Water Resource Projects: Peshastin Fishway
These projects update irrigation infrastructure to ensure fish screens are operable, provide fish passage, and/or improve water use efficiency.
A fishway was constructed at the Peshastin Irrigation District diversion structure on lower Peshastin Creek. The structure allows access to spawning and rearing habitat for steelhead, bull trout and Spring Chinook. The project structure is a roughened channel fishway at a channel slope of 3.9% upstream from the dam axis on the left abutment. The p roject also includes installation of fish screens at head gates. The dam was notched for a 16ft width. From that notch the roughened channel fishway extends upstream for approximately 87 feet. The fishway have two training walls for the entire length that extend to elevation 1180 (same as the left abutment elevation) and was constructed of steel plate sections with rock support. Boulders were placed in the fishway invert to create a meandering flow pattern and provide shelter for fish. Two boulder weirs woulwere placed immediately downstream from the fishway exit to backwater flashboard weirs at the channel's upstream exit. These weirs are required to meet hydraulic drop criteria of 6 inches. The existing dam notch will be closed when the fishway is in use. The goal of the project was to connect isolated habitat to increase the range and distribution of salmon.