Yakima River - River Modifications

River Modifications

The Yakima River and its tributaries have been heavily altered for the purpose of irrigated agriculture. There are numerous dams and irrigation canals. Irrigation runoff is in places returned to the river through canal drains. The irrigation system in the Yakima's watershed causes periods of both severe river dewatering and elevated flows, relative to the historic streamflow regime. As a result, discharge statistics for the Yakima River are heavily affected by the irrigation system. The USGS operates four streamflow gauges on the Yakima River. The highest average discharge recorded, 3,542 cubic feet per second (100.3 m3/s), is more than halfway up the river at Union Gap. The two downriver gauges show average flows of a reduced amount.