The Snake River near Idaho Falls, Idaho. Water quality in the upper Snake River Basin is degraded by numerous anthropogenic activities, including both nonpoint and point sources of pollutants. Other nonpoint sources of pollutants in the basin include beef and dairy cattle feeding operations, atmospheric deposition, and rangeland grazing. These nonpoint sources contribute sediment, bacteria, nutrients, and pesticides to streams and can result in alterations in stream habitat and water temperature. Primary point sources in the upper Snake River Basin include industrial discharges, municipal wastewater-treatment facilities, and fish farms.
Primary pollutants associated with point sources include nitrogen, phosphorus, and organic wastes.
The types and geographic distribution of land use and land cover, the types and numbers of industries and municipalities using the water resources, and the manner in which the water resources are used are factors that create the water-quality conditions in the upper Snake River Basin as described in this report. Approximately 18,000 square miles of rangeland compose roughly one-half of the basin area. Forested and agricultural lands compose 23 and 21 percent, respectively, of the upper Snake River Basin. Urban areas compose less than 1 percent of the basin area. Primary land uses and land cover in the mountainous northern and eastern parts of the basin are forested land and rangeland, and although forest practices and grazing may degrade water quality, water resources and the aquatic biological communities in these areas are generally of high quality.