DESCRIPTION
The goal of this project was to evaluate the potential of a levee modification project in the lower White River (WR) that would provide essential rearing habitat for juvenile salmonids, particularly WR steelhead and spring Chinook, the most distinctive stock (genetically) in central and south Puget Sound. Restoration of off-channel rearing habitat in this reach of the WR has been identified as critical in the recovery of Chinook in the WRIA 10/12 salmon strategy and EDT modeling. This application covered the feasibility, evaluation and analysis of options to modify an existing levee to improve juvenile salmonid habitat, and a permit ready (30%) design for a levee modification project to be completed at this site.
The study used an alternatives analysis to select a preferred alternative for meeting stated project goals and objectives. Project goals and objectives were written to complement goals in the WRIA 10/12 Salmon Habitat Protection and Restoration Strategy and the King County Flood Hazard Management Plan. A preferred alternative was selected for its ability to restore riverine process, minimize flood risk, and meet cost-effectiveness goals. The preferred alternative was to remove levee rock armor, install engineered log structures, and build buried revetments to protect adjacent landowners. Further geotechnical, channel migration, and cultural resources analyses will be required to finalize design. The recommendations generated from this feasibility study will be considered by King County in continuing to advance efforts to improve habitat conditions in this river reach in collaboration with the MIT, City of Auburn, landowners, and other stakeholders.