Region 10, U.S. EPA, has conducted chemical and biological monitoring during low-flow conditions from 1972 to 1986 along the South Fork Coeur d'Alene River in northern Idaho, a stream with a long history of severe metals pollution from mining activities. During 1986, metals analysis of sediments and tissues from the lower Coeur d'Alene River and Coeur d'Alene Lake was also conducted. Due chiefly to effluent controls at the Bunker Hill Complex Superfund site, concentrations of zinc, cadmium and lead were reduced since the 1970's. Although levels of zinc and cadmium remain well above national criteria for protection of cold water biota, recovery of aquatic life has been substantial, with the lower mainstream now supporting a successful sports fishery. Sediments in the lower Coeur d'Alene system remain heavily contaminated with toxic metals, although high levels in edible fish tissues were not found. Allowable permit limits (as of 1986) for metals (primarily cadmium) have the potential of increasing in-stream metals concentrations. Water quality-based permits are particularly important for aquatic life protection of the South Fork upstream of Mullan and the mainstream downstream of the S.F. confluence.

"September 1988." "EPA 910/9-88-216." PB89-217962. Includes bibliographical references (p. 13-14).