About the Project

Between 1911 and 1923, 10 dams were built on eight high mountain lakes in Montana’s Rattlesnake Creek headwaters to augment water supply for the City of Missoula. These dams are located deep in the Rattlesnake Wilderness Area, which folds into the Lolo National Forest. After a long legal battle with the Mountain Water Company, the City of Missoula in June 2017 assumed ownership of Rattlesnake Creek Dam, the 10 wilderness storage dams, and all associated water rights. The wilderness dams create significant hazard and are costly to maintain. After removing Rattlesnake Creek Dam in August 2020, the City turned its attention toward improved management of the obsolete water system upstream.

In 2018, the City, Trout Unlimited, and Montana Fish, Wildlife and Parks (MFWP) completed an initial assessment of the best course of action for the wilderness dams. The assessment recommended removing eight dams to address watershed hazards, reduce the City’s maintenance requirements, rid the watershed of non-native rainbow trout species, and re-naturalize the sites to protect their wilderness character. The assessment also recommended rehabilitation of the two dams on the largest wilderness lakes so they can provide a failsafe source of cold water for release into Rattlesnake Creek during drought and summer months to manage streamflow and temperatures for the benefit of the community and native fish.

Removing the eight wilderness dams is expected to take at least 10 years and will include significant regulatory and logistical challenges given the inherent obstacles of removing dams deep in a wilderness area. In 2024, Open Rivers Fund supported Trout Unlimited, in partnership with the City and MFWP, to complete a pilot dam decommissioning for one of the wilderness dams to test and refine the permitting process with the US Forest Service. McKinley Dam was successfully removed with the help of explosives packed into the site by mules in August 2024. The project provides a roadmap and helps build momentum for subsequent removals.