Mill Creek Passage – Division to Roosevelt

The Mill Creek Flood Control Project was built by the Corps of Engineers in the 1940s. It has saved Walla Walla many times from flooding, most recently in 2020.

However, the flood control channel is a barrier to over 50 miles of headwater habitat for salmon, steelhead, and bull trout. Beginning in 2011, six construction projects have improved passage in a two-mile long concrete section of the channel.

In September 2022, passage improvements were completed for a 1,200-foot-long section of the channel. The original plan was to complete 2,100 feet of channel. But inflation and COVID-related supply issues caused costs to increase significantly, so the project was scaled down to maximize available funding.

The project involved concrete cutting and demolition, rebar tying, and forming and pouring of new concrete. The completed work changes the depth and velocity of water in the channel so that it is passable for adult and juvenile salmonids. Funding partners were the Brian Abbott Fish Barrier Removal Board, Confederated Tribes of the Umatilla Indian Reservation, and Bonneville Power Administration.

To date, nearly 70% of the concrete channel has been improved for passage.

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