Threemile Creek Watershed Assessment

Threemile Creek is tributary to the South Fork Clearwater River in north-central Idaho. Through the USFWS partners program, RDG assisted the Idaho Soil and Water Conservation District and USFWS with a watershed assessment and restoration plan for Threemile Creek near Grangeville, Idaho. The project goal is to address elevated water temperatures, fine sediment loading and impaired salmonid habitat. RDG completed remote sensing analyses to identify 32 potential sites for restoration based on ability to achieve project goals and other project screening criteria developed collaboratively with the project partners.

Potential restoration sites were evaluated in the field to validate remote sensing observations and determine restoration alternatives. UAS imagery was collected at project sites to support project design. RDG developed restoration concepts and cost estimates for 8 top priority sites. Proposed restoration treatments included floodplain restoration, wetland restoration, stream restoration, revegetation, streambank stabilization, and fencing. The findings and recommendations of this study are intended to support efforts to reduce TMDL targets for temperature, sediment and nutrients in the South Fork Clearwater River.