To Dam or Not to Dam

To Dam or Not to Dam

News Type: Regional Source: Hakai Magazine
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For the past two decades, dams have been falling across the United States in a bid to reverse a legacy of destruction of fish and their habitat. American Rivers, a nonprofit advocacy organization, estimates that 1,200 dams were dismantled nationwide from 1999 to 2019, including major dams on the Elwha and White Salmon Rivers in Washington State.

But in southwestern Washington, a local flood control district is going against the flow by proposing a major new dam on the Chehalis River. At close to 200 kilometers long, the free-flowing Chehalis River drains 7,000 square kilometers before emptying into Grays Harbor on the Pacific Ocean. The Chehalis is a critical salmon stream and the largest river system fully contained within the state’s boundaries.

The proposed concrete dam, measuring 472 meters long and 82 meters tall, will be located in Lewis County, in the upper reaches of the watershed. Construction could begin as soon as 2025 and last seven years at a cost currently estimated at more than US $600-million, although critics suggest it could swell to $1-billion.

Dams typically employ reservoirs for hydroelectric production or irrigation, but this one would allow the river to continue flowing and would only hold it back during extreme flood events. These are expected to worsen in coming years because of climate change.