Lemhi River L-52 Removal

Actions completed on this project include: (1) Abandonment of the L-52 irrigation canal that captured water from Lemhi Little Springs before transporting this water a distance of about 7 miles.
(2) Installed a new pressurized sprinkler irrigation system that converts from flood irrigation and conserves water: three pivots, water pumping station, and pipeline that irrigate approximately 88 acres. (3) Upgraded power transmission lines to 3-phase power. (4) Removed three fish passage barriers (2 diversion dams and 1 diversion dam, tarp and rock). The irrigation ditches behind all three diversions were filled in. The removal of the diversions increased access for a total of 4.5 miles: L52 – 0.3 miles, Little Springs Creek – 2.2 miles, and Mill Creek-2.0 miles. None of these blockages were road crossings. Through this diversion removal Mill Creek was reconnected with Little Springs Creek and ultimately the Lemhi River. (5) Natural function was restored to Berg-Green Springs and DC Gulch Springs, neither of which are fish bearing at this time. (6) Re-contoured L-52 at points where ephemeral draws bisect the canal to allow natural water flow during run-off events approximately 7 miles. (7) Transferred water rights and completed an agreement between the livestock company and the Idaho Department of Water Resources to not divert from Lemhi Little Springs Creek: Upper Lemhi River-4.06 cfs for approximately 7 miles, Little Springs Creek - 2.0 cfs for approximately 3.5 miles, and Mill Creek – 1.0 cfs for approximately .5 miles. This resulted in 11 miles of stream protected for adequate flow. (8) Though not originally proposed channel reconfiguration and connectivity was addressed. A total of approximately 0.3 miles of stream was treated for channel reconfiguration and connectivity through enhancement of 0.23 miles of the Lemhi River flood plain and creation of 0.02 miles of off channel habitat created. (9) Although not originally proposed, a concrete vault was constructed and a pump installed at a spring head to pump and supply water to five water troughs that were purchased and installed to provide water to livestock. Approximately 120 feet (0.02 miles) of jack pole fence was constructed around the spring head to exclude livestock, promote vegetation and protect the pump and pump and equipment. (10) Approximately 0.1 acres of slope was stabilized for sediment control. (11) Approximately 0.1 miles wetland acres were treated through the removal of a ditch to create a floodplain and planting vegetation.

The primary focus of this project was to improve flow to functionally reconnect Lemhi Little Springs Creek to the Lemhi River. The project actions have and will continue to improve spawning and rearing habitat for ESA listed species.

The removal of barriers and improved flow and stream habitat will benefit abundance, productivity, spatial structure, and genetic integrity of ESA listed Chinook salmon and steelhead in the Lemhi River sub-basin. These species will have greater access to good quality spawning and rearing habitat in Little Springs and Mill creeks. Specific benefits to the habitat include: (1) increased flows from 2-13 cfs for more than 6 miles of upper Lemhi River and/or Little Springs, (2) increased connectivity of lower Mill Creek with Little Springs, (3) improved connectivity of Little Springs with the Lemhi River (4) elimination of fish passage barriers in Little Springs, Mill Creek and a channel of the upper Lemhi River, (5) elimination of fish entrainment at L-52 and Little Springs as well as L-52 and Mill Creek, and (6) reduction of sediment and water temperatures in Little Springs