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Environmental Health - Toxic Substances

Toxics Program Remediation Activities

Evaluation of Selenium Remediation Plans

  • Feasibility Studies
  • Site Characterization
Location California Central Valley and San Francisco Bay, CA
  • Computer Simulations
  • Load Allocations
Contaminants Selenium

Understanding the fate and effects of selenium is critical to evaluating remediation options. USGS scientists developed a computer model and applied it to evaluate one of the most complex and controversial agricultural drainage problems in the Nation—irrigation of western San Joaquin Valley agricultural fields and disposal of agricultural-drainage water containing selenium via a proposed extension of the San Luis Drain into the San Francisco Bay. The model can forecast environmental selenium concentrations, bioaccumulation of selenium, and selenium effects on resource fish and aquatic birds living in waters receiving drainage from agricultural activities. Accurate forecasting of the environmental fate of selenium is crucial because of selenium's effect on reproduction in aquatic birds and fish. Water resource managers in the San Joaquin Valley and San Francisco Bay area have proposed several plans, some dating back to 1955, to remediate drainage from irrigated lands and the associated salt buildup in soils. Some of the plans include extending the San Luis Drain, which has been closed since 1986, so that agricultural drainage water can be discharged to the San Francisco Bay. When the San Luis Drain was active and discharging drainage water into a national wildlife refuge in the San Joaquin Valley in the past, the selenium in the water caused fish mortality and deformities in aquatic birds, such as ducks. USGS scientists evaluated several realistic options (ones that meet current water needs) using the model, and predicted that selenium concentrations in water, sediment, clams, ducks, and fish in the Bay would exceed proposed criteria during the low-flow season for all options that were evaluated.

The U.S. Fish and Wildlife Service, the San Francisco Estuary Project, and other state and federal agencies have held workshops on agricultural (irrigation) drainage that featured the results and application of the model. The results of the modeling study and additional model applications are being used to further evaluate and help design options to remediate selenium contamination and to help with the overall restoration efforts for the San Francisco Bay under the auspices of the CALFED Bay-Delta Program.

More Information
  • Samuel N. Luoma, USGS, National Research Program, Menlo Park, CA,
  • Theresa S. Presser, USGS, National Research Program, Menlo Park, CA,
Luoma, S.N., and Presser, T.S., 2000,
Forecasting selenium discharges to the San Francisco Bay-Delta Estuary--Ecological effects of a proposed San Luis Drain extension: U.S. Geological Survey Open-File Report 00-416, 387 p.

San Francisco Bay Information

Selenium Information

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Page Last Modified: Friday, 29-Apr-2016 14:24:48 EDT