Monday, June 11, 2012

Northwest Dam Removal Update

Last fall dam removal began on the Elwha and White Salmon Rivers, two places where aging dams had obstructed spawning salmon for a century. The dam removals were the culmination of decades of work by government, non-profit and tribal representatives, and mark a major turning point in the effort to recover wild salmon and steelhead in the Pacific Northwest. On the heels of one of the most important and memorable years of dam removal and river restoration, recovery is proceeding more of less as expected with some exciting results.

Elwha Dam, the lower of the two dams on the Elwha is already gone, giving salmon and steelhead access to 8 miles of river and two crucial tributaries, the Little River and Indian Creek. Already just a few short weeks after the dam removal was completed biologists documented one the first natural colonists to the Little River, a 35 inch adult steelhead. By this time next year Glines Canyon Dam will also be gone, opening access to the rest of the Elwha watershed for the first time in 100 years. In the near-term tributaries such as the Little River and Indian Creek will provide important refugia for spawning fish, as large amounts of stored sediment works its way through the Elwha watershed and out to sea. While the lower and middle reaches of the mainstem may take several years to recover, the river is already on its way, and as the Elwha carves its new channel through the long trapped sediment, the first generation of riparian plants are recolonizing the floodplain. Large stumps and logs left from logging a century ago are also providing an unexpected benefit, stabilizing banks and providing crucial large woody debris. An article from last week in the Seattle Times reports on the progress of the recovery.

On the White Salmon, demolition of the dam is proceeding, even as the river runs beneath it. Last fall engineers on the White Salmon opted for a strategy of blasting a channel for the river under the dam allowing the river to transport stored sediment throughout the winter and spring high flow period. Engineers also recently removed an old crib dam that had been buried under water and sediment, from the river just above the dam. This years steelhead, chinook and coho will be the first generation of fish in the watershed to have natural access to the river above the dam.  More from the White Salmon Timelapse blog

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