The Shields River watershed is a stronghold for YCT, but relatively recent invasion of Brook Trout places this population at risk. The watershed is a conservation priority due to the exceptionally low extent of hybridization, and its placement within a climate shield, which should retain suitable habitat for the foreseeable future. This project is a component of a watershed level effort to secure this highly imperiled population, which has included multiple years of basin-wide electro-fishing to remove nonnative Brook Trout, installation of a large barrier at the downstream end of the project area to protect the area from re-invasion, strategic placement of temporary barriers to prevent further invasion of Brook Trout, and temporary maintenance of existing impassible culverts to protect stream from invasion. The culverts slated for replacement are on 2 tributaries that are free of Brook Trout and have barriers near their confluences with the Shields River that will continue to protect these streams, while mechanical Brook Trout removal continues. These culverts slated for replacement are not protective and are preventing free movement of YCT within the streams.