Lower Lemhi and Upper Big Springs

Project Narrative

Lemhi Regional Land Trust sponsored the design of two habitat restoration projects on the Leadore Land Partners (LLP) Conservation Easement: the LLP Lower Lemhi Project and the Upper Big Springs and Pond Outlet Project. The project areas are lacking riparian habitat, are over-straightened, and over widened. The project area has been heavily impacted by historic land use practices which have reduced channel complexity, floodplain connection, and riparian vegetation resulting in degraded habitat for anadromous fish. Project designs maximize short-term and long-term riparian and shade conditions to address established shade targets, reduce the channel width to a more appropriate geometry, increase in-stream hydraulic diversity and velocity gradients, increase pool size and frequency, increase interstitial space along margins, and increase in-stream cover. The Lower Lemhi Engineering was completed at 80% design (including wetland delineation) for 4,200 feet (0.80 miles) of the Lemhi River and 4.2 acres of floodplain development adjacent to the river. The Big Springs and Pond Engineering was completed at 80% design (including wetland delineation) for 2,050 feet (0.39 miles) of Big Springs Creek, the installment of a pond spring outlet to assure cool exit water, and 2.53 acres of floodplain development adjacent to the Creek. Project goals are to improve habitat for limiting life stages of ESA-listed fish, restore natural channel processes to maintain diverse habitat, and to address shade targets set in the Conservation Easement. The project is intended to improve habitat for Endangered Species Act (ESA) listed spring Chinook Salmon (Oncorhynchus schawytscha), summer steelhead (Oncorhynchus mykiss), and bull trout (Salvelinus confluentus).