Rimrock Lake

Rimrock Lake
Name	Rimrock Lake
Location	Kittitas County, Washington and Yakima County, Washington, United States
Type	Reservoir
Inflow	Cle Elum River
Outflow	Cle Elum River
Basin countries	United States
Area	3,220 acres
Max-depth	180 ft
Elevation	1,900 ft

Rimrock Lake is a reservoir on the Cle Elum River in central Washington (state), formed by an impoundment constructed in the mid-20th century. The reservoir lies within the eastern foothills of the Cascade Range and is an integral component of regional water projects serving the Yakima River Basin and associated irrigation districts. Managed for multiple uses, the site is surrounded by public lands administered by federal and state agencies.

Geography

Rimrock Lake occupies a valley carved by the Cle Elum River between the Cascade Range and the Yakima Fold Belt, near the city of Ellensburg, Washington and downstream from the City of Cle Elum. The reservoir straddles Kittitas County, Washington and Yakima County, Washington, with shoreline abutting parcels managed by the United States Forest Service in the Okanogan–Wenatchee National Forest and public recreation lands overseen by the Washington State Department of Natural Resources. Prominent nearby features include Mount Daniel, the Alpine Lakes Wilderness, and the state highway U.S. Route 97 corridor. The lake's catchment connects to tributaries draining high-elevation basins near Keechelus Lake and Kachess Lake, which are part of the broader Yakima Project water network.

Hydrology

The reservoir receives inflow primarily from the Cle Elum River and tributaries sourced in subalpine basins on Kittitas County, Washington’s eastern slopes. Water storage is coordinated with upstream facilities in the Yakima Project, including Keechelus Lake and Kachess Lake, under compacts and authorizations involving the United States Bureau of Reclamation and regional irrigation districts such as the Kittitas Reclamation District. Seasonal runoff driven by Pacific Northwest snowpack patterns and influences from the Pacific Ocean storm track determine inflow volumes, while releases downstream to the Yakima River corridor support municipal water suppliers like the City of Yakima, Washington and agricultural enterprises in the Yakima Valley. Hydroelectric installations on the Cle Elum River and conveyance works, including diversion tunnels and canals, link operations to the Yakima Basin Integrated Plan and federal water rights adjudications.

History and development

The impoundment was created as part of early 20th-century and mid-century water development initiatives championed by proponents of irrigation for the Columbia Basin Project era and allied regional planners. Construction involved contractors and engineers associated with the United States Bureau of Reclamation and drew on legislative authorities passed by the United States Congress, influenced by broader New Deal and post-war public works policies. Local stakeholders included the Kittitas County commissioners, the Yakima Indian Nation, and agricultural entities such as the North Yakima Irrigation District. Historic events shaping the site include land acquisition disputes, federal environmental reviews under the framework of statutes administered by agencies like the United States Fish and Wildlife Service and litigation touching on water rights adjudicated in state courts and by the Washington State Department of Ecology.

Ecology

The reservoir and adjacent riparian zones provide habitat for anadromous and resident fish species managed under conservation frameworks involving the National Marine Fisheries Service and the Washington Department of Fish and Wildlife. Populations of steelhead, sockeye salmon, bull trout, and rainbow trout have been central to recovery plans coordinated with the Yakama Nation and tribal co-managers. Terrestrial ecosystems around the lake include mixed-conifer forests dominated by Ponderosa pine and Douglas-fir, supporting wildlife such as mule deer, black bear, coyote, and avifauna including bald eagle and peregrine falcon. Invasive species monitoring and mitigation involve collaborations with the Washington Invasive Species Council and research institutions like Washington State University’s extension programs.

Recreation and access

Rimrock Lake is a regional destination for boating, angling, camping, and hiking, with facilities and trailheads linked to the Pacific Crest Trail corridor and local trail systems maintained by volunteer groups and the American Hiking Society. Shoreline recreation areas provide campgrounds and boat ramps overseen by the United States Forest Service and the Washington State Parks and Recreation Commission. Access is primarily via state routes connecting to Ellensburg, Washington and Cle Elum, Washington, with seasonal constraints due to snow and road maintenance administered by Washington State Department of Transportation. Recreational use is subject to permits and regulations coordinated with tribal authorities, federal wilderness rules for nearby protected areas, and fishing regulations set by the Washington Department of Fish and Wildlife.

Infrastructure and management

Operations of the reservoir are integrated into the Yakima Project water-storage system, with dam infrastructure, spillways, and outlet works maintained under the oversight of the United States Bureau of Reclamation. Water allocation involves coordination among municipal utilities like City of Yakima, Washington, irrigation districts including the Kittitas Reclamation District, and tribal governments such as the Yakama Nation. Emergency planning and dam safety follow standards promulgated by the Federal Emergency Management Agency and the United States Army Corps of Engineers for hydrologic and seismic resilience. Ongoing management priorities encompass sedimentation control, habitat restoration funded through state and federal grants, and long-term planning under interagency initiatives like the Yakima Basin Integrated Plan.

Category:Reservoirs in Washington (state) Category:Kittitas County, Washington Category:Yakima County, Washington