Can Puget Sound’s orca and salmon survive Seattle’s dams?

Federal regulators are reassessing the ecological impacts of the Skagit River dams.

Devin Smith wasn’t impressed as he looked out across the stagnant water of Barnaby Slough, a pond near the edge of the Skagit River in northern Washington. “Steelhead like fast-moving water,” Smith said, a steady May rain pelting his glasses. The slough, however, was more like “a big bathtub.” Smith is the habitat restoration director for the Skagit River System Cooperative, a natural resources consortium of the Swinomish Indian Tribal Community and the Sauk-Suiattle Indian Tribe.

Barnaby hasn’t always been such a bad place for young fish. Over a century ago, this valley of towering cedars and moss-drenched maples was one of the most productive salmon habitats in the entire Pacific Northwest. Back then, the Skagit River meandered across the valley floor in a maze of waterways, which exist today as glades etched into the forest, and Barnaby Slough was the river’s mainstem. The complex network of side channels this produced protected young salmon from heat and predators. But by the 1940s, the Skagit River had straightened and separated from Barnaby, cutting off hundreds of acres of salmon habitat. Eventually, Washington state added small barriers to turn the slough into a fish-rearing pond, further isolating it. Today, the river remains detached from the surrounding fish habitat, and scientists are wondering why.

Barnaby Slough was once the Skagit River’s mainstem, but today the slough and its surrounding salmon habitat are rarely connected to the river. The dams’ obstruction of sediment and logs could be to blame. David Moskowitz / High Country News.

Seattle’s three Skagit River dams, approximately 25 miles upriver from Barnaby, are a likely culprit. Commissioned between 1924 and 1952, they generate roughly 20% of Seattle’s power. But they also limit the river’s seasonal flooding and starve it of the sediment and fallen trees that would naturally raise its water level and help salmon access side channels. Now, researchers want to know: Could the Skagit and Barnaby reconnect if the sediment currently locked behind the dams was released into the river?

Read the rest of the story at https://www.hcn.org/issues/53.8/north-dams-can-puget-sounds-orca-and-salmon-survive-seattles-dams.