WALLA WALLA -- Fish in Mill Creek now will have improved passage as well as resting opportunities as they move through downtown Walla Walla between Colville and Spokane streets, according to the Tri-State Steelheaders.
The group's project is the third in a series of passage improvements and is scheduled to be completed in early September. The projects are intended to help fish reach the high-quality spawning and rearing habitat in upper Mill Creek, according to a news release from the group.
The total project budget is $502,877 and includes all engineering and design, permitting, and construction expenses.
Sections of the concrete-lined channel have been removed, and replaced with precast concrete panels that provide "surface roughness," the release said.
The roughness provides a zone of lower-velocity water where adult steelhead, bull trout and spring chinook can migrate upstream. Previously, the fish would experience velocities in the channel that were too fast for passage, and there were no resting areas, the release said.
The project also will reconfigure baffles in the bottom of the channel to improve passage for juvenile fish during low flow.
The passage design, which has been model-tested, provides passage over a range of flows while providing access for channel-maintenance vehicles, without negatively affecting flood-flow capacity.
Funding for the project comes from the Salmon Recovery Funding Board, Confederated Tribes of the Umatilla Indian Reservation and Bonneville Power Administration.
Tri-State Steelheaders is a nonprofit conservation organization that has conducted fish passage and habitat enhancement projects in southeastern Washington since the 1980s.