Monday, July 25, 2011

As Water Levels Drop, Elwha Finding it's Course Again

photo from the Seattle Times

An interesting article today in the Seattle Times on the early stages of the Elwha dam removal process. As reservoir levels drop in preparation for dam removal the river is cutting down through the layers of fine sediments which have settled out in the lake over the decades. Scientists are tracking the progress and it appears to be going as planned. Another interesting aspect of the dewatering is the amount of large woody debris it is unearthing. Waterlogged logs long ago buried or sunk in Lake Aldwell are visible once again, and could play a major role in shaping the river's channel downstream of the dam once the river flows freely again. The first few years after the dam removal will be extremely dynamic as the channel moves freely across the historic floodplain cutting down through the layers of fine sediment. In past dam removal projects researchers have been extremely surprised by the ability of the river to move fine sediment and restore a more natural, stable channel. The Elwha is the largest project of its type ever attempted and it will be fascinating to watch the recovery unfold, it's already underway. More in the Times:

http://seattletimes.nwsource.com/html/localnews/2015718925_elwha25m.html

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