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HENRY'S FORK AND SNAKE RIVER BASIN, IDAHO - WATER QUALITY REPORT, 1973
Description:
Reported problems in the Henrys Fork and Snake River Basin (17040202, 17040203, 17040201) include bacteria levels exceeding water quality standards, dissolved oxygen standards violations, and excessive algal blooms resulting in aesthetic problems and contributing to DO depressions. During August 1973, the EPA conducted an intensive 3-day survey of the Henrys Fork from Henrys Lake outlet to the mouth and the Snake River from Palisades Reservoir to Roberts. In addition, EPA has been routinely monitoring selected stations in the upper Snake Basin since May 1973. During spring and summer, total phosphorus levels in the Henrys Fork below St. Anthony are above algal bloom potential. Major contributors of phosphorus were the discharge during drawdown of Island Park Reservoir, the Teton River, and return flows. Waters emerging from Island Park Reservoir were significantly warm, depressed in dissolved oxygen, high in total phosphorus, and high in ammonia nitrogen. Nitrate levels increase significantly below St. Anthony. Bacteria levels in Ashton, St. Anthony, and Rexburg sewage treatment plant effluents were above water quality standards. Bacteria levels were found to be high in the Teton River near the mouth and in some canals and wasteways. Irrigation return flow and runoff contribute significant levels of phosphorus and nitrogen to the Upper Snake River Basin.