L50 and LSC3 Removal

Project Narrative

Previously a 1.8 cfs water right was delivered via the Lemhi River L-50 diversion for 0.3 miles to be comingled into Lemhi Little Springs Creek (LLSC). The comingled water conveyed another 1.2 miles in LLSC, then was re-diverted from LLSC at the LSC-3 diversion into an unscreened open ditch for 2.8 miles to the point of use, traveling a total of 4.3 miles. As part of this project, the landowner exchanged the point of diversion (POD) from L-50 and LSC-3 to an existing screened diversion, L46a, effectively closing L-50 and LSC-3. This improved Lemhi River stream flow by 0.9 cfs (652 acre-feet/year). The L-50 POD was not a fish passage barrier, but was removed as part of improving flow. A total of approximately 1.08 miles of stream is protected for sufficient flow for spawning and rearing habitat. The open ditch irrigation system was converted to a pressurized pivot sprinkler system. The existing 49.2 acre irrigation footprint remains the same. A pump station, pivot and 960 feet (0.18182 miles) of irrigation pipeline were installed. The new irrigation system improved water conveyance and distribution efficiency. The fish passage barrier at the LSC-3 (diversion) was removed by the landowner thereby preventing fish entrainment in the unscreened diversion. A total of 2.7 miles of stream was made accessible by removing this fish passage barrier. The objective of this project was to close and remove both the L-50 diversion from the Lemhi River LSC3 diversion (fish passage barrier) on LLSC. This project was another step in the reconnection of LLSC with the Lemhi River.