The City of Yakima is working on a project to replace Nelson Dam to improve fish passage and water reliability.
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 Co. 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 pour 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.
Yakima County has developed a plan for replacing the dam with a roughened channel and regrading the riverbed.
The city of Yakima plans to invest $7.5 million in the $26 million multi-agency collaboration — part of the Yakima Basin Integrated Plan — over the next four to five years. About $6 million of that total will come from bonds, and about $1.5 million will come from reserves.
The City of Yakima and Yakima County are together requesting $8.2 million from the state’s Capital Budget to complete the project.