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.  

Timber harvest began occurring in the Yankee Fork in the mid-1800s and was conducted primarily to support mining.  By approximately 1904, the hills for miles around the town of Custer (on the Yankee Fork River above the current restoration sites) were denuded of trees, as huge quantities of wood had been used for homebuilding, mine supports, and mills.  This timber harvest was followed, in the dredged area, by clearing to facilitate additional dredging.

Over the past several years, partner agencies and conservation groups that make up the Yankee Fork ID Team (e.g., Trout Unlimited, Shoshone-Bannock Tribes, U.S. Forest Service, Bureau of Reclamation, BPA) have partnered to implement several projects (e.g,. West Fork Yankee Fork Confluence, Preacher's Cove) throughout the dredged reach. Building on the progress made in past years' restoration work, the ID Team believes that the Bonanza City reach of the Yankee Fork has the potential to be improved substantially through removal of dredge tailings to form a flood-plain, construction of a new channel within that flood-plain, and additions of large wood in the reaches up and downstream from that area.

The goal of the three-phase Bonanza project is to return the mainstem Yankee Fork River in the project reach to more natural hydraulic and complex habitat conditions. It will therefore 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 will benefit from this project include spring/summer Chinook salmon, summer steelhead, bull trout, and westslope cutthroat trout.  

Work conducted in this contract renewal will be the final phase of a three-phase channel reconstruction project at the Bonanza City site. Bonanza Phases I and II were contracted under previous contracts (79310 and 81598). Phase I (in 2018) consisted of site preparation and mine tailing removal to ready the stream reach and staging areas for Phase II construction. Stream substrates, including riffle material and spawning gravel, were also generated and sorted during Phase I by screening dredge tailings. Phase II (in 2019) consisted of channel reconstruction, grading, side channel modifications, and instream habitat structure placement.  

Phase III of the Bonanza City Floodplain Restoration project (to be completed in 2020) includes bypassing water from the current channel into a series of bypasses and portions of the newly created channel segments, connecting the channel segments with the existing main channel and creating fish habitat in the existing main channel, and introducing water into the newly created channel.  Vegetation planting will occur during 2020 and 2021.

Cost share for construction at Phase III will be provided through the Pacific Coast Salmon Recovery Fund (PCSRF).