Eighteenmile Creek Restoration (Beyeler)

Eighteenmile Creek is a headwater tributary to the Lemhi River. The Eighteenmile Creek Restoration Beyeler Project was implemented by the Lemhi Soil and Water Conservation District and addressed the lowest fish passage barrier on Eighteenmile Creek. Approximately three miles of fish habitat was made accessible to all life stages of ESA-listed spring/summer Chinook Salmon and steelhead.

In the past, Eighteenmile Creek had been appropriated from its original channel and modified to accommodate irrigation needs. The landowner annually created a push-up dam within the channel to divert water for irrigation. This project removed the push-up dam, relocated the point-of-diversion upstream to a new diversion structure and relocated 0.34 mile of Eighteenmile Creek back into its historic channel. Approximately 0.3 mile of the old channel, which was straightened, devoid of vegetation and impacted by cattle, was abandoned and filled in with excavated material from the downstream portion of the new channel. The new channel is 0.34 mile long and consists of pools separated by riffles, and follows the historic channel alignment through the willows. Construction of the new channel included both excavation and fill, as well as the creation of 31 pools and 31 riffles. The riffle crests were built up with material excavated from the pools. During construction of the new channel, the contractor removed sod mats, excavated the new channel, and then built the banks with the intact sod mats. Approximately, 0.19 mile of jack fence was installed along the east stream bank of Eighteenmile Creek at a 35-foot setback from water’s edge to promote the recovery of the riparian zone.

As part of this project, irrigation improvements were made for the Beyeler Ranch. This included installation of 865 ft. of 15” irrigation pipe from the new point-of-diversion and fish screen location (IDFG) to the existing pipeline and two new pumps and a Variable Frequency Drive (VFD). Livestock water pipeline (860 ft.) and 3 rubber tire troughs were installed to mitigate lost access for livestock to water from the creek. IDFG installed a new head gate, log weir and fish screen under separate funding.

Project partners included Governor’s Office of Species Conservation, Natural Resources Conservation Service, Trout Unlimited, the Upper Salmon Basin Watershed Program, Idaho Department of Fish and Game and Bureau of Reclamation. More importantly, the willing participation of three local land owners, without whom the project would never have happened. Match funding was provided by the Bonneville Power Administration, and non-match funding was provided by the Natural Resources Conservation Service EQIP contracts.

The suite of project tasks to be completed for this project will improve passage and instream complexity for a total of 3.34 miles of stream for spawning and rearing of ESA-listed spring/summer Chinook Salmon and steelhead in their respective Lemhi River populations.