The potential for selenium to severely affect fish and bird populations became clearly evident after the events at Belews Lake (North Carolina) and Kesterson Reservoir (California) in the late-1970s and mid-1980s, respectively. Since then, substantial research has been conducted on the fate and effects of selenium in aquatic systems, which have proven to be quite complex. The fate of selenium and its bioavailability to aquatic organisms are highly variable depending on
site-specific biogeochemistry. The amount of selenium that is bioavailable at the base of the food web largely determines the exposure potential of sensitive fish and bird taxa, which are predominantly exposed to selenium via their diets. This means that there is a wide range of waterborne selenium concentrations among sites that could ultimately have adverse effects on fish and birds.
Windward’s extensive experience in critically reviewing selenium toxicity studies with fish and birds has been used to recommend selenium guidelines for these taxa; we have also provided technical reviews of toxicity studies and draft ambient water quality criteria (AWQC) documents on behalf of the US Environmental Protection Agency (EPA). Our staff have supported clients in the development of selenium bioaccumulation models for linking tissue-based selenium guidelines to waterborne concentrations. And lastly, Windward has worked on several site-specific selenium risk assessments for clients in the mining industry.