The Academy of Natural Sciences of Philadelphia has been conducting biological and water quality studies of the Savannah River since 1951. These studies are designed to assess potential effects of Savannah River Site (SRS) contaminants and warm-water discharges on the general health of the river and its tributaries. The study design includes multiple biological groups spanning a broad range of ecological roles, both because no single group is the best indicator of every component of water quality and because there is wide-spread agreement that protecting the entire system is important.