## Open File Report 00-416

By Samuel N. Luoma and Theresa S. Presser



## Note: This report has been superseded by USGS Professional Paper 1646

The full report is available in pdf. Links to the pdf

. 

## CONTENTS

ABSTRACT INTRODUCTION Generic Selenium Issues Selenium Issues in the Bay-Delta ISSUES ARE CHANGING APPROACH TO UNDERSTANDING CHANGING ISSUES SOURCES Inputs of Selenium from Agricultur e in the Western San Joaquin Valley The problem Prediction of long-term reservoir: how sustainable is discharge? Selenium concentrations in source waters Drainage management Forecasting loads of selenium: general consideratons How to determine load Characteristics of agricultural subareas Development of forecasts Forecasting selenium loadings using the sum of data from all subareas Forecasting selenium loadings using data from individual subareas Loading scenarios Scenarios based on the capacity of an extension of the San Luis Drain The San Joaquin River as a convey ance facility, a de facto drain Summary Inputs of Selenium from Oil Refineries Inputs of Selenium from the Sacramento River Summary HYDRAULIC CONNECTIONS AND CONVEYANCE OF SELENIUM TO THE BAY-DELTA CONCENTRATIONS OF SELENIUM IN THE BAY-DELTA 

### Open-File Report 00-416--Forecasting Se lenium discharges to the San F. .. http://pubs.usgs.gov/of/2000/ofr00-416/

1 of 5 4/21/2016 12:00 PMInterpreting Effects of Source Water Se Loads on Receiving Water Se Concentrations Existing Concentrations in the Bay-Delta Regional baseline Concentrations observed in the Bay-Delta CHEMICAL FORMS OF SELENIUM (SPECIATION) PARTICULATE AND SEDIMENT-ASSOCIATED SELENIUM Processes Affecting Particulate Selenium Partitioning Transformation Range of distribution coefficients (Kd’s) Sources of Particulate Selenium in the Bay-Delta Particulate selenium in the San Joaquin River Particulate selenium in the Delta Particulate selenium in existing portion of the San Luis Drain Sedimentary selenium in Suisun Bay and San Pablo Bay Suspended particulate selenium in Suisun Bay and San Pablo Bay Summary BIOACCUMULATION OF SELENIUM BY INVERTEBRATES Processes Selenium in Invertebrates from the Bay-Delta Summary of Selenium in Inve rtebrates from the Bay-Delta Modeling Selenium Bioaccumulation in the Bay-Delta: DynBaM BIOACCUMULATION OF SELENIUM BY PREDATORS Dietary Exposure Existing Selenium Concentrations in Tissues of Birds and Fish in the Bay-Delta EFFECTS OF SELENIUM ON WILDLIFE Relating Selenium Concentrations in Food (Prey) to Effects in Predators Fish Birds Relating Selenium Concentrations in Tissue to Effects in Predators Fish Birds Comparison to Selenium Hazard Index FORECASTS Forecasts of Composite Input Loads and Volumes to the Bay-Delta Forecasts of Waterborne Selenium Concentrations Calculating composite selenium input (or freshwater endmember) concentrations Comparing forecasted selenium concentrationsto observed conditio ns prior to refinery cleanup Forecasting influence of a San Luis Drain extension: seasonal waterborne selenium concentrations Forecasting influence of selenium release vi a the San Joaquin River: seasonal waterborne selenium concentrations Monthly waterborne selenium concentrations Summary of forecasts Forecasts of Speciation and Transformation Defining speciation, transformation, and bioavailability Comparison to Bay-Delta condit ions prior to refinery cleanup Forecasts of Particulate Selenium Concentrations Sediment quality guidelines Particulate selenium concentrations (all conc entrations are in μg Se/g dry weight, dw) Cumulative summary Other possible scenarios 

### Open-File Report 00-416--Forecasting Se lenium discharges to the San F. .. http://pubs.usgs.gov/of/2000/ofr00-416/

2 of 5 4/21/2016 12:00 PMForecasts of Bioaccumulation in Consumer Organisms Calculating bioaccumulation in a generic bivalve (modeling) Comparing model predictions to Bay-Delta conditions prior to refinery cleanup Bivalves as food for predators Generic bivalve selenium concentrat ions (i.e., contamination of prey) Effects on predators based on se lenium concentrations in food Forecast of Selenium Concentrat ions in Tissues of Predators Choice of predators Relation of selenium concentrations in bivalv es to selenium concentrations in predators Selenium concentrations in predators CONCLUSIONS Cumulative Impacts on the Bay-Delta Extent and Sustainability of Agricultur al Discharge from the San Joaquin Valley Implications and Monitoring Needs ACKNOWLEDGMENTS REFERENCES



# Abstract

During the next few years, federal and state ag encies may be required to evaluate proposals and discharge permits that could significantly change selenium (Se) inputs to the San Francisco Bay-Delta Estuary (Bay-Delta), particularly in the North Bay (i.e., Suisun Bay and San Pablo Bay). These decisions may include discharge requirements for an extension of the San Luis Drain (SLD) to the estuary to convey subsur face agricultural drainage from the western San Joaquin Valley (SJV), a renewal of an agreement to allow the ex isting portion of the SLD to convey subsurface agricultural drainage to a tributary of the San Jo aquin River (SJR) (coincid ent with changes in flow patterns of the lower SJR), and refi nements to promulgated Se criteria for the protection of aquatic life for the estuary. Understanding the biotransfer of Se is essential to evaluating the fate and impact of proposed changes in Se discharges to the Bay-Delta. However, past monitoring programs have not addressed the specific protocols necessary for an element that bioaccumulates. Confusion about Se threats in the past have stemmed from failure to consider the full complexity of the processes that result in Se toxicity. Past studies show that pred ators are more at risk from Se contamination than their prey, making it difficult to use traditio nal methods to predict ri sk from environmental concentrations alone. In this report, we employ a novel procedure to model the fate of Se under different, potentially realistic load scenarios from the SJV. For each potential load, we progressively forecast the resulting environmental concentrations , speciation, transformati on to particulate form, bioaccumulation by invertebrates, trophic transferto predators, and effects in those predators. Enough is known to establish a first order understan ding of effects should Se be discharged directly into the North Bay via a conveyance such as the SLD. Our approach uses 1) existing knowledge concer ning the biogeochemical reactions of Se (e.g., speciation, partitioning between dissolved an d particulate forms, and bivalve assimilation efficiency) and 2) site-specific data mainly from 1986 to 1996 on clams and bottom-feeding fish and birds. Forecasts of Se loading from oil refine ries and agricultural drainage from the SJV enable the calculation of a composite freshwater endmembe r Se concentration at the head of the estuary and at Carquinez Strait as a foundation for modeling. Our analysis of effects also takes into account the mode of conveyance for agricultural drainage (i.e., the SLD or SJR). The effects of variable flows on a seasonal or monthly basis from the Sacramento River and SJR are also considered. The results of our forecasts for external SJV watershed sources of Se mirror predictions made since 1955 of a worsening salt (and by inference, Se) buildup exac erbated by the arid climate and irrigation for agricultural use. We show that the reservoir of Se in the SJV is sufficient to provide loading at an annual rate of appr oximately 42,500 pounds (lbs) of Se to a Bay-Delta disposal point for 63 to 304 years at the lower range of our projec tions, even if influx of Se from the California 

### Open-File Report 00-416--Forecasting Se lenium discharges to the San F. .. http://pubs.usgs.gov/of/2000/ofr00-416/

3 of 5 4/21/2016 12:00 PMCoast Ranges could be curtailed. Disposal of wa stewaters on an annual basis outside of the SJV may slow the degradation of vall ey resources, but drainage alone cannot alleviate the salt and Se buildup in the SJV, at least within a century. Our forecasts show the different proportions of Se loading to the Bay-Delta. Oil refinery loads from 1986 to 1992 ranged from 11 to 15 lbs Se per day; with treatment and cleanup, loads decreased to 3 lbs Se per day in 1999. In contra st, SJV agricultural drainage loads could range from of 45 to 117 lbs Se per day across a set of reasonable conditions. Components of this valley-wide load include five source subareas (i.e., Grassland, Westlands, Tulare, Kern, and Northern) based on water and dr ainage management. Loads vary per subarea mainly because of proximity of the subarea to geologic sources an d irrigation history. Loads from the Sacramento River, depending on flow conditions, range from 0.8 to 10 lbs Se per day. A consistent picture of ecologic al risk emerges for the Bay-Delta based on concurrent lines of evidence. The threat to the estuary is greate st during low flows and dry years. Where Se undergoes reactions typical of low flow or longer residence time, highly problematic bioaccumulation in prey (food) is forecast to result. The Bay-Delta predators—surf scoter, greaterand lesser scaup, and white sturgeon—appear to be most at risk because they feed on filterfeeding bivalves. Recent findings add Sacramento spli ttail to that list. During the low flow season of dry years, the lower range of proposed protective guidelines for waterbor ne, particulate, dietary, and predator tissue Se is exceeded under the mo st likely forecast of Se inputs from a proposed SLD extension. Also under low flow conditions, the upper range of guidelines (i.e., high certainty of adverse effects) is exceeded in all instances exceptat the lowest load considered. High flows afford some protection in the forecast SJR scenario s under certain conditions. However, meeting a combined goal of releasing a specific load du ring maximum flows and keeping Se concentrations below a certain objective to protect against bi oaccumulation may not al ways be attainable. Management of the SJR on a constant concen tration basis could also create problematic bioaccumulation during a wet year , especially during the low fl ow season, because high flows translate to high loads that are not always offset by seasonal inflows. Prior to refinery cleanup, Se contamination wa s sufficient to threaten reproduction in key species within the Bay-Delta ecosystems and human health advisories were posted based on Se concentrations in livers of diving ducks. During this time, Se concentratio ns in the Bay-Delta were well below the most stringent water quality crit eria. Enhanced biogeochemical transformations to bioavailable particulate Se and efficient uptake by bivalves and then predators characterized the system. If these biogeochemical conditions continue to prevail, the forecasts suggest the risk of adverse effects will be difficult to eliminate under an out-of-valle y resolution to the Se problem. The forecasts for Se loading present a new tool to evaluate ecological effects based upon the major processes leading from loads through consum er organisms to predators. It is a feasible approach for site-specific analys is and could provide a framewor k for developing new protective criteria. We conclude that credible protective criteria should be based on 1) contaminant concentrations in sources, such as particulate ma terial, that most influe nce bioavailability and 2) concentrations in media and orga nisms relevant to vulnerable fo od webs. Existing criteria for water, particulate material, and tissue of prey and predators should be used in combination to evaluate risk or hazard. Bivalves appear to be the most sensitive indicator of Se contamination in the Bay-Delta.
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### Open-File Report 00-416--Forecasting Se lenium discharges to the San F. .. http://pubs.usgs.gov/of/2000/ofr00-416/

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### POINTS OF CONTACT AND ADDITIONAL INFORMATION

Samuel N. Luoma Theresa S. Presser U.S. Geological Survey 345 Middlefield Road, MS 439 Menlo Park, CA 94025



### Copies of this report may be purchased from:

U.S. Geological Survey Information Services Box 25286 Federal Center Denver, CO 80225 Or call: 1-888-ASK-USGS
(updated 3/27/2007 by Mike Diggles)



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### Open-File Report 00-416--Forecasting Se lenium discharges to the San F. .. http://pubs.usgs.gov/of/2000/ofr00-416/

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