Upper Clark Fork diversions

Restoring headwaters after a legacy of mining pollution

About the Project

The Clark Fork River winds through western Montana and Idaho before draining into the Columbia River. It provides abundant recreational, economic, and cultural resources, as well as vital habitat and migration corridors for fish and wildlife, including westslope cutthroat trout, bull trout, and sculpin. It is also home to the nation’s largest Superfund site, a legacy of the copper mines and smelters in and around Butte, Montana. A massive flood in 1908 deposited millions of tons of metal-laced tailings along 120 miles of floodplain, with devastating and lasting impacts to stream life. The cleanup has progressed enough to sustain fish populations, but dams in the Upper Clark Fork present additional obstacles to restoration.

The Clark Fork Coalition and Trout Unlimited are removing and modernizing eight of the most problematic irrigation dams on the mainstem river between Warm Springs and Deer Lodge, Montana. These efforts will restore streamflow for fish, improve irrigation infrastructure for landowners and water users, and address safety risks to waders and boaters. Most dam owners are on board, due largely because maintenance costs are rising for their aging structures. Where feasible, they will introduce water efficiency measures. Mining-related remediation funds are expected to cover a significant amount of the construction costs to remove or modernize the diversion dams once designs are finalized and landowner agreements are secured.

Owner: Private Landowners
Size: Two pin and plank diversions and six rockfill or earthen fill diversions that span the river, 2-6 feet high
Project Cost: $21 million
ORF Investment: Design, engineering, project management, landowner outreach, and construction
Miles Opened: 63 miles
Fish: ESA-listed fluvial bull trout, westslope cutthroat trout, mountain whitefish, and sculpin
Status: Three dams removed, opening 35 river miles, with one dam removal expected per year through 2027

  • Restore fish passage to 63 miles of mainstem river and tributary habitat – including access to cold water refugia
  • Improve water use efficiency and flows for agricultural uses and reduce maintenance costs
  • Improve recreational fishing
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Project Partners

Clark Fork Coalition

Trout Unlimited

Watershed Restoration Coalition

Anaconda Sportsmen

Montana Natural Resource Damage Program

Montana Department of Environmental Quality

Montana Department of Resources and Conservation

Montana Department of Fish, Wildlife and Parks

Clark Fork River Technical Assistance Committee

Clark Fork Watershed Education Program

Powell County