Naches - Cowiche

The Naches Cowiche canal diversion (approximately 40 cfs) is located on the left bank of the Naches River near the city of Yakima, Washington. The current Naches Cowiche screen and bypass replace a facility that did not meet design criteria for the approach velocity and attraction flows.

The facility now consists of two rotary drum screens, each 5feet in diameter by 12 feet long. The screens are constructed of 4.5-12 stainless steel woven wire mesh (1/8-inch openings).

The bypass entrance channel is a full-depth, 18-inch wide rectangular channel that is 8.5 feet long. An adjustable weir gate at the end of this channel controls flows that then drop into 3-foot wide by 8-foot long downwell. Bypass flows are then conveyed through an 18-inch diameter PVC pipe for 203 feet to the river.