Snake River
Winding for more than 1,000 miles, the Snake River originates in Wyoming, flowing north along the Idaho-Oregon border, eventually making its way into Washington, where it joins the Columbia River as its largest tributary.
Tribal Nations have relied on this river and its salmon for their culture and sustenance since time immemorial. In addition to supporting the entire Northwest food web, salmon provide essential nutrients to thousands of Northwest freshwater streams and sprawling evergreen forests. They are also intertwined with the regional economy, worth billions of dollars annually.
Historically, the Snake experienced the most abundant wild fish runs in the whole Columbia Basin, with 2 to 6 million salmon and steelhead returning to the river and its tributaries every year. Among them is the giant Chinook salmon, which endangered Southern Resident orcas depend upon as a vital food source. Other top predators, including wolves, grizzly bears, and bald eagles, also depend on Snake River salmon and steelhead for survival.
Yet many of the Snake River’s native fish species are extinct or threatened with extinction under the Endangered Species Act. This is largely because their habitat is upstream of four federal dams on the lower Snake River. Above these dams exists the most extensive, high-elevation freshwater salmon habitat within the lower 48 states, but construction in the mid-20th century has made the journey upriver to spawn almost impossible.
What states does the Snake River cross?
Idaho, Washington, Wyoming, Oregon
What River Basin is the Snake River a Part of?
The Snake River is part of the Columbia River Basin.
Why were the Lower Snake Dams Originally Built?
The four federal dams on the lower Snake River were originally built to turn Lewiston, Idaho, into a seaport.
Threats and Opportunities
The Snake has been named as one of America’s Most Endangered Rivers® 15 times since 1991, the latest listing in 2023. Credible science has long concluded that removing or breaching four dams and restoring a free-flowing lower Snake River will bring back healthy, fishable salmon and steelhead runs.
Four Reasons to remove the dams on the lower Snake River:
- The dams and the 140 miles of warm slack water they create prevent salmon from migrating to and from high-elevation spawning and rearing habitat in central Idaho, northeast Oregon, and southwest Washington.
- A free-flowing river would give salmon and steelhead quicker, safer access to high-elevation habitat that is expected to remain hospitable, even with substantial rises in global temperatures.
- The Lower Granite, Little Goose, Lower Monumental, and Ice Harbor dams create a hostile gauntlet of deadly turbines and warm, stagnant reservoirs full of hungry predators, leading to dramatic declines in the Snake’s salmon runs. The warm reservoir temperatures are lethal to salmon for weeks to months each year.
- The system of dams and reservoirs kills 50 to 80 percent of juvenile salmon and steelhead as the fish make their way downstream to the ocean.
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American Rivers’ Involvement in Dam Removal on the lower Snake River
American Rivers recognizes that the four dams on the lower Snake River provide valuable regional services. Before they are removed, plans for continuing those services with thoughtful, cost-effective alternatives that prepare the region for a healthy and prosperous future must be in place.
To assist in making that happen , American Rivers is engaged in and closely tracking studies that the Washington State Legislature has directed state agencies to undertake in four key areas:
- Transportation. The Washington State Department of Transportation (WSDOT) is identifying the most efficient and cost-effective way for farm enterprises to transport wheat if the dams are removed and barge portage through the locks on this 140-mile section of river ends.
- A recent WSDOT analysis has found that replacing barge services with rail options could reduce regional truck miles by more than 18 million miles per year. Among other benefits, this would reduce carbon and other emissions, leading to better air quality.
- The analysis found that this change would increase total transportation costs by $8 million a year – an amount dwarfed by the $4.5 billion to $8.35 billion that taxpayers are projected to spend over the next 50 years to keep the four dams.
- WSDOT’s final Lower Snake River Dams Transportation Study is progressing on schedule, with a final report due to the Washington Legislature by December 2026.
- Water. The Washington Department of Ecology partnered with the U.S. Bureau of Reclamation to analyze how to continue water supplies for irrigation, municipal, and industrial purposes.
- Today, the reservoir behind Ice Harbor Dam is used to irrigate up to 55,000 acres of farmland, and the towns of Lewiston and Clarkston receive their water from the reservoir behind Lower Granite Dam.
- In December 2024, the draft Lower Snake River Water Supply Replacement Study concluded there would be enough water in a free-flowing river to meet these current uses. It provides several viable water supply alternatives.
- Ecology anticipates publishing the final report by fall 2026.
- Recreation. The Washington State Recreation and Conservation Office and the Department of Fish and Wildlife are expected to analyze the recreational business opportunities a restored river would bring to the region. The experience of other regions shows that increased fishing, boating, hunting, and river rafting activities contribute to a healthy economy.
- The analysis will build on information in 2025’s Lower Snake River Recreation Study.
- Energy. Pacific Northwest National Labs completed phase one of this study in 2025. It determined that the dams’ energy production is overshadowed by upriver federal storage dams. It also found that:
- The four lower Snake dams produce an average of 700 megawatts each year, which is less than 4% of the Northwest’s total average power generation.
- The dams are not designed to significantly increase output when it’s most needed, particularly during extreme weather events. Other national studies show that strategically placed battery storage can provide the fastest reactive power for communities and grid support.
Washington Governor Bob Ferguson has asked that the full energy study be completed by 2027.
A Call for Action
Salmon are an icon of spiritual and cultural identity in the Northwest. All life here and our intertwined local economies depend on them. Washington state’s public-facing studies provide a rare opportunity to build fresh momentum for removing the lower Snake River dams, an effort that has been stymied for decades and is a key action for recovering the health of the entire Columbia River Basin.
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