Pratt Creek Channel Rehabilitation

The Pratt Creek channel was relocated into 1,774 (0.34 mi) of new channel in fall 2018 from where it had been pushed to the side of the canyon and into a ditch. Approximately 561’ (0.11 mi) of existing channel at the mouth was improved. This 0.45-mile section of Pratt Creek now has complex fish habitat, complete with meanders, riparian vegetation, livestock fencing, toe log structures, pools and riffles. Approximately 1 acre of new floodplain was constructed. Newly constructed floodplain, streambanks, and disturbed upland equaling 3.4 acres (0.38 linear mile on each side of the creek) were seeded with native mesic and xeric species. The streambanks (0.38 miles of stream) were planted with potted native plants. Livestock fencing was installed on each side of the newly realigned channel (0.69 miles of fence) to protect and improve success of revegetation efforts along 0.45 miles of stream. One ford was installed to allow livestock crossing and three water troughs were installed. A new domestic well was installed for the landowner in fall 2021 to address issues of water loss associated with this project in their existing well. Noxious weeds were treated throughout the project site.



Two amendments to the contract allowed for higher-than-anticipated bids for planting, irrigation and stockwater installation, and to install the domestic well, explained above. Modifications to the proposed included 14 more pools and 7 additional instream structures. The riparian acres treated were 1.0 compared to 3.4 acres proposed. This was likely an error in the proposal as there were 3.4 acres of upland treated.

The project benefited the Lemhi River Snake River Steelhead population within the Salmon River Major Population Group (MPG) and the Lemhi River Snake River Spring/Summer Chinook Salmon population within the Upper Salmon River MPG.



The project accomplished these specific restoration goals:

- Created a new morphologically appropriate channel segment through existing low ground.

- Improved water quality through vegetation of newly created streambanks to reduce fine grained sediment input and prevent increases in water temperature.

- Improved thermal refuge by increasing the frequency and magnitude of self-maintaining pools.



Habitat quantity was increased by improving fish passage conditions to upstream habitat and increasing channel complexity. Creation of a new channel promoted increased channel diversity, allowing for the natural development and maintenance of scour pools and refugia. Development of an appropriate width-to-depth ratio reduced open water surface area at low flow, reducing localized thermal loading, and increased floodplain connectivity for natural recruitment and growth of native seed sources. Bank treatments and altered land use practices increased bank stability and reduced localized fine-grained sediment inputs.



Development of a robust riparian corridor will, over time, increase shade, reduce thermal loading, increase bank stability and aid in sediment retention.



This project will address five of the nine limiting factors identified by FCRPS including water temperature, increased sediment, bed and channel form, floodplain condition, and riparian condition.