ECOLOGICAL RISK ASSESSMENT FOR SELENIUM IN THE EVALUATION OF RESTORATION ALTERNATIVES FOR SALTON SEA, CALIFORNIA

摘要

Selenium (Se) is a chemical of ecological concern at the Salton Sea because it occurs at elevatedrnconcentrations in water, sediment, and biota of this terminal lake in southern California. Most Sernin the Salton Sea enters through flows from the Alamo, New, and Whitewater rivers or in flowsrnfrom agricultural drains discharging directly to the Sea. The State of California is required tornevaluate alternatives for restoration of long-term stable aquatic and shoreline habitats for thernhistoric levels and diversity of fish and wildlife that depend on the Salton Sea and for protectionrnof water quality. Ecological risks associated with Se were evaluated under eight restorationrnalternatives (as well as current conditions and no action) in a programmatic-level environmentalrnimpact report. Varying types and configurations of marine, estuarine, freshwater, and terrestrialrnhabitats would exist under the different alternatives. Ecological risks were associated primarilyrnwith existing and future Se concentrations in sediment and inflow waters. In addition torncompleting an ecological risk assessment for each of the habitat types in each of the alternatives,rnwe developed an approach for ranking risk among alternatives based on the combination ofrnhabitats, representative receptors evaluated, and area of each habitat. Results of the rankingrnenable a comparison of alternatives with respect to their expected Se-associated risks for fish andrnaquatic birds (the main receptors of concern) and facilitate a maximization of habitat creationrnwhile minimizing Se exposure and risk.