King County Combined Sewer Overflow Water Quality Assessment for the Duwamish River and Elliott Bay Volume 1: Summary Report Prepared by the Duwamish River and Elliott Bay Water Quality Assessment Team Working Draft - July 17, 1998 Parametrix, Inc. King County Department of Natural Resources 5808 Lake Washington Boulevard, NE Wastewater Treatment Division & Kirkland, Washington, 98033-7350 Water and Land Resources Division 821 Second Avenue Seattle, Washington 98104-1598 King County Combined Sewer Overflow Water Quality Assessment for the Duwamish River and Elliott Bay TABLE OF CONTENTS Introduction ....................................................................................................................1 Overview of Approach....................................................................................................6 Fundamental Elements of the Approach .................................................................... 10 Rationale for the Computer Modeling Approach ....................................................... 12 Stakeholder Committee ............................................................................................. 13 Peer Review.............................................................................................................. 15 Project Team............................................................................................................. 16 Problem Formulation .................................................................................................... 18 The Study Area ......................................................................................................... 18 CSOs......................................................................................................................... 20 Stressors.................................................................................................................... 21 Chemicals.............................................................................................................. 21 Physical Disturbances............................................................................................ 23 Changes in Conventional Water Quality Parameters.............................................. 23 Microbial Contaminants ........................................................................................ 25 Summary of Study Stressors ..................................................................................... 25 Measures of Assessment............................................................................................ 25 Fish ....................................................................................................................... 33 Benthos ................................................................................................................. 33 Shore Birds, Wading Birds, Raptors, and Aquatic Mammals ................................. 34 People ................................................................................................................... 34 Risk Hypotheses........................................................................................................ 34 Hypothesis #1........................................................................................................ 34 Hypothesis #2........................................................................................................ 34 Hypothesis #3........................................................................................................ 35 Hypothesis #4........................................................................................................ 35 Hypothesis #5........................................................................................................ 35 Findings........................................................................................................................ 36 Overall Findings........................................................................................................ 36 Aquatic Life .......................................................................................................... 36 Water Column Dwelling Organisms ...................................................................... 37 Sediment Dwelling Organisms .............................................................................. 37 Wildlife................................................................................................................. 39 People ................................................................................................................... 39 Risks to Aquatic Life ................................................................................................ 41 Risks to Aquatic Life in the Water......................................................................... 41 Risks to Salmon..................................................................................................... 50 Risks to Aquatic Life (Benthos) in the Sediments...................................................... 50 Sediment PAH Biomarkers.................................................................................... 75 Risks to Wildlife ....................................................................................................... 76 Spotted Sandpipers................................................................................................ 83 River Otter ............................................................................................................ 87 July 17, 1998 Volume 1: Summary Report Page iii Working Draft A:\Table of Contents.doc King County Combined Sewer Overflow Water Quality Assessment for the Duwamish River and Elliott Bay Bald Eagle............................................................................................................. 90 Great Blue Heron .................................................................................................. 94 Risks to People.......................................................................................................... 95 Risks to People from Direct Exposures to Sediment and Surface Water............... 107 Risks to People Who Eat Seafood from the Duwamish River and Elliott Bay...... 126 Next Steps................................................................................................................... 143 CSO Related Issues ................................................................................................. 143 Recommendations ............................................................................................... 143 Watershed Related Issues ........................................................................................ 144 Recommendations ............................................................................................... 144 ESA Related Issues ................................................................................................. 144 Recommendations: .............................................................................................. 145 Public Education and Outreach ............................................................................... 145 Recommendations: .............................................................................................. 145 Literature Cited........................................................................................................... 146 Glossary...................................................................................................................... 151 ACCOMPANYING VOLUMES Volume II Problem Formulation and Analysis Plan Volume III Issue Papers Volume IV Modeling LIST OF APPENDICES Appendix A Field Sampling Work Plan Appendix B Stakeholder Report Appendix C Peer Review Report Appendix D Effects Characterization Data and Methods Appendix E Exposure Assessment Data and Methods Appendix F Risk Characterization Methods Appendix G Results of the Aquatic Life Risk Assessment Appendix H Results of the Wildlife Risk Assessment Appendix I Results of the Human Health Risk Assessment Appendix J Human Health Microbiological Risk Assessment Appendix K Results of a Survey on Seafood Collection and Consumption From the Shores of the Duwamish River and Elliott Bay Appendix L Bibliography of Data Reports and Quality Assurance Reviews Appendix M Benthic Infaunal Communities in the Vicinity of the Duwamish/Diagonal Way Combined Sewer Overflow/Storm Drain July 17, 1998 Volume 1: Summary Report Page iv Working Draft A:\Table of Contents.doc King County Combined Sewer Overflow Water Quality Assessment for the Duwamish River and Elliott Bay LIST OF TABLES 1 Fundamental Elements and Approach Used in the Water Quality Assessment .........8 2 CSO Water Quality Assessment Stakeholder Committee....................................... 14 3 Duwamish River and Elliott Bay Water Quality Assessment Project Team............ 17 4. Number of Overflows and Average Volume of Study Area CSOs in the King County Sewage System ......................................................................................... 21 5 Receptors, Assessment Endpoints, Exposure Pathways and Stressors Evaluated in the Duwamish River and Elliott Bay Water Quality Assessment............................ 22 6 Use/Causes and Contributing Sources of Stressors to the EFDC Model and the Impact of Stressors on Primary Receptors ............................................................. 27 7 Summary of Duwamish River and Elliott