Bozeman City Commissioners heard at least two alternatives to building a dam and reservoir on Sourdough Creek on Monday night.
The city is considering constructing a reservoir about half the size of the one on Hyalite Creek to add to the city's water supply.
Deb Stephenson, of WestWater Research, said a landowner near Gallatin Gateway is proposing to lease or sell the city rights to water on a 500-acre property. The Farmer's and West Gallatin canals run through the land, she said, and both surface-storage and underground reservoirs could be constructed.
Doug Chandler, of Bozeman-based Allied Engineering, suggested the city take water from Sourdough Creek and store it in the Madison aquifer. He said small dams could be built on the creek, and, beneath the ground, the creek bed and aquifer could be hydraulically fractured and expanded to hold more water.
But both proposals, like the city's plan to build a larger dam, would come with legal challenges.
"Anything you do will be based on whether you are harming anyone else with a water right and how you're able to mitigate that," water rights attorney Cal Erb told city commissioners.
Constructing a dam and reservoir on Sourdough Creek could be, well, "damn hard," considering the possible legal roadblocks, said Dave Schmidt, a consultant with Helena-based Water Right Solutions.
In addition to weighing protests from environmentalists, farmers who use the water system for irrigation and others, such as a Great Falls power company that is a significant user, may object, Erb and Schmidt said.
City commissioners did not take any action on the issue Monday night. The meeting was intended for commissioners to learn about the issue and hear from city staff, legal consultants and the public. About two dozen people attended the meeting.
The reservoir the city is proposing to build would be around 100 acres in surface area and would be located downstream from the old Mystic Lake dam. The Mystic Lake dam was breached by a landslide in 1984 and knocked down in 1985.
The added water supply would allow Bozeman to grow to about 80,000 people, city officials said. The city's current population is about half that.
Amanda Ricker can be reached at email@example.com or 582-2628.