Wanawish Dam Improvement Project

Project abstract:

The Yakama Nation, Ecology, U.S. Bureau of Reclamation, and project partners are implementing the Wanawish Dam Improvement Project, about 18 river miles upstream from the Columbia River. The Wanawish Dam Improvement project is a multi-year effort consisting of three main phases: (1) identifying suitable Wanawish Dam alternatives, (2) permitting and design, and (3) construction of the partner-selected preferred alternative, which is expected to begin in 2030. The Wanawish Dam Improvement project is a multi-objective effort designed to benefit Yakima River fish populations, the local agricultural economy, river ecosystem form and function, and Yakama Nation Treaty Rights.

Project goals:

Preliminary Project Objectives:

Substantially reduce juvenile and adult salmonid predation rates by piscivorous birds and fishes.
Reduce entrainment and mortality of juvenile fish as fish pass through the existing headgates, by redesigning headgates and placing them parallel to the riverbank, or, if feasible, eliminate entrainment by using in-river fish screens.
Improve sediment transport, reduce aquatic vegetation entrainment and help sweep juvenile fish past the diversion intake to improve irrigation water delivery reliability and reduce smolt mortality.
Reduce facility maintenance needs.
Ensure the uninterrupted supply of water to CID and Barker Ranch during construction.
Eliminate dam hazards to recreationalists by addressing the severe hydraulics beneath the dam.
Ensure that fish passage and water delivery objectives can be met, including during extreme low flow conditions.
Identify and assess opportunities for adding fish monitoring and evaluation capabilities at Wanawish Diversion.
Enhance Tribal fish harvest opportunities by improving fishing access and considering adult fish migration routes through the diversion.