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Restoring the Lower Snake River

From the Wild Salmon and Steelhead News, June 2013...

A Brief History of “spill”: our best near-term option for helping endangered wild salmon and steelhead.

Spill – the act of sending water over the Columbia and Snake River’s federal dams rather than through the turbines – is the most effective salmon survival measure with dams in place. In a dammed river, spill is an important step toward the natural template – the conditions under which salmon evolved, which scientists overwhelmingly agree we must seek to mimic if we are to restore salmon.


The Columbia Basin is large - roughly the size of Texas. The Columbia River’s headwaters are located in Canada while the Snake originates near Yellowstone National Park in Wyoming. This Basin was once the most productive salmon landscape on the planet – with up to 30 million fish returning annually for the benefit of people and ecosystems.

Today, it’s something of a stretch to call the Columbia and Snake “rivers” at all, given the back-to-back dams and reservoirs. Of the Columbia’s 600 non-tidal miles in the United States, just 51 still flow freely today – through the Hanford Reach in south-central Washington State (not coincidentally, also the home to the Basin’s strongest chinook populations). And in eastern Washington, many locals now refer to the Columbia’s biggest tributary as “Snake Lake”.

When compared with all other human causes of decline, dams are the biggest harvester of Columbia and Snake salmon. It’s the juvenile salmon – the smolts – migrating to the ocean through as many as eight dams and reservoirs that suffer the greatest casualties from the slack waters, long migration times, hot temperatures, high predator populations, and spinning turbines. Dams also inflict delayed mortality – fish that, while still alive when they hit the salt water, are so weakened by the cumulative stresses of migration through dams and reservoirs that they die at a higher rate in the ocean than do salmon from undammed or less-dammed rivers.

spill.schematicWhile far from perfect (the removal of the four lower Snake River dams would be considerably more helpful), spill helps mitigate the effects of dams in many ways: it shortens travel time to the ocean, reduces exposure to predators, helps move salmon through warm waters, keeps more fish out of spinning turbines, reduces human and mechanical handling, and reduces delayed mortality by reducing cumulative stress. Spill also reduces barging and trucking of juvenile salmon, the Army Corps’ preferred method of salmon migration despite its 30-year record of failure to restore salmon.

Scientists have long recognized the benefits of salmon spill and urged its expansion to help protect and recover endangered fish. Bonneville Power, on the other hand, has long opposed it, since spilled water does not spin turbines, produce electricity, or generate energy revenue. (It produces millions of dollars in salmon revenue, but BPA’s books don’t account for that.) BPA has long sought, and still seeks, to keep spill as discretionary as possible, so the agency could choose when, where and for how long to implement it.

A breakthrough came in 2005, when the U.S. District Court in Portland granted a spill injunction sought by the State of Oregon, Columbia River Tribes, and fishing and conservation groups. With the injunction, a base level of salmon spill has occurred each spring and summer for the last 8 years. This has generated many thousands more salmon and steelhead for people, economies and ecosystems. As you read these words, per federal court order, spill is pouring over the eight dams of the lower Snake and Columbia Rivers, carrying young salmon and steelhead more quickly and safely toward the Pacific Ocean.

In addition, these eight years of steady spill have provided a great deal of new data, over a range of water and weather conditions, on spill’s benefits and how best to manage it. The longest-running scientific study of Columbia and Snake River salmon passage and mortality recently concluded that additional spill, above the base level provided by the injunction, will boost salmon survival and adult returns even more - but only if the people and leaders of the Northwest choose to adopt it...We’ll dig into that more deeply in our July newsletter.

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