Sediment transport by irrigation return flows in four small drains within the DID-18 drainage of the Sulphur Creek basin, Yakima County, Washington, April 1979 to October 1981

Suspended sediment, water discharges, and water temperatures were monitored in four small drains in the DID-18 basin of the Sulphur Creek basin, a tributary to the Yakima River, Washington. Water outflow, inflow, and miscellaneous sites were also monitored. The information was used to evaluate the effectiveness of management practices in reducing sediment loads in irrigated areas. This study was one of seven Model Implementation Plan projects selected by the U.S. Soil Conservation Service and the U.S. Environmental Protection Agency to demonstrate the effectiveness of institutional and administrative implementation of management plans. Sediment discharges from the four basins could not be correlated with changes in management practices, because Imhoff Cone readings collected for the study showed no statistical differences between the three irrigation seasons. However, one drain acted as a sink for sediment where more lands were sprinkler irrigated; this drain had a smaller proportion of row crops than did the other three drains. (USGS)