*rflfilt.utf' IM.t' Rollins Point Mt. Johnson Island l' .. .&d& u .. uo111 l"'I' Peach Bottom Atomic Power Station Burkins Run 215 * , 189 * .* N t Lt!fltmd

• rP .... "-H\ \ P. 'JI \ '.O .. Broad Creek Dissolved Oxyge n Monitoring Localions 0.7S 1.5Mil e. .. E_,. O.u..m. "'-'Vi'EO GEICO. U$01 , FAD NP&, NACA:N.. *Gtf N L. OntNn:e SWIW)' E*!t JllPM 1ro1en E1tt a.i

• • -1* .. 111t lltltm.111 Peters Creek e208 Peach Bottom Beach Williams Tunnel Frazer Tunnel f . < J t ... ..,.., .* !{ Figure 5-1. Dissolved Oxygen monitoring locations in Conowingo Pond during 2016. 52 PBAPS Post-EPU Study Table 5-1. Descriptive statistics for dissolved oxygen monitoring in Conowingo Pond, June through September 2016. Station Dissolved Oxygen (mg/L) 1 208 215 189 Total Number of Hourly Measurements 2,338 2,500 2,537 Total Number Hourly Measurements

< 5.0 mg/L 26 98 18 Total Days with Hourly Measurements

<5.0 mg/L 13 35 9 Minimum Daily Average 5 5.0 5.2 Total Days Daily Average < 5.5 mg/L 3 11 5 Number of Occurences 7-day Average < 5.5 mg/L 0 02 0 Instantaneous Maximum 11.4 8.5 9.3 Instantaneous Minimum 4.4 4.4 4.4 1 § 93. 7. Specific water quality criteria for Warm Water Fishery (WWF): 7-day average 5.5 mg/l; instantaneous minimum 5.0 mg/l. 2 A total of 26 occurrences of 7-day average of 5.5 mg/l 53 PBAPS Post-EPU Study Station 189 12

• Hourly OIS\OIVf:'d OxygPn II -snwi 10 *

• 19 *

• i *

• i f

• g R * .. ! a 7 i

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• s * ---*-----Figure 5-2. Hourly dissolved oxygen measurements at Station 189, June through September 2016. 54 ll 11 10 9 l ti .. g R .. i: 1 iS 7 .._ .. *

• 6 * .. *

• s * * :i * ,, f; . ,. * * *

• PBAPS Post-EPU Study Station215

• t *

• 11uu1 ly l.lt>wlwd O"Yll*" -Smsfl * *

• Figure 5-3. Hourly dissolved oxygen measurements at Station 215, June through September 2016. 55 1l

• 11 * **

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• PBAPS Post-EPU Study Station208

• * : I

• Hourly Di.-oM>d OllV8rn

• * * * *

• S* 4 + I +* ** ------------

Figure 5-4. Hourly dissolved oxygen measurements at Station 208, June through September 2016. 56 PBAPS Post-EPU Study 6 Biological Monitoring and Assessment

6.1 Introduction

This section describes the benthic macroinvertebrate and fisheries components of the Post-EPU Study. As described in the Post-EPU Study Plan, the primary objective of the biological monitoring component of the study was to determine the characteristics of the fish and benthic macroinvertebrate communities after implementation of the EPU. The characteristics of the communities observed in 2016 Post-EPU Study will be compared to Pre-EPU Demonstration Study observations completed from 2010-2013 during the 31 Sa Demonstration Study (Normandeau and ERM 2014). These comparisons will focus on whether any discernable changes have occurred to the aquatic communities that resulted from the increase in water temperature associated with the EPU. Sampling and data collection for the 2016 monitoring program was performed from May 1 through September

30. A total of 35 benthic macroinvertebrate samples were collected at seven stations (Figure 6-1) Fish community surveys were completed to determine distribution and relative abundance within and outside of the thermal plume. A total of 25 collections were completed using a seine at five stations (Figure 6-2) and 30 collections were completed using a boat electrofisher at six stations (Figure 6-3). Table 6-1 provides a description of seine, benthos, electrofishing, and water temperature stations and the distance each station is from the PBAPS discharge canal. Methodologies and analyses for the benthic macroinvertebrate community sampling, and fish community surveys are summarized below. 6.2 Benthic Macroinvertebrate Community A study of the benthic macroinvertebrate community was conducted to determine the influence of the thermal plume post-EPU on the composition and relative abundance of the benthic macroinvertebrate, or benthos, community inhabiting shallow-water shoreline habitat in Conowingo Pond. Previous benthos surveys were conducted at the same monitoring locations using identical methodology during 2010-2013.

Comparison between the pre-EPU and EPU communities was completed to evaluate the potential effect of the temperature rise associated with the EPU. The benthic macroinvertebrate sampling included an assessment of habitat quality each month at each of the collection locations.

Methods Habitat Assessment The quality, quantity, and variety of physical habitat are well-known determinants of macroinvertebrate community composition.

When comparing sample stations, habitat assessments are used to infer whether observed differences in macroinvertebrate communities are the result of water quality degradation (in this case, increases in temperature) or due to 57 PBAPS Post-EPU Study variations in habitat. The PADEP methodology used for this study is for low gradient streams and is referenced in the Post-EPU Study Plan. The methodology involves visual inspection and quantification of nine habitat parameters listed below. Habitat Parameters Epifaunal Substrate/Available Cover Bank Vegetative Protection Channel Alteration Sediment Deposition Pool Substrate Characterization Riparian Vegetative Zone Width Bank Stability Channel Flow Status Pool Variability Each habitat parameter is awarded a score between 0 and 20 for a possible maximum total of 180. The resulting values can be used to rate habitat quality into four categories:

Optimal (166-180), Sub-optimal (113-153), Marginal (60-100), and Poor (<47). Scores falling between these ranges are given a dual rating. Macroinvertebrate Collection and Analysis Macroinvertebrates were collected monthly from May through September 2016 with a D-frame kick net according to a PA DEP (2007) multi-habitat protocol.

Benthic macroinvertebrates were collected from seven locations throughout Conowingo Pond, spatially covering a large portion of the Pond (Figure 6-1). Two locations were well upstream from PBAPS and not influenced by the thermal plume. Station 208 was located across from PBAPS and is exposed to thermal plume during low-flow conditions during MRPSF pumpback operations.

The other four stations (214, 215, 189, and 216) are located downstream from PBAPS along the west shoreline and are within the thermal plume during the entire year. Each multi-habitat sample was a composite of 10 "kicks," collected from five habitat types including cobble/gravel, snag, coarse particulate organic matter, submerged aquatic vegetation, and sand/fine sediment.

Where all five habitat types were present, two "kicks" were taken from each to produce the composite.

If one or more habitat types were absent, the "kicks" that would have been assigned to them were proportioned according to the predominant habitat types remaining.

Samples were sorted and identified following the methods described in PADEP (2007) habitat protocol.

The resulting data were condensed to six ecological metrics developed by PADEP (2007). The metrics are Total Richness, EPT Richness, Beck's 4 Index, Shannon Diversity, Mayfly Taxa Richness, and Caddisfly Taxa Richness.

Table 6-2 provides a brief summary of the metrics and whether their values increase or decrease in response to water or habitat quality degradation.

Standardized scores for each metric were used to produce an Index 58 PBAPS Post-EPU Study of Biotic Integrity (IBI} value for each station. The IBI is a means to integrate information from the metrics into a station score ranging between O and 100. Habitat Assessment Results and Discussion The results of the habitat assessment are provided in Table 6-3. Average station scores ranged from 95 to 133 producing similar descriptors of sub-optimal/marginal or marginal at each location.

Placed into context, the habitat constraints observed in the Conowingo Pond are essentially due to channel alteration inherent to impoundment; i.e., a free-flowing section of the Susquehanna River has been transformed into a reservoir where shoreline habitat is much less varied and the current is much slower than it would be in a natural state. This habitat alteration would be expected to produce a negative response in what was initially a riverine benthic community; one which should be, and is, characterized by low IBI scores. Because the station scores show habitat quality to be relatively similar at each sample location, differences in the benthic community resident in the thermally influenced versus the non-thermally influenced locations may be considered, in part, attributable to temperature increase.

However, other habitat features such as the amount of submerged aquatic vegetation (SAV}, water velocity, and spatial location in reference to tributaries or other Pond features are not accounted for in the habitat assessment.

Macroinvertebrates 2016 Results Benthic macroinvertebrate collections made at seven stations in 2016 yielded a total of 7,097 organisms that were processed and identified.

A total of 59 taxa were collected.

The identity of common macroinvertebrate taxa (>1% of total organisms}

was similar among collection locations and six to 12 common taxa were collected at individual stations (Table 6-4). The samples contained taxa expected to be found in a lentic environment, including representatives of most of the orders of aquatic insects as well as worms (Oligochaeta}, snails (Elimia, Ferrissia, and Gyraulus, etc.}, clams (Corbicula), and crustaceans (Caecidotea and Gammarus) (Table 6-5). A few benthic macroinvertebrate taxa comprised a large proportion of all organisms collected at each of the stations.

With few exceptions, Chironomidae, Gammarus, and Oligochaeta were among the most abundant organisms at all stations (Table 6-5). Other common taxa included Corbicula, Physel/a, Hydrachnidea, and Caenis. No Plecoptera (stoneflies) and few Trichoptera (caddisflies) were collected.

The mayfly Caenis was the only mayfly commonly collected among stations.

Other Ephemeroptera and Trichoptera that comprised

>1% of total organisms included Stenonema, Stenacron, Oecetis, Hexagenia, Orthotrichia, and Maccaffertium.

Differences were observed in composition of common taxa among stations.

Fewer common taxa were collected at Station 214, compared to the other locations.

Chironomidae, Oligochaeta and Corbicu/a comprised a greater proportion (88%) of 59 PBAPS Post-EPU Study the benthic community at Station 214 compared to the other stations (Table 6-5). In contrast, Chironomidae, Oligochaeta and Corbicu/a comprised the lowest proportion (34.5 %) of the benthic community at Station 220. 2016181 and Metrics 181 scores were generally low for all stations within and outside of the thermal plume and ranged between 11.5 and 49.4 (Figure 6-4). The lowest 181 scores were observed at Stations 214 (181 score 11.5) in September and 221 (181 Score 14.9) in June. However, 181 scores at the other thermal and non-thermal stations were similar with 181 scores generally higher from July through September for all stations.

Other slight spatial differences were observed both between and within non-thermal and thermal station groups. The highest scores at the non-thermal stations were observed at Station 220 and for the thermally influenced stations the highest scores varied from month to month. Individual metrics that comprised the 181 scores were also evaluated for each monthly collection.

Table 6-7 through Table 6-12 provide the monthly metric values for each station. Total richness values were higher during July, August, and September for most stations with the most taxa observed at Station 220 (n= 17) during July and September.

However, the fewest taxa (n = 5) were observed at Station 214 during September. EPT Richness values followed the general pattern of Total Richness with the highest values observed from July through September for all stations.

The EPT Richness values ranged between zero to seven taxa among stations.

Similar to EPT Richness, Ephemeroptera Richness values were low and variable, ranging zero to five taxa among stations.

Few Trichoptera were collected, as indicated by low richness values for all stations with the highest richness (5 taxa) observed at Station 220 in July (Figure 6-7). Modified Beck's Index values were similar among stations with the highest value observed at Station 220 in August. Shannon Diversity ranged between 0.63 for Station 214 in September to 2.33 for Station 220 in September. Shannon Diversity values were generally lower for Station 214 during most months. Water Temperature vs /Bl scores all vears The observed 181 scores in relation to mean water temperature for the month of collection were similar between post-EPU and pre-EPU monitoring.

Figure 6-10 provides a scatter plot which illustrates the relation between mean water temperature and 181 score for each month during pre-EPU and post-EPU monitoring.

Generally, similar patterns were observed for 181 scores across the range of measured water temperatures.

Except for the low post-EPU September 181 score, the 181 scores tended to be higher during post-EPU period for temperatures

>90 °F. The post-EPU scores clustered between 25 and 40, whereas; the pre-EPU scores were between 10 and 25. A consistent trend between water temperatures and 181 score was not observed.

However, a seasonal pattern was observed with lowest scores occurring during May at most Stations and during August at the thermally influenced stations (Stations 214 and 215) with the highest water temperatures.

The lowest scores (<10) recorded during pre-EPU monitoring occurred in May and August.

Generally for both pre-and post-EPU monitoring 181 Scores were highest during July through September at water temperatures between 80 and 90 °F. The lowest September 181 score occurred post-EPU (Station 214) at temperature

>90 °F. 60 PBAPS Post-EPU Study Post-EPU /Bl Score Comparison to Pre-EPU Comparison of post-EPU 181 scores during 2016 to the pre-EPU 181 scores (2010-2013) allows for inspection of potential differences that may have been a result of the increase in temperature from the EPU. Figure 6-5 through Figure 6-9 provide box plots of 181 scores by month and by station from May through September.

The May post-EPU 181 scores were within the range of 181 scores observed pre-EPU for all stations except 189 which was lower than pre-EPU. June EPU 181 scores were within the range of 181 scores observed pre-EPU for all stations except 189 (thermally influenced) and 221 (non-thermal) which were lower than pre-EPU and just outside of the interquartile (IQ) range. July post-EPU 181 scores were within the range of 181 scores and most were higher than pre-EPU observations with the exception of Station 208 which was lower than pre-EPU scores and outside of the IQ range. For August generally higher 181 scores were observed during the Post-EPU Study as compared to the pre-EPU study. The Station 216 (thermal) post-EPU score in August was lower than all pre-EPU observations and just outside of the IQ range. In September similar 181 scores were observed during pre-and post-EPU except for Stations 214 and 215 which were both outside the IQ range. The lowest 181 Score observed during September occurred at Station 214 during post-EPU monitoring. For most months and stations the 181 scores were generally higher during the post-EPU monitoring except for Stations 214 and 215 in September.

Post-EPU Metric Comparison to Pre-EPU Similar to 181 scores, a comparison of pre-EPU and post-EPU metric values allows for inspection of potential differences that may have been a result of the increase in temperature from the EPU. Figure 6-11 through Figure 6-15 provide box plots of the six metrics that comprise the 181 Score. pre-and post-EPU metric values for Total Richness, EPT Richness and Ephemeroptera Richness were comparable for most stations with the exception of Station 189. Lower values for all three metrics at this station were observed during May post-EPU monitoring.

For all other stations Total Richness, EPT richness and Ephemeroptera richness metric values were comparable or higher during the post-EPU monitoring period. For Trichoptera richness the post-EPU values were within the range observed pre-EPU. Similarly, Shannon Diversity values were comparable to or higher during the post-EPU monitoring period. Beck's Index values were also comparable between pre-and post-EPU monitoring.

The only exception was station 189 which had one monthly value (May collection) below the range of values observed pre-EPU. All other station post-EPU values were within the range of the EPU observations.

8enthic community composition as measured by these six metrics was similar to pre-EPU monitoring with no measurable impacts from the EPU on the community.

Discussion The macroinvertebrate community composition and relative abundance observed in 2016 was similar to the pre-EPU observations.

Most of the macroinvertebrate taxa collected in this study prefer lentic habitats and are considered fairly tolerant of water/habitat quality degradation.

Few intolerant taxa were collected.

The observed taxa are representative of a warmwater aquatic community in a lentic waterbody.

The most abundant taxa were Chironomidae , Gammarus, and Oligochaeta.

During September when measurable impacts of the thermal plume were observed 61 PBAPS Post-EPU Study at Stations 214 and 215 several taxa were not present or present in low numbers including Ephemeroptera and Trichoptera.

Overall, few taxa were present in September at these two stations and the benthic community was predominated by Oligochaeta, Chironomidae, and Enallagma. Station 214 is the benthic macroinvertebrate station located closest to the end of the discharge canal. The IBI scores for May through August 2016 at Station 214 were comparable to the other non-thermal and thermal stations and higher than most pre-EPU observations at this station for July and August. However, the lowest IBI Score for all stations was observed at Station 214 in September indicating benthos effects attributable to the heated effluent.

Station 215 is the next closest station to the PBAPS discharge canal. IBI scores at Station 215 were not substantially different from the other thermal or non-thermal stations from May through August. However, similar to Station 214, a low IBI score was observed at this station during September as compared to the other stations.

For both stations a decline in benthic community diversity was observed in September.

Metric and I Bl scores indicate that the thermal effect to the benthos community from the PBAPS thermal plume is confined to the western shoreline at Stations 214 and 215. Low IBI scores were observed at Stations 214 and 215 during September after a prolonged period of high water temperatures.

Based on previous observations from pre-EPU monitoring (Normandeau and ERM 2014) improvement in both IBI scores and metric values occurred during subsequent months, indicating re-colonization and recovery of the benthic community at these stations.

Metric values and IBI scores during post-EPU monitoring indicated no measurable impact to the benthic community at monitoring locations downstream from Stations 214 and 215. These results show only a short-term seasonal effect attributable to the discharge for Stations 214 and 215 during the month of September.

The shoreline area between Stations 214 and 215 likely experiences similar conditions and similar changes to the benthic community as the stations that bracket this area. Moreover, observations of IBI scores and metric values at Stations 214 and 215 were similar to the non-thermal stations.

Station 215 benthic community observations were not substantially different from the non-thermal stations.

Conclusions Benthic community effects resulting from the thermal plume are localized and temporary and consistent with the observations during pre-EPU monitoring.

The area of measurable impact was limited to Station 214 and 215 and small in comparison to the amount of similar thermally impacted Conowingo Pond shoreline.

Benthic macroinvertebrate collections were successfully completed during 2016. The data indicate that:

• The composition and relative abundance of the benthic community observed in 2016 was similar to pre-EPU observations.

• The benthic community was characterized by similar diversity both within and outside of the thermal plume. 62 PBAPS Post-EPU Study 181 scores for individual monitoring stations were similar between the pre-EPU and EPU monitoring.

• Temporary impact, in terms of lower 181 scores, was observed at Stations 214 and 215 in September.

The lower 181 scores during post-EPU monitoring occurred after a sustained period of high water temperatures.

In contrast, the lowest scores for these stations during pre-EPU monitoring occurred during July and August. Relatively high 181 scores at these stations were observed in July and August during post-EPU monitoring.

• There was no observed impact to the benthic community at the two thermally-influenced Stations (189 and 216) that are farther downstream from the discharge canal. Similar to pre-EPU observations the benthic community effects resulting from the thermal plume are local and temporary.

• The biological modeling results for the Pre-EPU Demonstration Study were bounded by the actual sampling results during EPU operation in an extreme flow and temperature period. There is a balanced indigenous benthic community within Conowingo Pond. 63 PBAPS Post-EPU Study \ ... ..,, i '* ' *; r ,.. \ \ I. Boat Launch Muddy Run Station " \ '-,;" Muddy Creek 220

• Rollins Point 221 1

• Fishing Creek 1*nm111f1*

l"l1 Mt. Johnson Island \ *' \ l\111 t* I 11 1* ... hh lh,.lmn h\f' .. Peach Bottom Atomic Power Station -* B k. R 214 ur ms un

• 215

• 189 , ,. .. <' * ..,. P1*IL t , ..... .. .. .J -. ..,. '

... tl\ \NI,\ M\f.\I ,,..., 216 * *** 1 N t .. :..

• .. ,. Le1end " ... .. r"' I "' Broad Creek .* l...-:"P' ... ,.::) -*, nnd tJ"e GIS Utet ,r / Peters Creek e208 J; Peach Bottom Beach Williams Tunnel f Frazer Tunnel ,l t' /"

"' Hopkins Cove Conowingo Dam Figure 6-1. Location of benthic macroinvertebrate collection stations.

64 J i '

Boat Launch Muddy Run Station Muddy Creek 220

• Rollins Point Peach Bottom Atomic Power Station PBAPS Post-EPU Study .._ ..... *' >:.-: .. ... ...;" ;>' .. ..

221 lfrl**1HJ

..

• Fishing Creek llJlllllllH Mt. Johnson Island Uutlcom Peters Creek e208 . , h* ..... .... ..... : .. ,. \ \ \ I .** , luU*** '""I' r ... 1d1 ll\p B k. R 214 ur ms un

• 215 Peach Bottom Beach , *lf*I N t Le11end

• 0 '*' Seining Stations l'['-N'-,._1

\\..,;I\ M\f.'I \'"jlJ .* < 0.75 1.5Mtles

• Broad Creek , .. sift.1ct ... Sotirtn Et rt 0.1..crm..

NA-VTEQ JOmTom. ln\tn'Np o1 11t:rtmn p Cotp CEICO. USO!ll FAQ ,,.PS NRCAN r ** os .... mN t<ai.f.HIMNl..Df'dlwlUIS l""<tf E'u crww. 1Hong kong). !1"...+t*'PO

"'1d !ht> GIS u.., , Figure 6-2 Location of seine collection stations.

65 Williams Tunnel Frazer Tunnel r ..-J Hopkins Cove ,. Conowingo Dam .* \ > \ *' 4 I Ul ll"'IU

---

PBAPS Post-EPU Study {

Boat Launch Muddy Run Station Muddy Creek Rollins Point 187

• Peach Bottom Atomic Power Station \ "' Fishing Creek Mt. Johnson Island 165

• 1'1"11 h Uollom Peters Creek . < I \ \ lulhlu h\r 161 Burkins Run e Peach Bottom Beach N Legend t

• 0 ::,.1.,

J r:\"'1491" \ \'-lA M\ll'1 \Ntl . , ; r . .,,. \'

Electrofishing Stations , ' ,, D.75 1.5 Miles ' <' ...,.;

189

• y 190 ---{, --" ,.. / .-tf' * \> *"* Broad Creek I l'oi11'1/

...... * ., . Service LayerCntcit&.

Sources Esrl. CklL.or ,,... NAVTEO lbmTom l ntermap inc r emem P Co rp. G EBCO USGS FAO NPS NRCAN GaoBns.o IGN Kud1:11 tor Nl Ontl lll nc a fa rt Ja pun ME TI e ,1i C 'ill (Hong Kor.g), swtSttopo und lho GIS Lst1r C ornmuniy Figure 6-3. Location of electrofishing collection stations.

66 ' ' Williams Tunnel Frazer Tunnel 217 * ' \ ' ' .,.\"'" .. ' ' \ \. ... ':. Hopkins Cove Conowingo Dam / *. <

PBAPS Post-EPU Study Table 6-1. Description of seine, benthos, electrofishing, and water temperature stations in Conowingo Pond (negative values indicate distance upstream from the discharge canal). Distance From End Of Monitoring Discharge Canal Station Description Description Meters Miles 221 B,S,T Fishing Creek confluence

-northwest side of shoal. -4,765 -2.96 220 B,S,T Coal Cabin boat launch. -4,410 -2.74 187 E South of Rollins Point to first cabin. -3,325 -2.07 208 B,S,T Peach Bottom Beach. -2,449 -1.52 165 E East shoreline above Peters Creek. -2,159 -1.34 161 E, T 1 Rock outcropping above Burkins Run to PBAPS 545 0.34 discharge structure.

214 B,S,T Beach at the mouth of Burkins Run. 591 0.37 215 B,S,T Campground boat launch' -about 250 m below the 1,049 0.65 mouth of Burkins Run. 189 B,E,T Rock outcropping at north side of Michael's Run to 2,128 1.32 'IVlcClellan's Rock'. 190 E,T First cabin below Michaels Run to mouth. 3,285 2.04 216 B,T Below site 190, small cove at end of Line Bridge 3,919 2.44 Road 217 E,T 2,000 m above the mouth of Conowingo Creek. 6,466 4.02 S =Seine, F = Electrofish, B = Benthos, T = Temperature 1 Station 214 temperature monitoring representative of this location ---------------------------------67 PBAPS Post-EPU Study Table 6-2. Descriptions of benthic macroinvertebrate community metrics. Metric Richness EPTlndex Description The total nurri>eroftallll. The PA DEP95th percentile value is 31 tallll. A count of the numberofrmyfly

@hemeroptera), stonefly (flecoptera), and caddisfly (Irichoptera) genera. The PA DEP 95th percentile value is 17 genera. Modified Beck's 4 Index A weighted count oftallll with Pollution Tolerance Values between 0 and 4_ Tallll with Toi. Values ofO or I are given 2 points. T8llll with Toi. Values between 2 and 4 are given I point. The PA DEP 95th percentile index value is 22. Shannon Diversity (H') A measure of community balance in base e based on the distribution of the t8llll present (H = -Sum P, log P;). The PA DEP 95th percentile indexvalue is 2.43. Nurri>er of Mayfly Tallll A count of the number of genera in the order Ephemeroptera. The PA DEP 95th percentile value is 6 genera. NumberofCaddisfly Tallll A count of the number of genera in the orderTrichoptera. The PA DEP 95th percentile value is 11 genera. Response to lfl1'&i rmmt decreases decreases decreases decreases decreases decreases Table 6-3 Average habitat assessment scores for the seven benthic macroinvertebrate collection locations, May through September 2016. Non-Thermal Stations Thermal Stations Parameter 220 221 208 214 215 189 216 Epifaunal Substrate/Available Cover 13 10 14 13 15 11 13 Pool Substrate Characterization 17 14 15 16 16 11 15 Pool Variability 13 3 11 9 14 12 13 Channel Alteration 16 6 11 10 17 16 13 Sediment Deposition 10 10 11 10 11 10 11 Channel Flow Status 14 17 7 14 15 18 16 Condition of Banks 11 9 12 11 17 6 14 Bank Vegetative Protection 5 14 9 12 15 17 15 Riparian Vegetative Zone Width 3 18 5 12 14 18 13 Total Score 101 102 95 107 133 120 124 68 PBAPS Post-EPU Study Table 6-4. Total number of benthic macroinvertebrates collected at each station in Conowingo Pond from May through September 2016. Station Taxon 214 215 216 189 208 220 221 Total Number Amnicola 1 1 Anthopotamus 1 1 Argia 25 17 2 46 Baetis 1 Bezzia 1 1 Caecidotea 30 45 2 77 Caenis 36 18 46 11 254 31 41 437 Callibaetis 1 1 5 1 5 13 Ceraclea 1 5 6 Ceratopogon 1 1 Cheumatopsyche 1 1 Chironomidae 479 548 438 361 267 316 307 2716 Cipangopaludina 3 4 7 Climacia 2 2 Corbicula 152 68 28 89 11 27 50 425 Cyrnellus 1 1 Dasyhelea 1 Dromogomphus 1 1 Dubiraphia 2 3 Dugesia 2 3 Elimia 18 2 21 1 42 Enallagma 2 45 6 13 18 31 115 Erpobdella 1 Ferrissia 5 39 45 Galba 1 1 1 3 Gammarus 2 79 182 245 95 218 152 973 Gloiobdella 2 2 G:traulus 8 1 6 1 29 161 100 306 ------69 PBAPS Post-EPU Study Table 6-4. Continued.

Station Taxon 214 215 216 189 208 220 221 Total Number Helobdella 1 1 1 3 Hexagenia 56 1 3 5 7 3 75 Hyalella 1 1 Hydrachnidea 13 41 31 35 101 21 73 315 Hydroptila 1 3 1 1 4 7 17 Leptoxis 1 Libellulidae 2 3 Maccaffertium 8 2 11 5 28 Mcrocylloepus 1 1 Micromenetus 4 1 3 16 14 38 Nematoda 2 1 2 5 Nigronia 1 1 Oecetis 3 8 6 14 10 3 3 47 Oligochaeta 287 56 155 71 106 8 118 801 Orconectes 1 1 3 5 Orthotrichia 5 13 1 19 Oxyethira 3 3 Paraleptophlebia 1 1 Phylocentropus 1 1 Phys ell a 45 50 12 54 80 52 65 358 Pisidium 1 1 Planorbella 2 1 1 2 6 Pleurocera 1 2 2 5 10 Probezzia 1 1 Prostoma 1 1 Sialis 1 4 1 1 7 Stenacron 3 25 13 18 13 72 Stenelmis 2 9 1 12 Stenonema 8 16 6 30 Triaenodes 1 1 Tricorythodes 2 2 Total Number 1,041 1,033 1,040 988 1,021 995 979 7,097 Total Taxa 19 25 28 23 29 36 24 59 Total Ephemeroptera Taxa 4 4 5 3 3 7 4 9 Total Tricho12tera Taxa 2 3 2 3 5 6 1 8 70 PBAPS Post-EPU Study Table 6-5. Percent composition of common benthic macro invertebrates

(>1% of total organisms) collected from Conowingo Pond, May through September 2016. Station Tax on 214 215 189 216 208 220 221 Argia 1.7 2.4 Caecidotea 4.6 2.9 Caenis 3.5 1.7 1.1 4.4 24.9 3.1 4.2 Chironomidae 46.0 53.0 36.5 42.1 26.2 31.8 31.4 Corbicula 14.6 6.6 9.0 2.7 1.1 2.7 5.1 Elimia 1.7 2.1 Enallagma 4.4 1.3 1.8 3.2 Ferrissia

3.9 Gammarus

7.6 24.8 17.5 9.3 21.9 15.5 Gyraulus 2.8 16.2 10.2 Hexagenia

5.4 Hydrachnidea

1.2 4.0 3.5 3.0 9.9 2.1 7.5 Maccaffertium

1.1 Micromenetus

1.6 1.4 Oecetis 1.4 Oligochaeta 27.6 5.4 7.2 14.9 10.4 12.1 Orthotrichia

1.3 Physella

4.3 4.8 5.5 1.2 7.8 5.2 6.6 Stenacron 2.4 1.8 1.3 1.3 Stenonema

1.5 Total

Taxa 6 10 12 12 10 12 10 Total EPT Taxa 1 3 4 3 1 2 1 71 PBAPS Post-EPU Study Table 6-6. Percent composition of common benthic macroinvertebrates

(>1%) collected from Conowingo Pond, May through September 2010-2013.

Station Tax on 214 215 189 216 208 220 221 Acariformes 1.2 2.9 3.8 2.7 14.4 2.6 4.5 Caecidotea 2.3 1.7 Caenis 5.0 2.9 13.2 17.8 12.7

1.5 Callibaetis

1.3 Chironomidae

55.1 45.3 39.5 32.2 30.2 43.8 49.9 Corbi cul a 14.9 20.1 12.0 5.2 2.0 5.8 2.4 Crangonyx

1.6 Enallagma

1.3 Fossaria

3.5 1.6 Gammarus 1.6 4.7 26.5 14.1 10.0 11.7 5.6 Gyraulus 5.6 3.0 6.1 He Ii soma 2.1 Hexagenia 2.8 1.5 1.2 Oecetis 1.2 Oligochaeta 10.7 9.5 4.6 20.9 7.5 11.2 18.6 Orthotrichia

1.7 Physa

3.2 4.6 1.2 2.0 1.1 Stenacron

2.5 Stenelmis

1.5 Ste none ma 2.3 Total Taxa 8 10 9 9 11 8 10 Total EPT Taxa 1 2 2 2 4 2 1 72 PBAPS Post-EPU Study Table 6-7. Total Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016. Station fv'lonth 214 215 216 189 208 220 221 May 8 12 9 7 9 15 7 June 8 14 10 9 10 13 8 July 10 15 16 14 9 17 10 August 11 13 14 15 16 15 14 September 5 9 16 12 19 17 13 Mean 8.4 12.6 13.0 11.4 12.6 15.4 10.4 Table 6-8. EPT Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016. Station fv'lonth 214 215 216 189 208 220 221 May 1 3 2 0 2 2 1 June 3 6 3 2 3 3 0 July 4 6 5 5 4 7 3 August 3 5 4 6 6 6 3 September 1 3 5 4 6 6 4 Mean 2.4 4.6 3.8 3.4 4.2 4.8 2.2 Table 6-9. Ephemeroptera Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016. Station fv'lonth 214 215 216 189 208 220 221 May 1 3 1 0 1 1 1 June 1 4 2 2 1 2 0 July 4 4 3 3 2 2 3 August 2 4 3 4 3 5 2 September 1 2 5 2 2 5 3 Mean 1.8 3.4 2.8 2.2 1.8 3.0 1.8 73 PBAPS Post-EPU Study Table 6-10. Trichoptera Richness values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016. Station IVlonth 214 215 216 189 208 220 221 May 0 0 1 0 1 1 0 June 2 2 1 0 2 1 0 July 0 2 2 2 2 5 0 August 1 1 1 2 3 1 1 September 0 1 0 2 4 1 1 Mean 0.6 1.2 1.0 1.2 2.4 1.8 0.4 Table 6-11. Modified Beck's Index values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016. Station IVlonth 214 215 216 189 208 220 221 May 3 3 2 1 1 4 2 June 1 4 2 3 1 2 2 July 3 3 4 3 1 3 2 August 2 4 3 4 6 7 2 September 1 3 3 3 3 4 2 Mean 2.0 3.4 2.8 2.8 2.4 4.0 2.0 Table 6-12. Shannon Diversity values by month for benthic macroinvertebrate collection locations in Conowingo Pond, May through September 2016. Station IVlonth 214 215 216 189 208 220 221 May 1.08 1.83 1.32 1.56 1.30 1.29 1.34 June 1.11 1.87 1.68 1.26 1.43 1.62 1.32 July 1.56 1.66 1.97 1.72 1.36 2.11 1.71 August 1.48 1.09 1.48 1.62 1.62 1.75 2.24 September 0.63 1.29 1.65 1.67 2.04 2.33 1.89 Mean 1.17 1.55 1.62 1.56 1.55 1.82 1.70 74 PBAPS Post-EPU Study 60 so 40 May June July Ausust September Figure 6-4. Bar chart showing the 181 scores for each station by month, May through September 2016. 75 45 40 35 20 15 10 PBAPS Post-EPU Study May 0 0 0 0 PU St214 5t215 St189 5t216 St208 St220 St221 Station PU Figure 6-5. Box plot of May IBI scores for all stations during pre-EPU (2010-2013) and EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal.

June 45 EPU 40 35 0 ID 0 J 30 l!I 0 8 .* 0 25 0 0 20 15 St214 St215 St189 St216 St208 St220 St221 Station Figure 6-6. Box plot of June IBI scores for all stations during pre-EPU (2010-2013) and EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal. (boxes = interquartile range containing 50% of the values, the line across the box= median value, vertical lines extending from the box = highest and lowest values, open circle = 181 score, the post-EPU value is labeled EPU, and asterisk=

outlier) 76 PBAPS Post-EPU Study July so 0 40 II 0 PU § 30 Iii 20 0 10 0 51214 51215 5t189 51216 51208 51220 51221 Station Figure 6-7. Box plot of July IBI scores for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal.

August so 40 g" @." EPU ! 30 OEU Iii 20 10 0 0 0 0 51214 51215 5t189 51216 51208 51220 51221 Station Figure 6-8. Box plot of August IBI scores for all stations during pre-EPU (2010-2013) and EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal. (boxes =interquartile range containing 50% of the values, the line across the box= median value, vertical lines extending from the box = highest and lowest values, open circle = /Bl score, the post-EPU value is labeled EPU, and asterisk=

outlier) 77 PBAPS Post-EPU Study September so 0 EPU 0 EPU 40 0 eoo GI 0 30 SEPU el EPU 20 0 0 10 EPU 51214 51215 St189 51216 51208 51220 51221 Station Figure 6-9. Box plot of September 181 scores for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring.

Stations 208, 220, and 221 are considered non-thermal. (boxes = interquartile range containing 50% of the values, the line across the box= median value, vertical lines extending from the box = highest and lowest values, open circle = 181 score, the post-EPU value is labeled EPU, and asterisk=

outlier) so 40 GI 30 iii 20 10 0 IBI Score vs Mean Water Temperature 60 70 80 90 100 Post-EPU Pre-EPU I .... I I I I I ........ I I I " .... :. /}-.. I * ... : . ! ...... I .... .,,,,.. I II> I * * ..... 4 ** I I C> ... *t : ..... *

• e ,/' "lll I

• I . : .... ** " ... I>*

• I ...... *

• I **** f

• I ** I I I _________________ ...J..._!

___ ------------------+..-

---

I . : I I I .... I I I I 60 70 80 90 100 Mean Water

{f) 10 MONTH_! e May *June Jutv ..i.. August .. Sepll!lnber Figure 6-10. Relation of mean water temperature measured during the month of benthos collection to the corresponding IBI Score for that month for post-EPU (left panel) and pre-EPU (right panel) monitoring, May through September 2010-2016.

78 PBAPS Post-EPU Study 20.0 17.5

• lU 0 i 15.0 12.5 i ii 10.0 l 7.S 5.0 Perlod 2 2 2 2 2 2 2 2 it it it 2 it it w w w w w w w w w w w w w w l l l £ cV &:: X! l l station § :!; "' "' t; t! Figure 6-11. Box plot of Total Richness for all stations during pre-EPU (2010-2013}

and EPU (2016} monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal.

9 8 7 "' .. 6 ot il 5 "' ij i 4

• 3 -0 Perlod it it it it it it it it 2 it it it w w w w w w w w w w w w l ii .!. &:: l £ £ l l station 1ll :!; "' "' ... N tl t! t! Figure 6-12. Box plot of EPT Richness for all stations during pre-EPU (2010-2013}

and EPU (2016} monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal. (boxes = interquartile range containing 50% af the values, the line across the box = median value, vertical lines extending from the box = highest and lowest values, open circle = metric value, and asterisk = outlier) 79 PBAPS Post-EPU Study 6 .. i j 4 ] i I! .. l 2 I 0 Period it it it it it it it it it it it it $ w w w w w w w w w w w w & & & .. ,:, & .. ,:, & station ! :!; !!l :g 't;; t! t! t! Figure 6-13. Box plot of Ephemeroptera Richness for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal. 5 4 I (l 3 *

• I! 1 : n * : :

• Period station Figure 6-14. Box plot of Trichoptera Richness for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal. (boxes= interquartile range containing 50% of the values, the line across the box= median value, vertical lines extending from the box = highest and lowest values, open circle = metric value, and asterisk = outlier) 80 7 4 3 2 0 Period station PBAPS Post-EPU Study Figure 6-15. Box plot of Beck's Index for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered thermal. 2.5 2.0 h f j It f 1 5 1.5 § c 1.0 a II! 0.5 II! o.o Period it it it it it it it it it it it it it it w w w w w w w w w w w w w w

!!! a.. & & & & & cli &: station :ill :!; "' .. N ti tl tl tl Figure 6-16. Box plot of Shannon Diversity for all stations during pre-EPU (2010-2013) and post-EPU (2016) monitoring, May through September.

Stations 208, 220, and 221 are considered non-thermal. (boxes= interquartile range containing 50% of the values, the line across the box= median value, vertical lines extending from the box = highest and lowest values, open circle = metric value, and asterisk = outlier) 81 PBAPS Post-EPU Study 6. 3 Fish Community The spatial and temporal distribution of fish was evaluated in Conowingo Pond by monthly sampling at both thermally influenced and non-thermally influenced locations from May through September 2016. Sampling sites were separated into non-thermal and thermal stations based on their location in relation to the PBAPS thermal plume. Stations downstream of the discharge canal that experience elevated water temperatures above ambient water temperature for the entire collection period are considered to be thermally influenced (electrofisher Stations 161, 189, 190, and 217; seine Stations 214 and 215). Stations located upstream of the PBAPS thermal discharge that experience natural water temperature conditions are considered thermal (electrofisher Stations 165 and 187; seine Stations 208, 220, and 221). As previously discussed seine Station 208 does experience elevated water temperatures during a portion of the year resulting from thermal plume movement upstream during low flow conditions; however, this station is considered non-thermal because it does not experience a prolonged year-round thermal influence.

The relative abundance of all fish was determined by standardizing the number of individuals of each species collected per unit of collection effort for each sampling gear. Comparison between the pre-EPU and post-EPU communities was completed to evaluate the potential effect of the temperature rise associated with the EPU on the fish community.

Eleven fish species were previously designated as representative important species (RIS) for the most recent pre-EPU 316a Demonstration Study (Normandeau and ERM 2014). The species were agreed upon with PADEP. Most of these species are appropriate representative species for assessment of potential thermal impact consistent with the concept of RIS, as established by the USEPA (1977), e.g., recreational value, representative of the balanced indigenous community, or an important food item for other RIS. The eleven RIS were Bluegill, Bluntnose Minnow, Channel Catfish, Gizzard Shad, Largemouth Bass, Chesapeake Logperch, Smallmouth Bass, Spotfin Shiner, Walleye, White Crappie, and White Sucker. The composition and relative abundance of the RIS at each of the monitoring stations are evaluated and compared between pre-and post-EPU monitoring.

The selected RIS did not include migratory fish species. 6.3.1 Methods E/ectrofishinq Electrofishing was conducted at night at six stations located along the shores of Conowingo Pond (Table 6-1 and Figure 6-3). The electrofishing system consisted of a Smith-Root WP-15B variable voltage pulsator, powered by a 3.5-kW generator, and mounted in an 18-ft aluminum boat equipped with a bow-mounted T-boom cathode array and flood lights. Fishes were collected using pulsed direct current to minimize fish injury. Sampling at each location consisted of a 30-minute run and was typically completed in one pass through the sampling location.

The electrofishing boat was maneuvered slowly through the site, as close to shore as possible.

82 PBAPS Post-EPU Study Stunned fish were netted at the bow and placed in a live well. Large stunned specimens of Common Carp and Quillback were not netted, but were counted by the netting crew and recorded.

At the end of 30 minutes, the boat was returned to the center of the station, and the catch processed.

Each fish was identified to species, measured to the nearest millimeter (mm) total length (TL), weighed to the nearest gram, and released.

When a large number (>50) of a single species was collected, a subsample of 50 specimens was measured into 10 mm TL intervals , batch weighed, and an exact count was made of the remainder and released. Seining was conducted at five shoreline stations {Table 6-1, Figure 6-1) Conowingo Pond. A 10 x 4-ft straight seine with %-inch mesh was used. The seine was deployed and moved parallel to shore for a short distance, then moved into shore to trap fish; this effort constituted one seine haul. Since size and habitat of seine stations varied, an effort was made to collect a representative sample based on complete coverage of all available habitats, limiting the number of hauls at each station to five. All specimens were identified, counted, and released near the capture site. Specimens that were too small to accurately identify to species in the field were only identified to genus. Catch Overview This section provides a general summary of the fish catch information produced by the seine, and electrofishing sampling conducted in 2016. Table 6-13 provides a list of common and scientific names of fish species observed in Conowingo Pond during the course of this study. The sampling methods used in this study were deployed in similar habitats but targeted certain species and sizes of fish. Seining targeted small-bodied fishes (Cyprinidae) and young of year of large-bodied fishes (Centrarchidae).

Electrofishing was effective for both large and small fish. A total of 14,568 individuals representing 34 species was collected in this study by seining and electrofishing in Conowingo Pond. A diverse warmwater fish community was represented by eight families of fish with three families (Cyprinidae, Centrarchidae, and Percidae) predominating the catch. Twenty-four of the species collected were within these three families.

The summary of the electrofishing data, with the results grouped by thermally affected and thermally affected stations , are presented in Table 6-14. A total of 12,879 individuals and 31 species was collected with boat electrofisher in 2016. Bluegill and Gizzard Shad was the most numerous species taken by boat electrofisher. Other numerous species included Channel Catfish, Comely Shiner, Green Sunfish, Smallmouth Bass, and Spotfin Shiner. Table 6-15 through Table 6-19 provide the monthly electrofishing catch for each station. The summary of the seine data, with the results grouped by thermally affected and thermally affected stations are presented in Table 6-20. A total of 1,689 individuals and 17 species was collected with seine in 2016. Bluegill and Spotfin Shiner was the most numerous species taken by seine. Other numerous species included Banded Killifish, Golden Shiner, and Comely Shiner. Table 6-21 through Table 6-25 provide the monthly seine catch for each station. 83 PBAPS Post-EPU Study Table 6-13. List of common and scientific names of fishes collected in Conowingo Pond, May through September 2016. Anguillidae Anguilla rostrala Clupeidae Dorosoma cepedianum Cyprinidae Campostoma anomalum Cyprine/la spiloptera Cyprin11s carpio Notemigonus crysoleucas Notropis amoenus Notropis h11dsoni11s Notropis voluce/lus Pimepha/es notallls Rhinichthys atratulus Semotilus corpora/is Catostomidae Carpiodes cyprinus Catostonms conunersoni Hypentelium nigricans Moxostoma macrolepidolllm Jctaluridae lctalurus punc/allls Pylodictis o/ivaris Cyprlnodontidae Fzmdulus diaphanus Percicht/1yidae Morone americana Eels American eel Herrings Gizzard shad Carps and minnows Central stoneroller Spotfm shiner Common carp Golden shiner Comely shiner Spottail shiner Mimic shiner Bluntnose minnow Blacknose dace Fallfish Suckers Quillback White sucker Northern hogsucker Shorthead redhorse Bullhead catfishes Channel catfJSh Flathead catfJSh Killifishes Banded killifJSh Temperate basses White perch 84 Centrarc/1/dae Ambloplites rupestris Lepomis aurillls Lepomis cyane/lus Lepomis gibbosus Lepomis macrochirus Micropterus dolomieu Micropter11s salmoides Pomoxis annularis Percldae Etheostoma blennioides Etheostoma o/mstedi Perea flavescens Percina bimaculata Percina peltata Stizostedion vitreum Sunfishes Rock bass Redbreast sunfJSh Green sunfJSh Pwnpkinseed Bluegill Smalhnouth bass Largemouth bass White crappie Perches Greenside darter TesseDated darter Yellow perch Chesapeake logperch Shield darter Walleye PBAPS Post-EPU Study Table 6-14. Total number of fish collected with boat electrofisher from Conowingo Pond, May through September 2016. Tax on Thermally Affected Non-thermally Affected Total Number 161 189 190 217 165 187 American Eel 1 1 Banded killifish 1 1 Bluegill 168 384 615 1141 364 2194 4866 Bluntnose minnow 16 12 1 12 33 74 Channel catfish 97 34 58 74 83 60 406 Comely shiner 119 26 73 2 116 25 361 Common carp 19 10 11 17 3 9 69 Fallfish 2 2 4 Flathead catfish 8 12 9 5 4 38 Gizzard shad 1010 170 1620 291 81 1128 4300 Golden shiner 137 22 51 1 211 Green sunfish 156 126 234 235 100 19 870 Greenside darter 1 1 Largemouth bass 3 25 18 38 12 10 106 Chesapeake Logperch 3 7 21 17 24 n Northern hogsucker 2 2 Pumpkinseed 1 2 1 2 1 7 Quill back 1 1 1 3 Redbreast sunfish 1 1 2 Rock bass 2 12 9 42 80 94 239 shield darter 2 2 Shorthead redhorse 4 1 7 1 5 18 Smallmouth bass 45 88 149 176 209 117 784 Spotfin shiner 70 48 94 17 13 37 279 Spottail shiner 1 2 13 9 20 45 Tessellated darter 3 3 20 26 Walleye 1 1 1 2 2 30 37 White crappie 1 1 White perch 18 6 3 27 White sucker 1 1 Yellow perch 6 3 17 26 Total Number 1717 1101 2939 2141 1117 3838 12879 Total Species 14 20 20 22 22 22 31 Total RIS species 5 6 7 7 8 8 10 Species designated as Representative Important Species {RIS) during the 316a Demonstration Study are represented with bold font 85 PBAPS Post-EPU Study Table 6-15. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, May 2016. Taxon Thermally Affected Non-thermally Affected Total Number 161 189 190 217 165 187 American Eel 1 1 Bluegill 71 31 107 128 35 14 386 Bluntnose minnow 2 5 2 17 26 Channel catfish 8 13 28 26 14 10 99 Comely shiner 113 1 4 1 22 141 Common carp 15 2 2 2 1 22 Fallfish 2 2 4 Flathead catfish 5 4 9 Gizzard shad 300 7 14 12 1 334 Golden shiner 1 1 4 6 Green sunfish 28 14 80 13 14 2 151 Largemouth bass 3 22 17 22 11 7 82 Northern hogsucker 1 1 Pumpkinseed 2 1 1 4 Rock bass 2 4 4 15 36 35 96 Shorthead redhorse 4 3 7 Smallmouth bass 26 26 59 73 76 35 295 Spotfin shiner 56 7 1 5 18 87 Spottail shiner 7 7 Tessellated darter 1 15 16 Walleye 1 1 1 1 2 12 18 White crappie 1 1 White perch 18 6 3 27 White sucker 1 1 Yellow perch 6 3 13 22 Total Number 646 147 326 304 202 218 1843 Total Species 13 17 15 13 14 19 25 Total RIS species 7 8 8 7 8 8 10 Shannon Diversity 1.71 2.35 1.83 1.74 1.86 2.55 Maximum Diversity 2.56 2.83 2.71 2.56 2.64 2.94 Evenness 0.67 0.83 0.67 0.68 0.70 0.87 Species designated as Representative Important Species (RIS) during the 316a Demonstration Study are represented with bold font 86 PBAPS Post-EPU Study Table 6-16. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, June 2016. Tax on Thermally Affected Non-thermally Affected Total Number 161 189 190 217 165 187 Banded killifish 1 1 Bluegill 2 31 64 93 8 3 201 Bluntnose minnow 5 5 Channel catfish 4 4 8 8 18 7 49 Comely shiner 4 5 11 1 1 22 Common carp 1 2 3 Flathead catfish 2 6 5 1 1 15 Gizzard shad 3 1 29 33 Green sunfish 30 14 34 30 8 1 117 Largemouth bass 1 1 2 Chesapeake Logperch 2 2 1 1 6 Northern hogsucker 1 1 Pumpkinseed 1 1 Quill back 1 1 Redbreast sunfish 1 1 Rock bass 1 1 5 17 32 56 Shorthead redhorse 1 1 2 Smallmouth bass 13 10 25 10 33 35 126 Spotfin shiner 5 14 36 3 4 62 Spottail shiner 1 1 Walleye 1 1 2 Yellow perch 1 1 Total Number 65 92 186 157 88 120 708 Total Species 10 11 9 12 9 16 22 Total RIS Species 5 6 5 6 5 8 9 Shannon Diversity 1.70 1.96 1.74 1.38 1.65 1.83 Maximum Diversity 2.30 2.40 2.20 2.48 2.20 2.n Evenness 0.74 0.82 0.79 0.55 0.75 0.66 Species designated as Representative Important Species (RIS) during the 316a Demonstration Study are represented with bold font 87 PBAPS Post-EPU Study Table 6-17. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, July 2016. Tax on Thermally Affected Non-thermally Affected Total Number 161 189 190 217 165 187 Bluegill 27 67 300 331 55 19 799 Bluntnose minnow 7 3 3 6 19 Channel catfish 72 7 3 3 30 15 130 Comely shiner 17 36 22 1 76 Common carp 2 4 3 1 2 5 17 Flathead catfish 1 1 3 3 2 10 Gizzard shad 27 390 17 23 4 461 Golden shiner 69 9 29 107 Green sunfish 40 49 64 52 20 10 235 Largemouth bass 3 1 8 12 Chesapeake Logperch 3 4 17 8 20 52 Quill back 1 1 Redbreast sunfish 1 1 Rock bass 5 1 15 17 20 58 shield darter 2 2 Shorthead redhorse 4 4 Smallmouth bass 1 20 25 25 39 32 142 Spotfin shiner 3 21 26 7 1 6 64 Spottail shiner 1 2 13 3 8 27 Tessellated darter 3 1 5 9 Walleye 14 14 Yellow perch 3 3 Total Number 146 302 870 526 229 170 2243 Total Species 7 16 15 15 15 16 22 Total RIS Species 4 8 8 7 6 7 9 Shannon Diversity 1.22 2.16 1.44 1.48 2.19 2.48 Maximum Diversity 1.95 2.77 2.71 2.71 2.71 2.n Evenness 0.63 0.78 0.53 0.55 0.81 0.89 Species designated as Representative Important Species (RIS} during the 316a Demonstration Study are represented with bold font 88 PBAPS Post-EPU Study Table 6-18. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, August 2016. Tax on Thermally Affected Non-thermally Affected Total Number 161 189 190 217 165 187 Bluegill 34 160 82 223 142 2050 2691 Bluntnose minnow 2 4 6 12 Channel catfish 9 6 4 10 7 36 Comely shiner 2 3 9 1 50 1 66 Common carp 2 2 2 1 7 Flathead catfish 1 1 1 3 Gizzard shad 79 81 1094 236 35 1047 2572 Golden shiner 26 6 17 49 Green sunfish 34 25 26 2 44 131 Largemouth bass 1 1 2 Logperch 1 4 5 Rock bass 2 1 1 4 2 10 Shorthead redhorse 1 1 2 Smallmouth bass 5 10 13 39 19 5 91 Spotfin shiner 6 5 14 1 4 30 Spottail shiner 4 4 Tessellated darter 1 1 Walleye 1 1 Total Number 169 317 1259 529 310 3129 5713 Total Species 7 11 13 13 10 12 18 Total RIS Species 5 5 6 7 5 8 9 Shannon Diversity 1.43 1.43 0.61 1.18 1.61 0.71 Maximum Diversity 1.95 2.40 2.56 2.56 2.30 2.48 Evenness 0.74 0.60 0.24 0.46 0.70 0.29 Species designated as Representative Important Species {RIS) during the 316a Demonstration Study are represented with bold font 89 PBAPS Post-EPU Study Table 6-19. Total number (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) of fish collected with boat electrofisher from Conowingo Pond, September 2016. Tax on Thermally Affected Non-thermally Affected Total Number 161 189 190 217 165 187 Bluegill 34 95 56 366 124 108 783 Bluntnose minnow 1 7 4 12 Channel catfish 4 10 13 33 11 21 92 Comely shiner 13 43 56 Common carp 1 2 4 10 1 2 20 Flathead catfish 1 1 Gizzard shad 628 54 122 26 22 48 900 Golden shiner 41 6 1 1 49 Green sunfish 24 24 30 138 14 6 236 Greenside darter 1 1 Largemouth bass 7 1 8 Chesapeake Logperch 1 1 4 3 9 Pumpkinseed 1 1 2 Quill back 1 1 Rock bass 2 6 6 5 19 Shorthead redhorse 1 1 1 3 Smallmouth bass 22 27 29 42 10 130 Spotfin shiner 1 17 6 7 s 36 Spottail shiner 6 6 Walleye 2 2 Total Number 691 249 292 625 291 218 2366 Total Species 5 8 12 13 16 15 20 Total RIS Species 3 4 6 1 1 1 9 Shannon Diversity 0.39 1.63 1.79 1.32 1.81 1.59 Maximum Diversity 1.61 2.08 2.48 2.56 2.n 2.71 Evenness 0.24 0.78 0.72 0.52 0.65 0.59 Species designated as Representative Important Species (RIS) during the 316a Demonstration Study are represented with bold font 90 PBAPS Post-EPU Study Table 6-20. Total number of fish collected in seine collections from Conowingo Pond, May through September 2016. Station 2 Taxon 1 Thermally Affected Non-thermally Affected Total Number 214 215 208 220 221 Banded killifish 53 1 19 1 208 282 blacknose dace 1 1 Bluegill 193 76 105 180 2 556 Bluntnose minnow 3 9 3 18 1 34 central stoneroller 1 1 Comely shiner 92 1 5 98 Gizzard shad 1 1 Golden shiner 187 187 Green sunfish 24 9 4 5 42 Largemouth bass 1 1 Chesapeake Logperch 2 2 Mimic shiner 1 1 2 Pumpkinseed 1 1 Rock bass 2 9 11 Smallmouth bass 2 1 3 Spotfin shiner 165 108 3 157 12 445 Spottail shiner 3 11 6 20 Tessellated darter 2 2 Total Number 720 207 143 390 229 1689 Total Species 10 7 10 11 5 17 Total RIS 3 3 6 5 3 7 1 Representative Important Species represented with bold font 2 Five seine hauls completed during each month at each station; therefore, total number equivalent to CPUE 91 PBAPS Post-EPU Study Table 6-21. Total number (CPUE) of fish collected with seine from Conowingo Pond, May 2016. Station 2 Taxon 1 Thermally Affected Non-thermally Affected Total Number 214 215 208 220 221 Banded killifish 40 1 2 1 155 199 Blacknose Dace 1 1 Bluntnose minnow 3 1 4 Comely shiner 92 92 Mimic shiner 1 1 Spotfin shiner 34 20 54 Total Number 171 21 2 1 156 351 Total Species 6 2 1 1 2 6 Total RIS 2 1 0 0 1 2 Shannon Diversity 1.13 0.19 0.00 0.00 0.04 Maximum Diversity 1.79 0.69 0.00 0.00 0.69 Evenness 0.63 0.28 0.00 0.00 0.06 1 Representative Important Species represented with bold font 2 Five seine hauls completed at each station; therefore, total number equivalent to CPUE 92 PBAPS Post-EPU Study Table 6-22. Total number (CPUE) of fish collected with seine from Conowingo Pond, June 2016. Station 2 Taxon 1 Thermally Affected Non-thermally Affected Total Number 214 215 208 220 221 Banded killifish 6 2 15 23 Bluegill 1 3 4 Bluntnose minnow 1 1 Largemouth bass 1 1 Rock bass 1 1 2 Smallmouth bass 2 2 Spotfin shiner 10 1 2 7 2 22 Spottail shiner 1 1 Total Number 17 2 8 12 17 56 Total Species 3 2 5 4 2 8 Total RIS 2 1 3 3 1 5 Shannon Diversity 0.85 0.69 1.56 1.08 0.36 Maximum Diversity 1.10 0.69 1.61 1.39 0.69 Evenness 0.77 1.00 0.97 0.78 0.52 1 Representative Important Species represented with bold font 2 Five seine hauls completed at each station; therefore, total number equivalent to CPUE 93 PBAPS Post-EPU Study Table 6-23. Total number (CPUE) of fish collected with seine from Conowingo Pond, July 2016. Station 2 Taxon 1 Thermally Affected Non-thermally Affected Total Number 214 215 208 220 221 17 Banded killifish 2 1 14 214 Bluegill 97 52 2 63 6 Bluntnose minnow 6 1 central stoneroller 1 3 Comely shiner 3 187 Golden shiner 187 18 Green sunfish 16 1 1 1 Mimic shiner 1 1 Smallmouth bass 1 146 Spotfin shiner 56 56 31 3 15 Spottail shiner 2 7 6 609 Total Number 359 117 3 107 23 1201 Total Species 6 5 2 7 3 12 Total RIS 1 3 1 3 1 4 Shannon Diversity 1.17 0.98 0.64 1.08 0.92 Maximum Diversity 1.79 1.61 0.69 1.95 1.10 Evenness 0.65 0.61 0.92 0.56 0.84 1 Representative Important Species represented with bold font 2 Five seine hauls completed at each station; therefore, total number equivalent to CPUE 94 PBAPS Post-EPU Study Table 6-24. Total number (CPUE) of fish collected with seine from Conowingo Pond, August 2016. Station 2 Taxon 1 Thermally Affected Non-thermally Affected Total Number 214 215 208 220 221 Banded killifish 12 14 26 Bluegill 12 20 37 85 2 156 Bluntnose minnow 3 2 5 Gizzard shad 1 1 Green sunfish 8 2 10 Pumpkinseed 1 1 Rock bass 8 8 Spotfin shiner 24 8 1 29 7 69 Spottail shiner 4 4 Tessellated darter 1 1 Total Number 36 36 56 130 23 281 Total Species 2 3 7 6 ,. 3 10 Total RIS 2 2 4 3 2 4 Shannon Diversity 0.64 1.00 1.05 1.02 0.88 Maximum Diversity 0.69 1.10 1.95 1.79 1.10 Evenness 0.92 0.91 0.54 0.57 0.80 1 Representative Important Species represented with bold font 2 Five seine hauls completed at each station; therefore, total number equivalent to CPUE 95 PBAPS Post-EPU Study Table 6-25. Total number (CPUE) of fish collected with seine from Conowingo Pond, September 2016. Station 2 Taxon 1 Thermally Affected Non-thermally Affected Total Number Banded killifish Bluegill Bluntnose minnow Comely shiner Green sunfish Chesapeake Logperch Rock bass Spotfin shiner Tessellated darter Total Number Total Species Total RIS Shannon Diversity Maximum Diversity Evenness 214 215 5 83 8 41 137 4 2 0.95 1.39 0.69 4 3 1 23 31 4 3 0.82 1.39 0.59 208 220 221 2 66 4 1 1 74 5 1 0.47 1.61 0.29 10 29 15 2 2 2 90 140 10 6 ,. 1 4 0 1.03 0.00 1.79 0.00 0.58 0.00 1 Representative Important Species represented with bold font 2 Five seine hauls completed at each station; therefore, total number equivalent to CPUE Fish Metrics and CPUE 17 182 18 3 14 2 1 154 1 392 9 4 Comparison of catch per unit effort (CPUE) and community based metrics among collection locations is useful in describing differences in the fish community among stations.

Gear specific CPUE normalizes the catch based on level of effort and, therefore, allows standardized comparisons of relative abundance.

Several metrics that describe the fish community at individual stations were calculated for the seine and electrofishing collections.

Monthly metric values were compared among locations to determine if differences existed between individuals stations.

For this analysis stations are discussed as either non-thermal or thermal based on their location in relation to the PBAPS thermal plume. Electrofishing Stations 161, 189, 190, and 217 are considered thermally influenced and Stations 187 and 165 are considered non-thermal.

Seine Stations 214 and 215 are considered thermally influenced and Stations 220, 221, and 208 are considered non-thermal.

As previously discussed, Station 208 does experience elevated water 96 PBAPS Post-EPU Study temperatures during a portion of the year resulting from thermal plume movement upstream during low flow conditions.

However, this station is considered non-thermal because it does not experience a prolonged thermal influence.

6.3.2 E/ectrofishinq Results 2016 Four metrics were calculated to provide a description of the fish community among stations and across monthly collections in Conowingo Pond from May to September 2016. Table 6-26 through Table 6-29 provide the metric values for each station and Figure 6-17 through Figure 6-20 provide box plots which graphically illustrate the monthly metric values among stations.

Catch per unit effort (no./0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) was generally similar among stations during each month with the lowest CPUE of 65 fish observed at Station 161 in June and the highest CPUE of 3, 129 fish observed at Station 187 in August. CPUE for most stations was highest in August with exception of Station161 which had the highest catch during September.

Total species richness ranged from five species at Station 161 in September to 19 species at Station 187 in May. Species richness was highest for most stations during May and July. The highest total richness was observed at Station 187 (non-thermal) during most months. Total richness at Station 161 was noticeably lower (range between five and seven species) during July through September compared to all other stations.

RIS richness ranged from three species at Station 161 in September to eight species collected at multiple stations during June to August. Similar to species richness, RIS richness was highest for most stations during May and July. RIS richness for Station 187 was generally higher or equal to the other stations for each month of collection.

Shannon Diversity values ranged from 0.39 at Station 161 in September to 2.55 at Station 187 in May. Shannon Diversity values were highest for most stations during May and July. Post-EPU Metric comparison to Pre-EPU A comparison of pre-and post-EPU electrofishing metric values allows for inspection of potential differences that may have been a result of the increase in temperature from the EPU. Figure 6-17 through Figure 6-20 provide box plots of the four metrics selected to describe the fish community.

The metrics include square root transformed CPUE, Total Richness, Total RIS, and Shannon Diversity.

pre-and post-EPU metric values for the four metrics were generally comparable for most stations and months. For CPUE the observed values during post-EPU monitoring were comparable to pre-EPU at all electrofishing stations with all post-EPU values within the range of the pre-EPU values. For total species, Stations 189, 190, 165, and 187 values observed post-EPU were greater than or equal to pre-EPU monitoring.

For Station 161 during September of the post-EPU monitoring the total of five species was less than pre-EPU observations with six species being the lowest number collected during pre-EPU monitoring.

Similarly, 12 species were collected post-EPU at Station 217, the lowest number total species at this station was 13 species during pre-EPU monitoring.

For Total RIS, Stations 189, 190, 165, and 187 values observed post-EPU were greater than or equal to pre-EPU monitoring.

Two Stations, 161 and 189, had one monthly post-EPU value less than pre-EPU monitoring.

For both of the stations the post-EPU value was slightly less (one species) compared to pre-EPU observations.

Shannon Diversity values during post-EPU monitoring were generally within the range of pre-EPU observations with a few exceptions at Stations 190 (thermally influenced) and 97 PBAPS Post-EPU Study Stations 165 and 187 (non-thermally influenced).

Overall, the metrics values for each month of monitoring during post-EPU were comparable to pre-EPU observations indicating that the fish community relative abundance, richness and composition has not measurably changed with the EPU. 6.3.3 Seine Results 2016 Four metrics were calculated to provide a description of the fish community among stations and across monthly collections in Conowingo Pond from May to September 2016. Table 6-30 through Table 6-33 provide the metric values for each station and Figure 6-21 through Figure 6-24 provide box plots which graphically illustrate the monthly metric values among stations.

Catch per unit effort (no./five seine hauls) was generally similar among stations during each month with lowest CPUE of one fish observed at Station 220 in May and the highest CPUE of 359 fish observed at Station 214 in July. Total species richness ranged from one species at Stations 208 and 220 to seven species at Stations 208 and 220. RIS richness ranged from zero species at Stations 208, 220, and 221 to four species collected at Stations 208 and 220. Shannon Diversity values ranged from 0.0 at Stations 208, 220, and 221 to 1.55 at Station 208. For each metric the observed values were variable with no consistent seasonal pattern observed.

Post-EPU Metric Comparison to Pre-EPU A comparison of pre-and post-EPU seine metric values allows for inspection of potential differences that may have been a result of the increase in water temperature from the EPU. Figure 6-21 through Figure 6-24 provide box plots of four metrics selected to describe the fish community.

The metrics include square root transformed CPUE, Total Richness, Total RIS, and Shannon Diversity.

Pre-and post-EPU metric values for the four metrics were generally comparable for most stations and months. For CPUE the observed values during post-EPU monitoring were comparable to pre-EPU at most seine stations with the exception of Stations 220 and 208 (non-thermal).

For total species, Stations 214 and 215 values observed post-EPU were greater than or equal to pre-EPU monitoring. For Stations 208, 220 and 221 a few monthly post-EPU observations were less than pre-EPU with the difference being one species. For Total RIS, the values observed at Stations 214 and 215 during post-EPU monitoring were greater than or equal to pre-EPU monitoring.

For Stations 208, 220 and 221 a few monthly post-EPU observations were less than pre-EPU with the difference being one species. Shannon Diversity values during post-EPU monitoring were generally within the range of pre-EPU observations with a few exceptions.

At Stations 208, 220, and 221 a few observations during post-EPU monitoring were less than pre-EPU observations.

Overall, the metrics values for each month of monitoring post-EPU are comparable to pre-EPU observations indicating that the fish community relative abundance, richness and composition has not measurably changed with the EPU. 98 PBAPS Post-EPU Study 6.3.4 Discussion The community metrics and CPUE provide a description of the fish community both spatially (station) and temporally (month) within Conowingo Pond. The electrofishing results illustrate variation in the data across stations and months. The metrics indicate that fewer fish species were present at Station 161 during July through September.

Fishes likely avoided this area because of the elevated water temperatures resulting from the PBAPS thermal discharge.

Station 161 is the station closest to PBAPS and experienced the highest water temperatures observed at the electrofishing stations.

Patterns of avoidance were not readily apparent from the monthly metric values for most of the other thermally affected electrofishing stations.

One exception was Station 189 where species richness was lower indicating avoidance in September.

However, species richness at Station 189 was comparable to observations during pre-EPU monitoring at this station. Patterns of avoidance were not readily apparent for the monthly metrics at the thermally affected seine stations.

For both electrofishing and seining collections the metrics values were useful in evaluating differences in the fish community and relative abundance of common species across locations and months of collection.

Fish tended to avoid stations that experienced the highest water temperatures during the summer months. This was most clearly evident at electrofishing Station 161 from July through in September where six to eight fewer species were collected as compared to May or June. 6.3.5 Conclusions

• A diverse fish community of 34 species was observed in Conowingo Pond during 2016; Characteristics of the fish community were similar between pre-EPU and post-EPU observations;

• CPUE among species, and between stations, was variable due to differences in year class strength, habitat preferences, and other environmental variables;

• Avoidance was observed at electrofishing Station 161 at high water temperatures from July through September-;

• Avoidance was not observed at the seine stations.

99 PBAPS Post-EPU Study Table 6-26. CPUE of fish by month for electrofishing collection locations in Conowingo Pond, May through September 2016. Station Month 161 189 190 217 165 187 May 646 147 326 304 202 218 June 65 92 186 157 88 120 July 146 302 870 526 229 170 August 169 317 1229 529 310 3129 September 691 249 292 625 291 218 Mean 343 221 581 428 224 771 Table 6-27. Total RIS by month for electrofishing collection locations in Conowingo Pond, May through September 2016. Station Month 161 189 190 217 165 187 May 7 8 8 7 8 8 June 5 6 5 6 5 8 July 4 8 8 7 6 7 August 5 5 6 7 5 8 September 3 4 6 7 7 7 Mean 4.8 6.2 6.6 6.8 6.2

7.6 Table

6-28. Total Species by month for electrofishing collection locations in Conowingo Pond, May through September 2016. Station Month 161 189 190 217 165 187 May 13 17 15 13 14 19 June 10 11 9 12 9 16 July 7 16 15 15 15 16 August 7 11 13 13 10 12 September 5 8 12 13 16 15 Mean 8.4 12.6 12.8 13.2 12.8 15.6 100 PBAPS Post-EPU Study Table 6-29. Shannon Diversity by month for electrofishing collection locations in Conowingo Pond, May through September 2016. Station Month 161 189 190 217 165 187 May 1.71 2.35 1.83 1.74 1.86 2.55 June 1.70 1.96 1.74 1.38 1.65 1.83 July 1.22 2.16 1.44 1.48 2.19 2.48 August 1.43 1.43 0.61 1.18 1.61 0.71 September 0.39 1.63 1.79 1.32 1.81 1.59 Mean 1.29 1.90 1.48 1.42 1.82 1.83 Table 6-30. CPUE of fish by month for seine collection locations in Conowingo Pond, May through September 2016. Station Month 214 215 208 220 221 May 171 21 2 1 156 June 17 2 8 12 17 July 359 117 3 107 23 August 36 36 56 130 23 September 137 31 74 140 10 Mean 144 41.4 28.6 78 45.8 Table 6-31. Total RIS by month for seine collection locations in Conowingo Pond, May through September 2016. Station Month 214 215 208 220 221 May 2 1 0 0 1 June 2 1 3 3 1 July 1 3 1 3 1 August 2 2 4 3 2 September 2 3 1 4 0 ----------.. -------------Mean 1.8 2 1.8 2.6 1 101 PBAPS Post-EPU Study Table 6-32. Total Species by month for seine collection locations in Conowingo Pond, May through September 2016. Station Month 214 215 208 220 221 May 6 2 1 1 2 June 3 2 5 4 2 July 6 5 2 7 3 August 2 3 7 6 3 September 4 4 5 6 1 Mean 4.2 3.2 4 4.8 2.2 Table 6-33. Shannon Diversity by month for seine collection locations in Conowingo Pond, May through September 2016. Station Month 214 215 208 220 221 May 1.1 0.2 0.0 0.0 0.0 June 0.8 0.7 1.6 1.1 0.4 July 1.2 1.0 0.6 1.1 0.9 August 0.6 1.0 1.0 1.0 0.9 September 1.0 0.8 0.5 1.0 0.0 Mean 0.9 0.7 0.7 0.8 0.4 102 PBAPS Post-EPU Study Electrofishing 80

• 70 60 0 161 0 50 * ' io

• 40 30 61' ( l llt 20 10 0 Period UJ UJ UJ UJ UJ UJ UJ UJ UJ UJ UJ UJ & & cL 5:. 0.. & & !!! 0.. 0.. station ... ..... ta ..... ID ... tO ... ... ti ti ti ... 1il 1il 1il Figure 6-17. Box plot of square root transformed CPUE (no./O.Shr) for all electrofishing stations, May to September, pre-EPU (2010-2013) and post-EPU (2016). Electrofishing 25

• 20 JI 0 l 15 en 10 5 Period ffi ffi UJ UJ UJ UJ UJ UJ UJ UJ cL 111 5:. /?. £ & cL 111 5:. /?. £ cL 111 5:. /?. station ... ..... "' ..... ID ID tO ti ... ti ti ti 1il Figure 6-18. Box plot of total species for all electrofishing stations, May to September, pre-EPU (2010-2013) and post-EPU (2016). (boxes= interquartile range containing 50% of the values, the line across the box= median value, vertical lines extending from the box= highest and lowest values, circle= metric value, and asterisk=

outlier) 103 PBAPS Post-EPU Study Electrofishing 10 8 9 8 0 7 0 6 5 4

• 3 Period it it w w w w w w w w w w w w :!! & di & & :!! 0.. 0.. &:: 0.. 0.. 0.. station .... gi ..... "' ..... "' .... "' CZ) ti .... ti t! ti ti 1il Figure 6-19. Box plot of total RIS for all electrofishing stations, May to September, pre-EPU (2010-2013) and post-EPU (2016). Electrofishing 4 0 3 '

• r.? " 2 § a

• 0 It> Period ffi ffi ffi w w w w w w w w & & :!! 0.. /?. & & £ station .... gi ..... "' ..... "' .... "' CZ) ti ti ti t! ti ti Figure 6-20. Box plot of Shannon Diversity for all electrofishing stations, May to September, EPU (2010-2013) and post-EPU (2016). (boxes = interquartile range containing 50% of the values, the line across the box= median value, vertical lines extending from the box= highest and lowest values, circle= metric value, and asterisk=

outlier) 104 PBAPS Post-EPU Study Seine 20_,--------------------, 15 Kl s 10 i 0 5 0 Period it it it it it it it it it it UJ UJ UJ UJ UJ UJ UJ UJ UJ UJ & t & & t & t :!! Cl. Cl. Cl. Cl. station ..,. "' :g ... ... ... N 'ill 'ill 'ill 'ill 'ill Figure 6-21. Box plot of CPUE for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016). Seine 14 12 0 JI 10 0 0 8 0 Ul 0 I 6 4 2 0 Per i od it it it it it it it it it it UJ UJ UJ UJ UJ UJ UJ UJ UJ UJ :!! 11! :!! 11! :!! 11! :!! & 11! Cl. Cl. Cl. Cl. station ..,. "' :g ... ... ... N 'ill 'ill tl 'ill 'ill Figure 6-22. Box plot of total species for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016). (boxes = interquartile range containing 50% of the values, the line across the box= median value, vertical Jines extending from the box= highest and lowest values, circle= metric value, and asterisk=

outlier) 105 PBAPS Post-EPU Study Seine 7 6 s Gil 0 4 D 3 2 0 0 Period it it it it it it ffi it it ffi w w w w w w w w & & t .. & a. a. a. a. &: station ..,. "' 23 0 .... .... § N N ti ti ti tl Figure 6-23. Box plot of total RIS for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016). Seine 3.0 2.5 li 2.0 f QI 1.5 D 8 1.0 c g a 0 0.5 0 o.o Period it ffi it it it it it ffi it it w w w w w w w w & .. & a. &: a. station ..,. "' 23 .... § .... N tl ti tl ti Figure 6-24. Box plot of Shannon Diversity for all seine stations, May to September, pre-EPU (2010-2013) and post-EPU (2016). (boxes = interquartile range containing 50% of the values, the line across the box = median value, vertical li nes extending from the box= highest and lowest values, circle = metric value, and asterisk=

outlier) 6. 3. 6 Length-Frequency Distribution Length-frequency distributions of fish populations can provide an indication of rates of reproduction, recruitment, growth, and mortality of the age groups present. The length distributions and their changes over time can help in understanding population variations and identifying problems such as year-class failures or low recruitment, slow growth, or excessive 106 PBAPS Post-EPU Study annual mortality (Anderson and Neumann 1996). The presence of small-sized fish represents successful spawning and subsequent survival and multimodal distribution is indicative of several age classes. Only fish collected during May through September were included in this analysis.

Stations were grouped into thermal and non-thermal stations as described previously.

Bluegill The length frequencies of Bluegill collected at the thermal and non-thermal stations exhibit similar multimodal distributions during pre-and post-EPU monitoring with a preponderance of the fish smaller than 60 mm (Figure 6-25). During each period the number of small individuals

(<60 mm) collected at the thermal stations was high, suggesting spawning activity in areas affected by the thermal plume. The annual mode of small (<70-mm) Bluegill for the pre-and post-EPU monitoring was within the 45 to 60-mm intervals for both the thermal and non-thermal locations.

Additionally, other modes were present, indicating multiple age classes were present at both thermal and non-thermal stations during both periods. The overall similarity of the length frequency distributions indicates substantially similar successful reproduction, recruitment and growth of Bluegill in and near the thermally affected and non-thermally affected habitats represented by the sampling stations during both pre-and post-EPU monitoring.

Bluntnose Minnow Although the sample sizes were small, comparisons of the length frequencies of Bluntnose Minnow between the thermal and non-thermal stations during both pre-and post-EPU monitoring exhibited similar multimodal distributions (Figure 6-26). Each mode roughly corresponds to a separate age group. Smaller (<50 mm) Bluntnose Minnow were collected in similar numbers at the thermal stations and the non-thermal stations during both pre-and EPU monitoring.

The presence of fish <50 mm suggests spawning activity in the thermally and non-thermally affected areas. Channel Catfish Comparisons of the length frequencies of Channel Catfish between the thermal and non-thermal stations exhibit similar multimodal distributions for the both the pre-and post-EPU monitoring (Figure 6-27). Each mode roughly corresponds to a separate age group. Like the other species, small (<100 mm) Channel Catfish were collected at the thermal stations suggesting spawning activity in the thermally affected areas during both periods. Gizzard Shad Comparisons of the length frequencies of Gizzard Shad between the pre-and post-EPU monitoring exhibited similar distributions with a preponderance of the fish being smaller than 100 mm; few adult fish were collected (Figure 6-28). Gizzard Shad was collected in greater numbers at the thermal stations than the non-thermal stations, including large numbers of individuals less than 100 mm, suggesting spawning activity near the thermally affected areas. 107 PBAPS Post-EPU Study Largemouth Bass Size structure of Largemouth Bass was similar between pre-and post-EPU monitoring (Figure 6-29). Smaller fish {<100 mm) were collected in similar numbers at both thermally and thermally influenced locations during both periods. Most individuals were between 120 and 240 mm in length with few fish greater than 300 mm being collected during either period. Chesapeake Logperch A similar size structure was observed between pre-and post-EPU monitoring (Figure 6-30). Most fish were between 50-75 mm in total length. During both periods smaller fish {<60 mm) were collected at both thermally and non-thermally influenced locations suggesting spawning activity near the collection stations.

The mean length and length range were similar between pre-and post-EPU monitoring (Table 6-34). Smallmouth Bass Length frequencies of Smallmouth Bass at the thermal and non-thermal stations during both pre-and post-EPU monitoring exhibited similar multimodal distributions (Figure 6-31). Each mode roughly corresponds to a separate age group. During both periods smaller fish (<100 mm) were collected at both thermally and non-thermally influenced locations suggesting spawning activity near the collection stations.

Greater numbers of Smallmouth Bass greater than 250 mm were collected during post-EPU at both thermally influence and non-thermally influenced locations compared to pre-EPU monitoring.

The average size of Smallmouth Bass was greater during post-EPU monitoring (Table 6-34). Spotfin Shiner Comparisons of the length frequencies of Spotfin Shiner between the thermal and non-thermal stations exhibit similar multimodal distributions for the both the pre-and post-EPU monitoring (Figure 6-32). Similar multimodal distributions suggest the presence of multiple age classes and spawning activity.

The average size of Spotfin Shiner was similar between both periods (Table 6-34). Wal/eve A similar size structure was observed between pre-and post-EPU monitoring (Figure 6-33). Most fish were between 150-300 mm in total length. Few fish were collected during post-EPU monitoring within the thermally influenced locations.

The mean length and length range were similar between pre-and post-EPU monitoring (Table 6-34). White Crappie A figure of length distributions for White Crappie was not generated, as only 28 individuals were collected and measured during pre-EPU monitoring and only one individual was collected during post-EPU monitoring.

Due to the extremely small numbers of White Crappie that were collected 108 PBAPS Post-EPU Study from all stations, comparisons of the length frequencies between the two periods would not have been meaningful.

White Sucker A figure of length distributions for White Sucker was not generated, as only 18 individuals were collected and measured during pre-EPU monitoring and only one individual was collected during post-EPU monitoring.

Due to the extremely small numbers of White Sucker that were collected from all stations, comparisons of the length frequencies of between the thermal and non-thermal stations would not have been meaningful.

Discussion and Conclusions For the RIS that were evaluated multimodal length distributions indicated multiple age classes present at both the thermal and non-thermal stations during both pre-and post-EPU monitoring.

Differences in length frequency distributions between pre-and post-EPU monitoring are not directly attributable to changes in the thermal plume from the EPU. Differences in length frequency distributions among species are likely due to habitat differences between stations.

For most RIS, small individuals (young-of-the-year) were collected at the thermal stations, suggesting reproduction by the species near the collection location.

Comparison of length frequency distributions did not indicate distorted distributions (e.g., absence of year or presence of only one year-class), and for most species many age-classes were present including young individuals and several age classes of mature fish. This analysis indicates that the RIS were able to reproduce, grow, and be recruited to the fish community within Conowingo Pond after the EPU was implemented.

No measurable change to the length frequency distribution of fish was observed that is attributable to the EPU. 109 PBAPS Post-EPU Study Table 6-34. Descriptive statistics for total length of RIS collected in Conowingo Pond. Data obtained using seine and electrofisher for sample stations that were surveyed during both pre-EPU {2010-2013}

and post-EPU {2016) monitoring for non-thermal and thermally influenced locations, May through September.

Pre-EPU Post-EPU Taxon Location Mean Minimum Maximum Total Number Mean Minimum Maximum Total Number Bluegill Nonthermal 99 21 220 626 119 21 201 115 Bluegill Thermal 92 11 250 1150 103 11 219 406 Bluntnose minnow Nonthermal 58 31 91 239 62 38 91 36 Bluntnose minnow Thermal 58 22 90 316 59 38 84 27 Channel catfish Nonthermal 174 41 535 765 194 45 413 142 Channel catfish Thermal 166 31 611 1294 225 41 496 210 Gizzard shad Nonthermal 101 21 398 304 102 37 372 82 Gizzard shad Thermal 93 19 400 494 98 7 340 107 Largemouth bass Nonthermal 229 45 453 36 154 91 225 22 Largemouth bass Thermal 204 52 465 168 206 66 475 82 Logperch Nonthermal 74 40 99 lll 66 44 105 36 Logperch Thermal 71 32 112 144 63 44 102 24 Small mouth bass Nonthermal 174 41 508 384 187 12 490 316 Small mouth bass Thermal 150 32 494 551 206 34 471 428 Spotfin shiner Nonthermal 69 11 106 298 74 36 104 47 Spotfin shiner Thermal 66 22 108 549 72 31 108 149 Walleye Nonthermal 216 122 470 70 182 114 424 32 Walleye Thermal 293 97 635 67 292 222 470 4 White crappie Nonthermal 158 131 195 4 155 155 155 1 White crappie Thermal 136 47 263 24 * *

• 0 White sucker Nonthermal 136 50 260 12 * *

• 0 White sucker Thermal 151 96 232 6 271 271 271 1 110 JO PBAPS Post-EPU Study llueg!U Pre-EPU 35 7D IDS 14D l7S 210 245 28D Total Longth (nm) 12D.-------------.

,......,...,,.,_--.

9D JO 3S 7D IDS 14D 175 21D 245 28D Total Longth (mm)

Figure 6-25. Length-frequency distribution of Bluegill collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

45 JO I .!; 15 lluntnoY Minnow Pre*EPU n Q ro H rn Total Longth (nm) '*-* ..... 45 JO ! ... 15 Bluntnose Past*EPU M n Q ro M rn To .. 1 Longth (""") ..._ B"""".rmtl

.,. ..... Figure 6-26. Length-frequency distribution of Bluntnose Minnow collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

111 JOO 80 M' 60 x lf .t 40 PBAPS Post-EPU Study Chlnnel C.lllSh Pte-EPU 80 160 240 320 400 480 s60 Taul Length (mm) 80 M' 60 B i 40 20 Channel C.lfish FOsHPU 80 160 240 320 400 4111 560 640 Taul Length (nwn) Figure 6-27. Length-frequency distribution of Channel Catfish collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

80 70 60 M' so i 40 . .t JO 20 10 J Gillilrd Shad Pre-EPU ggg 80 160 240 320 400 480 560 640 Tat*I Length (mm) 20 10 Shad F'Osl*EPU 80 160 240 320 400 480 560 640 Tata! Length (mm) Figure 6-28. Length-frequency distribution of Gizzard Shad collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

112 PBAPS Post-EPU Study Largemoud\

Bass Pre-EPU 18_,-.------------.

....... 16 14 12 f ID I 8 8D 160 240 32D 400 480 560 6-10 Tot*! Length(...,,)

UrgemouCh Bass Posl*EPU 18....-------------.

..---...,_----.

16 a::..--12 .. ID l 8 so 160 24D 32D 400 480 560 64D Toto! Length (1m1) Figure 6-29. Length-frequency distribution of Largemouth Bass collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

Chesape.a'2 lllgp°'ch Posl*EPU 12 ...... 14

...... 12 14,-.------------.

..--,.---.

ID ID 8 I ' 25 SD 75 100 125 150 25 5D 75 !DD 125 150 Total Length(...,,)

Total Length(""")

Figure 6-30. Length-frequency distribution of Chesapeake Logperch collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

113 Smdmouth BHs Pre-EPU 60 so 40 .. 130 ot 20 10 BO 160 210 310 400 480 Tot*l l.ongth (nm) PBAPS Post-EPU Study -560 640 60 50 10 8 JO ... 20 10 Smallmouth BiJss Post*EPU 80 160 140 JlO 400 480 560 640 Tob>l l.ength (nm) Figure 6-31. Length-frequency distribution of Smallmouth Bass collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and eost-EPU (2016) monitoring for non-thermal and thermally influenced locations.

5pottn Pre-EPU Spcdin Shiner Post*EPU JS .. ,_ JS Ill--JD OeiwlT'lll JO 25 lS 10 10 8 ! I 1s .. 15 10 10 25 50 75 100 125 15 50 75 100 125 Tata! l.ongth (nm) Total l.ongth (nm} Figure 6-32. Length-frequency distribution of Spotfin Shiner collected in Conowingo Pond using seine aad electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

114 PBAPS Post-EPU Study Wa .. ye Pre-£PIJ Wal<'I" ""5t*EPU 80 160 240 llO 400 480 560 l>IO Total Longth (nwn} 80 160 240 llO olOQ 480 560 Total l.A!ngth (n-.n} Figure 6-33. Length-frequency distribution of Walleye collected in Conowingo Pond using seine and electrofisher for sample stations that were surveyed during both pre-EPU (2010-2013) and post-EPU (2016) monitoring for non-thermal and thermally influenced locations.

6. 3. 7 Fish Condition Relative weight 0Nr) is an index of condition or well-being for a fish. Relative weight and other condition assessments are commonly employed by fisheries personnel for evaluating fish populations and communities.

This is a standard, widely accepted and used method for assessing fish body condition.

Relative weight was calculated following Murphy and Willis (1996). Relative weight is one indicator of overall fish condition and describes the relative plumpness of an individual fish. Plump fish may be indicators of favorable environmental conditions (e.g., habitat conditions, ample prey availability);

whereas, thin fish may indicate less favorable environmental conditions.

A relative weight of 100 for an individual fish would indicate that the weight is equal to the average weight of a fish with the identical length for the larger population that was used to develop the standard weight equation.

Relative weights were calculated for Bluegill, Smallmouth Bass, Largemouth Bass, and Channel Catfish collected from the electrofishing stations during May through September for pre-EPU (2010-2013) and post-EPU (2016). A total of six stations were assessed (non-thermal:

Stations 187 and 165; thermal: Station 161, 189, 190, and 217). Weight measurements were not taken for these four species collected using a seine because most were smaller, young individuals.

These four RIS were selected for analysis because sufficient numbers of individuals and weight measurements were taken to enable valid comparisons of individuals collected at both thermal and non-thermal stations during pre-and post-EPU monitoring.

The purpose of this analysis is to determine whether W, was different between the pre-and post-EPU monitoring periods. Conceptually, fishes living in elevated water temperatures may be affected by insufficient food availability, physiological stress associated with elevated temperatures, higher metabolic demands, and therefore, poorer body condition indicated by low W, values. Obvious erroneous W, values were excluded from the analysis as determined by the range of species-specific length-weight values provided in Carlander (1969 and 1977). 115 PBAPS Post-EPU Study Relative weights were calculated for a total of 805 Bluegill with mean Wr of 103 (Table 6-35). Mean Wr was generally higher for most stations during post-EPU monitoring as compared to pre-EPU monitoring for both thermal and non-thermal stations.

Mean Wr ranged from 85 at Station 189 (post-EPU) to 131 at Station 161 (post-EPU).

The distribution of Wr among the sample stations was similar for non-thermal and thermal stations with post-EPU values generally higher than pre-EPU monitoring (Figure 6-34). The mean Wr was near or above 100 for most sample stations.

Relative weights were calculated for a total of 176 Largemouth Bass with an overall mean Wr of 108 (Table 6-36). Mean Wr ranged from 98 at Stations 189 EPU) and 217 (post-EPU) to 119 at Station 161 (post-EPU).

The distribution of Wr among the sample stations was comparable for thermal and non-thermal stations during pre-and post-EPU periods, with mean Wr above 97 for all stations (Figure 6-35). Note that Wr was calculated for few individuals at stations 165, 187, and 161. Relative weights calculated for a total of 1, 931 Channel Catfish resulted in an overall mean Wr of 112 (Table 6-37). Mean Wr ranged from 107 at Station 189 (pre-EPU) to 126 at Station 189 (post-EPU).

The distribution of Wr among the sample stations was similar for non-thermal and thermal stations with median and mean Wr above 100 for all stations.

Figure 6-36 provides a box plot which illustrates the spread of the Wr values for each station during pre-and post-EPU monitoring. Relative weights calculated for 757 Smallmouth Bass resulted in a mean Wr of 99 (Table 6-38). Mean Wr ranged from 92 at Station 217 (pre-EPU) to 104 at Stations 190 and 187 (post-EPU). The distribution of Wr among the sample stations in reference to Wr of 100 was comparable with most stations having mean and median Wr near 100. Figure 6-37 provides a box plot which illustrates the spread of the Wr values for each station during pre-and post-EPU monitoring.

For most stations Wr values tended to be slightly higher during post-EPU period. Discussion and Conclusions Relative weights for all four species (i.e., Bluegill, Smallmouth Bass, Largemouth Bass, and Channel Catfish) were similar between non-thermal and thermal stations during pre-and EPU monitoring.

Although mean and median Wr values showed some variation among the stations, the relative weight observations did not indicate low Wr values for the near-field or field thermal stations during pre-or post-EPU monitoring.

Differences in Wr were likely due to seasonality, reproductive status (pre-or post-spawn), length frequency distribution of individuals at a station, and differences between the sexes. The observations for these four species indicate no detrimental effect of the thermal plume on fish condition as measured by relative weight. Fish condition of these four species was similar between the pre-and post-EPU monitoring.

116 PBAPS Post-EPU Study Table 6-35. Descriptive statistics for Bluegill relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September.

Station st161 st161 st189 st189 st190 st190 st217 st217 st165 st165 st187 st187 Overall Period Pre-EPU Post-EPU Pre-EPU Post-EPU Pre-EPU Post-EPU Pre-EPU Post-EPU Pre-EPU Post-EPU Pre-EPU Post-EPU Mean 101 131 97 85 88 107 108 108 97 107 102 126 103 Relative Weight (Wr) Standard Error Median 3.4 94 2.7 128 3.2 3.2 3.2 3.1 3.3 2.9 2.6 1.8 4.2 2.8 1.1 Bluegill 94 82 81 109 105 105 99 106 100 127 104 Total Number 92 80 99 53 91 56 94 23 106 44 41 26 805 200

• 175

• 150 125 100 75

• so Period station Figure 6-34. Box plot of Bluegill relative weight by station during pre-EPU and post-EPU monitoring, May through September. (boxes = interquartile range containing 50% of the values, the line across the box= median value, circle = mean, and the vertical lines extending from the box= highest and lowest values, asterisk=

outlier) 117 PBAPS Post-EPU Study Table 6-36. Descriptive statistics for Largemouth Bass relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September.

Relative Weight (Wr) Station Period Mean Standard Error Median Total Number st161 Pre-EPU ... ... ... 0 stl61 Post-EPU 114 3.1 113 3 st189 Pre-EPU 98 4.1 97 17 st189 Post-EPU 117 8.9 107 22 st190 Pre-EPU 116 5.7 125 13 st190 Post-EPU 103 7.5 104 17 st217 Pre-EPU 111 2.6 110 57 st217 Post-EPU 98 2.2 94 27 st165 Pre-EPU 100 ... 100 1 st165 Post-EPU 101 14.5 88 4 st187 Pre-EPU 99 10.3 100 7 st187 Post-EPU 119 14.2 105 8 Overall 108 1.9 104 176 Largemouth Bass 200 * '>:' 175 * .... 150 * .!il' 125 QI Iii

• 8 .It .... 100 + .!!I 75 so Period ffi ffi ffi ffi ffi ffi ffi ffi ffi ffi ffi w cL 11: & di 111 cL & di &:: &:: &:: &:: station .... Cl\ ...... 11'1 ...... \0 co .... \0 co t! t! t! tl t! tl Figure 6-35. Box plot of Largemouth Bass relative weight by station during pre-EPU and EPU monitoring, May through September. (boxes = interquartile range containing 50% of the values, the line across the box= median value, circle = mean, and the vertical lines extending from the box= highest and lowest values, asterisk=

outlier) 118 PBAPS Post-EPU Study Table 6-37. Descriptive statistics for Channel Catfish relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September.

Relative Weight (Wr) Station Period Mean Standard Error Median Total Number st161 Pre-EPU 112 2.1 109 236 st161 Post-EPU 116 4.4 109 25 st189 Pre-EPU 107 1.8 106 251 st189 Post-EPU 126 5.8 119 34 st190 Pre-EPU 110 1.9 103 287 st190 Post-EPU 115 4.7 104 58 st217 Pre-EPU 118 2.1 118 204 st217 Post-EPU 116 3.9 109 74 st165 Pre-EPU 111 1.9 103 345 st165 Post-EPU 118 2.7 115 80 st187 Pre-EPU 112 1.9 109 279 st187 Post-EPU 115 2.4 111 58 Overall 112 0.7 108 1931 Channel Catfish 200 *

• 175 * ...... lt

• 31 lt ...... 150 * .51' 125 GI .i!! 100 ... Jll 75

• so Period ffi ffi ffi ffi ffi ffi ffi ffi w w w w tl ' tl tl di di g: Q. station .... 0\ s: " "' " \0 co .... \0 co ti ti ti ti ti ti --------Figure 6-36. Box plot of Channel Catfish relative weight by station during pre-EPU and post-EPU monitoring, May through September.

119

---PBAPS Post-EPU Study Table 6-38. Descriptive statistics for Smallmouth Bass relative weight by station for individuals collected during pre-EPU and post-EPU monitoring, May through September.

Relative Weight (Wr) Station Period Mean Standard Error Median Total Number st161 Pre-EPU 98 1.8 96 86 st161 Post-EPU 99 4.3 94 28 st189 Pre-EPU 97 4.4 92 11 st189 Post-EPU 97 2.9 95 33 st190 Pre-EPU 87 4.7 87 21 st190 Post-EPU 104 1.8 102 101 st217 Pre-EPU 92 2.8 89 27 st217 Post-EPU 95 1.5 93 123 st165 Pre-EPU 99 2.1 94 78 st165 Post-EPU 99 1.5 97 121 st187 Pre-EPU 98 2.1 97 56 st187 Post-EPU 104 2.5 100 72 Overall 99 0.7 96 757 Smallmouth Bass 175 * * ..... 150 *

• 31 i lt * ..... *

• 125 * .SP 8 GI 100 .i!: ... JI Ii 75

• so *

• Period it it it ffi ffi it it ffi ffi it ffi it w w w w w w w di di di di di & station ... °' ,... "' ,... ID co ... ID co tl tl tl t! tl tl Figure 6-37. Box plot of Smallmouth Bass relative weight by station during pre-EPU and post-EPU monitoring, May through September. (boxes = interquartile range containing 50% of the values, the line across the box= median value, circle = mean, and the vertical lines extending from the box= highest and lowest values, asterisk=

outlier) 120 --------

PBAPS Post-EPU Study External Anomalies (DEL Ts) During the course of field processing fish were examined for external anomalies or DEL Ts. The term DEL Ts refers to deformities, erosions, lesions, and tumors. This examination is a visual assessment completed with the naked eye that is commonly used during fisheries investigations to document the external condition of captured fish. Types of external anomalies that were determined during the course of study included deformities, eroded fins, lesions, tumors, anchor worm, black spot, leeches, and fungal infections.

See PADEP protocol provided in the Study Plan (Appendix 11.1). The occurrence of DEL Ts was tabulated for both non-thermally influenced and thermally influenced stations during post-EPU monitoring.

The incidence

-0f DEL Ts in the Conowingo Pond fish community was low during the post-EPU monitoring.

DEL Ts were observed on 21 individuals of six species with 15 individual observed at thermal stations and six observed at non-thermal stations.

The most commonly observed DEL Ts were eroded fins and lesions. The highest incidence of DEL Ts for a species was 12 Smallmouth Bass observed with DEL Ts; a proportion of 1.6% of the Smallmouth Bass examined during 2016. Overall, 5,324 fish collected with electrofisher were examined with 0.40% of all individuals with DEL Ts. The incidence of DEL Ts was similar, given the number of sampling locations and fish collected, for those stations closest to the end of the PBAPS discharge canal as compared to the non-thermal monitoring locations.

No DEL Ts were observed on fish collected with seine. During the 4 years of pre-EPU field investigations DEL Ts were observed on 103 individuals of 18 species. The highest incidence of DEL Ts for any species or year occurred in 2013 with 1 O Smallmouth Bass observed with DEL Ts; a proportion of 1.2% of the Smallmouth Bass examined during the year. The occurrence of DEL Ts was low and comparable between the EPU and post-EPU monitoring.

The low proportion of fishes with DELTs during recent monitoring indicates an aquatic environment where stressful water quality conditions are minimal or such that conditions did not result in significant occurrence of DEL Ts. It is important to note that we do not know for certain where fishes lived prior to being collected at individual stations, thus, the thermal history is assumed to be that of the collection station. The occurrence of DEL Ts in Conowingo Pond is comparable or lower than other monitoring locations within the Susquehanna River, in particular, for Smallmouth Bass where higher disease rates have been observed for young of year fish at several upstream monitoring locations in the vicinity of Harrisburg, PA. Typical background occurrence of DEL Ts for Age 1 or older Smallmouth Bass and other fish species in the Susquehanna River is approximately 1-2% (G. Smith PAFBC, personal communication).

121 PBAPS Post-EPU Study Table 6-39. Total number of each species with DEL Ts for all sample locations in Conowingo Pond, May through September 2016. Total number of DELTs Total Individuals of Percent of species Species 1 Thermal Stations Non-thermal Stations Species Processed Total DELTs with DELTs Bluegill 3 1296 3 0.23 Channel catfish 2 1 387 3 0.78 Flathead catfish 1 38 1 2.63 Largemouth bass 1 104 1 0.96 Smallmouth bass 7 5 749 12 1.60 White sucker 1 1 1 100 Total lS 6 21 1 All fish collected during e/ectrofishing; no external anomalies observed for fish collected with seine Table 6-40. Types of external anomalies observed by species for fish collected in Conowingo Pond, May through September 2016. .... 0 c E 0 ::> "' "' 'B Q) Q) Q) c -0 *.;::; <;: Q) .£ 0 0 0 .E .... -0 ra 'iii "' Vl .... .... .... Q) *o c c ra 0 0 -0 ra QO :i:l Q) Q) E E -e E c c. c. Q) Species Q) ::> .... ::> Total 0 UJ UJ u.. 0 0 I-I-Bluegill 1 2 3 Channel catfish 1 1 1 3 Flathead catfish 1 1 Largemouth bass 1 1 Smallmouth bass 1 5 3 1 1 1 12 White sucker 1 1 Total 2 5 4 1 1 5 1 1 1 21 6.3.8 Relative Abundance and RetrosQ.ective Ana/Y.,sis of RIS Knowledge of the abundance of fish populations is an important component in management of fisheries.

The most common indices of relative abundance are computed from catch per unit effort (CPUE) data for samples from a fish population.

A common application in fisheries management is using CPUE to evaluate temporal patterns in relative abundance. Here, relative abundance is illustrated with time series plots for select RIS in Conowingo Pond. Temporal patterns in CPUE are illustrated for both seine and electrofishing gears. A long-term data set for select RIS is available for the Pond for the period 1966 to 2016. This period covers fish collections at many locations throughout Conowingo Pond prior to operation of PBAPS (1966-1973) and after PBAPS became operational (1974-2016).

Electrofishing surveys were not initiated until 197 4, thus no pre-operational relative abundance data for this sampling gear are available.

The data set for 1993 includes only October sampling and the 1996 data set includes multiple samples each month. This data set includes several time intervals associated with prior PBAPS 316(a) demonstration studies (PECO 1975, and 1979; Normandeau Associates 1997-2000a; Normandeau and ERM 2014). 122 PBAPS Post-EPU Study Relative abundance data provided in each figure includes fish collections throughout the entire Conowingo Pond. Sampling station locations varied throughout the course of these studies within the Pond, thus not all stations sampled previously are the same as the present study. However, the long-term data set still provides useful information regarding abundance trends and although station locations differed over time, the collections occurred in similar habitats. The data reflect collections that occurred from June-October for 1974 through 2013 and September for 2016. CPUE data were square root transformed to decrease the effects of single year extreme CPUE values. Relative abundance data from all stations surveyed in the Pond using a seine are provided for Bluegill, Smallmouth Bass, Spotfin Shiner, Bluntnose Minnow, and Chesapeake Logperch.

This subset of RIS represents species that are more commonly collected using a seine. CPUE values during 2016 were within or above the historical range for all species (Figure 6-38 through Figure 6-42). CPUE for Bluegill, Smallmouth Bass, and Spotfin Shiner during 2016 was comparable to pre-EPU observations.

For Bluntnose Minnow and Chesapeake Logperch the post-EPU CPUE was lower than the pre-EPU observations but within the range of historic values. No long-term temporal trends in CPUE were observed for these species. Short-term trends were observed for Spotfin Shiner and Bluntnose Minnow. Bluntnose Minnow CPUE was lower during 2016 as compared to 2010-2013 and the 1990's, but higher than most values during 1960-1970s.

Spotfin Shiner CPUE was lower in 2016 and 2010-2013 as compared to historic collections which varied widely from year to year and over the short-term relative abundance appears to be declining in the Pond. Chesapeake Logperch relative abundance was higher during the 1996-2016 period compared to prior years. Bluegill 6 IM * ::> fJ 4 1/L'v-c I'll QI 2 0 ..... ..... ..... ..... ..... ..... ..... ..... ..... "' "' "' ID ID ID ID tB tB 0 0 0 ...., ...., ...., ...., ..... ..... ..... C7I 00 0 "' """ C7I co C7I co ..... ""' C7I Figure 6-38. Square root transformed mean CPUE for Bluegill collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016. 123 w 1.8 1.6 1.4 1.2 1 0.8 u ; 0.6 QI 0.4 ":> 0.2 0 PBAPS Post-EPU Study Smallmouth Bass * ........ l.D l.D l.D l.D C'l 00 Figure 6-39. Square root transformed mean CPUE for Smallmouth Bass collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016. 12 Spotfin Shiner w :::> 6 IJ c 4 -:E "> 2 .....__ ________________

_ Figure 6-40. Square root transformed mean CPUE for Spotfin Shiner collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016. 124 PBAPS Post-EPU Study 7 ---------------------

Bluntnose Minnow 6 -----------------

A : _+ ___ w 3 +4----------------+--

fi c "' QI 1 * "" "" "" 0 0 0 .........

... u..i O'l Figure 6-41. Square root transformed mean CPUE for Bluntnose Minnow collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016. 1.4 --------*-------------

Chesapeake Logerch 1.2 1 ------------------

0.8 II.I ;:) t; 0.6 c ..

• Ill 0.4 +----------------Jc=*---* Figure 6-42. Square root transformed mean CPUE for Chesapeake Logperch collected using a seine in Conowingo Pond, June-October 1966-2013 and May-September 2016. E/ectrofishinq Relative abundance data from all stations surveyed in the Pond using boat electrofisher are provided for Bluegill, Smallmouth Bass, Gizzard Shad, White Crappie, Channel Catfish, Walleye, and Chesapeake Logperch.

Figure 6-43 through Figure 6-49 compare the annual mean CPUE for each species during the period of available electrofishing data from 1975-2016.

This subset of RIS represent species that are commonly collected using a boat electrofisher in the Pond. CPUE values during 2016 were within or above the pre-EPU observations for most species. Gizzard Shad relative abundance was comparable to pre-EPU and much higher than historic 125 PBAPS Post-EPU Study observations.

White Crappie relative abundance was comparable to pre-EPU but lower than previous years. Smallmouth Bass and Channel Catfish CPUE was comparable to pre-EPU values and within the historic range of observations.

Bluegill relative abundance was comparable to pre-EPU and much higher than historic observations. Long-term trends for White Crappie and Gizzard Shad were evident. White Crappie relative abundance showed a long-term decline over time and Gizzard Shad relative abundance indicated a long-term increase over time. CPUE of Chesapeake Logperch in 2016 was within the range observed pre-EPU and higher than the historic values. Walleye CPUE was slightly lower in 2016 than pre-EPU observations but within the range of historic values. 18 Gizzard Shad 16 14 -12

• 10 w :::> 8 e c: Ill QI 4 :E 2 0 I ..... ..... ..... ..... ..... ..... N "" N \D \D is is 0 0 0 ....i ....i ..... ..... ..... IJ1 ....i VJ IJ1 en co ..... VJ en Figure 6-43. Square root transformed mean CPUE(no/O.Shr) for Gizzard Shad collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016. 126 I.I.I 4.5 4 3.5 3 2.5 2 u c 1.5 co 1 ";> 0.5 0 PBAPS Post-EPU Study White Crappie -f * . -r ---...... ...... N N N \0 \0 0 0 0 \0 \0 ...... ...... ...... O'I 00 ...... w O'I Figure 6-44. Square root transformed mean CPUE(no/0.5hr) for White Crappie collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016. 9 Smallmouth Bass 8 7

Figure 6-45. Square root transformed mean CPUE(no/0.5hr) for Smallmouth Bass collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016. 127 PBAPS Post-EPU Study 16 ------Bluegill 14 -+--------------....,....---

• 12 10 I.a.I 8 -+-+-----+-----.oi.------

• ---::::> e; 6 c 111 QI 4 +---===-------*-"--------2 -*--------

0 Figure 6-46. Square root transformed mean CPUE(no/0.5hr) for Bluegill collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016. I.a.I ::::> 10 Catfish IJ 4 4--'-------

-'---"1-------. c 111 QI 2 l------------

---

0 ...... ...... "" "" "" is is 0 0 0 ...... ...... ...... O'I 00 ,_. u.i O'I Figure 6-47. Square root transformed mean CPUE(no/0.5hr) for Channel Catfish collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016. 128 PBAPS Post-EPU Study 3.5 ,--------Chesapeake Logperch 3 2.5

..... 2 ;-------------

11-----::::> Cl. u 1.5 -r-----------

""="--:---t---------c ra 1 .... -'It-------------

.... 0.5 +---------------------N N N N N s s s s s 0 i-> N UJ O"t Figure 6-48. Square root transformed mean CPUE(no/O.Shr) for Chesapeake Logperch collected using a boat electrofisher in Conowingo Pond, June-October 1996-2013 and September 2016. 3 Walleye 2.5 -!-------------------

2 0 -N N N s s s 00 Figure 6-49. Square root transformed mean CPUE(no/O.Shr) for Walleye collected using a boat electrofisher in Conowingo Pond, June-October 1975-2013 and May-September 2016. Discussion and Conclusions Temporal differences in CPUE were evident for several species and reflect variations in the fish community associated with year-class strength and changes in species composition.

CPUE during 2016 was comparable to pre-EPU study observations and within the range of historic observations for all species except White Crappie. Long-term trends in electrofishing CPUE were observed for Gizzard Shad and White Crappie. No long-term trends in the seine collections were evident for the selected RIS. 129 PBAPS Post-EPU Study Many confounding factors affect fish population dynamics in Conowingo Pond, including changes in water quality, year-to-year differences in river flow, species introductions, and immigration from Conowingo East Fish Lift and emigration through the Holtwood Fish Lift. Fish populations are not static and differences in relative abundance reflect these changes. Many environmental factors including floods, droughts, and water quality changes (e.g. phosphorous loading from upper basin) can affect relative abundance. Based on the comparison of relative abundance results of this study and the available historic data we can conclude:

Relative abundance of the RIS was comparable to pre-EPU observations, Relative abundance of most RIS in 2016 was within their historic ranges,

• Considerable variation in relative abundance occurred over the available data period, Variable year-class strength for some species resulted in a wide range of relative abundance, and Changes in fish populations were within normal ranges and the result of naturally variable environmental conditions. 130 PBAPS Post-EPU Study 7 Juvenile American Shad Migration This section of the report addresses PADEP draft NPDES permit comments related to the potential effect of the post-EPU PBAPS thermal discharge on migratory fishes. In particular, PADEP raised a question regarding the potential for PBAPS's thermal plume to block migration of juvenile American Shad in Conowingo Pond. 7. 1 Analysis Under the previously licensed thermal power conditions (prior to EPU) the design plant discharge temperature increase above ambient intake temperature (fl T) was approximately 22°F without cooling towers in operation.

However, during the Pre-EPU Demonstration Study (Normandeau and ERM 2014) temperature monitoring determined that the b.T was less than 22°F and averaged 19.4°F during July and August; the months with warmest ambient water temperature.

The post-EPU temperature monitoring completed in 2016 indicated that the increase in PBAPS discharge temperature did not exceed 3°F which corresponded well with the expected (based on engineering specifications) maximum increase in the b.T of 3°F. Thus during 2016 monitoring period (May 1 through September

30) the observed maximum post-EPU b.T was 22.4°F (19.4°F + 3°F). The modelling analyses provided herein use the maximum design b.T of 25.0°F (22°F + 3°F) which is higher than the observed conditions and provides an additional conservative margin of +2.6°F. Evidence of absence of impedance to emigration of juvenile American Shad in Conowingo Pond was gathered from two sources: (1) field sampling, and (2) a 3-D time varying hydrodynamic model. There is no reported reproduction of American Shad in Conowingo Pond. Most juvenile American Shad use Conowingo Pond as an emigration corridor during their seaward journey. These juveniles originate from Pennsylvania Fish and Boat Commission stocking of chemically marked hatchery-reared fry during late May and June upstream of the hydroelectric dams on the Susquehanna River. Historically, three fixed locations had been monitored for juvenile American Shad during the fall months which may be used as indices for the time of entry of the juveniles into Conowingo Pond, residency duration of juveniles within Conowingo Pond, and exit of the juveniles out of Conowingo Pond. The monitoring locations were: sampling at the Holtwood Hydroelectric Dam inner forebay by lift net (entry), PBAPS outer screens (duration of residency), and Conowingo Dam cooling water strainers (exit time). The entry of juvenile American Shad into Conowingo Pond generally occurs in October and November at water temperatures between 50 to 65°F (10.0°C-18.3°C) with peak emigration generally occurring between 50 to 55.4°F (10.0 -13.0°C) coincident with a fall freshet typically in late October to mid-November.

Table 7-1 summarizes the number of juvenile American Shad collected at the three monitoring locations between 2005 and 2009. Historically, water temperatures of 50 to 60° F (10.0-15.6°C), as measured at Holtwood Hydroelectric Dam, occurred 25% of the time in October and 23% in November.

At these 131 PBAPS Post-EPU Study ambient water temperatures, with the designed rise in temperature of 25°F (13.9 °C), the temperature of the PBAPS effluent at the point of discharge structure would be 75.0°F (23.9 °C) and 85.0°F (29.5°C), respectively.

At an ambient water temperature of 65° F, the water temperature of the discharge at the point of entry into Conowingo Pond is predicted to be 90 °F. Allowing for rapid dissipation via the "jet" type discharge, the actual temperature will be less than 90°F. However, results of the 3-D time varying hydrodynamic model more accurately quantify the size and temperature of the plume because it takes into account the effects of other factors including river flow and operation of the MRPSF. The emigration period for juvenile American Shad through Conowingo Pond is October and November.

The analyses provided herein focus on water temperatures and the configuration of the PBAPS thermal plume during these months. The long-term data set for daily water temperatures and flows at Holtwood Hydroelectric Dam were used to determine near worst case conditions for combined low flows and high temperatures during juvenile American Shad emigration.

Two modelling scenarios were selected:

ambient temperatures of 65 °F and river flows of 10,000 cfs and ambient temperatures of 55° F and river flows of 15,000 cfs. The joint probability occurrence of these river flows and water temperatures ranged from 1.65 to 14.66% (Table 7-2). We modeled these hydrological conditions and integrated the model results with the reported avoidance temperature of juvenile American Shad to delineate the potential areas of avoidance.

For this analysis water temperature greater than 86°F was assumed to be an impedance to juvenile shad emigration.

Experimental studies (Moss 1970; Marcy et al.1976) have reported that juvenile American Shad avoid water temperatures above 86°F. We used a time-varying 3-D hydro-thermal model (Generalized Environmental Modeling System for Surface waters or GEMSS to identify (a) PBAPS plume size and configuration and (b) areas in Conowingo Pond exceeding 86°F during the migration period in the fall months. Figure 7-1 and Figure 7-2 show the thermal plume dispersion at river flows of 10,000 cfs and 15,000 cfs with ambient water temperatures of 65 and 55°F, respectively at four depths (surface, 5ft, 10ft, and 15ft). No area above 86.0°F exists during the month of November.

In October at ambient water temperature of 65°F only a small narrow area exists at the surface along the western shore. Subsurface temperatures are all less than 86°F. Virtually the entire pond is available for downstream migrating juveniles.

These model results suggest an absence of impedance to emigration of juvenile American Shad in Conowingo Pond. 7.2 Summary and Conclusions A 3-D time varying hydrodynamic model was used to predict the areas in Conowingo Pond during October and November at two hydrological conditions:

ambient temperatures of 55° F and 65°F and river flows of 10,000 cfs and 15,000 cfs; the EPU maximum rise in water temperature was assumed to be 25°F with no cooling towers C?Perating.

The joint probability occurrences of these hydrological events in October and November ranged from 1.65 to 14.66%. Modeling results indicated that only a very small, narrow area hugging the west shoreline downstream of the PBAPS discharge structure contains surface water temperature

> 86°F (assumed an impedance to juvenile shad emigration) at an ambient temperature of 65°F; 132 PBAPS Post-EPU Study at ambient water temperatures of s 61.0 °F no area of 86.0 °F exists. Virtually the entire Conowingo Pond is available for juvenile American Shad emigration.

Therefore, there is no potential for thermal blockage.

This is supported to a large extent by the collection of emigrating juvenile American Shad at cooling water strainers at Conowingo Dam (7 mi downstream of PBAPS). 133 PBAPS Post-EPU Study Table 7-1. Juvenile American Shad Outmigration Data for Holtwood Lift Net, PBAPS travelling screens, and Conowingo Dam Strainer, September 11 through December 12, 2004 through 2009. Conowingo Conowingo Holtwood Lift PBAPS Fall Dam Strainer Holtwood PBAPS Fall Dam Strainer Date Net a Sampling b Sampling c Date Lift Net a SamplinG b Sampling c Sept.11 0 0 0 Nov. 11 0 1 Nov.12 0 1 0 Oct.12 0 0 0 Nov.13 0 1 Oct. 13 0 3 0 Nov.14 0 0 Oct. 14 0 0 Nov.15 0 0 0 Oct.15 0 0 0 Nov.16 0 0 Oct. 16 0 Nov.17 0 0 Oct. 17 0 Nov.18 0 0 Oct.18 0 0 0 Nov.19 0 2 0 Oct.19 0 1 Nov. 20 0 6 0 Oct. 20 0 2 0 Nov. 21 0 8 Oct. 21 0 1 5 Nov. 22 0 0 0 Oct. 22 0 0 0 Nov. 23 0 0 Oct. 23 0 7 Nov. 24 0 1 0 Oct. 24 8 46 5 Nov. 25 0 0 Oct. 25 2 15 0 Nov. 26 0 1 2 Oct. 26 0 23 4 Nov. 27 0 2 Oct. 27 0 25 Nov. 28 0 1 0 Oct. 28 181 7 7 Nov. 29 0 0 Oct. 29 0 1 1 Nov. 30 0 0 Oct. 30 0 0 Dec.1 0 1 Oct. 31 17 20 7 Dec. 2 0 0 Nov.1 0 26 0 Dec. 3 0 1 Nov. 2 0 3 2 Dec.4 0 0 Nov. 3 0 9 Dec. 5 0 2 0 Nov. 4 0 7 Dec. 6 0 0 Nov. 5 0 12 0 Dec. 7 0 Nov.6 0 Dec. 8 0 11 Nov. 7 0 8 1 Dec. 9 0 Nov. 8 0 2 1 Dec.10 5 Nov. 9 1 1 1 Dec.11 0 Nov.10 0 1 1 Dec. 12 0 -*------------.. --------.. -.. *-----.. --------------.. -.... -.... --.. -----*-.... -----.. _ ----.. ------Conowingo Dam Holtwood Lift Net PBAPS Fall Strainer Sam pl Overall Total 209 264 37 a Am. Shad collected by Lift Net in 2005, 2006, and 2008 b Am. Shad collected at PBAPS in 2005, 2006, 2007, 2008, and 2009 c Am. Shad collected in Conowingo Strainers in 2005, 2006, 2007, and 2008 Peak outmigration water temperature range: 10.o*c to 13.0"C 134 PBAPS Post-EPU Study Table 7-2. Joint probability occurrence

(%) of average daily water temperature and river flows measured at Holtwood Dam in October and November, 1956-2012.

October -November are emigration periods of juvenile American Shad in lower Susquehanna River. River Water Temperature

(°F) Flow (cfs) 46-50 51-55 56-60 61-65 66-70 71-75 76-80 >80 Total October* 0-9,999 2.26 7.64 14.66 12.65 5.19 1.10 0.31 43.80 10,000-14,999 1.71 4.58 7.45 2.93 0.92 0.06 0 17.65 15,000-19,999 0.24 1.10 3.85 2.69 1.16 0.49 0.06 0 9.59 20,000-24,999 0.06 1.34 2.50 2.02 0.73 0.18 0 0 6.84 November*

0-9,999 3.44 6.93 4.07 1.65 0.45 0 0 0 17.37 10,000-14,999 3.31 5.22 0.83 0.51 0 0 0 0 12.21 15,000-19,999 2.93 2.99 0.57 0.25 0 0 0 0 9.16 20,000-24,999 3.05 1.97 0.89 0.25 0 0 0 0 9.80 *Emigration period for juvenile American Shad in the lower Susquehanna River Note: shaded cells referred to in the text 135 PBAPS Post-EPU Study End of Pumpback

..... ;,

"'< "" ... .r.. y .. .. )en.k , ... _ .. 7 30 'I 20 Ambient Temp 65" F, River Flows 10,000cfs t .._.,,, '"'peatl.trw fUN IF) ,. Point .. Jotmtoft .... "'. 15 _ * .,., .... .. / .. :,, /* .* ,/ ,. -, .. /i;. * , End of Pumpback '** ' ' ' *'-PMch8'1ttftf9. c llowtf Station .... /"\A -ss*F Ambient Temp 65" F, River Flows 10,000cfs

.. Po ... '"! .* 1' 1-L I I I I I Sft End of Generation

' ........ \ ' End of Generation

\ . \ \ '* \ c.n-11.1* Figure 7-1. Predicted thermal plume at surface, 5ft, 10ft, and 15ft during MRPSF pumping (left panel) and generation (right panel) at river flow of 10,000 cfs and water temperature 65" F (representing the month of October).

MRPSS pumping (28,000 cfs) continuously for 12h followed by generation (28,000 cfs) for 12h. Peach Bottom operating under EPU conditions resulting in temperature rise (color coded) above the ambient temperature of 65" F. 136 End of Pumpback ;, *Po"11 1-** I I I End of Pumoback Tempemur.

RIM (F) ;JO H 15

• Figure 7-1. Continued.

PBAPS Post-EPU Study Ambient Temp 65" F, River Flows 10,000cfs End of Generation

\ \ ,---.-.. -r-::;-.r-i*i --iott ..,,,;; -.... -.r* ... ). .. .( ... 1* ....... I I I T.rnperat:&lre RI** (f) ;JO ... ......_ ....... 20 I 15

• -* .i;:. . r.r:. c:.-l ... **,. \ .---Ambient Temp 65" F, River Flows 10,000cfs End of Generation .. ::/ t' ,,., *' / ..., *hlnl ,I . i/. -,,, *. r' Pfl.'leh llml'MI *.

... \ ;.. t \ / . }" .. -...,.-.. -;* -,; I ....... I I I 137 *.JaMNn&lllntl

• 15

• f ,.. .,,.: / '* _,. l'eKh 8ottMll euctt ,..

.. .................

End of Pumpback ,,.,.\ldf'ftunluuvn

.. -PM1.t\8'11tnnt

,_. __ tPower8111tion

\ *-End of Pumeback r I I Surface r..,,pemur.

Alff tFJ JO 20 ,. PBAPS Post-EPU Study Ambient Temp SS" F, River Flows 15,000tfs End of Generation Surface ,....,.. ...... iu..tFJ lO 20 .... ,,,. 111. "'11V1Mn laLlnlt 15 ,.,...r .. *** ... \ ... '!"':... Ambient Temp 55" F, River Flows 15,000tfs

... \. -\ \ "I"

• I I I * . ...... rru*rTunNI End of Generation

-0.N Figure 7-2. Predicted thermal plume at surface, 5ft, 10ft, and 15ft during MRPSF pumping (left panel) and generation (right panel) at river flow of 15,000 cfs and water temperature 55° F (representing the month of November).

MRPSS pumping (28,000 cfs) continuously for 12h followed by generation (28,000 cfs) for 12h. Peach Bottom operating under EPU conditions resulting in temperature rise (color coded) above the ambient temperature of 55°F. 138 End of Pumpback ;-p--t' 10ft PBAPS Post-EPU Study Ambient Temp 55" F, River Flows 15,000cfs 10ft End of Generation

,\ --.... :.:;r' L.;;;;.,"""""" .. Tom.....,...RIMCFI TtrnS*ftn RfH IFl JO MsN111Cnell

' .. "'ww..f* 111.. .Johnlon I . ' fkdlnsltt.lft . ;' ;r-.":;:I'

r. End of Pumpback Figure 7-2. Continued JO n 15 * * -*. .... , ... -,. .... '"' PMchBntttu*

c .,.,_, $1oUon Our11klsaUl'I r I I I 20 15 * * ..... ' \ . \: -;.;;;;--.... Ambient Temp 55° F, River Flows 15,000cfs End of Generation

\ ..... *' ., 139 T""'pon1ureRl,.lFI 1 ... / 30 r*, *, **rimon&allntl

..! .... ".J ,;..:.c: / 20 *** i& .-........ c:an-. r::

PBAPS Post-EPU Study 8 Gizzard Shad Seasonal Distribution This section of the report addresses United States Fish and Wildlife Service (USFWS) comments related to the seasonal distribution of Gizzard Shad in Conowingo Pond relative to the PBAPS thermal plume. The USFWS raised a question about whether the thermal plume may provide a winter refuge for Gizzard Shad which, otherwise, may not survive extreme cold temperatures during the winter. Exelon agreed to provide a compilation of information from previous studies related to Gizzard Shad seasonal distribution in Conowingo Pond relative to the thermal plume. This compilation of data available from previous studies includes information related to winter water temperatures in the pond, Gizzard Shad distribution, and winter survival.

8. 1 Analysis Gizzard shad, native to eastern North America (Jenkins and Burkhead 1993), was inadvertently introduced into Conowingo Creek, a tributary to Conowingo Pond in May 1972 during an American Shad transport from the Conowingo Dam West Fish Lift. Successful reproduction ensued the same year and the species dispersed into the Muddy Run Reservoir and Muddy Run Recreation Lake. A chronology of Gizzard Shad population expansion in Conowingo Pond is provided in Appendix 10.2. Gizzard Shad are present in much of the Pennsylvania portion of the Susquehanna River including some upstream reservoirs (Stauffer et al. 2016) which are most likely subject to extreme winter conditions and do not receive heated effluent from power plants. Gizzard Shad are reported to become disoriented at cold water temperatures and may suffer high mortality at water temperatures below 3.3 °C (38.0 °F) with mortality being size selective such that larger sized Gizzard Shad have a higher survival than smaller individuals (Bodola 1965; Jester and Jensen 1972; Adams et al. 1985; Fetzer et al. 2011; Michaletz 2010). Natural winter "die offs" of Gizzard Shad, particularly young Gizzard Shad have been reported from water bodies with and without thermal discharge.

Depending upon the severity and duration of winters, a natural winter "die off' of Gizzard Shad, particularly young-of-the year, has been reported from water bodies with or without thermal discharges including Conowingo Pond. However, a complete "kill" has not been reported or inferred.

Presumably an unknown number of older fish survive over winters as evident by capture of adults the following spring in water bodies unaffected by thermal discharge.

Bodola (1965) reported winter "die off' of Gizzard Shad in multiple years from Lake Erie, PA, Jester and Jensen (1972) from Elephant Butte Lake, NM, and Fetzer et al. (2011) from Oneida Lake, NY. In Conowingo Pond, the Gizzard Shad seems to tolerate temperatures<

2.2 °c (< 36.0 °F) and does not appear to need a "thermal refuge" to sustain its population.

The average water temperature in December 1972 (first winter month exposure) the year Gizzard Shad were inadvertently introduced into Conowingo Pond (PBAPS was not operating), was 37.8 °F (3.2 °C). In January and February 1973 the average temperatures were 1.9 °C (35.5 °F) and 1.3 °C (34.3 °F), respectively.

These temperatures were measured at Holtwood Dam, 7 miles upstream of PBAPS. From a historical perspective, the long term (1956-2007) average incoming water 140 PBAPS Post-EPU Study temperatures (as measured at the upstream Holtwood Dam, 1956-2007) in December, January, and February, respectively are: 3.1 °C (37.6 °F), 1.5 °C (34.7 °F), 1.5 °C (34.7 °F), similar to those experienced in December 1972, and January-February 1973. The complete shutdown of PBAPS (i.e., no thermal refuge) between 1987 and 1989 did not seem to affect the Gizzard Shad population in Conowingo Pond; the population survived the winters despite the absence of PBAPS thermal discharge.

The incoming average water temperatures

(°F) in December-February (1987-1989) were: Month 1987 1988 1989 December 39.3 36.2 33.5 January 34.8 32.5 34.2 February 34.0 33.1 36.3 The tolerance of Gizzard Shad to low water temperatures was also corroborated by recent electrofishing sampling of non-thermally affected areas at Mt. Johnson Island (Station 164) and the East Shore (Station 165) in Conowingo Pond in January 2013. Some 22 Gizzard Shad were collected at Mt. Johnson Island and 21 on the East Shore (water temperature of 2.0 °C or 35.6 °F compared to 20 specimens each collected at the two locations in the thermal discharge (Stations 189 and 190). Therefore, the lower temperature tolerance of Gizzard Shad appears to be < 2.2 °C (< 36.0 °F). During the fall large numbers of Gizzard Shad have been observed emigrating from Conowingo Pond downstream past Conowingo Dam. The annual migration (fish lift introductions) of Gizzard Shad from the lower Susquehanna River (up to 1 million Gizzard Shad) likely contributes substantially to the total population of this species in the Pond, and these fish do not benefit from overwintering in the Pond within the extent of the PBAPS thermal plume. 8.2 Summary and Conclusions The Gizzard Shad population expanded rapidly after being inadvertently introduced into Conowingo Creek, a tributary to Conowingo Pond in May 1972. PBAPS was not operating then. The average water temperatures in subsequent January and February 1973 were 1.9 °C (35.5 °F) and 1.3 °C (34.3 °F), respectively.

Again, when PBAPS was completely shut down (no thermal discharge) for two years (between 1987 and 1989) the Gizzard Shad population appeared to survive extreme winter conditions (water temperature between 32.5 and 36.3 °F). Gizzard Shad population experienced extreme winter temperatures in subsequent years and colonized other upstream areas. The population is thriving in areas unaffected by thermal discharges in the Susquehanna River and elsewhere.

Conowingo Pond is an open system and recruits Gizzard Shad from both downstream and upstream sources. Gizzard shad are distributed throughout Conowingo Pond and each year upwards of 1 million adult Gizzard Shad 141 PBAPS Post-EPU Study are introduced into Conowingo Pond from the Conowingo Dam East Fish Lift. A "thermal refuge" is not necessary for propagation and sustenance of the Gizzard Shad population in Conowingo Pond. 142 PBAPS Post-EPU Study 9 Conclusions

9.1.1 Temperature

An important component of the pre-EPU 316(a) Demonstration Study was modeling temperatures and temperature increases for extreme low flow and high temperature conditions using the post-EPU thermal discharge rate. In 2016, Susquehanna River flows and temperatures were very close to the flow and temperature values used to predict worst case biological impacts post-EPU.

Because direct measurement was completed of net temperature increases from the EPU and reductions that occur when the cooling towers operate, the summer of 2016 was ideal for verifying the model and observing overall physical and biological impacts. Model verification was undertaken in two steps, validation of assumptions and comparison of model results to observations.

Modeling performed for the pre-EPU 316(a) Demonstration Study, and subsequently used in the biological evaluation, assumed a value of the temperature increase from the intake to the head of canal and a specific level of cooling tower performance.

Based on measurements obtained in 2016, these two modeling assumptions were validated.

The average temperature increase from the intake to the head of canal was 22.1°F, which was 0.3°F less than the assumed post-EPU condenser temperature rise of 22.4°F. Furthermore, each cooling tower provided about a third more cooling than expected (2.2°F instead of 1.6°F). Model results showed very good agreement with observations.

Agreement was tested by comparing temperature observations against model results at the warmest, most biologically sensitive monitoring stations, as identified in the pre-EPU 316(a) Demonstration Study. The observations were hourly, allowing between 400 and 1700 observations for comparisons to model results. Because the model was run for a single set of extreme Susquehanna River flows and temperatures, it was sufficient for the observations to be bounded by the model's estimate of maximum temperatures.

Only 0.05% of observations exceeded this upper bound; which constitutes satisfactory model verification.

9.1.2 Fish and benthic macroinvertebrate communities Water temperatures observed during 2016 at the biological monitoring locations were comparable to pre-EPU observations with the exception of late August through September period, which was warmer. Dissolved oxygen monitoring was completed within and outside of the PBAPS thermal plume to evaluate DO concentrations that may affect available fish habitat or cause blockage to fish migration past PBAPS. DO concentrations were protective of the aquatic community with sufficiently high DO to maintain fish habitat and allow for migration past PBAPS. Surveys of the benthic macroinvertebrate community indicated similar species composition to pre-EPU monitoring; the community was characterized by tolerant taxa, in particular, Oligochaeta, Chironomidae, Gammarus, Gastropods, and Corbicu/a which were abundant at most stations.

IBI scores and metrics indicated that the benthic community was similar to pre-143 PBAPS Post-EPU Study EPU observations for most months of monitoring.

181 scores and metrics were higher in July and August at the nearfield stations (214 and 215) during the post-EPU monitoring.

In contrast, EPU scores were lower at Stations 214 and 215 in September due to lower flows and higher ambient temperatures during this month. The areas with measurable effects from the thermal plume were along the west shoreline at Stations 214 and 215 as was the case during pre-EPU monitoring.

A diverse warmwater fish community represented by 34 species was observed during the 2016 monitoring.

Fish composition and relative abundance was similar between the thermal and thermal stations.

Observations of the fish community as characterized by the selected metrics indicated similar composition to the pre-EPU period. Avoidance of the highest water temperature was observed at the nearfield electrofishing station (161) from July through September.

The pattern of avoidance was comparable to pre-EPU observations with the exception of September where avoidance was not observed during pre-EPU monitoring.

The avoidance and measurable reduction in the fish diversity was observed along the west shoreline and was limited to periods with high water temperatures and low flows. Avoidance was not observed at the seine stations (214 and 215) that experience the highest water temperatures.

Observations of fish health (external anomalies) and fish condition (relative weight) indicated minimal differences between the thermally influenced and non-thermal locations. Fish health and condition were comparable to the Pre-EPU Demonstration Study with no measurable influence from the EPU identified.

The length-frequency distribution of the representative important species was comparable to Pre-EPU observations and relative abundance of most RIS was within their historic ranges. 9.1.3 Overall Post-EPU monitoring occurred during a period of low Susquehanna River flows coincident with high water temperatures.

These conditions provided an ideal opportunity to evaluate the impact of the EPU on Conowingo Pond during extreme conditions.

The monitoring results showed that cooling tower operation effectively mitigates the additional heat discharge by the EPU. This conclusion is based on the fact that observed water temperatures at the nearfield stations in 2016 for extreme low flow and water high temperature conditions were less than the modeled temperatures presented in the pre-EPU 316(a) Demonstration Study. The measurable spatial and temporal effects of the PBAPS thermal plume on the biota of Conowingo Pond were similar to those observed during the pre-EPU monitoring.

Temporal patterns of fish avoidance and decline in benthos diversity were apparent, related to high water temperatures and were also similar to those observed during the pre-EPU monitoring.

Periods of high temperatures occurred from July through September with measurable effects on the fish community as observed at Station 161 similar to pre-EPU results. The measurable loss in benthic community diversity was most evident during September at Stations 214 and 215 due to higher temperatures and lower flows during this month. The stations with measurable impacts are the same areas of the Pond where similar observations were made during pre-EPU 144 PBAPS Post-EPU Study monitoring.

These impacts are along the west shore at stations within approximately 0.6 mile of the PBAPS discharge canal. Both the fish and benthic macroinvertebrate community composition and relative abundance were similar to pre-EPU monitoring.

Indices used to describe the community structure of the biological community indicated that thermally influenced and non-thermally influenced stations were similar during pre-EPU and post-EPU monitoring.

Overall, a balanced indigenous community exists in Conowingo Pond with the EPU. 145 PBAPS Post-EPU Study 10 Literature Cited Adams, S.M., J.E. Breck, and R.B. McLean. 1985. Cumulative stress-induced mortality of gizzard shad in a southeastern U.S. reservoir.

Environmental Biology of Fishes 13: 103-112. Anderson, R. 0. and R. M. Neumann. 1996. Length, weight, and associated structural indices. Pages 447-482 in B. R. Murphy and 0. W. Willis, editors. Fisheries Techniques, 2nd edition. American Fisheries Society, Bethesda, Maryland. Bodola, A. 1965. Life history of the gizzard shad, Oorosoma cepedianum (Le Sueur), in western Lake Erie. Fishery Bulletin 65: 391-425. Brown, M. L. and B. R. Murphy. Relationship of relative weight CWr) to proximate composition of juvenile striped bass and hybrid striped bass. Trans. Am. Fish. Soc., 120: 509-518 (1991). Carlander, K. 0. 1969. Handbook of freshwater fishery biology. Iowa State Univ. Press, Ames. Vol. 1. Carlander, K. 0. 1977. Handbook of freshwater fishery biology. Iowa State Univ. Press, Ames. Vol. 2. Cooper, E. L. 1983. The fishes of Pennsylvania and the northeastern United States. Pennsylvania State University Press. 243pp. Fetzer, W.W., T.E. Brooking, J.R. Jackson, and L.G. Rudstam. 2011. Overwinter mortality of Gizzard Shad: Evaluation of starvation and cold temperature stress. Transactions of the American Fisheries Society 140: 1460-1471.

Jenkins, R.E., and N.M. Burkhead.

1993. Freshwater fishes of Virginia. American Fisheries Society, Bethesda, Maryland.

Jester, 0.8., and B.L. Jensen. 1972. Life history and ecology of the gizzard shad, Oorosoma cepedianum (Le Sueur) with reference to Elephant Butte Lake. New Mexico State University, Agricultural Experiment Station Research Report 218. Las Cruces, New Mexico. Marcy, B.C., P.M. Jacobson, and R.L. Nankee. 1976. Observations on the reactions of young American shad to a heated effluent.

Transactions of the American Fisheries Society 101: 7 40-743. Michaletz, P.H. 2010.0verwinter survival of age-0 gizzard shad in Missouri Reservoirs spanning a productivity gradient:

roles of body size and winter severity.

Transactions of the American Fisheries Society 139: 241-256. Moss, S.A. 1970. Then response of young American shad to rapid temperature changes. Transactions of the American Fisheries Society 99: 381-384. 146 PBAPS Post-EPU Study Normandeau Associates.

1997. A report on the assessment of fish populations and thermal conditions in Conowingo Pond relative to variable cooling tower operation at the Peach Bottom Atomic Power Station. Prepared for PECO Energy Company, Philadelphia, PA. Normandeau Associates.

1998. A report on the thermal conditions and fish populations in Conowingo Pond relative to zero cooling tower operation at the Peach Bottom Atomic Power Station. Prepared for PECO Energy Company, Philadelphia, PA. Normandeau Associates.

1999. A report on the thermal conditions and fish populations in Conowingo Pond relative to zero cooling tower operation at the Peach Bottom Atomic Power Station. Prepared for PECO Energy Company, Philadelphia, PA. Normandeau Associates.

1999. A report on the thermal conditions and fish populations in Conowingo Pond relative to zero cooling tower operation at the Peach Bottom Atomic Power Station. Prepared for PECO Energy Company, Philadelphia, PA. Normandeau Associates.

2000a. A report on the thermal conditions and fish populations in Conowingo Pond relative to zero cooling tower operation at the Peach Bottom Atomic Power Station (June-October 1999). Prepared for PECO Energy Company, Philadelphia, PA. Pennsylvania Department of Environmental Protection (PA DEP). 2013. 2012 Susquehanna River Preliminary Sampling Report Water Quality Standards Bureau Of Point & Non-Point Source Management Department Of Environmental Protection Commonwealth Of Pennsylvania.

May 2013. Pennsylvania Department of Environmental Protection (PA DEP). 2007. PA DEP Multi-habitat Stream Assessment Protocol.

PA DEP Div. of Water Quality Assessment and Standards, Harrisburg, PA. Pennsylvania Department of Environmental Protection (PADEP). 2016. Rationale For The Development Of Ambient Water Quality Criteria For Dissolved Oxygen Protection Of Aquatic Life Use. Bureau of Point And Non-Point Source Management, Harrisburg, PA. Available:

http://files

.dep.state.pa. us/publicparticipation/Public%20Participation%20Center/PubPartCenter Porta1Files/Environmental%20Qualitv%20Board/2012/EQB%20-

%20Apri1%2017.

%202012/Triennial%20Review/08%20TR13 Rationale-Dissolved%200xygen Criteria.pdf (December 2016) Philadelphia Electric Company (PECO). 1975. Materials prepared for the Environmental Protection Agency 316(a) demonstration for PBAPS Units No. 2 and 3 on Conowingo Pond. Philadelphia Electric Company, Philadelphia, PA. Philadelphia Electric Company (PECO). 1979. PBAPS post-operational report no. 11 on the ecology of Conowingo Pond for the period of July 1978-December 1978. March 1979. RMC Ecological Division.

1979. Relationships of preferred, avoided, upper, and lower lethal temperatures of fishes of Conowingo Pond, Pennsylvania.

Prepared for Philadelphia Electric Company, Philadelphia, PA. 147 PBAPS Post-EPU Study Smith, C.L. 1993. Fishes of New York State. The New York State Department of Environmental York. Stauffer, J.R., Jr., R.W. Criswell, and D.P. Fischer. 2016. The fishes of Pennsylvania.

Cichlid Press, El Paso, Texas. Susquehanna River Basin Commission (SRBC). 2013. Nutrient and Suspended Sediment in the Susquehanna River Basin. Publication

1. 296. December 31, 2014. U.S. Environmental Protection Agency (USEPA). 1977. lnteragency 316(a) technical guidance manual and guide for thermal effects sections of nuclear facilities environmental impact statements.

US EPA, Office of Water Enforcement.

Washington, DC. Draft May 1, 1977. 148 PBAPS Post-EPU Study 11 Appendices 11.1 PBAPS Post-EPU Study Plan 11.2 Chronology of Gizzard Shad Population Expansion 149 APPENDIX 11.1 STUDY PLAN STUDY PLAN FOR POST-EPU THERMAL AND BIOLOGICAL MONITORING PEACH BOTTOM ATOMIC POWER STATION Prepared for: Exelon Generation

.. : Prepared by: Normandeau Associates, Inc. and ERM, Inc. Revision 3, April 2016 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Introduction This study plan outlines the details for performing biological and thermal monitoring following Extended Power Uprates (EPU) for Peach Bottom Atomic Power Station (PBAPS) Unit Nos. 2 and 3. This biological and thermal study supports the monitoring requirements of fish and macroinvertebrate communities set forth in Part C of PBAPS's NPDES Permit No. PA0009733.

Section 1 of this study plan addresses the biological and thermal monitoring discussed above. Section 2 of this study plan addresses a review of potential impacts to American Shad migration as a result of the EPUs for PBAPS Unit Nos. 2 and 3. This review of American Shad migration is being performed based on PADEP's disposition of NPDES permit comments during the review period of the draft NPDES Permit. Section 3 of this study plan addresses USFWS comments related to distribution of Gizzard Shad in Conowingo Pond relative to PBAPS's thermal plume. Section 1 Thermal Plume Monitoring Objective:

Monitor water temperatures in Conowingo Pond to compare to 2010-2013 NPDES thermal study results regarding the characteristics of the plume after implementation of the EPU. Monitoring Period: May 1 through September 30, 2016. Monitoring Locations:

Thermal monitoring locations will include: cooling water intake outer screen structure; head of discharge canal; end of discharge canal; and at Transects 200, 300 and 400 in Conowingo Pond, specifically stations 201, 203, 205, 301 303, 401 and 403 (Figure 1 ). At the Transect stations, the temperature monitors will be installed at the surface (at approximately 1 foot depth) and at approximately 10 feet depth below surface, and bottom at each station. At the other referenced monitoring locations a single monitor will be installed at approximately mid-depth to characterize water temperature.

In addition, temperature monitors will be installed at ----the biological collection locations, specifically stations 221, 208, 214, 215, 189, 190, 216, and 217 (Figure 2). At the biological stations, a single temperature monitor will be installed on the bottom. Table 1 provides a summary of the proposed temperature monitoring locations and monitor depths. 1 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Table 1. Water temperature monitor location and monitor depth. Monitor Monitor Depth Location Water Surface 10ft Below Mid-Depth Bottom Surface Intake Screen x Head of Canal x End of Canal x 201, 203, 205, x x x 301, 303, 401, 403 221, 208, 214, x 215, 189, 190, 216,217 Monitoring Method: Water temperatures will be recorded hourly using temperature data loggers that are accurate to approximately 0.36 °F in the range of 32 to 122 °F. Deliverables:

A spreadsheet providing raw water temperature data will be created along with a list of collected daily average, minimum and maximum temperatures.

Temperature reporting will include tables or figures that provide the duration and frequency of high temperatures.

Temperature changes due to cooling tower operations will be recorded and evaluated.

A comparison of daily average, minimum, and maximum temperatures during the transition period (i.e., turning on a cooling tower) to values obtained from the thermal model will be prepared.

The comparison will consider that the forcing conditions (meteorology, river flows and plant operations) during 2016 will be different than the ones used in the thermal model. Analysis to compare the EPU temperatures with the predictive model will be completed to verify the model. This monitoring plan includes a sufficient number of monitoring stations and frequency of data collection such that the temporary loss of data from one or more thermistors will not interfere with the proposed analysis.

Furthermore, because data will be recovered approximately monthly, gaps due to malfunctioning or displaced thermistors will not exceed one month. Any loss of data will be noted in the report. Dissolved Oxygen Monitoring Objective:

Monitor dissolved oxygen in Conowingo Pond in shallow shoreline areas along west shoreline downstream of the PBAPS discharge canal. In particular, 2 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 monitoring will focus on periods of low-flow and high water temperature which could result in low dissolved oxygen concentrations. Monitoring Period: June 1 through September 30, 2016. Monitoring Locations:

Dissolved oxygen monitoring will be completed at biological stations 208, 215 and 189. A single monitoring device will be installed toward the bottom of the water column at each location.

Monitors will be installed in water with depth less than 10 ft. Monitoring Method: Dissolved oxygen concentrations will be recorded hourly using a Hydrolab water quality multiprobe or equivalent data logger. Deliverables:

A spreadsheet providing raw dissolved oxygen data will be created along with a list of collected daily average, minimum, and maximum dissolved oxygen concentrations.

Biological Monitoring Objective:

Monitor biological community in Conowingo Pond to determine characteristics of the fish and benthic macroinvertebrate communities after implementation of the EPU. Collection locations for fish and benthic macroinvertebrates are provided in Figure 3. Monitoring Period: May 1 through September 30, 2016 Sampling Procedure:

Fish sampling will generally employ the same field sampling protocols that were used during the 2010 through 2013 studies (Normandeau and ERM 2014). Collected fish will be identified to species (or genus for those too small to identify to species in the field), counted, measured, and examined for disease, external parasites , lesions, tumors (DEL Ts) and anomalies.

Fish DEL Ts and anomalies will be recorded using the acronyms provided in PADEP Field Data Sheet for Tissue Sampling (Attachment 1 ). Live fish will be released back to the Pond except for those retained to confirm identifications or retained as voucher or reference specimens.

Large numbers of collected fishes will be subsampled (maximum of 50 specimens per species) for individual length measurement.

Seine A seine measuring 10 ft by 4 ft with %-inch mesh will be used once monthly at each station. Most sites able to be sampled effectively with this gear are small beaches less than 100 ft long. To standardize results for each site, five hauls will be conducted at each sampling station. This sampling with fine mesh seines is intended to capture the young of many species and those fishes having a relatively small size as adults that frequent shallow, shore zone habitat. 3 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Data recorded at each station for each collection will include weather, date, time, Secchi disc transparency, air and surface water temperatures, dissolved oxygen, and estimated water depth. Electrofish ing Fish will be collected at night using boat electrofishing equipment employing pulsed direct current to minimize fish injury. The boat-mounted shocker will be maneuvered slowly through the stations as close to shore as practicable.

Each sample will consist of approximately 30 minutes of shocking.

Stunned fish will be netted and placed in an board live well for subsequent processing except for large specimens (e.g., common carp and quillback) which will not be brought on-board, but will be counted and recorded.

Boat electrofishing will collect larger fish that frequent the shallow, shore zone habitats that are not effectively sampled with seines. Data recorded at each station for each collection will include weather, date, time, air and surface water temperatures, dissolved oxygen, specific conductance, and estimated water depth. Benthic Macroinvertebrates Collections will occur within littoral benthic habitats and samples processed following the PADEP Multi-habitat Stream Assessment Protocol (PADEP 2008). A habitat assessment will be completed during each benthic macroinvertebrate collection following PADEP habitat assessment protocol (PADEP 2013). Monitoring Locations:

Electrofishing:

Upstream of thermal plume: 187 and 165 Downstream of thermal plume: 161, 189, 190, and 217 Seining: Upstream of thermal plume: 220, 221, and 208 Downstream of thermal plume: 214 and 215 Benthic Macroinvertebrates:

Upstream of thermal plume: 208, 220, and 221 Downstream of thermal plume: 189, 214, 215, and 216 Figure 3 provides a spatial representation of the monitoring locations.

Monitoring Interval:

Perform monthly fish and benthic macroinvertebrate collections at each station. 4 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 References Normandeau Associates and ERM. 2014. Final Report for the Thermal Study to Support a 316 (a) Demonstration, Peach Bottom Atomic Power Station. Prepared for Exelon Generation by Normandeau, Stowe, Pennsylvania and ERM, Exton, Pennsylvania, March 2013. Pennsylvania Department of Environmental Protection (PADEP). 2008. PADEP habitat Stream Assessment Protocol.

PA DEP Division of Water Quality Assessment and Standards, Harrisburg, PA. Pennsylvania Department of Environmental Protection (PADEP). 2013. Bureau Of Point And Non-Point Source Management.

Appendix C-Biological Field Methods. C1. Habitat Assessment.

Available:http://files.dep.state.pa.us/Water/Drinking%20Water%20and%20Facility%20R egulation/WaterQualityPortalFiles/Methodology/2013%20Methodology/AppendixC_Habi tat%20Methods.pdf. (June 2015). 5 Figure 1. Pond. Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Proposed temperature monitoring transects and locations in Conowingo 6

/ Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Holtwood Dam ; Muddy Run Station Boat Launch Muddy Creek .. ,,_ .J.,,/. 1t""'T 221 e Fishing Creek ,.. _....T Rollins Point Mt. Johnson Island Peach Bottom Atomic Power Station ' Ur ll.a Burkins Run* 214 *215 Peters Creek 2oae Peach Bottom Beach Williams Tunnel Pennsylvania Maryland e1eo *216 '. Frazer Tunnel Broad Creek Conowingo Dam N ,. Legend

• Temperature Monito ring S tat io ns 0 2 Miles Hopkins Cove serv1te Loyer l: ,.ait;"'Sou ,.., eut HERE Del.orme r ... rom lntermap. lrrcrom ont P Corp. GE9CO USGS. FAO NPS NRCA.N, GeoBaH. IGN Kactatter NL Ordnonc* SUrny , E'Sl'I Jep*n. MET!. E*rl c n1rra (Hong Kong/, *""nlllpo M1pmy1nclia Cl Open5treett..1*P contributors , eiio th* GIS User Commu ,n t:y Figure 2. Proposed temperature monitoring locations that coincide with biological collection locations in Conowingo Pond. 7 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Figure 3. Proposed biological collection locations in Conowingo Pond. 8 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Section 2 American Shad Study Objective:

To address draft NPDES permit comments related to the potential effect of the PBAPS thermal discharge on American Shad during post-EPU conditions on Unit Nos. 2 and 3. Exelon Deliverable:

A desktop study that will use existing information and current scientific understanding of American Shad in Conowingo Pond to address the draft NPDES permit comments.

This will be accomplished through use of the existing hydrothermal model and existing model outputs that characterize the thermal plume for several low-flow and high water temperature scenarios.

The existing model output for these scenarios will then be evaluated to determine the potential for PBAPS's thermal plume to block migration of American Shad in the Conowingo Pond. Section 3 Gizzard Shad Seasonal Distribution Objective:

To address USFWS April 2016 comments related to seasonal distribution of Gizzard Shad in Conowingo Pond relative to the PBAPS thermal plume. Exelon Deliverable:

Provide a compilation of information related to Gizzard Shad seasonal distribution in Conowingo Pond relative to the PBAPS thermal plume. This information will be obtained from existing reports, primarily the Final Report for the Thermal Study to Support a 316 (a) Demonstration at Peach Bottom Atomic Power Station, March 2013. 9 Peach Bottom Atomic Power Station Study Plan For Post-EPU Thermal and Biological Monitoring Rev. 3. April 2016 Deliverables:

After completion of monitoring a report will be submitted to PADEP. This report will include all three sections of the Study Plan. Section 1 will include data tables, analysis of the data, and comparison with pre-EPU biological and thermal monitoring data. The report will be submitted to PADEP for review by February 3, 2017. This monitoring plan includes a sufficient number of monitoring stations and frequency of data collection such that a minor interruption of data collection due to weather or other impacts will not interfere with proposed analysis.

Raw data files for biological monitoring will be submitted to PADEP in a database format such that for each observation a single independent row of biological data is provided and non-biological data is linked to the biological data through a common identifier.

10 STATION NUMBER: ATTACHMENT 1 COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION BUREAU OF WATER STANDARDS AND FACILITY REGULATION GENERAL INSTRUCTIONS FOR FIELD DATA SHEET TISSUE SAMPLING Enter WON Station Number, WQF Station Number or Survey Station Number as appropriate.

Leave blank if none of these apply. NOTE: If WQN Number is entered, then Waterbody Name, Location, County and Municipality can be left blank. DATE, COLLECTOR, AGENCY and COLLECTOR NUMBER: Must be completed.

NEW STATIONS:

TISSUE TYPE: If a WQF station number has not previously been assigned, Quad. Name, Quad. Number, either Lat/Long or inches-N/inches-W and RMI (to nearest 0.1 mile) must be entered (for STORET input). Standard samples are: 1. Skin-on, scaled fillets for gamefish, panfish and rough fish. 2. Skinless fillets for catfish and bullheads.

SAMPLE: A normal sample is a composite of 10 fillets from 5 fish. For large fish, 5 fillets can be used. 75 PERCENT RULE: The individual fish in each composite should be as close to the same size as possible.

A general guideline is that the length of the smallest individual in the composite should be no less than 75 percent of the length of the largest individual.

Fish Health: Black grub Bg Trematode Tr Frayed fins Ff Deformities De Tumor Tu Eroded fins Ef Eroded skin Es White cysts We Eroded gills Eg Fungal infection Fi Emaciated Em Frayed gills Fg Leeches Le Cloudy eve Ce Clubbed gills Cg Melanistic area Ma Exophthalmic eve Ee Spotted Gills Sg Open sore Os Hemorrhagic eve He Cyst on gills Cg Raised red sore Rr Missing eve Me Life History: Gravid G Post spawn Ps Milting male Mm -------

ATTACHMENT 1 COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION BUREAU OF WATER STANDARDS AND FACILITY REGULATION FIELD DATA SHEET TISSUE SAMPLING Station# ----------

Waterbody Date & Time ----------

---

Location County Municipality Collector Agency Coll.#

---

---

COMPLETE FOR NEW STATIONS Quad. Name Quad.# --------------------

RMI Lat. (inches N) ------------

Long. (inches W) -------Method: Tissue Type: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. D Electrofishing D Seine D Gill Net D Whole Fish D Skinless Fillet D Other (specify):

SPECIES D Rotenone 0Angling D Other (specify)

D Skin-on Fillet -Scaled D Skin-on Fillet -Not Scaled TL (inches) WT (lbs. oz.) *Use Fish Health & Life History Codes (if needed) Comments: (water/weather conditions, man-hours expended, problems, etc.) Fish Health & Life Historv* -

AP PEN DIX 11.2 CHRONOLOGY OF GIZZARD SHAD POPULATION EXPANSION Chronology of Gizzard Shad Population Expansion Gizzard shad, native to eastern North America, was inadvertently introduced (JOO+ specimens) into Conowingo Creek, a tributary to Conowingo Pond, in May 1972 during an American Shad transport from the Conowingo Dam West Fish Lift. The introduction of Gizzard Shad and its subsequent population explosion in Conowingo Pond occurred prior to the operation of Peach Bottom Atomic Power Station (PBAPS) Unit 2 in July 1974 and Unit 3 in December 1974. At present, Gizzard Shad has successfully colonized new habitats in the Susquehanna River (upstream of York Haven Dam) with or without a thermal plume. The spawning success of Gizzard Shad in 1972 was demonstrated by capture of its larvae the same year (Figure 1 ). Prior to 1972, no larval Gizzard Shad were collected but beginning in 1972 catch of larval Gizzard Shad became routine with high densities thereafter.

Although the Tropical Storm Agnes in June 1972 had a catastrophic effect on most of the fish community of Conowingo Pond, Gizzard Shad appeared to be quite resilient with continued expansion.

Trawl samples (Figure 2) in Conowingo Pond demonstrated a similar pattern indicating that the Gizzard Shad population was successfully established in the Pond in a relatively short time and became self-sustaining.

Although the Muddy Run Reservoir is not affected by thermal discharge Gizzard Shad successfully colonized this additional habitat since 1972. Block net samples in the Muddy Run Reservoir coves (Figure 3) show Gizzard Shad population continued to grow since 1972. Subsequently, a population developed rapidly and spread to the nearby Muddy Run Recreation Lake (unaffected by thermal discharge).

This population experiences same extreme winter temperatures as the population in Conowingo Pond. A large number of young Gizzard Shad is observed emigrating from Muddy Run Reservoir in the fall which may contribute to the Conowingo Pond population.

Gizzard Shad population in Conowingo Pond as noted elsewhere seems resilient despite severe winters, extreme hydrological/meteorological events (e.g., hl,lrricanes, storms, etc.) with only a small start-up (100+ fish) population needed for its explosive population growth. Installation of fish ways, first at Conowingo ( 1972, and 1991; Figure 4 and 5) then later at Holtwood and Safe Harbor in 1997, and at York Haven in 2000; Figure 6) at all the dams on the Susquehanna River in combination with its presence over 200 miles of the Susquehanna River (unaffected by thermal discharges) including the Muddy Run Reservoir assures a consistent supply of Gizzard Shad spawning stock for upstream and downstream dispersal (Figures 4-6); the system is basically open. Presently, fishes can and do volitionally move upstream to areas above York Haven Hydroelectric Dam (RM 56).

3000.00 +---------------Pr------------------

2700.00 ..__ ____________

__,,___...,_

________________

_ 2400.00 +--------------+----'Ir-----------------

> 2100.00 +------------------'1.-----------------1800.00 +--------------#----------------------

! c 1500.00

.. 1200.00 -l------------l---------'------------

900.00 +----------------------,....-------------

600.00 +------------#------------------------

300.00 0.00 1972 1973 1974 1975 1976 1977 1978 1979 Year -Meter Net Inshore Stations ---Meter Net Transect Stations Figure 1. Reproductive success of Gizzard Shad indexed by catch of larval gizzard shad (number of larvae S 25 mm per 1000 ml) at inshore stations (creeks and coves) and in the main Conowingo Pond (Transect stations), 1972-1979.

Densities of larval Gizzard Shad in 1972-1974 at inshore stations<

13.5 per 1000 ml could not be shown on the same vertical scale. Data source: RMC-Ecological Division (1979). 2 10.00 9.50 9.00 8.50 8.00 7.50 7.00 6.50 iii 6.00 5.50 i 5.00 ii 4.50 1= 4.00 0 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 Figure 2. -" I '\ I '\ I '\ I ' I '\ I '\ I '\ I '\ I '\ I ' I '\ I '\

• I .... ,, I ___ .._. // ' / I ----# ....... / I --;&; ,,, ...... / , d' "' --1972 1973 1974 1975 1976 1977 1978 1979 Year Catch per effort (number per 10 min trawl haul) of Gizzard Shad in Conowingo Pond, 1972-1979. 3 Zone 405 ..,._Trawl Zone 406 Trawl Zone 408 -++-Trawl Transects A 140000 120000 "Cl GI ] 100000 8 "Cl 80000 "' .I: "' "Cl 60000 .. .a "' 'O 40000 20000 0 B 2200 2000 1800 _ 1600

! E 1200 0 iii 1000 'iii ::I 800 c c c( 600 400 200 0 Figure 3.

net Stations 1972 1973 1974 197S 1976 1977 Year net Stations 1972 1973 1974 1975 1976 1977 Year Number (A) and biomass (kg per ha, B) of Gizzard Shad collected by block net in the Muddy Run Reservoir, 1972-1978.

Source: RMC-Ecological Division (1979). 4 300 § 2SO .. * 'i 200 '5 j Cl .. lSO j E

• z 100 so Figure 4. Spring Continuous Fl ows (1972-1981)

Hurricane Eloise Continuous Flows: Spring* Summer 1982-1989 Year Venting System Completed:

Present Flow Regime 1988*2012 Hurricane Irene Tropical Storm Passage counts of Gizzard Shad at the Conowingo West Fish Lift (1972-2012).

5 8 8 200 ..

• 1 i ISO i; 0 j e z 100 so ... T *** >nd T'""'Rlll1.ll!Plll!ll.bt.llPlla:

ilD Volitional 1997-2012 utilities 1991-1996

---, Agency requested shutdown of the EFL Hurricane Irene Tropical Storm Lee I I Fl>-Hurricane

\ 1" I sabel Settlement Flathead Agreeme J!!_ ---_catfisbl_ro---,__ -... -\ 1989 I"' -fl ii I I n 11 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year Figure 5. Passage counts of Gizzard Shad at the Conowingo East Fish Lift (1991-2012).

6 100 90 80 .... >C 70 "C nl 60 Q. "C nl so .c "' "C .. 40 30 ... 0 .. 20 GI .Cl E ::::i z 10 0 Figure 6. 1 1---1-; I* r r -ll r I * .... 1-t--I 11 II 11 I L 11 11 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Year

• Conowingo East Holtwood *Safe Harbor York Haven Passage counts of Gizzard Shad at the four fish ways showing rapid colonization of upstream areas, 1997-2011.

Voluntary passage at Conowingo EFL, Holtwood and Safe Harbor commenced in 1997; and York Haven in 2000. 7 The following sources/reports were reviewed to prepare the response and conclusions that a "thermal refuge" is not necessary for propagation and sustenance of Gizzard Shad and the population is thriving in areas unaffected by thermal discharges.

• Pre-operational report (1966-1973) and the initial 316(a) report (1977) describing the baseline water quality, benthic and zooplankton, fish composition, ecology, distribution, and abundance of fishes in the Pond and surrounding waters. The 316(a) report and a supplement compared the pre-operational and post-operational data on the studied parameters and provided thermal tolerances (temperature preference, avoidance, heat and cold shock) of approximately 27 species.

• Semi-annual post-operational reports (prepared as part of PBAPS as part of U.S. Nuclear Regulatory Commission Technical Specifications requirements relative to the operation of the station. These reports compared changes, if any, in the above mentioned parameters.

• Annual reports prepared relative to the operation of the Three Mile Island Nuclear Station (approximately 49 miles upstream of PBAPS) during forced shutdown, and subsequent start-up.

These reports show presence of Gizzard Shad in the 1990s before the fishways were installed at Holtwood, Safe Harbor dams ( 1997) or York Haven Dam (2000).

• Sampling in Conowingo Pond relative to operation of Peach Bottom Atomic Power Station: ( 1) meter net samples ( 1969-1977) to signify spawning success, time, temperature, and areas, and (2) trawling (1967-1980, 1996-1999), seining, trap netting, electroshocking to indicate survival and successful establishment of Gizzard Shad population in the Pond and exposures to a wide array of environmental changes, and (3) responses to natural catastrophic events such as Tropical Storm Agnes in 1972 and Hurricane Eloise in 1975.

• Sampling in Muddy Run Pumped Storage Reservoir (1970-1977) as part of licensing of the Muddy Run Pumped Storage Station: block net sampling and meter net sampling (1970-1977) to demonstrate successful establishment of Gizzard Shad population in 1972 and the potential for recruitment to Conowingo Pond, particularly during voluntary fall emigration;

• Annual Conowingo West Lift Fish (1972-present) and East Fish Lift (1991-present) operation reports. These reports provide (1) fish passage counts, (2) temporal changes in relative abundance and expansion of Gizzard Shad population before (1972-1996) and after (1997-present) voluntary passage at the EFL along with events deemed notable since 1972, (3) annual recruitment of Gizzard Shad into Conowingo Pond, and (3) __ ___ _ __ potential factors contributing to the species expansion;

• Holtwood, Safe Harbor Fish Lift Counts (1997-present), and York Haven Fish Ladder (2000-present) provide an estimate of the number of Gizzard Shad that may continue upstream migration into non-thermally affected areas with potential for downstream recruitment; and range expansion.

8 January 7, 2019 U.S. Nuclear Regulatory Commission ENCLOSURE13 13_PADEP_2011_NONEXELON.pdf

[PADEP] Pennsylvania Department of Environmental Protection.

2011. "Letter to Peach Bottom Atomic Power Station (J. Brozonis) regarding NPDES Permit PA0009733 Entrainment Characterization Study Work Plan." May 5, 2011.

1*

WATER MANAGEMENT PROGRAM MAY 5 2011 Mr. Joseph Brozonis Sr. Environmental Chemist Peach Bottom Atomic Power Station 1848 Lay Road

• Delta, PA 17314 Re: Peach Bottom Atomic Power Station NPDES Permit PA 0009733 ,

• Entrainment Characterization Study Work Plan

Dear Mr. Brozonis,

103 ID, Io I NON-EXELON The Department of Environmental Protection (DEP) has reviewed the "Work Plan for an Entrainment Characterization Study" for the Peach Bottom Atomic Power Station dated 25, 2011.

• The work plan is consistent with the NPDES permit requirements relating to the entrainment characterization study in Part C. Therefore, DEP has no additional comments and the work plan is approved.

As stated in the work plan, the sampling is scheduled to commence during the week of March 4, 2012. Please contact Heidi Biggs at hbiggs@state.pa.us or 717-772-5656 if you have any questions or comments.

Sincerely, Lee A. McDonnell, P .E. Program Manager . Water Management Program* cc: Scott Sklenar -Exelon Nuclear Paul Harmon -Normandeau Associates, Inc. Southcentral Regional Office I 909 Elmerton Avenue I Harrisburg, PA 17110-8200 717.705.4707 I Fax 717.705.4760 Printed .on Recycled Paper@ . www.depweb.state.pa.us January 7, 2019 U.S. Nuclear Regulatory Commission ENCLOSURE14 14_PADEP _2014b_NONEXELON.pdf

[PADEP] Pennsylvania Department of Environmental Protection.

2014b. "Letter to Exelon Generation Company, LLC (P. Navin) regarding "401 Water Quality Certification Peach Bottom Atomic Power Station Extended Power Uprate," DEP File No. EA 67-024, NRC Docket No. NRC-2013-0232, York and Lancaster County. July 23, 2014.

July 23, 2014 NON-EXELON Mr. Patrick D. Navin Exelon Generation Company, LLC Peach Bottom Atomic Power Station 1848 Lay Road Delta, PA 17314-9032 RE: 401 Water Quality Certification Peach Bottom Atomic Power Station-Extended Power Uprate DEP File No. EA 67-024 NRC Docket No. NRC-2013-0232 York and Lancaster County

Dear Mr. Navin:

This is in reference to your request for Water Quality Certification under Section 401 of the Federal Clean Water Act, submitted to our office on November 21, 2013. The request relates to the Exelon Generation Co., LLC-Peach Bottom Atomic Power Station-Extended Power Uprate (PBAPS) project that will take place at the Peach Bottom Atomic Power Station in York County, in the Commonwealth of Pennsylvania.

The Department of Environmental Protection (DEP) has reviewed your request for 401 Water Quality Certification and hereby grants the 401 Water Quality Certification for the Peach Bottom Atomic Power Station-Extended Power Uprate project. The approved certification is attached.

Any person aggrieved by this action may appeal, pursuant to Section 4 of the Environmental Hearing Board Act, 35 P.S. Section 7514, and the Administrative Agency Law, 2 Pa. C.S. Chapter SA, to the Environmental Hearing Board, Second Floor, Rachel Carson State Office Building, 400 Market Street, PO Box 8457, Harrisburg, PA 17105-8457, 717.787.3483.

TDD users may contact the Board through the Pennsylvania Relay Service, 800.654.5984.

Appeals must be filed with the Environmental Hearing Board within 30 days ofreceipt of written notice of this action unless the appropriate statute provides a different time period. Copies of the appeal form and the Board's rules of practice and procedure may be obtained from the Board. The appeal form and the Board's rules of practice and procedure are also available in braille or on audiotape from the Secretary to the Board at 717.787.3483.

This paragraph does not, in and of itself, create any right of appeal beyond that permitted by applicable statutes and decisional law. Southcentral Regional Office I 909 Elmerton Avenue I Harrisburg, PA 17110-8200 717.705.4802 I Fax 717.705.4760 Printed on Recycled Paper@ www.depweb.state

.pa.us Mr. Patrick D. Navin July 23, 2014 IF YOU WANT TO CHALLENGE THIS ACTION, YOUR APPEAL MUST REACH THE BOARD WITHIN 30 DAYS. YOU DO NOT NEED A LA WYER TO FILE AN APPEAL WITH THE BOARD. IMPORTANT LEGAL RIGHTS ARE AT ST AKE, HOWEVER, SO YOU SHOULD SHOW THIS DOCUMENT TO A LA WYER AT ONCE. IF YOU CANNOT AFFORD A LA WYER, YOU MAY QUALIFY FOR FREE PRO BONO REPRESENTATION.

CALL THE SECRETARY TO THE BOARD (717.787.3483)

FOR MORE INFORMATION.

If you have any questions, please contact me at 717.705.4799, or by email at scwilliams@pa.gov.

Scott R. Williamson Program Manager Waterways

& Wetlands Program Enclosure cc: Ms. Cindy Bladey, Chief, Rules, Announcements, and Directives Branch, U.S. Nuclear Regulatory Commission Ms. Maria Bebenek, DEP South-central Region Clean Water Program Manager Mr. Rich Janati, DEP Radiation Protection Mr. Andrew Shiels, Deputy Director for Field Operations, PA Fish and Boat Commission Mr. Andrew Dehoff, Executive Director, Susquehanna River Basin Commission Ms. Patricia Strong, US Army Corps of Engineers, Baltimore District Mr. Rick Ennis, Project Manager, U.S. Nuclear Regulatory Commission (by email) Lancaster County Conservation District York County Conservation District

pennsylvania

• . DEPARTMENT OF ENVIRONMENTAL PROTECTION WATERWAYS

& WETLANDS PROGRAM July 23, 2014 Ms. Cindy Bladey, Chief, Rules, Announcements, and Directives Branch (RADB) Office of Administration Mail Stop: 3WFN,06-44M U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Re: 401 Water Quality Certification Exelon Generation Co.-Peach Bottom Atomic Power Station DEP File No. EA 67-024 NRC Docket No. NRC-2013-0232

Dear Ms. Bladey:

Enclosed is the NRC Docket No. NRC-2013-0232, Section 401 Water Quality Certification for the Exelon Generation Co.-Peach Bottom Atomic Power Station-Extended Power Uprate project. Any person aggrieved by this action may appeal, pursuant to Section 4 of the Environmental Hearing Board Act, 35 P.S. Section 7514, and the Administrative Agency Law, 2 Pa. C.S. Chapter SA, to the Environmental Hearing Board, Second Floor, Rachel Carson State Office Building, 400 Market Street, PO Box 8457, Harrisburg, PA 17105-8457, 717.787.3483.

TDD users may contact the Board through the Pennsylvania Relay Service, 800.654.5984.

Appeals must be filed with the Environmental Hearing Board within 30 days of receipt of written notice of this action unless the appropriate statute provides a different time period. Copies of the appeal form and the Board's rules of practice and procedure may be obtained from the Board. The appeal form and the Board's rules of practice and procedure are also available in braille or on audiotape from the Secretary to the Board at 717. 787.3483.

This paragraph does not, in and of itself, create any right of appeal beyond that permitted by applicable statutes and decisional law. IF YOU w ANT TO CHALLENGE nns ACTION, YOUR APPEAL MUST REACH THE BOARD WITIIlN 30 DAYS. YOU DO NOT NEED A LA WYER TO FILE AN APPEAL WITH THE BOARD. Southcentral Regional Office I 909 Elmerton Avenue I Harrisburg, PA 17110-8200 717.705.4802 I Fax 717.705.4760 Printed on Recycled Paper@ www.depweb.state.pa.us Ms. Cindy Bladey July 23, 2014 IMPORTANT LEGAL RIGHTS ARE AT STAKE, HOWEVER, SO YOU SHOULD SHOW THIS DOCUMENT TO A LA WYER AT ONCE. IF YOU CANNOT AFFORD A LA WYER, YOU MAY QUALIFY FOR FREE PRO BONO REPRESENTATION.

CALL THE SECRETARY TO THE BOARD (717.787.3483)

FOR MORE INFORMATION.

If you have any questions, please contact me at 717.705.4799, or by email at scwilliams@pa.gov.

Scott R. Williamson Program Manager Waterways

& Wetlands Program Enclosure cc: Mr. Patrick D. Navin, Exelon Generation Co. Ms. Maria Bebenek, DEP South-central Region Clean Water Program Manager Mr. Rich Janati, DEP Radiation Protection Mr. Andrew Shiels, Deputy Director for Field Operations, PA Fish and Boat Commission Mr. Andrew Dehoff, Executive Director, Susquehanna River Basin Commission Ms. Patricia Strong, US Army Corps of Engineers, Baltimore District Mr. Rick Ennis, Project Manager, U.S. Nuclear Regulatory Commission (by email)

COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION WATER QUALITY CERTIFICATION PEACH BOTTOM ATOMIC POWER STATION EXTENDED POWER UPRATE PROJECT AND RELATED MITIGATION DEP File No. EA 67-024 NRC Docket ID-NRC-2013-0232 EXELON GENERATION COMPANY, LLC Mr. Patrick D. Navin Peach Bottom Atomic Power Station 1848 Lay Road Delta, PA 17314-9032 York and Lancaster Counties U.S. Army Corps Of Engineers, Baltim9re District Page 1of5 COMMONWEAL TH OF PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION Water Quality Certification under Section 401 of the Federal Clean Water Act for the Extended Power Uprate for Exelon Generation Company, LLC-Peach Bottom Atomic Power Station PA DEP File No. EA 67-024 Peach Bottom Atomic Power Station (PBAPS) is an existing nuclear-fueled boiling water reactor electric power generating facility located along the Susquehanna River in Peach Bottom Township, York County and Fulton and Drumore Townships, Lancaster County. PBAPS is owned by Exelon Generation Company, LLC (Exelon) (a wholly-owned subsidiary of Exelon Corporation) and PSEG Nuclear, LLC. The facility is operated by Exelon. Exelon has submitted a License Amendment Request (LAR) to the US Nuclear Regulatory Commission (NRC) for a proposed Extended Power Uprate (EPU) for units 2 and 3. The proposed EPU would allow the units to change from the currently licensed 3514 megawatts-thermal (MWt) to nominally 3951 MWt per unit. Impacts to aquatic resources associated with continued operation of the facility and the EPU include water withdrawal from the Conowingo Pond of the Susquehanna River, consumptive use, and the thermal impacts of the heated water discharges back to the Conowingo Pond. Water will continue to be withdrawn at a maximum rate of2,363.620 million gallons per day (MOD). Water intake will continue to have impingement and entrainment effects on the migratory and resident fish as well as other aquatic species. Consumptive water use at the facility is a maximum of 49.000 MOD. Discharge temperatures include a projected change in the temperature increase at a maximwn from existing 22°F increase to a 25°F increase due to the EPU. Exelon will mitigate the impacts of impingement and entrainment by providing one hundred thousand dollars ($100,000.00) per year for habitat/sediment improvement projects in Lancaster and York Counties.

This will include stream improvement projects, agricultural pasture and barnyard best management practices, and small dam removal projects.

Consumptive use impacts will be mitigated by adherence to the Susquehanna River Basin Commission (SRBC) consumptive use authorization.

Thermal impacts will be mitigated by adherence to the National Pollution Discharge Elimination System (NPDES) permit. Such payments hereunder shall be made for the duration of the operation of PBAPS as an electric generation facility.

On July 23, 2014 the.Commonwealth of Pennsylvania (Commonwealth)

Department of Environmental Protection (Department, DEP or PADEP), issued Section 401 Water Quality Certification to Exelon for the PBAPS EPU project. The P ADEP certifies that the construction, operation and maintenance of the EPU complies with the applicable provisions of sections 301-303, 306, 307 and 316 of the Federal Clean Water Act (33 U.S.C.A. §§ 1311-1313, 1316, 1317 *and 1326) and appropriate requirements of state law. The Department further certifies that the construction, operation and maintenance of the EPU complies with Commonwealth applicable Page 2 of5 water quality standards and that the construction, operation and maintenance of the EPU does not violate applicable Commonwealth water quality standards provided that the construction, operation and maintenance of the EPU complies with the conditions of this certification, including the criteria and conditions of the following conditions and pennits: 1. Discharge Permit -PBAPS shall obtain and comply with a PADEP National Pollutant Discharge Elimination System (NPDES) permit for the discharge of pollutants pursuant to Pennsylvania's Clean Streams Law (35 P.S. §§ 691.1 -691.1001) and all applicable implementing regulations (25 Pa. Code Chapter 92a). 2. Erosion and Sediment Control Permit -PBAPS shall obtain and comply with a PADEP's NPDES Permit for Stormwater Discharges Associated with Construction Activity pursuant to Pennsylvania's Clean Streams Law and Storm Water Management Act (32 P.S. §§ 680.1-680.17) and all applicable implementing regulations (25 Pa. Code Chapter 102) for any earth disturbance activities that require said permit. 3. Water Obstruction and Encroachment Permits -PBAPS shall obtain and comply with a P ADEP Chapter 105 Water Obstruction and Encroachment Permit or Dam Permit for the construction, operation and maintenance of all dams, water obstructions or encroachments associated with the project pursuant to Pennsylvania's Clean Streams Law (35 P.S. §§ 691.1 -691.1001), Dam Safety and Encroachments Act (32 P.S. §§ 673.1-693.27), and Flood Plain Management Act (32 P.S. §§ 679.101-679.601.)

and all applicable implementing regulations (25 Pa. Code Chapter 105).

• 4. Susguehanna River Basis Commission

-PBAPS shall implement the Consumptive Water Use Mitigation Plan as approved and conditioned by the Susquehanna River Basin Commission including any future amendments to that plan. 5. Habitat Improvement Projects-a. Commencing on the first March 1 after completion of the EPU of Unit 2, and by March 1 of each year thereafter, PBAPS shall provide a total ONE HUNDRED THOUSAND DOLLARS ($100,000.00) annually in compensatory mitigation to the Pennsylvania Fish and Boat Commission (PFBC), or to such other conservation district, resource agency or 501(c)(3) organization as directed by the PADEP, for the implementation of habitat/sediment improvement projects.

This will include stream improvement projects, agricultural pasture and barnyard best management practices, and small dam removal projects.

b. This annual compensatory mitigation shall be by corporate check, or the like, made payable to the PFBC in the amount of ONE HUNDRED THOUSAND DOLLARS ($100,000.00) for habitat/sediment Page 3of5 improvement projects in Lancaster or York Counties or to such other entities as the P ADEP shall direct. PBAPS and P ADEP shall receive from PFBC an annual accounting of projects implemented and fund expenditures.

The funds shall be deposited by the PFBC into a special non-lapsing interest bearing account established and to be used only for the HIP Projects required by this Water Quality Certification

("PBAPS HIP Funds"). Such payments shall be made for the duration of the operation of PBAPS as an electric generation facility, unless otherwise modified and approved in writing by PADEP in accordance with paragraph 5.d., below. c. P ADEP shall ensure that each project proposed by the PFBC shall be submitted to the DEP South-central Regional Office Waterways and Wetlands Program Manager, or the successor position, for approval.

No single project shall receive more than $75,000.00 in compensatory mitigation funding from the PBAPS HIP Fund. Funding priority shall be given for projects that include stream forested buffers of at least 50 feet in width and wetland creation projects.

Project funding shall not include any indirect administrative costs and, except where specifically authorized by the DEP, shall not include direct administrative costs. In no case shall direct administrative costs be greater than 10% of the project funding. At PBAPS's option, and subject to land owner approval, for each project signage shall be displayed acknowledging PBAPS's funding of the habitat improvement.

d. Exelon may request that the PADEP revise the compensatory mitigation in response to actions or activities by Exelon that reduce the degree of impingement and/or entrainment at the PBAPS. 6. Water Quality Monitoring

-PADEP retains the right to specify additional studies or monitoring to ensure that the receiving water quality is not adversely impacted by any operational and construction process that may be employed by PBAPS 7. Operation

-For the EPU under this certification, PBAPS shall at all times properly operate and maintain the PBAPS facilities and systems of treatment and control (and related appurtenances) which are installed to achieve compliance with the terms and conditions of this Certification and all required permits. Proper operation and maintenance includes adequate laboratory controls, appropriate quality assurance procedures, and the operation of backup or auxiliary facilities or similar systems installed by PBAPS. 8. Inspection

-The PBAPS, including all relevant records, are subject to inspection at reasonable hours and intervals by an authorized representative of PADEP to determine compliance with this Certification, including all required permits, appropriate requirements of state law and Pennsylvania's Water Quality Standards.

A copy of this Certification shall be available for inspection by the P ADEP during such inspections of the Projects.

Page 4 ofS

9. Transfer of Projects -If the owners of PBAPS intend to transfer any legal or equitable interest in the PBAPS, they shall serve a copy of this Certification upon the prospective transferee of the legal and equitable interest at least thirty (30) days prior to the contemplated transfer and shall simultaneously inform the P ADEP Regional Office of such intent. Notice to PADEP shall include a transfer agreement signed by the existing and new owner containing a specific date for transfer of Certification responsibility, coverage, and liability between them. 10. Correspondence

-All correspondence with and submittals to P ADEP concerning this Certification shall be addressed to: Department of Environmental Protection South-central Regional Office Waterways and Wetlands Program Manager 909 Elmerton A venue Harrisburg, PA 17110-8200

7. Reservation ofRights-PADEP may suspend or revoke this Certification if it determines that PBAPS has not complied with the terms and conditions of this Certification.

P ADEP may require additional measures to achieve compliance with applicable law, subject to PBAPS's applicable procedural and substantive rights. 8. Other Laws -Nothing in this Certification shall be construed to preclude the institution of any legal action or relieve PBAPS from any responsibilities, liabilities, or penalties established pursuant to any applicable federal or state law or regulation.

9. Severability

-The provisions of this Certification are severable and should any provision of this Certification be declared invalid or unenforceable, the remainder of the Certification shall not be affected thereby. Scott Williamson Program Manager Waterways and Wetlands Program t-/z-3 /;'/ I Date Page 5 of5