Big 8 Mile/Lee Creek Restoration

Project Narrative

Work funded for implementation in Lee Cr. under this contract was part of a suite of other related projects that included work in Big Eightmile Cr. and the Lemhi R. This description is for the PCSRF funded work (plus SBT Bonneville Accord and Lemhi County cost share funds) that returned flow to the creek, restored approximately 0.99 miles (Google earth measure) of lower Lee Cr. (including side-channel development), and removed the passage barrier between Lee Cr. and the Lemhi R. Two Lee Cr. diversions in the project worksite dewatered the stream during the irrigation season. These irrigation diversions were reconfigured and the associated ditches abandoned during the project. Flow is now protected in 0.84 miles of reconstructed creek for a minimum of 2 cfs and conservation of 714.06 acre feet of water per year; a stream gauge was installed in Lee Cr. near the confluence with the Lemhi R. Prior to implementation, three culverts impeded fish passage within the straightened portion of Lee Cr. in the project worksite that paralleled the north side of Cottom Road. Two of the three were eliminated as passage barriers when Lee Cr. was reconstructed into the historic stream channel which is on the south side of Cottom Road. The third culvert under State Hwy 28, a 5 CMP and passage barrier between Lee Cr. and the Lemhi R., was removed and replaced with a 15 bottomless arch culvert. Fish passage was opened to 0.99 miles in the project worksite and one mile of good habitat above the project worksite. Three other culverts, an old driveway, and a trailer were also removed in what became a portion of the reconstructed Lee Cr. to the historic channel. This area was revegetated as part of the worksite riparian treatments. Reconstruction of Lee Cr. into 0.67 miles of historic channel upstream of the State Hwy 28 culvert and restoration of 0.17 miles of stream below the State Hwy 28 culvert reconnected the stream, riparian area, and floodplain. In addition, a 0.15 mile side channel was constructed in the upper portion of the worksite. The total stream area treated was 0.99 miles. Structures were placed in the channel to add stream complexity, these included the following: 6 log cross vanes, 13 rock cross vanes, 37 log/rock cross vanes, these 56 structures will ultimately result in the scouring of 56 pools. Both sides of the 0.99 miles of Lee Cr., approximately 5.51 acres of riparian and floodplain were revegetated with native plants, including the following: Salix bebbiana, Salix geyeriana, Salix boothii, Rosa woodsia, Ribes aureum, Populus balsamifera, Populus tremeloides, Alnus incana, Carex nebrascensis, seed mix of Deschampsia caespitosa, Elymus lanceolatus ssp. Psammophilus, Leymus cinereus, Elymus trachycaulus ssp., seed mix of Carex nebrascensis, Juncus balticus, plants: Elymus lanceolatus ssp., psammophilus, and in the driveway/trailer area a seed mix including Sporobolus cryptandrus, Pseudoroegneria spicata, Hesperostipa comate, Poa sanbergii, Festuca idahoensis. Approximately 0.71 miles (Google earth measure) of Jack fence was installed enclosing about 0.40 miles (Google earth measure) of the reconstructed Lee Cr. channel to restrict livestock access to the stream. About 0.59 miles of stream (Google earth measure) in the upper portion of the worksite was already protected by an existing fence. A livestock stream crossing was installed between two pastures separated by Lee Cr. below the State Highway 28 culvert and an off-channel three-trough livestock watering system fed by a spring infiltration gallery was installed above the State Hiwy 28 culvert, protecting approximately 2 acres. The project application incorrectly identified 4.6 acres of wetland treatments, however none were implemented. This work was preceded by engineering design, environmental compliance and permitting, and water right transfers.