Montana Trout Unlimited (MTU) is leading the removal of the Shaw Diversion Dam on the Boulder River near Butte, Montana — a landmark project aimed at reversing decades of ecological decline in the Upper Missouri River Basin. Persistent drought, land-use changes, and climate-driven shifts have reduced stream flows, raised water temperatures, and caused sharp declines in native and wild salmonid populations across the region. The 2017 Montana Climate Assessment confirms these trends will intensify, making proactive restoration essential.
The Shaw Dam sits on the 2,840-acre Candlestick Ranch, owned by Golden Sunlight Mine (GSM). Removal of the dam and a smaller upstream diversion will restore fish passage to 111 miles of stream, reconnect cold-water habitat, eliminate fish entrainment, and enhance over two acres of wetlands. Most critically, fish will regain access to Cold Springs, providing vital thermal refugia for Westslope cutthroat, brown, and rainbow trout, along with numerous other native species. The project will also
improve floodplain connectivity, increase alluvial water storage, and sequester carbon in restored riparian soils and vegetation.
The Boulder River is the Jefferson River’s largest tributary and a key provider of cold water and spawning habitat along the Jefferson’s 83-mile length. The Jefferson Basin has experienced well-documented trout population declines, harming the region’s recreational economy and outdoor heritage. This project directly addresses that by keeping the Jefferson cold, connected, and resilient, as well as restoring important elk and turkey habitat along the river, all of which will increase the value for recreationists from anglers to rafters, birders and hunters.
MTU has navigated significant milestones to move this project forward. GSM will upgrade its irrigation infrastructure in spring 2027. Construction is planned for fall 2026, with dam removal and floodplain restoration slated for late 2027.
