Rimrock Lake, body of water

Rimrock Lake is a reservoir on the Tieton River in Yakima County, Washington, held back by the 319-foot Tieton Dam, built in 1925. Its active capacity is 198,000 acre-feet (244 million m³). The lake lies near the communities of Rimrock and Silver Beach and is part of the Yakima Project irrigation system.

Rimrock Lake was formed by Tieton Dam, a 97-metre-high structure completed in 1925 on the Tieton River as part of the Yakima Project of the United States Bureau of Reclamation. The rising water flooded the site of the Yakama village of Miya'wax and stretches of the Yakama-Cowlitz Trail, the route linking the Yakama east of the Cascades with the Cowlitz to the west.

The lake is easily accessible via US-12 with signage directing visitors to parking areas, boat ramps, and picnic spots. Basic facilities including open campgrounds and boat ramps are available during most seasons throughout the year.

The reservoir drowned Miya'wax, a Yakama village, along with stretches of the Yakama-Cowlitz Trail that linked the Yakama people east of the Cascades to the Cowlitz west of the mountains. Tieton Dam, 319 feet high and finished in 1925, holds back 198,000 acre-feet of water for the Yakima Project.