Description:

Goals of the Rock Creek, Idaho (17040212) Rural Clean Water Program are to significantly reduce the amount of sediment, sediment related pollutants, and animal waste discharging into Rock Creek. Weekly water quality sampling was done through the irrigation season (April - October) on the subbasin drains for suspended sediment, nutrients, and bacteria. Rock Creek itself was sampled for sediment, nutrients, bacteria, metals, minerals, pesticides, stream bank erosion, cobble embeddedness, stream bottom composition, macroinvertebrate population, and fish populations to quantify the off-site impacts of the changes in irrigation drain water quality. Suspended sediment showed a significant decrease in 5 of the 6 subbasins studied through 1985. Data for 1986 and 1987 indicated that in at least some of the subbasins, the suspended sediment loadings have increased. Analysis of substrate revealed that all sample stations are impacted by fine sediments. Three of the subbasins showed significant reductions in organic nitrogen. Pesticides were present in low concentrations in the water column, sediment, and fish tissue. Benthic macroinvertebrates showed greatest diversity at upstream (higher quality) Rock Creek stations and lowest diversity at the middle and lower (lower quality) stream stations. Fish populations in Rock Creek increased since the beginning of the project. 1987 presented a group of variables which compounded the water quality monitoring and data analysis tasks: the year was a drought year; 2 fish kills; several stream channel alterations; the Harrington Fork Fire; a break in the Highline Canal artificially giving Rock Creek a near 100-year flood of short duration; several rock sills placed on upper Rock Creek to help check stream bank erosion flooded a sample site; a precipitation event exceeding 1 in June; and a second hydroelectric facility planned for lower Rock Creek. This progress report contains agency progress reports from the Soil Conservation

Record Details:

Record Type:DOCUMENT

Product Published Date:10/03/1997

Record Last Revised:12/10/2002

Record ID: 5876

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Title :ROCK CREEK, IDAHO RURAL CLEAN WATER PROGRAM, 1987 ANNUAL PROGRESS REPORT

Version :1.0

State :ID

Quality Assurance:

Title :ROCK CREEK, IDAHO RURAL CLEAN WATER PROGRAM, 1987 ANNUAL PROGRESS REPORT

Data Use & Constraints :Quality control check samples for suspended sediment and nutrients demonstrated high precision for the years tested (1985-1987). Spiked samples showed excellent recovery (accuracy) for suspended sediment. Accuracy was also excellent for spiked samples of total Kjeldahl nitrogen, nitrate, total phosphorus, magnesium, sodium, calcium, potassium, and chloride. Recoveries were not as good for dissolved ortho-phosphate during 1985 but improved during 1986 and 1987. Recovery of spiked samples for fluoride was very poor, indicating a natural interference present in surface water. Precision between split samples was best for total Kjeldahl nitrogen, suspended sediment, nitrate, and total phosphorus. The precision was poor for duplicate samples of dissolved ortho-phosphate and fecal coliform bacteria during 1985 but improved to good in 1986.