Salmon River 12-Mile Reach Streambank Design

The project area is located within the 12-Mile Reach of the Salmon River near Challis Idaho. The Salmon River 12-Mile Reach Streambank Design project will develop an 80% design to address 1.8 mile of eroding banks in order to reduce sedimentation levels within spawning gravels. Portions of this reach experience high flows and icing, at times causing rapid erosion of the banks. Project actions prescribed to increase habitat for salmon and steelhead include an engineered design for root-wad structures and other woody debris structures to stabilize degraded streambanks. This design will complement PCSRF project 011 23 SA, a concurrent project to fence 1.8 miles in the project area and provide off stream stockwater. In order to protect the new fence and riparian vegetation landowners have requested the first step of design to address erosion.

To address the Upper Salmon River Watershed Project’s established “Goals and Priorities” for the 12-Mile reach projects, the main goal for riparian condition is to establish riparian vegetation along critical areas to provide cover and reduce temperatures. PCSRF Project 011 23 SA will install cattle fence and provide off stream stock-water in the design project area to allow growth of native vegetation, protect banks in good condition, and allow degraded streambanks to recover.

The Hannah Slough, immediately downstream of the project area on the Salmon River shows that the juvenile fish densities for Chinook are higher than anywhere documented in the Upper Salmon. Improving stream vegetation will enhance habitat capacity for juvenile life stages of salmon and steelhead above this key reach. Bank protection in key areas will help retain vegetation along this reach.

According to personal communication with the local NOAA fisheries staff, there are at least five of upstream populations, whose juveniles utilize this entire reach for summer and overwintering habitat. These types of projects would enhance the potential for recovery. The Lower Mainstem SR Chinook population is in dire need of increased abundance and higher productivity just to reach a maintained status.