Improve Flow in Big Timber Creek 1.4

Project Narrative

All components of project 005 07 SA PH2 were successfully implemented in 2010 and 2011, resulting in an additional 1.4 cubic feet per second (cfs) of flow for fish in lower Big Timber Creek. This flow augments approximately 4.5 cfs that was provided from a previous project, thus, a minimum of 6 cfs total flow volume is now available for migrating salmon and steelhead. Project components included upgrade and installation of new power lines, installation of irrigation pipe of various sizes, installation of a new irrigation diversion and fish screen, and installation of a common pump station.Reference to a common pump station involved designing and developing an irrigation system that utilizes multiple sources of water from three different drainages (Lemhi River, Big Timber Creek, and Canyon Creek), resulting in benefits to salmon and steelhead in each of these watersheds. Most of the project components of this contract were administered concurrent to contract 003 08 SA “Canyon Creek Reconnect” since both ultimately uses a common pump station site, power line, diversion and screen, and access road. This maximized efficiency between these two projects, and minimized implementation time and landscape/resource disturbance.The IDFG will complete compliance and effectiveness monitoring activities for this project under the ongoing Lemhi Conservation Program. The IDFG has already designed an effectiveness monitoring protocol to establish the extent to which projects in Big Timber Creek increase the quantity and improve the quality of existing habitat. Habitat response measures that will be monitored include adequate passage flows, the amount of wetted area provided by the target flow, the response of the riparian community, and changes in stream temperature. Fish passage conditions will be monitored in the historically dewatered stream segment during the irrigation season. Infrastructure necessary for this specific fishery monitoring (e.g. PIT Tag array) has already been installed. Fish response will be measured in Big Timber Creek at several reaches and intervals throughout the watershed. Response measures that will be monitored include expanded distribution of anadromous fish that pioneer into the newly reconnected habitats, improved survival, changes in size and age distribution of stream resident/fluvial trout, and changes in fish abundance.The overall benefit as a result of Phases I, II and III will be the reconnection of Lemhi River tributaries with the Lemhi River. This project will improve flow in Big Timber Creek and provide critical spawning and rearing habitat for salmon and steehead. Juvenile salmon produced in the Lemhi will be able to access cooler water in Big Timber Creek for rearing during summer, adult salmon will access the tributary for spawning, and adequate flow will be available for pre-smolts and smolts for their seaward migration.