Projects

Upper Big Hole Streambank Restoration

Project completed December 2021.

The focus of the 40 Bar Streambank Restoration project was to protect, restore and enhance approximately 1,260 feet of riparian area along 3 reaches of the Upper Big Hole River. Prior to this project, none of the proposed streambanks had healthy, native riparian vegetation, but rather undesirable, introduced/exotic plants with shallow rooting depths. Due to the poor rooting ability and lack of preferred riparian vegetation, these streambanks exhibited excessive lateral erosion, causing them to release large amounts of sediments into the stream. Additionally, the lack of riparian vegetation and resulting shade contributed to high water temperatures. The previous streambank conditions represented a highly degraded portion of the river and if left untreated, this stretch would have degraded further and potentially reduced the success of native species restoration.

Our restoration approach for this project was to implement a “soft” bioengineered design, to regrade the vertical, eroding banks, install a thin river cobble veneer on the newly excavated streambank toe, and plant riparian vegetation throughout each bank. Willow transplants that varied in age class were planted at baseflow and bank full elevations. Wetland (sedge/rush) sod mats were planted between the transplanted willow and on the regraded streambank slopes. All disturbed areas were seeded with a native riparian species mix. Lastly, an electric fence has been installed around each streambank to prevent lateral erosion from cattle grazing and trampling. This will allow sufficient time for riparian vegetation to able to establish without cattle disturbance.

This project is part of a much larger effort in the Upper Big Hole watershed to restore and enhance native fish, including Arctic grayling and Westslope cutthroat trout populations, within the upper reaches of their historic range.