In a remote and rugged setting, Confluence water resource engineers performed a site reconnaissance and survey to design a concrete fish barrier for protection of habitat for Yellowstone cutthroat trout. Site suitability, bedrock and stream conditions, and site access were considered. Confluence was particularly sensitive to minimizing vegetative disturbances and construction impacts to the site. A preliminary analysis and design was completed that included surveying topography, developing hydrology and a hydraulic model, and creating fish passage design criteria for a range of flows. The HEC-RAS model was used to simulate site hydraulics for both existing and proposed conditions.
Final design components included a geotechnical investigation, plans and specifications, designs, and details for construction. Confluence and a partner engineer firm oversaw all construction staking, testing, oversight, and contract administration to establish the exact placement of the fish barrier structure. The fish barrier withstood a roughly 50 year flood event in its first year with minimal impacts. The project was featured by Montana Fish, Wildlife, and Parks at an American Fisheries Society annual meeting.