South Fork Boise River Secondary Channel Project-Bull Trout Critical Habitat
Project ID: R25AP00597
Federal Agency: U.S. Bureau of Reclamation Partner Institution: University of Idaho Fiscal Year: 2025
Initial Funding: $42,031
Total Funding: $42,031
Principal Investigator: Tonina, Daniele Agreement Technical Representative: Polit, Christian
Abstract:
Background and Objectives
The South Fork (SF) Boise River downstream of Anderson Ranch Dam provides critical habitat for the federally protected bull trout. The area is defined by the US Fish and Wildlife Service as Foraging, Migratory and Overwintering habitat. Current water management practices on the SF Boise River include reduced frequency, duration and volume of flow that would mobilize and redistribute sediment throughout the watershed. As a result, sediment has accumulated in secondary channels over time. Under current water management practices, secondary channels are connected during the annual irrigation season when flows typically range between 1200 cfs and 2000 cfs. However, outside of the annual irrigation releases, discharge from Anderson Ranch Dam is typically maintained at 300 cfs, and at this flow most secondary channels lose connectivity. A lack of access to habitat in the secondary channels results in critical overwinter habitat being limited for bull trout and their prey.
Project objectives, described as “Tasks”, include the following:
- Inventory and describe each secondary channel and extent of seasonal and flow connectivity using existing data.
- Describe habitat benefit potential if secondary channel connectivity is maintained at winter minimum flow.
- Estimate the effort to restore upstream and/or downstream connectivity (during low flow scenarios) for each secondary channel.
- Prioritize all potential secondary channel reconnection project based on habitat benefits and estimated project costs.