MILTON-FREEWATER — A recently completed project has removed a barrier to migrating fish in the Walla Walla River near Milton-Freewater.
The project involved cutting an 11-foot wide, one-foot deep V-shaped notch in a concrete sill located in the river, said Brian Wolcott, director of the Walla Walla Basin Watershed Council. Workers also installed a 45-foot U-shaped roughened channel of boulders immediately downstream of the structure to ensure fish passage up to and through the notch.
“Over the last few years, a three-foot head cut in the river bed migrated up to this structure, creating a barrier for rainbow trout, bull trout, juvenile steelhead and juvenile Chinook salmon during low flows,” Wolcott said in a release. Bull trout, steelhead and chinook are listed as threatened species by the federal government.
Wolcott said there was also concern that if the concrete sill collapsed or was undermined, the toe of the flood protection levee could be exposed and vulnerable to erosion. The structure was built in the 1940s as part of the Milton-Freewater Levee flood protection project,
The watershed council worked with project partners to secure funding for design, permits, and construction, which was done by Partney Construction of La Grande, Ore., and completed in late September.
Funding for the Smith Grade Control Sill Fish Passage project was provided by the Oregon Watershed Enhancement Board, U.S. Fish and Wildlife Service, the Confederated Tribes of the Umatilla Indian Reservation, Oregon Department of Environmental Quality, Bonneville Power Administration, and the Milton-Freewater Water Control District.
Technical support was provided by Oregon Department of Fish and Wildlife and the Confederated Tribes of the Umatilla Fish Habitat Program. Design plans and construction oversight were completed by GeoEngineers Inc., Wolcott said.