The Swan River National Wildlife Refuge Wetland Restoration Project is located south of Swan Lake in Lake County, Montana. The Refuge was established by US Fish and Wildlife Service (USFWS) in 1973, prior to which an extensive network of wetland drainage ditches was excavated to drain hydrology from the wetlands to Swan Lake for agriculture and ranching development. Objectives of the project are to address habitat needs for wildlife, restore wetland hydrology, and alter the trajectory of the vegetation community from an invasive reed canarygrass-dominated environment to native sedge, rush, and horsetail communities.
USFWS retained River Design Group to analyze existing conditions, provide restoration alternatives, design, and engineering, as well as oversee project construction. RDG designed and implemented a groundwater monitoring network to inform the design and set a benchmark for future effectiveness monitoring; performed remote sensing analyses and ditch bathymetry surveys to quantify volumes of available on-site material and the optimal locations for strategic ditch fills; prepared preliminary and final design drawings, completed the Environmental Assessment to comply with NEPA including coordination of public scoping and outreach, and prepared regulatory permit documents including a wetland delineation and impact analysis.
The Proposed Action Alternative, which was implemented in Fall 2022, included filling wetland drainage ditches to the greatest extent possible utilizing all available original ditch spoil berm material and levees on-site. 25,000 cubic yards of material were excavated from berms and levees across the 1,600-acre Refuge, and 5,000 feet of main drainage ditch was filled to elevate the water table and improve the overall functions and values of the wetlands. Implementation challenges included building and then reclaiming 5.4 miles of temporary access roads through the Refuge, ensuring both heavy construction equipment access and minimal disturbance to sensitive wetland habitat. The wetland restoration project is projected to restore wetland hydrology to 655 acres of previously drained wetlands and decrease reed canarygrass dominance in favor of native wetland plant species.