Whitworth- Upper Patterson-Big Springs Restoration Project

Project Narrative

Idaho Department of Fish and Game (IDFG) improved habitat complexity on 1.57 miles of upper Patterson-Big Springs Creek near the town of May, ID. This project completed construction in 2023. Conditions in the spring channel prior to construction included limited instream habitat and channel complexity, disengaged lateral habitat, and degraded riparian habitat. Project objectives included increasing both habitat and channel complexity and reconnecting side channels. Restoration actions included channel spanning log jams, habitat wood, constructed islands and riparian benches, and riparian planting. A 1-mile fence was constructed to protect the channel, riparian, and floodplain zones from cattle impacts. Though increased lateral connectivity on the floodplain and excavated side channels were proposed to increase channel length, modeling iterations and landowner preferences decreased the amount that occurred. Through multiple modeling iterations, channel spanning log jams were used to increase depth and spread water instead of engineered riffles and brush mattresses. Water was spread into the floodplain at certain flows, and side channels were activated. One major network of braided side channels was removed from the design due to landowner preference. The project will increase habitat capacity for juvenile salmon and steelhead. IDFG worked with the Bureau of Reclamation (USBR) to develop designs and implement the project in order to improve habitat complexity and promote a healthy riparian zone. The landowner is allowing utilization of a large portion of the property (under a conservation easement) for this purpose. Rehabilitating upper Patterson-Big Springs as part of a multi-project effort to improve floodplain and riverine processes and functions on several springs as well as mainstem Pahsimeroi on this property will directly increase habitat capacity for juvenile salmonids. Under the proposed project, current conditions will be improved by restoring instream channel habitat using woody habitat structures and improving lateral connectivity to the floodplain and side channels. This will result in improved survival for all freshwater life stages. The project will provide increased foraging and rearing (summer and winter) opportunities for juvenile salmonids near the Patterson-Big Springs production reaches for Chinook and steelhead.