Middle Snake River water quality study; Phase I. Final report

The purpose of the project was to collect, analyze, assemble, and assess water quality data and resulting chemical/nutrient loads entering and transported in the Middle Snake River Reach of Idaho. This reach is defined as the reach between Milner Dam and King Hill. A database of historical, pertinent water quality data were prepared and formatted for inclusion in the STORET national water quality database. Concurrent sampling of 55 sites, including 13 instream sites, effluent from 10 fish hatcheries, 19 irrigation return flow streams, and 13 tributary streams, was conducted for the period of June 1, 1990 through July 25, 1991. Data will be utilized in a river water quality model being developed by the EPA. This reach of the Snake River accumulates and transports up to 30 tons/day of nitrate+nitrite N, 2 tons/day of phosphate P, and 350 tons/day of suspended solids. Water quality in the reach is impaired by the nutrient and sediment loads and extreme low flows experienced over the last four years. Submitted to the Idaho Department of Health and Welfare, Division of Environmental Quality