Salmon above Grand Coulee

Grand Coulee Dam, finished in 1941, and Chief Joseph Dam, finished in 1955 about 51 miles downstream, were built without fish passage.¹⁰ Salmon and steelhead were cut off from the upper Columbia, and the reservoir behind Grand Coulee flooded Kettle Falls in 1940, a fishery that 1,000 to 2,000 fishers once used regularly.^8,11 Colville, Spokane and Coeur d'Alene tribes, with the Upper Columbia United Tribes, are now testing whether salmon can return.⁵ A 2019 study by the tribes projected 76,000 adult sockeye and 44,000 adult summer and fall Chinook could be produced under current habitat, if effective passage were built at the dams.² A 20-year research phase is funded under a 2023 agreement with the federal government, in which Bonneville Power Administration committed $200 million over 20 years.^5,9 About 165,000 juvenile summer Chinook were released above the dams between the autumn of 2023 and spring 2024,⁹ and in 2025 over 4,500 adult salmon were released there.³ Tagging over several years shows about 75% of adults released into upper Lake Roosevelt swim on into Canada, where some have spawned.³ On the Canadian side the Syilx Okanagan, Ktunaxa and Secwépemc nations run their own reintroduction effort with Canada and British Columbia.¹²

Who needs an answer

• The Colville, Spokane and Coeur d'Alene tribes and the Canadian nations, deciding after the research phase whether to ask for permanent passage, and for which species and rivers.
• Bonneville Power Administration, the Bureau of Reclamation and the Army Corps of Engineers, which fund the work and must approve and permit passage facilities on federal dams and lands.^4,5 The 2023 agreement says the research should not require material changes to how the river system is run.⁴
• The negotiators of the Columbia River Treaty between the United States and Canada, whose July 2024 agreement in principle adds salmon reintroduction in the Canadian upper basin and gives British Columbia more control over flows and reservoir levels at its treaty dams.¹⁴ Negotiations on the treaty text are now paused.^13,14
• Downstream fishing tribes and fisheries managers, since the plan aims not to cut harvest below the dams or bring in listed fish.²

The domains it chains

Reservoir levels, flows and water temperature set by flood control and hydropower; juvenile fish passing two very high dams and the reservoirs behind them; donor stocks and hatcheries; spawning habitat in tributaries in two countries; the power and flood control the dams provide, which any passage work has to fit around; treaty terms between two countries; the food, ceremony and fishing rights of the tribes and nations upstream.

What a twin should let people try

• Passage: the plan's sequence runs from upstream passage at Chief Joseph, to downstream then upstream passage at Grand Coulee, to the Spokane River dams.² Which order brings the most fish back for the money?
• Survival: how many juveniles reach the ocean through the reservoirs, and how does that change with reservoir level and spring flow?
• Across the border: if most adults released in upper Lake Roosevelt head into Canada, how do Canadian reservoir operations under the treaty change what spawns there?
• Projections: how far do the 2019 run estimates move with warmer water or different donor stocks?

Where to start

The tribes' Phase 2 plan sets out the acoustic and PIT-tag studies, release sites and the passage sequence,² and the Bureau of Reclamation's P2IP page holds the 2025 environmental assessment.⁴ River flows are in USGS Water Data, and a food-web model such as Ecopath with Ecosim could take the reservoir side.