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SELECTED TRIBUTARIES OF THE LOWER PORTNEUF RIVER, BANNOCK COUNTY, IDAHO- WATER QUALITY STATUS REPORT, 1987
Description:
The Lower Portneuf River, Idaho (17040208) was identified in the Agricultural Pollution Abatement Plans as a first priority stream segment for the reduction of agriculture related pollutants above Marsh Creek. Below Marsh Creek, it was identified as being moderately affected by agricultural pollution. A water quality study was conducted from November 19, 1985 to July 8, 1986. Eight tributaries of the Portneuf River were chosen as sampling sites. Nutrients and sediment are the major pollutants during times of high flow, although every stream consistently exceeded most EPA nutrient standards throughout the entire study period. Bacterial counts are inversely related to flow and are another major pollutant during low creek flows. Only 3 of the 8 streams sampled (Rapid Creek, Dempsey Creek and the North Fork of Pocatello Creek) did not exceed State water quality standards for coliform bacteria. Sediment loss peaked at 237 tons on 11 April 1986 for the tributaries sampled. Sediment loading for the study period averaged 63.8 tons/day for all the monitoring stations combined. Drewes, B. 1987. Water Quality Status Report No. 72. Idaho Department of Health and Welfare, Water Quality Bureau, Boise, ID. 28 pp.