Sandy River Basin, OR

Restoring the Sandy River Basin

The biggest dam removal in the Northwest in over 40 years was the removal of the Marmot Dam on the Sandy River in 2007.  This removal was followed by the removal of Little Sandy dam on the Little Sandy River in 2008. The removals have already started to restore salmon and steelhead populations, improve recreation, and create a wild river refuge in Portland’s backyard.

American Rivers helped negotiate this important dam removal and river restoration agreement with Portland General Electric and more than 20 other groups and agencies. As part of the restoration agreement, more than 5,000 acres of land along the Sandy River are also being protected.

More than 200 years ago, Lewis and Clark came upon this beautiful river that flows from the flanks of Oregon’s Mount Hood, down through forests and beautiful deep gorges before joining the mighty Columbia. Noticing the sediment-laden waters, they named it the Sandy River.  But the dams that have, until recently, clogged the river, have impeded its ability to provide valuable services to the community like clean water and fish passage to maintian healthy fish populations.

However, thanks to these two dam removals, the Sandy is now a free-flowing river from its origins on Mt. Hood to its confluence with the Columbia and fish are returning to the Little Sandy for the first time in about 100 years. And those sediments first noted by Lewis and Clark have played a powerful role in the river’s restoration, quickly rebuilding the sandbars and pools that are restoring wildlife habitat and creating an outstanding opportunity for outdoor recreation.

 
Sandy River Film

This film, advocating for dam removal, was shot in May 2007.

How the Marmot and Little Sandy Dams were deconstructed

PGE’s contractors built a shallow dirt and rock coffer dam upstream from each dam to keep the river away during removal. They ware built on top of the river sediment. The bypass channel allowed fish to pass. The solid concrete dams were then removed piece by piece. 

After the concrete dams were removed, coffer dams were extended across the river. Normal high water flows washed away these coffer dams. 

Sediment continues to flow downstream naturally as the river is restored toward its natural state.

Background Information:

• Sandy Basin locator map  (PDF)
• Bull Run project: water flow and diversion (PDF) 
• Fish passage in the Sandy Basin after dam removal (PDF)
• Sandy River brochure (PDF).

For more information contact Amy Kober, 206-213-0330 x 23 or Brett Swift, 503-827-8648.