Tin Cup Creek a restoration success story

by Michael Howell

There was a time when Tin Cup Creek would run dry in late summer. That time has passed. Thanks to a cooperative agreement between the Tin Cup Water & Sewer District and the Clark Fork Coalition, continuous flows in the creek have been restored and the Montana Department of Natural Resources and Conservation (DNRC) is currently in the process of approving a change in water rights that would give this success story an official stamp of approval.  

Low flows in late summer became a serious issue when it was determined that the dam impounding water at the Tin Cup Reservoir had some dangerous structural problems and constituted a serious safety hazard. The dam was essentially condemned as a safety hazard and, unable to afford the cost of restoration, the decision was made in 1998 to breach the dam, reducing the reservoir’s storage capacity by over 1,000 acre-feet. This drastically reduced the amount of water available for release in late summer when stream flows are at their lowest. Not only were the irrigators going to suffer, but it spelled disaster for the fishery as well. 

That’s when the Clark Fork Coalition stepped in on behalf of the fishery and began working with the dam owners on a cooperative solution. Those efforts culminated in 2011 in a water right lease agreement between the Clark Fork Coalition (the Coalition) and the Tin Cup Water & Sewer District (the District) whereby the District agreed that, in exchange for significant funding from the Coalition for improvements to the dam, the District would lease 3.3 cubic feet per second (cfs), up to 400 acre-feet of water per year, and release the water from August 1 to September 30 (approximately 60 days) annually to the Coalition for instream use for a 99-year period. While the water is already being used for instream flow, and has been since 2012, a Change Application is required by the Montana DNRC and by the Coalition’s funding entities to finalize the process.

According to Andrew Gorder, Legal Director for the Coalition, the change application, if approved, will not change any terms or conditions in the existing agreement between the District and the Coalition. The District will continue to lease and allow the same portion of its stored water (400 acre-feet annually) to be used for instream flow in Tin Cup Creek, just as it has since 2012.

The Water Right Change only applies to one of the stored water rights in Tin Cup Lake. The District owns all the water rights for Tin Cup Lake, and only the District has the right to use and distribute this stored water. Montana DNRC has determined that no other water users on Tin Cup Creek will be adversely impacted by this instream flow water right change.

Under state law, changes to “instream flow” are temporary and last 10 years. After 10 years, an instream flow change authorization may be renewed. If it is not renewed, the water right reverts back to its original use of irrigation. Pursuant to the agreement between the Coalition and the District, this water right change will be renewed every 10 years for the entirety of the 99-year lease.

DNRC proposes to grant the application to change the water right. The preliminary determination documenting the Findings of Fact and Conclusions of Law and any conditions attached to the water right are available on the internet at https://dnrc.mt.gov/Water-Resources/Water-Rights/application-status-environmental-assessments/ . The objection deadline is February 17, 2025. The Department can only accept objections filed on an Objection to Application Form 611. Any questions pertaining to the application, or to obtain the preliminary determination, or the Objection Form, should be directed to the Water Resources Office at 2705 Spurgin Road, BLDG C, PO Box 5004, Missoula, MT 59804. Or FAX:406-542-5899. Or Phone:406-721-4284.

According to Clark Fork Coalition Stream Restoration Director Jed Whitely, about 25 years ago MT FWP leased a senior water right at the bottom of Tin Cup Creek to use for instream flow to keep water in the creek all year. The agency tired of managing the water and about 15 years ago transferred the lease to the Coalition. Then about 10 years ago the Coalition purchased the water outright. 

“That 4 cfs did reconnect the creek but was barely keeping enough water in the creek for the fishery on bad water years,” said Whitely. “Since we have leased this additional 3.3 cfs in 2012, the creek has not gone dry. By pairing up our surface water right and our leased water we have a great success story here.” He said, although the water right use had not been officially changed, the District had been honoring the lease.

“This water right change will make the instream use of that water official now,” said Whitely. 

“This solution on Tin Cup Creek has benefitted all parties,” said Whitely. “By getting the reservoir up to 2,000 acre feet again the District now has the use of close to 1,600 acre feet, up from the 900 they were reduced to, and we have 400 acre feet to keep water in the creek for the fish.” 

He said this success story can serve as a model for dealing with aging irrigation dams across the watershed that are going to require major investment at some point to address safety issues and preserve or even increase their capacity. He said by cooperating with instream flow advocates to make improvements or enhancements to existing dams it can be a win/win situation for everyone across the watershed.

According to Whitely, the coalition is already working with the Charlos Heights District which holds water at Twin Lakes up Lost Horse Creek. They are conducting a feasibility study right now, he said, to see if there is any potential to increase capacity up there for irrigators and for instream flow.

Whitely said that the Tin Cup reservoir, like many of the dams in streams along the Bitterroot Front, is located in designated Wilderness. This makes working on the dam structures difficult. He said the Bitterroot National Forest has been a great partner in working out solutions to the difficulties. He said the Coalition was working closely with the Forest Service’s new Aquatic Team to make many improvements in the Lost Horse drainage. 

The Coalition is currently partnering on a 150 cfs fish screen on the BRID Ditch off of Lost Horse Creek to keep migrating cutthroat trout from being lost down the ditch and are working with Charlos Heights water users to screen two or three of their diversions. 

“We are hoping to be able to screen almost every diversion on Lost Horse Creek,” Whitely said, “all funded by the Forest Service. They are also putting money into upgrading almost the entire road up to Twin Lakes to help stop sediment from going into the creek with new relief culverts, upgraded crossings, new gravel lifts and in-sloping on the roads.” He said they are also working along with Trout Unlimited as well in replacing the culvert crossing at Ten Mile Creek up Lost Horse which keeps blowing out and washing tons of gravel and dirt into the creek. 

“We are looking at Lost Horse from every angle we can,” said Whitely, “including sediment, flow and fish entrainment. One by one we are trying to get these creeks shaped back up. The Bitterroot River is a good fishery, but it could be even better if we can stop this death by a thousand cuts on the tributaries.”