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SOUTH FORK COEUR D'ALENE RIVER, NORTHERN IDAHO. DISTRIBUTION OF HEAVY METAL LOADINGS
Description:
The purpose of this study is to determine the current distribution of metals loadings to the South Fork Coeur dAlene River, Idaho (17010301, 17010303). Water quality and flow data obtained from EPA Region 10 for September 1986 and September 1987 are used to determine loadings during the low-flow season. Data from May of 1988 are used to determine loadings for the high-flow season. Total and dissolved loads of arsenic, cadmium, copper, lead, mercury, and zinc are calculated for the river and tributary streams. For the point-source discharges, loadings are calculated using average flow rates and metals concentrations as recorded on monthly NPDES discharge monitoring reports. Diagrams of the South Fork River basin showing sample locations and total metals loadings for cadmium, lead, and zinc are compiled. Because most point sources of metals to the South Fork have been effectively controlled, water quality degradation in the basin is in large part a result of non-point sources and remobilization of floodplain and river sediment. Tailings are dispersed throughout the floodplain and continue to degrade the waters by their availability to leaching and erosion. Impacts to the river are greatest during high flows which result in an increase in contaminant loads to the river. Water quality also becomes critical for aquatic life during low-flow periods when metal concentrations peak. Ridolfi, C.A. 1990. Final report submitted to U.S. EPA Region 10 for the National Network for Environmental Management Studies. 36 pp.