Rattlesnake Dam

An aerial photograph shows the dam, reservoir and associated structures during a reservoir drawdown in 2017.

The dam's coming down and trails are going in.

The city’s Parks and Recreation Department has big plans to demolish a dam and reservoir on Rattlesnake Creek and restore the area to a more natural state for wildlife and recreationists. And they want public input on how to best accomplish that.

The dam and 3 million-gallon reservoir, located 4 miles upstream from the Clark Fork River, will be demolished in the summer of 2020.

On Tuesday, city Conservation Lands Manager Morgan Valliant gave a presentation to the Parks Board about plans to take public comment on the conceptual recreation plan for the area.

“We’ve been working on this for over a year,” he said. “The primary goals are habitat and connectivity with passive recreation on site.”

The 45-acre site could eventually have historical interpretive signs and stream access points, he said. Trout Unlimited has identified rare wetlands below the dam, and Valliant said he believes those same types of riparian wetlands will be found once the reservoir is removed upstream from the dam.

“These are 10,000- to 12,000-year-old forested fens,” he explained. “It’s really rare habitat in the Missoula Valley. We don’t have any others of this type on conservation lands. When we remove the reservoir, it’s not going to be an area where we want to actively promote recreation. It’s a full, soupy Montana jungle.”

Other areas around the fens, though, will have trails.

Missoula got its drinking water from the reservoir until a giardia outbreak in 1983, and the system hasn’t been used since. A NorthWestern Energy substation is in the area, and Valliant said his staff has negotiated an easement to connect more trails.

Valliant said the Rattlesnake Creek was once an important bull trout spawning habitat that was destroyed by the implementation of the dam.

“Rattlesnake was set aside because of a key wildlife corridor,” he said.

Ladd Knotek, a fisheries biologist with Montana Fish, Wildlife and Parks, has studied Rattlesnake Creek and its bull trout numbers. The three main partners on the project are the City of Missoula, FWP and Trout Unlimited.

"The dam removal is one important step in revitalizing the creek and will certainly help with bull trout passage," he explained. "It will also really help with cutthroat and cutbow (rainbow trout and cutthroat trout hybrid) passage. That's the main thing providing the fishery through town."

The number of redds, or spawning beds, fluctuate wildly year to year on the creek. However, the number of redds found by Knotek's team dropped from a high of 36 in 2006 to just six in 2014. The dam was bad for bull trout, because they can't get over it to spawn, but climate change has exacerbated the problem, he said.

"The water temperatures are significantly higher than they were 10 years ago,” Knotek told the Missoulian. “The types of temperatures we’re seeing in late summer and early fall, we never saw those 10 to 15 years ago. Water temperature is driving a lot of what we’re talking about. It’s definitely stressful on fish. It doesn’t spell good news for bull trout.”

Valliant said the Rattlesnake Creek corridor was used by Native Americans to reach bison-hunting areas. The area still provides a major pathway for people in the Missoula area to access the Rattlesnake National Recreation Area and the Rattlesnake Wilderness.

Valliant said he’ll be putting a link up at Missoulaparksandrecreation.com this Friday for people to comment on the plan for 20 days. Then in April and May, Valliant will go before the City Council and try to finalize and adopt the plan.

The move to restore the dam and reservoir comes after Missoula County voters approved a $15 million open space bond last fall. City voters also approved a perpetual 4-mill conservation lands maintenance and stewardship levy, which will provide about $500,000 per year.

Valliant said he hopes to add five new positions to his office between fiscal year 2020 and fiscal year 2022. Other projects that will use the money include a new trailhead on Waterworks Hill and more river access points throughout Missoula.

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