Middle Fork Project 5

Background: The Middle Fork of the West Fork of the Gallatin River (Middle Fork) is one of six tributaries of the Gallatin River that does not meet state water quality standards. Resource concerns include erosion, vegetation loss, and pollutants (i.e. sediment, nutrients, and E. Coli) which impact aquatic life, wildlife habitat, and recreational uses. In order to address these resource concerns, the Task Force worked with Trout Unlimited to develop five restoration projects aimed to improve water quality, habitat conditions, and build water storage capacity. The first Middle Fork Project was completed in October 2021.

Project Description: Project 5 will be the second river restoration project proposed for the Middle Fork to bolster wetland and riparian conditions, improve fish habitat, and water quality.  The project will utilize low-tech, process based restoration (LTPBR) techniques. LTPBR focuses on creating the right conditions for natural processes to resume in order to improve ecological health of the stream and surrounding wetlands. Taking cues from nature, low-tech restoration, utilizes natural materials and restoration techniques such as beaver dam analogs (BDA’s) and post assisted log structures (PAL’s). This project is part of our proactive work to improve water quality and protect streamflows by making the most of Big Sky’s winter snowpack.

Existing Conditions: The project is adjacent to the winter and summer recreational trail system maintained by Lone Mountain Ranch. Historically, the stream channel was located within a meadow rather than its current location along the recreational trail and a large eroding streambank. Additionally, the channel is a continuous riffle lacking diverse in-stream habitat. Riparian health in the project area is defined as moderate-fair, meaning mature vegetation exists along 20% or less of the stream and the width of riparian vegetation is generally 10 feet or less.

Proposed Improvements: 
The primary goals are to reconnect the steam with the floodplain, enhance wetland/riparian vegetation, eliminate sediment loading, raise the water table throughout the meadow, and improve trail conditions. These goals will be met by achieving the following objectives:

• Restore the channel into the center of the meadow
• Relocate the channel away from the eroding streambank and revegetate the hillside
• Enhance wetland features with woody debris jams and artificial beaver dams
• Relocate trail off of eroding streambank