River Revives After Largest Dam Removal in U.S. History


In August 2014, workers completed the largest dam removal project in U.S. history, as the final part of the 210-foot-high (64-meter-high) Glines Canyon Dam was dismantled on the Elwha River in northwestern Washington State.

The multistage project began in 2011 with the blessing of the U.S. National Park Service, which administers the surrounding Olympic National Park. The goal was to remove unneeded, outdated dams and restore a natural river system, with presumed benefits for fish and other wildlife.

Indeed, salmon have already returned to the Elwha after nearly a century of absence, and other fish and marine creatures are thriving.

But the restoration hasn’t just been about the river channel itself, says Anne Shaffer, a marine biologist with the nonprofit Coastal Watershed Institute in nearby Port Angeles, Washington. (Watch spectacular time-lapse video of another Northwest dam coming down.)

Shaffer has been working on the Elwha system since the early 1990s, with a particular focus on what’s called the “nearshore environment.” This is an ecological zone of aquatic habitat along the shoreline that “offers refuge and feeding areas for fish and other organisms that helps them transition from freshwater to marine habitat,” says Shaffer.

Nearshore environments include deltas and estuary systems near the mouths of rivers as well as seagrass beds in shallow water.

Shaffer says, “It was really surprising to us how fast things changed. We have seen an increase in good habitat by about a hundred acres (40 hectares) and an immediate response in the fish community. We found new species coming to the area within weeks of the dam removal starting.

“We’re now into the second year post-dam removal. The seafloor near the mouth of the river has risen by about 10 meters (33 feet), creating a whole new delta. The estuary had been badly reduced because of sediment starvation, but its return has been incredible to watch.” (Learn more about the dam removal movement.)

shared via: news.nationalgeographic.com/2016/06/largest-dam-removal-elwha-river-restoration-environment/
article: Brian Clark Howard
photo: Jason Jaacks, National Geographic Creative


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