Saturday, October 29, 2011

The Elwha River Gets a Makeover

The Elwha River, which runs through the heart of Olympic National Park in Washington State, is getting a makeover. Last month, the National Parks Service began removing the Upper Elwha Dam and the Glines Canyon Dam from the river. Both lack passageways for migrating salmon.

The five species of Pacific salmon which live in the Elwha River.
  The Elwha River provides habitat for five species of Pacific salmon: chinook, chum, coho, pink and sockeye. By removing the two dams it will open up more than 110 km of river and tributary habitat for these fish. Currently only about 3,000 salmon return each year to spawn in the eight kilometers of habitat below the dams. Ecologists predict that number could rise to 400,000 once the dams have been removed and the ecosystem fully restored.
Salmon are classified as diadromous, meaning they migrate between salt and fresh water. More specifically, they are anadromous, meaning that they spend most of their lives at sea and migrate to fresh water to spawn. Cutthroat trout, which also inhabits the Elwha, are anadromous too. The other type of diadromous fish are called catadromous. They spend most of their lives in fresh water and migrate to the sea to spawn. Most eels are catadromous.

The 182 million dollar project was funded by the Elwha River Ecosystem and Fisheries Restoration Act of 1992—the largest dam removal project in U.S. history. 
Since 1999, a total of 145 dams have been removed in the U.S., but none have been anywhere near the size of the Elwha dams which have trapped 14 million cubic meters of sediment since the first dam was completed in 1913. That’s enough sediment to fill 13 Empire State Buildings with some left over. The dams will have to be dismantled in stages to mitigate the effects of sediment removal on wildlife. It is expected that the restoration project will take another three years to complete. After the dams are removed, the area that lies under the lake will be revegitated to secure its banks from erosion.
Tearing down the dams is the culmination of eight years of preparation, including the design of a new fish hatchery for the Lower Elwha Klallam tribe that lives there. The hatchery will release fish into the Elwha to help repopulate it. The tribe has a special connection to the Elwha because historically the river provided them with everything they needed to live. For centuries, their culture revolved around salmon which was the most important part of their diet. They have great respect for the salmon which they celebrated through ceremonies and rituals.

The Elwha dam removal and restoration project provides a unique research opportunity. The watershed offers scientists ideal study conditions since most of the watershed lies within the protected boundaries of Olympic National Park. If successful, restoration efforts in the Elwha River watershed may become a template for other watersheds in less-than-ideal conditions.

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