Thursday, November 11, 2010

Elwha Weir is Up and Running

This fall, in preparation for the removal of the Elwha river dams in September 2011, biologists from the Elwha Klallam Tribe, NOAA, WDFW and the USFWS installed a resistance board weir on the lower river. The project is the largest floating weir on the westcoast and will allow for the safe capture and handling of all migrating salmonids while the river is below 2000 cfs. The Elwha once supported robust runs of all 5 species of pacific salmon as well as summer and winter steelhead, anadromous bull trout and cutthroat however since the construction of Elwha Dam in 1910, migrating fish have been blocked at river mile 4.9. With 90% of the river protected within the national park, the Elwha is perhaps the most pristine river in the Lower 48 states. Now with the dams coming out, the Elwha will be the largest dam removal and salmon restoration project in history with the weir giving biologists the unique opportunity to accurately monitor the recolonization process.

While the purpose of the Elwha dam removal has always been to restore robust populations of wild salmon and steelhead, concerns about high sediment loads in the period following the dam removal have prompted managers to implement a strategy that calls for the continued supplementation of Chinook, Coho, Chum and Steelhead in the Elwha. The weir however will allow biologists the opportunity to track the reproductive success of all species and compare between hatchery and wild spawners, and ultimately serve as a way to sort hatchery fish out of the spawning population.

For more information about the weir and to see photos check out:

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