Rattlesnake Wilderness Dams

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Photo of Big Lake in the Rattlesnake Wilderness Area with a portion of the dam structure in the foreground.

Exploring Solutions

The City has many options as it considers the future of the ten wilderness lake dams it owns in the Rattlesnake Wilderness and National Recreation Area.

We want the public's opinion on possible solutions.

Missoula Water is responsible for repairing and maintaining the dams following the the City's purchase of the water utility in 2017. The 2018 Rattlesnake Dams Feasibility Study concluded that Missoula Water should start planning to either decommission or rehabilitate each dam because the City does not have the staff or financial resources to make necessary repairs and maintain all ten dams. So, decisions need to be made about how to handle these problems now and into the future. The study suggests that most of the dams should be decommissioned with the City repairing and continuing to maintain the largest dams with the largest storage water rights.

However, there are many options for the City to consider, including decommissioning some or all dams, reconstructing some dams in order to store water that would add to Rattlesnake Creek stream flows, or improving the dams to meet U.S. Forest Service standards. The City must also think about long-term community needs, regulatory agency requirements, environmental impact and climate change, public safety, repair costs, maintenance costs, and water rights.

Seeking Public Input

On April 7, 2021, City staff from the Public Works & Mobility and Parks & Recreation departments, Trout Unlimited, U.S. Forest Service, and Montana Fish, Wildlife & Parks held an informational public forum presentation webinar to provide a brief history of the wilderness lakes and dams; an explanation of the City's maintenance challenges; project vision and goals; a brief description of fish, wildlife, reptile/amphibian, and vegetation data; and a project timeline.


For details, please watch the video presentation or review the slideshow presentation. Then, take our survey below. We want to hear your opinion about the project!

There will be many more opportunities for the public to engage in this decision-making process.


Background

In 2017, the City of Missoula acquired the lower Rattlesnake dam and surrounding property and buildings, ten dams in the Rattlesnake Wilderness Area, and related water rights as part of its purchase of the former Mountain Water Company. Rattlesnake Creek was the original water supply for the early settlers in Missoula, providing water for lumber mills and homesteaders. Because the flow on Rattlesnake Creek is variable in the summer, ten dams were constructed on eight high mountain lakes between 1911 and 1923 in order to add to the water supply. Most of the dams are located on former glacial cirque lakes at elevations between 6,000 and 7,000 feet. They were built from logs, earth, and rock with basic metal headgates, which are opened and closed manually to release or store water.

In 1980, much of the land in the headwaters of Rattlesnake Creek was designated as the Rattlesnake Wilderness and National Recreation Area. Shortly thereafter, the water company discontinued using Rattlesnake Creek as a daily water supply source after Giardia was discovered in 1983 and began using only groundwater wells as its water source. As a result, the dams have not been used for water delivery in more than 30 years. They suffer from a maintenance backlog, and for the most part, are not fully functional.

Following the successful removal of the lower Rattlesnake dam in 2020, the City continues to collaborate with Montana Fish, Wildlife, and Parks; Trout Unlimited; the U.S Forest Service; and other partners to develop a strategy for improving conditions at the wilderness dams, preserving valuable water rights when economically feasible, and addressing site restoration, fisheries, public recreation, and public safety and liability concerns.





Exploring Solutions

The City has many options as it considers the future of the ten wilderness lake dams it owns in the Rattlesnake Wilderness and National Recreation Area.

We want the public's opinion on possible solutions.

Missoula Water is responsible for repairing and maintaining the dams following the the City's purchase of the water utility in 2017. The 2018 Rattlesnake Dams Feasibility Study concluded that Missoula Water should start planning to either decommission or rehabilitate each dam because the City does not have the staff or financial resources to make necessary repairs and maintain all ten dams. So, decisions need to be made about how to handle these problems now and into the future. The study suggests that most of the dams should be decommissioned with the City repairing and continuing to maintain the largest dams with the largest storage water rights.

However, there are many options for the City to consider, including decommissioning some or all dams, reconstructing some dams in order to store water that would add to Rattlesnake Creek stream flows, or improving the dams to meet U.S. Forest Service standards. The City must also think about long-term community needs, regulatory agency requirements, environmental impact and climate change, public safety, repair costs, maintenance costs, and water rights.

Seeking Public Input

On April 7, 2021, City staff from the Public Works & Mobility and Parks & Recreation departments, Trout Unlimited, U.S. Forest Service, and Montana Fish, Wildlife & Parks held an informational public forum presentation webinar to provide a brief history of the wilderness lakes and dams; an explanation of the City's maintenance challenges; project vision and goals; a brief description of fish, wildlife, reptile/amphibian, and vegetation data; and a project timeline.


For details, please watch the video presentation or review the slideshow presentation. Then, take our survey below. We want to hear your opinion about the project!

There will be many more opportunities for the public to engage in this decision-making process.


Background

In 2017, the City of Missoula acquired the lower Rattlesnake dam and surrounding property and buildings, ten dams in the Rattlesnake Wilderness Area, and related water rights as part of its purchase of the former Mountain Water Company. Rattlesnake Creek was the original water supply for the early settlers in Missoula, providing water for lumber mills and homesteaders. Because the flow on Rattlesnake Creek is variable in the summer, ten dams were constructed on eight high mountain lakes between 1911 and 1923 in order to add to the water supply. Most of the dams are located on former glacial cirque lakes at elevations between 6,000 and 7,000 feet. They were built from logs, earth, and rock with basic metal headgates, which are opened and closed manually to release or store water.

In 1980, much of the land in the headwaters of Rattlesnake Creek was designated as the Rattlesnake Wilderness and National Recreation Area. Shortly thereafter, the water company discontinued using Rattlesnake Creek as a daily water supply source after Giardia was discovered in 1983 and began using only groundwater wells as its water source. As a result, the dams have not been used for water delivery in more than 30 years. They suffer from a maintenance backlog, and for the most part, are not fully functional.

Following the successful removal of the lower Rattlesnake dam in 2020, the City continues to collaborate with Montana Fish, Wildlife, and Parks; Trout Unlimited; the U.S Forest Service; and other partners to develop a strategy for improving conditions at the wilderness dams, preserving valuable water rights when economically feasible, and addressing site restoration, fisheries, public recreation, and public safety and liability concerns.





Questions & Comments

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  • Share on Facebook Share on Twitter Share on Linkedin Email this link

    Would proponents of the dam removal want to use Rotenone in the future to poison the non-native fish species?

    Libby asked about 1 month ago

    From Logan McInnis, Deputy Public Works Director—Utilities:

    Libby,

    I am not aware of any plan to poison non-native fish species. There would need to be a public process before any plan like that could be enacted in the Wilderness.

     Thanks for your interest.

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    How important are these water resources when combatting wildfires, especially in the Wildland/Urban Interface ? It seems to me they would be critical to helicopter dipping operations. Also, there would be no danger of flying over occupied homes, vehicles or people. Turn-around times for refilling would also be reduced by shorter flight times.

    John 28 asked about 1 month ago

    From Logan McInnis, Deputy Public Works Director—Utilities:

    John,

    I don’t know the specifics of how the Forest Service utilizes these lakes for fighting fire. These lakes are miles from the Wildland/Urban interface so I doubt they would be used as a source of water to fight fires near that interface. These lakes are all natural lakes, so even if a decision is made to decommission some dams, there will still be a lake there to utilize for fire fighting in the wilderness.

     Thanks for your interest.

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    I am a Soil Scientist, a 50 year resident of Missoula, former chairman of the Water Quality Advisory Council and regular user of the Rattlesnake area. In the early 1980s I mapped the soils of the Rattlesnake drainage as part to the Missoula County Soil Survey getting dropped off by helicopter and hiking down the drainage. I encourage preserving the water right associated with these dams where possible if they can be maintained for this purpose while meeting biological and other natural resource concerns. Otherwise, I encourage restoration of the sites to a natural state based on recommendations from biologists and Trout Unlimited staff.

    Barry Dutton asked about 1 month ago

    Thank you for weighing in on this project, Barry! 

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    Are there any plans regarding the stumps and discarded logs that have accumulated over the years from dam construction and maintenance?

    Sarah Capdeville asked about 1 month ago

    Hi Sarah—We have no specific plans at this time to do anything with the logs and stumps that have accumulated near the spillways. Any major project we do on any of these lakes will require us to complete environmental reviews and Minimum Tool Analyses to meet US Forest Service guidelines, so I would expect that this issue would arise during those processes. These reviews will include a public process so you would have an opportunity to raise this particular issue in these project-specific reviews. Thanks for your interest, Logan McInnis, Engineering Manager, Public Works & Mobility Engineering Section