Pratt Creek Lemhi Back Road Bridge Project

Project Narrative

The Pratt Creek Lemhi Back Road Bridge installed a bridge to provide 2.6 miles of unimpaired fish passage. Pratt Creek previously passed through an undersized culvert underneath the countys Lemhi Back Road. The Pratt Creek Lemhi Back Road Bridge project was implemented by the Lemhi Soil and Water Conservation District in conjunction with the Pratt Creek Channel Rehabilitation project sponsored by Trout Unlimited and funded by PCSRF (project 019 16 SA). The Trout Unlimited project moved the Pratt Creek channel to more closely mimic its historic alignment. The old culvert, which passed Pratt Creek water under the Lemhi Back Road, was too small to pass the higher flows anticipated as a result of numerous irrigation efficiency projects completed upstream, creating a velocity barrier to fish. In addition, the new channel intersected the Old Lemhi Back Road in a different location and required a bridge adequate to pass the anticipated high flows. Project partners included Trout Unlimited, the Upper Salmon Basin Watershed Program, and Idaho Department of Fish and Game. Match funding was provided by the Bonneville Power Administration and non-match funding was provided by a US Fish and Wildlife Service grant. This project will improve fish passage through the replacement of the existing CMP culvert with a clear span structure. Habitat quantity will be increased by improving fish passage conditions to upstream habitat for ESA-listed Chinook salmon and steelhead.