2019 ANNUAL MARINE ENVIRONMENTAL ANALYSIS AND INTERPRETATION San Onofre Nuclear Generating Station ANNUAL MARINE ENVIRONMENTAL ANALYSIS AND INTERPRETATION San Onofre Nuclear Generating Station July 2020 Page intentionally blank Report Preparation/Data Collection – Oceanography and Marine Biology MBC Aquatic Sciences 3000 Red Hill Avenue Costa Mesa, CA 92626 Page intentionally blank TABLE OF CONTENTS LIST OF FIGURES ........................................................................................................................... iii LIST OF TABLES ...............................................................................................................................v LIST OF APPENDICES ................................................................................................................... vi EXECUTIVE SUMMARY .............................................................................................................. vii CHAPTER 1 STUDY INTRODUCTION AND GENERATING STATION DESCRIPTION 1-1 INTRODUCTION ................................................................................................................... 1-1 PURPOSE OF SAMPLING ......................................................................................... 1-1 REPORT APPROACH AND ORGANIZATION ........................................................ 1-1 DESCRIPTION OF THE STUDY AREA ................................................................... 1-1 HISTORICAL BACKGROUND ............................................................................................ 1-3 GENERATING STATION OPERATION - 2019 ........................................................ 1-3 2019 RECEIVING WATER MONITORING PROGRAM .................................................... 1-3 LITERATURE CITED ............................................................................................................ 1-5 CHAPTER 2 OCEANOGRAPHIC PROCESSES AND WATER QUALITY .......................... 2-1 INTRODUCTION ................................................................................................................... 2-1 METHODS .............................................................................................................................. 2-1 DATA COLLECTION PROGRAM............................................................................. 2-1 RESULTS AND DISCUSSION .............................................................................................. 2-5 OCEAN TEMPERATURE ........................................................................................... 2-5 WATER QUALITY AT FIXED MONITORING STATIONS ................................. 2-20 AERIAL PHOTOGRAPHIC SURVEYS ................................................................... 2-22 LITERATURE & SOURCES CITED ................................................................................... 2-27 CHAPTER 3 KELP DENSITY STUDY ........................................................................................ 3-1 INTRODUCTION ................................................................................................................... 3-1 BACKGROUND .......................................................................................................... 3-1 STUDY APPROACH ................................................................................................... 3-2 METHODS .............................................................................................................................. 3-4 STUDY SITES.............................................................................................................. 3-4 SAMPLING .................................................................................................................. 3-4 DATA ANALYSIS ....................................................................................................... 3-6 RESULTS ................................................................................................................................ 3-6 BIOLOGICAL RESULTS ............................................................................................ 3-6 SUBSTRATE COMPOSITION ................................................................................. 3-13 DISCUSSION ........................................................................................................................ 3-16 GIANT KELP AT SOK .............................................................................................. 3-16 COMPARISON WITH GIANT KELP AT SMK ...................................................... 3-22 SUBSTRATE .............................................................................................................. 3-23 UNDERSTORY KELPS ............................................................................................ 3-26 LARGE INVERTEBRATE SPECIES ....................................................................... 3-27 CONCLUSIONS.................................................................................................................... 3-31 LITERATURE CITED .......................................................................................................... 3-32 i CHAPTER 4 IN-PLANT FISH ASSESSMENT ........................................................................... 4-1 INTRODUCTION ................................................................................................................... 4-1 CHAPTER 5 FISH POPULATION MONITORING .................................................................. 5-1 INTRODUCTION ................................................................................................................... 5-1 METHODS .............................................................................................................................. 5-1 STUDY SITES.............................................................................................................. 5-1 SAMPLING .................................................................................................................. 5-2 ANALYSIS ................................................................................................................... 5-3 RESULTS ................................................................................................................................ 5-3 2019 FISH CATCH ...................................................................................................... 5-3 LIFE HISTORY ANALYSIS ....................................................................................... 5-9 HISTORIC ABUNDANCES ...................................................................................... 5-11 CONCLUSION ...................................................................................................................... 5-15 LITERATURE CITED .......................................................................................................... 5-17 ii LIST OF FIGURES Figure 1-1. Location of Study Area. Isobaths in meters. .......................................................... 1-2 Figure 2-1. Locations of continuous temperature monitoring Stations C2S, F2S, and C22S offshore San Onofre. .......................................................................................................... 2-2 Figure 2-2. Locations of temperature and water quality profiles offshore San Onofre. ........... 2-4 Figure 2-3. Coastal ocean mean sea surface temperature (SST °C) deviations from normal, January through June 2019. NOAA Coast Watch, MUR Analysis SST Anomalies. ........ 2-6 Figure 2-4. Coastal mean sea surface temperature (SST °C) deviations from normal, July through December 2019. NOAA Coast Watch, MUR Analysis SST Anomalies. ............. 2-7 Figure 2-5. Pacific Sea Surface Temperature Anomalies for October 2019 showing above average temperature conditions along the central-Pacific Equatorial Region while the nearshore temperatures along the southern California coast of the United States were slightly above normal. ........................................................................................................ 2-8 Figure 2-6. Daily mean surface and bottom water temperatures at Station C22S for 2019. Short-term temperature decreases are marked with arrows. ............................................ 2-10 Figure 2-7. Daily mean surface and bottom water temperatures at Station C2S for 2019. .... 2-10 Figure 2-8. Daily mean surface and bottom water temperatures at Station F2S for 2019. .... 2-10 Figure 2-9. Comparison of daily surface temperatures during 2019 at San Onofre with daily regional surface temperatures from the San Clemente area from 1955-2019 (SIO 2020). .............................................................................................................................. 2-13 Figure 2-10. Daily mean vertical temperature gradients at Stations C22S, C2S, and F2S for 2019. Note: scales vary slightly. ................................................................................. 2-15 Figure 2-11. Daily mean surface temperature differences between the reference Station (C22S) and the impact Stations (C2S and F2S) for 2019. (Note: vertical scale varies). 2-17 Figure 2-12. Daily mean bottom temperature differences between the reference Station (C22S) and the impact Stations (C2S and F2S) for 2019. (Note: vertical scale varies). 2-17 Figure 2-13. False-color surface water temperature contour plots recorded during quarterly water quality cruises in 2019. ..........................................................................