Priest Rapids Dam

Priest Rapids Dam is a major concrete gravity dam and hydroelectric facility on the Columbia River in central Washington, United States. Owned and operated by the Grant County Public Utility District, the dam creates Priest Rapids Lake and has a generating capacity of 955 MW. Its construction was part of the mid-20th century development of the Columbia River Basin for power and irrigation, significantly impacting the local environment and the Yakama Nation.

History

The site's history is deeply tied to the Yakama Nation, for whom the rapids were a vital fishing and cultural site known as *Wanawish*. Early exploration by the Lewis and Clark Expedition noted the area's significance. Development interest surged post-World War II as part of the broader Columbia River Basin development led by entities like the Bonneville Power Administration. The Grant County Public Utility District initiated the project, with construction authorized under the Federal Power Act and a license granted by the Federal Energy Regulatory Commission. The dam was completed amidst the larger context of Cold War industrial growth and regional projects like the Grand Coulee Dam.

Design and construction

Priest Rapids Dam is a monolithic concrete gravity dam structure approximately 178 feet high and 4,950 feet long. Its design was overseen by the engineering firm Harza Engineering Company, incorporating ten Francis turbine generators. Primary construction materials included mass concrete aggregate sourced locally from the Columbia River Basin. Key construction challenges involved managing the powerful flow of the Columbia River and coordinating with concurrent projects like the Wanapum Dam upstream. The project required significant infrastructure, including temporary cofferdams and collaboration with contractors like Peter Kiewit Sons'.

Operations and power generation

The dam's powerhouse contains ten units with a combined nameplate capacity of 955 MW, typically generating over 5,000 GWh annually for the Northwest Power Grid. Operations are managed by the Grant County Public Utility District under license from the Federal Energy Regulatory Commission, with power distributed by the Bonneville Power Administration. The dam provides crucial load following and frequency regulation services, integrating with other Columbia River projects like Rock Island Dam and Wells Dam. Water release schedules are coordinated for flood control and to support downstream uses, including irrigation in the Columbia Basin Project.

Environmental impact and fish passage

The dam's construction permanently inundated the historic Priest Rapids, altering riverine ecology and blocking anadromous fish migration. It employs an extensive fish ladder system designed for Chinook salmon and Steelhead trout, alongside state-of-the-art juvenile fish bypass facilities. Operations are governed by biological opinions from the National Marine Fisheries Service and agreements with the Yakama Nation, focusing on habitat mitigation. Ongoing efforts include turbine upgrades for improved fish survival and participation in regional recovery plans under the Endangered Species Act.

Cultural significance

The dam site holds profound cultural importance for the Yakama Nation, representing the loss of a central fishing and ceremonial site at *Wanawish*. The project prompted legal and political actions, influencing later policies like the Columbia River Fish and Wildlife Program. The nearby Wanapum people, a band of the Yakama Nation, were directly displaced, a history documented in treaties like the Treaty of 1855. The dam's legacy is a focal point in discussions of Native American treaty rights and environmental justice in the Pacific Northwest.

Category:Dams in Washington (state) Category:Hydroelectric power plants in Washington (state) Category:Buildings and structures in Grant County, Washington Category:Columbia River Category:Dams completed in 1961