A project that began just over a year ago to remove and replace Nelson Dam reaches a milestone this week with the removal of a fish ladder. The fish ladder removal will be Wednesday through Friday, August 10th-12th, marking the conclusion of demolition on the project.
As always, the schedule for this type of project is subject to change daily dependent on weather, equipment failure, and emergencies.
Going forward, the remainder of the project will focus on concrete work to divert water for fish passage. The Nelson Dam project is scheduled for completion in April 2023.
The diversion structure, known as a roughened channel, will not only aid fish but also help with flood mitigation. “It will make a much bigger pathway so all that sediment trapped up above will start moving, lowering the flood risk,” said Assistant Public Works Director Dave Brown.
Nelson Dam, on the Naches tributary of the Yakima River, was built in the 1920s to divert irrigation water for Yakima and the Naches-Cowiche Irrigation Association. The original design did not allow any fish passage.
The dam has held back tons of sediment and silt over the years, raising the river bed and causing the Naches River to overflow its banks and move into the surrounding community during even minor flooding.
The project will improve fish passage and sediment continuity to improve habitat, increase flow conveyance to decrease flooding risks for nearby landowners, and improve water supply reliability.
The City of Yakima and Yakima County have been collaborating on the design and implementation of this project. The dam removal and replacement is one of several major public works projects initiated by the Yakima Basin Integrated Plan.
For more about the project, contact City of Yakima Assistant Public Works Director Dave Brown by phone at 509-575-6154 or by email at David.Brown@yakimawa.gov