Site-Specific Selenium Criterion (Idaho)
Formation Environmental designed and implemented a multi-year field and laboratory study to develop a selenium criterion for protection of aquatic life. Field studies characterized the ambient biological, chemical, and physical conditions in local streams. Laboratory toxicity studies assessed the potential of site-specific exposure to selenium to cause effects on trout reproduction.
Eggs from two species of wild-collected trout were tested in a laboratory setting to examine a number of endpoints, including among those, survival, growth, and deformities. Tissue-based effects thresholds were derived for each of the two trout species studied.
Thresholds were input into a food-web-based, trophic transfer model to derive a protective selenium concentration for water in local streams based on resident trout and ambient exposure conditions. That threshold was then evaluated relative to the monitored water-quality conditions and trout populations present during the field studies.