WALLA WALLA — Steelhead and bull trout swimming up Mill Creek should soon find the going a little easier.
Workers on Friday poured the first concrete for a project to provide easier passage for endangered fish through the Mill Creek flood control project. Work is scheduled to be completed by mid-September.
The project will create a series of notches in the concrete ridges that run across the creek. Intended to slow and dissipate waters rushing down the channel, the concrete bumps are a barrier to fish migrating upstream.
“This will lower the weir, put cooler water on the bottom (of the channel) and give fish a way to move upstream,” said Mark Smith, manager for the U.S. Army Corps of Engineers Project. The work being done this year is a prototype project that will notch three of the weirs in the south side of the channel as a test.
“We’ll make sure all the hydraulics works and that it’s what the fish need. So hopefully, if these work, we’ll do more of them,” Smith said Friday morning as crews prepared to pour concrete.
According to Gina Baltrusch, public affairs specialist with the Corps Walla Walla District Office, the contractor doing the work is TML Construction of Hayden, Idaho. The firm was awarded the $231,000 contract in December and began work July 15, during the time when fish in the stream are least likely to be affected.
Using concrete barriers, workers have dammed the stream above the work site and channeled the water flowing downstream past the construction via a pipe, which empties into the downstream channel. After breaking out the old concrete in the weir and excavating earth to create the notch, crews pumped fresh concrete into forms in the creek bed to create the new structures.
The channel weir project is not the first of its kind in Mill Creek, Baltrusch said.
Last year, Walla Walla County and the Tri-State Steelheaders installed a number of notches in weirs on the county’s section of the Mill Creek Channel to improve fish passage. Four of the notched weirs can be seen from the Tausick Way bridge over the creek, she said.