Forecasting Selenium Discharges to the San Francisco Bay-Delta Estuary: Ecological Effects of A Proposed San Luis Drain Extension Open-File Report 00-416 U.S. Department of the Interior U.S. Geological Survey FORECASTING SELENIUM DISCHARGES TO THE SAN FRANCISCO BAY-DELTA ESTUARY: ECOLOGICAL EFFECTS OF A PROPOSED SAN LUIS DRAIN EXTENSION By Samuel N. Luoma Theresa S. Presser ___________________________________________________________ U.S. GEOLOGICAL SURVEY Open-File Report 00-416 Water Resources Division National Research Program This project has been funded in part by the United States Environmental Protection Agency Interagency Agreement DW-14-95534701-4 (Region 9, Water Division) and Joint Funding Agreements with Contra Costa County and Contra Costa Water District. The contents of this document do not necessarily reflect the views and policies of the U.S. Environmental Protection Agency, Contra Costa County, or Contra Costa Water District. Menlo Park, California 2000 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. _________________________________________________________________ For information write to: Copies of the report can be purchased from: Samuel N. Luoma U.S.Geological Survey Theresa S. Presser Information Services U.S. Geological Survey Box 25286 345 Middlefield Road Federal Center Menlo Park, CA 94025 Denver, CO 80225 303-202-4200 ii CONTENTS ABSTRACT 1 INTRODUCTION 3 Generic Selenium Issues ......................................................................................................................6 Selenium Issues in the Bay-Delta.........................................................................................................9 ISSUES ARE CHANGING 15 APPROACH TO UNDERSTANDING CHANGING ISSUES 20 SOURCES 22 Inputs of Selenium from Agriculture in the Western San Joaquin Valley.........................................23 The problem ....................................................................................................................................23 Prediction of long-term reservoir: how sustainable is discharge? ..................................................24 Selenium concentrations in source waters ......................................................................................25 Drainage management.....................................................................................................................27 Forecasting loads of selenium: general consideratons....................................................................28 How to determine load....................................................................................................................30 Characteristics of agricultural subareas ..........................................................................................32 Development of forecasts................................................................................................................37 Forecasting selenium loadings using the sum of data from all subareas ........................................38 Forecasting selenium loadings using data from individual subareas..............................................39 Loading scenarios ...........................................................................................................................40 Scenarios based on the capacity of an extension of the San Luis Drain.........................................42 The San Joaquin River as a conveyance facility, a de facto drain..................................................43 Summary .........................................................................................................................................44 Inputs of Selenium from Oil Refineries .............................................................................................45 Inputs of Selenium from the Sacramento River .................................................................................46 Summary.............................................................................................................................................47 HYDRAULIC CONNECTIONS AND CONVEYANCE OF SELENIUM TO THE BAY-DELTA 47 CONCENTRATIONS OF SELENIUM IN THE BAY-DELTA 49 Interpreting Effects of Source Water Se Loads on Receiving Water Se Concentrations...................49 Existing Concentrations in the Bay-Delta..........................................................................................51 Regional baseline ............................................................................................................................51 Concentrations observed in the Bay-Delta......................................................................................52 iii CHEMICAL FORMS OF SELENIUM (SPECIATION) 54 PARTICULATE AND SEDIMENT-ASSOCIATED SELENIUM 55 Processes Affecting Particulate Selenium..........................................................................................55 Partitioning......................................................................................................................................55 Transformation................................................................................................................................56 Range of distribution coefficients (Kd’s)........................................................................................58 Sources of Particulate Selenium in the Bay-Delta .............................................................................59 Particulate selenium in the San Joaquin River................................................................................59 Particulate selenium in the Delta ....................................................................................................61 Particulate selenium in existing portion of the San Luis Drain ......................................................61 Sedimentary selenium in Suisun Bay and San Pablo Bay ..............................................................62 Suspended particulate selenium in Suisun Bay and San Pablo Bay ...............................................63 Summary .........................................................................................................................................64 BIOACCUMULATION OF SELENIUM BY INVERTEBRATES 64 Processes ............................................................................................................................................64 Selenium in Invertebrates from the Bay-Delta...................................................................................65 Summary of Selenium in Invertebrates from the Bay-Delta..............................................................68 Modeling Selenium Bioaccumulation in the Bay-Delta: DynBaM....................................................69 BIOACCUMULATION OF SELENIUM BY PREDATORS 71 Dietary Exposure................................................................................................................................71 Existing Selenium Concentrations in Tissues of Birds and Fish in the Bay-Delta............................73 EFFECTS OF SELENIUM ON WILDLIFE 76 Relating Selenium Concentrations in Food (Prey) to Effects in Predators........................................78 Fish..................................................................................................................................................78 Birds................................................................................................................................................78 Relating Selenium Concentrations in Tissue to Effects in Predators.................................................79 Fish................................................................................................................................................. 79 Birds................................................................................................................................................81 Comparison to Selenium Hazard Index..............................................................................................83 FORECASTS 85 Forecasts of Composite Input Loads and Volumes to the Bay-Delta ................................................85 Forecasts of Waterborne Selenium Concentrations ...........................................................................89 iv Calculating composite selenium input (or freshwater endmember) concentrations.......................89 Comparing forecasted selenium concentrations to observed conditions prior to refinery cleanup 90 Forecasting influence of a San Luis Drain extension: seasonal waterborne selenium concentrations .................................................................................................................................91 Forecasting influence of selenium release via the San Joaquin River: seasonal waterborne selenium concentrations .................................................................................................................................92 Monthly waterborne selenium concentrations................................................................................94 Summary of forecasts......................................................................................................................96 Forecasts of Speciation and