Fish habitat in the Yankee Fork River has been drastically altered as a result of historical land use in the Yankee Fork drainage, particularly where dredge mining occurred.  Dredging occurred intermittently between 1940 and 1952 and obliterated the Yankee Fork stream channel, eliminating or substantially reducing the floodplain.  The new channel that formed was often trapped between dredge tailings and the valley hillside, where it was unable to re-establish a natural meander pattern. Further, flood-flows contained between the hillside and dredge tailings resulted in increased stream energy, which mobilized spawning gravels and wood out of the reach. The inability for this area to naturally recover has also been exacerbated by past removal of trees from the landscape, especially the riparian areas.  

Over the past several years, partner agencies and conservation groups that make up the Yankee Fork ID Team (i.e., Trout Unlimited, Shoshone-Bannock Tribes, U.S. Forest Service, Bureau of Reclamation, BPA) have partnered to implement several projects (e.g,. Bonanza Reach, West Fork Yankee Fork Confluence, Preacher's Cove) throughout the dredged reach. The following Projects will be accomplished under this agreement:

1) Bonanza City Floodplain Restoration Project - Fish Migration Impacts Mitigation 2023
The mainstem Bonanza reach floodplain project (completed in 2020) removed dredge tailings, constructed a new channel within the floodplain, and added large wood in the reaches up and downstream from the main project area. The goal of the Bonanza project is to return the mainstem Yankee Fork River in the project reach to more natural hydraulic and complex habitat conditions. Habitat restoration in this reach was designed to enhance fish habitat for all life-stages of migratory and resident fish, provide cover during high and low flows, provide winter habitat for juvenile salmonids, and provide spawning areas for all salmonids. Salmonids that benefit from this project include spring/summer Chinook salmon, summer steelhead, bull trout, and westslope cutthroat trout.  

Bonanza Phases I-III were contracted under previous contracts (79310, 81598, and 84695). During Phase III of the project (in 2020), water from the Yankee Fork was moved from the straight, armored, plain-bed channel, where it had been left following dredging, to its historic location from which dredge tailings had been removed to form a meandering channel and floodplain.  This new channel that was built over unconsolidated dredge tailings was porous and substantial amounts of water seeped through the permeable gravel and cobble channel and then re-entered the channel as springs further downstream within the project area.  As flows declined in the fall of 2020, flow rates eventually decreased below seepage rates, resulting in three constructed riffle sections going dry within the project area for several weeks. The project reach was surveyed for migrating Chinook, steelhead, and bull trout in fall 2020, and fish were captured and moved past the dry sections as needed. Flows have been monitored continuously since the fall of 2020 to determine timing and extent of the dry reaches of the project area.

In 2021, Trout Unlimited worked with Yankee Fork basin partners to address passage limitations for upstream migration of adult Chinook salmon and downstream migration of juvenile Chinook salmon and steelhead, and juvenile and adult bull trout. The "Bonanza City Floodplain Restoration Project Fish Migration Impacts Mitigation Plan for 2021" (attached to contract 88434) outlines measures for addressing fish passage under flow restrictions.  Trout Unlimited coordinated installation and operation of a fish weir and trap at the head of the downstream most pool that maintains perennial flow; the weir was moved to a more suitable location in the riffle above Side-Channel 8 in late July.  Trapping was intended to allow Chinook Salmon and Bull Trout to be captured and moved if they attempt to migrate upstream from this location.  Trapped adult fish were to be transported upstream from the dewatered project sections and released above Jordan Creek, where they could continue their migration. No adult fish were actually trapped in 2021, although the weir and trap were operated from July 18th through August 15th 2021. Juvenile migrating salmonids were collected and moved downstream past the dewatered section throughout the late summer and early fall.

In 2022, Trout Unlimited worked with Yankee Fork basin partners to implement adaptive management to speed the natural sealing of the section of new channel in the Bonanza Project that is prone to dewatering during low flows. Approximately 320 cy of placed material was added during the spring and summer of 2022. The additions were monitored for effectiveness to reduce channel permeability. Trout Unlimited planned to address any remaining passage limitations for upstream migration of adult Chinook salmon and downstream migration of juvenile Chinook salmon and steelhead, and juvenile and adult bull trout. However, flow was maintained throughout the project throughout the fish migration period.

In 2023, Trout Unlimited will repeat the adaptive management actions. Any passage limitations for fish will also be addressed, should they occur, the same as previous years.

2) Shoshone-Bannock Tribes - Yankee Fork Fish Passage Improvement
Outyear planning and preliminary design will be done for passage work in several side channel sites. The implementation work will be primarily funded by NOAA for implementation in 2024-26, but will require coordination with the BPA SBT and TU contracts for design and planning. The Yankee Fork Fish Passage Improvement Project will restore fish passage and connectivity for native resident and three ESA-listed anadromous and migratory fish species (Snake River Spring/Summer Chinook Salmon, Snake River Steelhead, and Bull Trout) in the Yankee Fork watershed.  The project goal is to restore fish passage and connectivity in Pond Series 4.  This project will achieve measurable and lasting benefits for ESA-listed migratory fishes, support indigenous management of culturally and ecologically resilient fisheries, enhance watershed resilience to threats from climate hazards, and increase the capacity for the Shoshone-Bannock Tribes to effectively manage tribal trust resources for cultural, spiritual, and subsistence purposes.

Pond Series 4 is a series of dredge ponds that the Shoshone-Bannock Tribes connected to the Yankee Fork in the mid 1980s.  This pond series is connected with the Yankee Fork during high spring flows, but as flows recede, the inflow and outflow channels go dry.  This excludes ingress and egress from the pond series, but also prevents access to a small unnamed spring, present in Pond Series 4, that was historically connected to the Yankee Fork.  

Building on the success of previous habitat restoration actions, the TU and the Tribes will utilize the Yankee Fork ID Team’s experience and expertise to plan, design, permit, and implement this project that will reconnect and enhance more than 500 meters of existing pond and side channel habitat by removing in-stream barriers.  The Pond Series 4 reconnection project will benefit adult and juvenile salmonids by providing: 1) perennial connectivity and passage to the mainstem Yankee Fork; 2) access to thermal refuge during winter months (i.e., winter-warm habitat) including refuge from supercooling and frazil ice; 3) access to high-water refugia during spring run-off; and 4) increased forage opportunities in productive side-channel habitat.

3) Yankee Fork Habitat Capacity Estimate Report
Over the past ten years, numerous organizations have cooperated to implement habitat improvement projects to benefit juvenile Chinook Salmon and steelhead in the Yankee Fork. Habitat improvement projects have varied in extent, risk, and cost. Therefore, as future improvement projects are planned, it is important to understand past project types’ relative contribution to fish populations. However, the fish population response to improvements can be masked by variable adult returns affected by out-of-basin factors. Therefore, an assessment of change in fish habitat quantity and quality is necessary for this assessment. From 2013 to 2022, fish habitat measurements were collected in the Yankee Fork drainage, including in habitat improvement areas, using the Columbia Habitat Monitoring Protocol (CHaMP). This protocol produces over 100 metrics that quantify various aspects of fish habitat. However, how these habitat metrics relate to fish populations is unclear. Recently, a quantile random forest model was developed to estimate Chinook Salmon parr carrying capacity using a subset of CHaMP metrics. We will use this model to assess habitat capacity in various areas in the Yankee Fork drainage and to assess habitat capacity uplift of various habitat improvement types. Habitat capacity comparisons before and after habitat improvement will also be made. These comparisons and the relative risk and cost of habitat improvement projects will help guide future habitat improvement strategies for the Yankee Fork.  

Under this agreement, Trout Unlimited will draft and submit a manuscript to a scientific journal for publication.