Dams in Washington (state)

Dams in Washington (state)
Name	Selected dams of Washington
Location	Washington (state), United States
Purpose	Hydropower, flood control, irrigation, water supply, recreation, navigation
Status	Operational, retired, removed
Owner	Federal, state, tribal, municipal, private utilities

Dams in Washington (state)

Dams in Washington have shaped the state's Columbia River and Puget Sound regions through hydroelectric development, irrigation projects, flood control works, and municipal water supplies, generating tensions among stakeholders such as the U.S. Army Corps of Engineers, Bureau of Reclamation, Bonneville Power Administration, and numerous tribal nations. Major barriers on rivers including the Columbia River, Snake River, Skagit River, and Methow River have influenced fisheries, transportation, and urban growth in places like Seattle, Tacoma, Spokane, Vancouver, Washington, and Olympia.

History

Early impoundments in Washington trace to territorial-era mills in Olympia (Washington), with large federal initiatives emerging from New Deal-era programs under the Tennessee Valley Authority model influence and the Bonneville Power Act ethos. The mid-20th century saw expansive projects led by the U.S. Bureau of Reclamation and the U.S. Army Corps of Engineers, including dams constructed during or after World War II to support industrial growth in Seattle-Tacoma, irrigated agriculture in the Columbia Basin Project, and navigation improvements tied to the Port of Seattle and Port of Vancouver USA. Controversies over fish passage and treaty rights escalated with litigation involving the Swinomish Indian Tribal Community, Yakama Nation, and other tribes asserting rights under the Treaty of Point Elliott and the Treaty of Medicine Creek. Landmark environmental actions invoked statutes such as the Endangered Species Act and decisions of the U.S. Supreme Court affecting salmon management.

Major Dams and Reservoirs

Washington hosts several significant dams: Grand Coulee Dam and its reservoir Franklin D. Roosevelt Lake on the Columbia River built by the Bureau of Reclamation; Bonneville Dam operated by the U.S. Army Corps of Engineers near Cascade Locks and linked to the Bonneville Power Administration grid; Chief Joseph Dam and Wells Dam managed for hydropower and navigation; McNary Dam and The Dalles Dam along the Columbia influencing interstate commerce with Oregon; and Wanapum Dam and Rocky Reach Dam supporting hydroelectricity for utilities like Pacificorp and Avista Corporation. In western Washington, the Skagit River Hydroelectric Project including Ross Dam, Gorge Dam, and Diablo Dam serves Seattle City Light and supplies Mount Vernon and Bellingham. Other notable works include Cowlitz Falls Dam, Howard Hanson Dam on the Green River, Liberty Lake Dam, and smaller reservoirs such as Lake Roosevelt and Lake Chelan.

Purposes and Uses

Dams in Washington serve multifaceted roles: large-scale hydroelectric generation feeding the Northwest Power Pool and serving utilities including Seattle City Light, Tacoma Power, and Puget Sound Energy; irrigation infrastructure for the Columbia Basin Project and agriculture in regions like the Yakima Valley; municipal and industrial water supply for cities such as Spokane and Everett; flood control protecting communities along the Skagit River and Yakima River; recreation supporting tourism in areas like Lake Chelan and Lake Roosevelt; and navigation locks facilitating barge traffic to the Port of Portland and international shipping to Longview, Washington.

Environmental and Ecological Impacts

Dam construction and operation have altered habitat for anadromous species such as Chinook salmon, Coho salmon, Sockeye salmon, and Steelhead trout, prompting mitigation measures including fish ladders, hatchery programs run by entities like the Washington Department of Fish and Wildlife, and litigation involving tribes including the Confederated Tribes and Bands of the Yakama Nation. Reservoirs have affected river temperature regimes, sediment transport influencing estuaries like the Columbia River Estuary, and riparian ecosystems near Olympic National Park and the North Cascades National Park Complex. Environmental review and mitigation processes invoke agencies and statutes such as the National Environmental Policy Act and the Environmental Protection Agency, and have spurred restoration projects by organizations including The Nature Conservancy and the Washington State Recreation and Conservation Office.

Ownership, Management, and Regulation

Ownership spans federal agencies like the U.S. Bureau of Reclamation and the U.S. Army Corps of Engineers, regional federal power marketing authorities such as the Bonneville Power Administration, municipal utilities like Seattle City Light and Tacoma Public Utilities, investor-owned utilities such as Puget Sound Energy and Avista Corporation, and tribal authorities including the Muckleshoot Indian Tribe. Regulatory oversight involves the Federal Energy Regulatory Commission for non-federal hydroelectric projects, the Washington State Department of Ecology for water rights and permitting, and coordination with regional entities like the Northwest Power and Conservation Council. Interagency compacts and litigation with tribal governments have shaped operations through consent decrees and biological opinions under the National Marine Fisheries Service.

Engineering and Design Characteristics

Engineering in Washington includes diverse dam types: concrete gravity structures exemplified by Grand Coulee Dam, earthfill embankments like some components of the Columbia Basin Project reservoirs, and roller-compacted concrete used in modernization efforts. Design addresses seismic considerations informed by studies of the Cascadia Subduction Zone and crustal faults near Seattle and the Puget Lowland, spillway capacity to manage flood events like those reconceived after Pacific Northwest floods of 1948, and fish passage technology including ladder designs and surface bypass systems. Powerplants integrate Kaplan and Francis turbines sized for variable flows of the Columbia River and Snake River systems, with transmission interties to the Northwest Regional Transmission Organization infrastructure and balancing by the Bonneville Power Administration.

Future Challenges and Projects

Future challenges include relicensing by the Federal Energy Regulatory Commission, dam safety upgrades prompted by seismic risk assessments of the Cascadia Subduction Zone, ecosystem restoration commitments involving the Yakama Nation and Nez Perce Tribe, and proposals to modify operations for climate resilience in response to projections from the National Oceanic and Atmospheric Administration and the Intergovernmental Panel on Climate Change. Debates over removal or modification of lower Snake River dams implicate stakeholders such as the City of Seattle, the Grocery Manufacturers Association, and agricultural groups in the Washington State Farm Bureau, while modernization projects led by entities like Seattle City Light seek to improve fish passage and power efficiency.

Category:Dams in Washington (state)