US Army Corps of Engineers
Portland District

Sandy River Delta dam removal

Image of the Sandy River Delta dam siteThe Sandy River Delta dam removal project will restore fish habitat at the confluence of the Sandy and Columbia rivers.

 

In the 1930s, the Oregon Game Commission redirected the main branch of the Sandy River, also known as the East Channel, in an attempt to improve fish runs.

 

A 750-foot long dam was constructed on the East Channel to direct water flow toward the West Channel of the Sandy River.

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About this project

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Project slide showing relative locations of the Sandy River Delta dam removal project 

Prior to dam construction, extensively braided shallow-water habitat in the East Channel and abundant backwater habitat throughout the Sandy River delta provided excellent conditions for rearing juvenile salmon and steelhead. After the dam’s construction, the East Channel gradually silted and became a slough. The delta lost much of its hydrologic complexity and now has fewer backwater habitat areas. The dam impedes access and limits cool water flow from the Sandy River to the East Channel, resulting in summer ponding and an increased potential for juvenile stranding and death. Restoration work will begin July 5, 2013, when the Corps’ contractor begins mobilizing equipment and preparing the site.

The Corps’ contractor will construct a low-flow pilot channel within the East Channel, connecting the Sandy and Columbia Rivers. The dam will be removed by both the Corps and Portland Water Bureau. Removing the dam and reconnecting the East Channel will benefit juvenile salmonids spawned in the Sandy River system and fish migrating down the Columbia River by providing yearlong access to the East Channel during a variety of flow conditions. The changes will reduce stranding potential during summer low flow conditions in the East Channel and introduce cool water to the East Channel from the Sandy River during summer. The restoration project is expected to be completed by November 30, 2013.
The National Marine Fisheries Service 2008 Biological Opinion for Operation of the Federal Columbia River Power System, Habitat Strategy 2 directs the Corps to improve juvenile and adult fish survival in estuary habitat. Reasonable and Prudent Alternative #37, Estuary Habitat Implementation 2010-2018, calls for achieving habitat quality and survival improvement targets and directs the BiOp action agencies (the Corps, Bonneville Power Administration, and the Bureau of Reclamation) to fund projects as needed to achieve survival rates in the estuary for listed salmonids as described in the FCRPS Biological Assessment.

The 2010 BiOp implementation plan includes habitat restoration in the Sandy River Delta as a specific action that the Corps should pursue. The BiOp requires habitat restoration in the estuary because a) all listed salmonid runs in the Columbia River Basin have been found to use estuarine habitat; b) restoration enhances juvenile survival as they prepare for ocean entry; and c) reconnecting shallow water habitat to cold water refugia should protect juveniles against expected climate change impacts.

The Corps is working with the following organizations to complete the habitat restoration: 

 U.S. Forest Service logo Bonneville Power Administration logo  Oregon Dept. of State Lands logo  Oregon Dept. of Fish and Wildlife logo   and Northwest Pipeline.