Bonneville Dam

Dams

Beginning in 1933 as part of a plan to launch into a more hopeful future after the Depression, dam construction began on the Columbia River. Over the course of the next 42 years, for both flood control and hydroelectricity, 274 dam projects were completed on the Columbia and Lower Snake river.

It should come as no surprise that returns of salmon and steelhead to their spawning grounds in Washington, Idaho, and Oregon declined sharply as this gauntlet of dams was constructed. Dams changed what was once a free-flowing river into a series of reservoirs, which raised water temperatures and slowed both upstream- and downstream-migrating fish traffic and made salmon more susceptible to predation.

More than 55 percent of the spawning and rearing habitat once available to salmon and steelhead in the Columbia River Basin became (and still is) permanently blocked by dams.[1] Even with fish passage systems in place, only a very small percentage of migrating fish reach their native spawning grounds. The same is true for juvenile fish traveling downstream to the Pacific Ocean.

An estimated 10 to 15 percent of all smolts (out-migrating juvenile fish) are killed in turbines at each dam. This means that for every 100 fish leaving Lewiston, Idaho, as few as zero to 20 will survive the 8 dams blocking their trip to the sea. And for the possible 20 of that original 100 that do survive the turbines, they still face all of the other hazards dams create (increased predation, increased temperature, increased travel time).

Today, we know that dams are bad for fish. But what can we do? These dams have permanently transformed the once mighty Columbia into an entirely new landscape. Changing it back to its natural state would require a massive effort. For example, Grand Coulee Dam contains enough concrete to cover the entirety of Manhattan with four inches of pavement. Just one of Grand Coulee’s steel turbines weighs 20,000 pounds. Plus, the amount of power generated at Grand Coulee—21 billion kilowatt-hours, the highest producer in the U.S.—makes removing this dam impractical. Dams are here to stay on the Columbia River system, but what could be done that would increase salmon abundance? And, do all the dams need to stay?

One common sense solution is to breach the Lower Snake River dams. Historically, the Snake River produced roughly 40% of the Columbia River chinook, or 1.5 to 4 million fish[1]. Today, with four dams obstructing 140 miles of free-flowing river, fewer than 50,000 wild fish return every year, representing a loss of 80% of this resource.

Studies that examine possible causes of mortality for the Snake River salmon show that the lower Snake River dams are the most significant factor preventing a higher return rate.

A more recent study by ECONorthwest, the Pacific Northwest’s largest and most respected economic consulting firm published in July 2019 stated that “…the benefits of dam removal are large enough to fully compensate individuals or industries that could experience costs if the dams are removed.”

The 179-page report goes on to conclude that “benefits accruing to the public from a restored natural river system and a reduced extinction risk of wild salmon outweigh the net costs of removing the dams by over $8.6 billion.”[1] Meaning it’s cheaper to remove them and it will add to the local economy to do so.

Breaching these dams would also provide a source for the most consistent cold water supply to the Columbia system, where reservoirs become to warm for fish survival.

[1] Ibid

[1] https://www.nwfsc.noaa.gov/publications/scipubs/techmemos/tm200/sum.htm

[1] https://www.nwcouncil.org/reports/columbia-river-history/damsimpacts