DESCRIPTION
This project designed measures to protect and restore flood plain processes for nine (9) miles of spawning, rearing, and migratory habitat supporting listed steelhead, chinook, and sockeye salmon at the confluence of the Okanogan/Similkameen rivers. The goal to assess a suite of possible restoration actions that include dike modification, riprap removal, riparian plantings, and acquisition of 90 acre Eyhott Island were met. Objectives included biological and engineering assessments, and restoration planning coordinated among state, federal and private landowners, resulted in preliminary designs of measures to protect and restore habitat-forming processes and an adaptive management plan for implementation of these measures. Final design and implementation will be performed under separate funding.
The project area, in the vicinity of Driscoll and Eyhott islands, contains "Category 2 and 3" reaches designated by the UCSRB Regional Tech Team. The productive capacity and natural alluvial processes in this area, including some 4.5 miles of spawning habitat supporting the largest concentration of summer chinook in the watershed, are degraded from hydraulic disruption caused by flood control dikes and riprap banks that accelerate high-flows. These altered flow patterns have led to unnatural bank erosion, siltation of spawning and rearing habitat, disconnected side channels, disrupted channel-forming processes, and loss of riparian habitat and wood recruitment.