Some hydropower dams in the Columbia River Basin block passage of anadromous fish, primarily but not exclusively salmon and steelhead, from large areas of historic spawning and rearing habitat.

It is a principle of the Northwest Power Act to protect, mitigate, and enhance fish and wildlife, including related spawning grounds and habitat, of the Columbia River and its tributaries that have been affected by dams. The Act specifically calls out the impact of dams on anadromous fish, which the Act says “are of significant importance to the social and economic well-being of the Pacific Northwest and the nation.”

The program recognizes the blocked area above Grand Coulee and Chief Joseph dams in Washington state, and also other blocked areas in the Columbia River Basin, including in the Willamette and Deschutes river basins of Oregon.

The Council has supported reintroduction of anadromous fish to blocked areas since the 2000 revision of the fish and wildlife program, recommending that reintroduction be pursued where it is determined to be feasible. Consistent with the Power Act, the Council believes that the abundance of native fish species should be restored throughout blocked areas where original habitat conditions exist or can be feasibly restored or improved.

This mitigation may include the use of resident fish, anadromous fish reintroductions, wildlife, habitat, and projects to identify or resolve data gaps. The program gives highest priority to weak, but recoverable, native fish populations identified by state and federal fish and wildlife agencies and tribes. Next in priority would be actions that investigate reintroductions of salmon and steelhead into blocked areas, where feasible, in areas where they once were present but are not today.

Reintroduction could have important economic benefits from increased fisheries and tourism. For tribes, reintroduction could restore harvest opportunities and also would have cultural and spiritual importance.

(Static map of blocked areas)

Related links:

  • Columbia River History page on the impacts of dams on salmon and steelhead
  • U.S. Entity’s recommendation on the future of the Columbia River Treaty, which includes the proposal to jointly investigate returning fish to the Canadian Columbia