Assessing the Need for Development of Site-Specific Water-Quality Objectives for Selenium for the Newport Bay, California, Watershed

The Newport Bay watershed, including San Diego Creek and Newport Bay, California, has been listed as impaired due to toxic constituents, including selenium. Various studies, initiated as part of the Total Maximum Daily Load (TMDL) implementation program for the watershed, have characterized sources, loads, transport, and fate of selenium in the watershed, including biological uptake. The available database and general understanding of the watershed were used to construct separate conceptual models for exposure pathways and food-web relationships for selenium in freshwater and saltwater habitats of the Newport Bay watershed. The conceptual models were used in conjunction with focused sampling to fill data-gaps and data summary to describe the selenium in sediment, water, and food web categories, and to expand the database so it would be most useful for future modeling of selenium transport, fate, and effects. Preliminary data summaries indicate that bird eggs do not show bioaccumulation of selenium to concentrations as elevated as those in prey items for birds, but fish tissue concentrations more generally match invertebrate prey levels. Such information will be useful in designing the final model that will link selenium loading to potential biological effects.