Officials are optimistic about the Madison River a year after dam malfunction, but unknowns remain

The upper Madison River flows past dead vegetation along its bank on Dec. 15, 2022.Rachel Leathe/Chronicle

The water was gently bubbling, occasionally cresting into small waves on a narrow side channel of the Madison River south of Cameron.

Kelly Galloup pointed to trout that occasionally breached the surface of the snow-lined channel. Further down was a newly-built beaver dam. The two foot deep channel was bubbling and teeming with life, and looked drastically different a little over a year ago.

An early morning malfunction at the Hebgen Dam dewatered stretches of the Madison River in late November 2021. Side channels like the one behind Galloup’s Slide Inn and fly shop were the most affected.

Kelly Galloup, owner of Galloup’s Slide Inn, poses for a photo in his fly shop on Dec. 15, 2022.Rachel Leathe/Chronicle

He recalled looking out his window that November morning and seeing normal water levels. A few hours later he estimated there was a 95% decrease in water in the two-foot deep channel.

Galloup’s employees were some of the first people to arrive at the bottom of Hebgen Dam. His business became a de facto operations center for people to meet before heading up the road to the dam.

But the scene at the side channel Thursday was a far cry from the hectic couple of days early last December — it was quiet, with untouched snow and flowing water. Galloup remembered how he felt when he got word of the malfunction.

“The immediate thing was anger, I couldn’t understand,” Galloup said. “No failsafe, no backups.”

NorthWestern Energy, the dam’s operator, has been busy addressing the incident over the last year.

The dam has been outfitted with new parts and systems aimed at preventing a similar situation, plans have been produced to monitor the fishery and to meet standards set by the federal government and environmental groups once ready for a fight with the energy company have cooled.

The main concern for many was the exposure of brown trout spawning redds. There were impacts to the fishery, according to a monitoring plan produced by the energy company, but officials see signs that it wasn’t catastrophic. The full extent may not be known for another three years.

Kelly Galloup, owner of Galloup’s Slide Inn, gestures to a side channel of the Madison River that flows behind his business on Dec. 15, 2022.Rachel Leathe/Chronicle


In the early hours of Nov. 30, 2021, a coupling attached to a gate stem at Hebgen Dam broke.

That caused the flow gate attached to the stem to drop suddenly, and shrank the underwater opening from 18 inches to 6 inches, which dramatically decreased flows from Hebgen Lake into the Madison River.

The stretch of river between the dam and Quake Lake was the most severely impacted — flows from the dam dropped from 648 cubic feet per second to 278 cubic feet per second in a 15 minute period in that reach.

However, NWE did not identify the issue until later in the day because monitoring equipment at the dam did not register a drop in flows. Calls from bystanders helped tip off NWE that there was an issue at the dam.

Water spills down a culvert coming from the Hebgen Dam into the upper Madison River on Wednesday, Dec. 1, 2021. A malfunction at the dam caused flows in the upper Madison River to drop suddenly Tuesday morning, leaving parts of the river dry and prompting state officials to order a full fishing closure for the upper river.Samuel Wilson/Chronicle/Report for America

Jon Malovich, executive director of the Madison River Foundation, said a friend of his was traveling by the Madison River and noticed that the side channel closest to the road was no longer flowing.

Then came a picture of the dewatered side channel.

“I was fortunate to receive basically the first phone call,” Malovich said.

He reached out to NWE and Montana Fish, Wildlife and Parks to inform them of the situation. Malovich said that the company and agency checked their systems and that everything looked okay on their end. Then he sent them the picture as proof.

An army of volunteers worked to save as many stranded fish as they could find in the immediate aftermath the following day. Meanwhile, the Anaconda Foundry Fabrication Company made a new coupling. It was installed on the dam late that night, and flows were restored — about two days after the malfunction.

Volunteers search a channel of the upper Madison River for fish stranded by drastically lowered water levels below Hebgen Dam on Wednesday, Dec. 1, 2021. A malfunction at Hebgen Dam caused flows in the upper Madison River to drop suddenly Tuesday morning, leaving parts of the river dry and prompting state officials to order a full fishing closure for the upper river.Samuel Wilson/Chronicle/Report for America

Jeremy Clotfelter, the director of hydro operations for NWE, said that the first focus for the company was to do an analysis to understand why the failure happened.

“Once we could understand why and how it happened, only then we could adequately address it going forward,” Clotfelter said.

The component that failed was a bronze coupling used to hold pieces of pipe together that raises and lowers the flow gate. Clotfelter said that there was stress corrosion cracking in the metal part, which can normally happen during the forging process.

That cracking in the submerged coupling, combined with chemical components in the water, caused it to fail.

According to a report from the energy company the coupling design and material were the industry standard, and approved by the Federal Energy Regulatory Commission — the federal agency that NWE holds a license from to operate the dam.

Clotfelter said that new couplings made with a new material were installed on the gate toward the end of summer this year. While working to replace the bronze couplings on the gate, workers inspected couplings on an adjacent gate, and found cracks.

Those couplings are also being replaced, Clotfelter said. The company also added more alarms that Clotfelter said would “definitely alert us” to a similar event in the future.

He also hopes to install better quality cameras around the dam for remote viewing. That upgrade could require routing fiber optic cable to the site because of restrictive bandwidth in the area, he said.

It did not take long for repercussions to hit the utility company after the incident at the dam.

A crane is used at Hebgen Dam to make repairs on the dam’s gate.Photos courtesy of NorthWestern Energy


NorthWestern Energy was hit with two violations of its federal license to operate the dam in early December 2021.

One violation was for flows rapidly dropping by 57% in a 15 minute period — FERC required that flows not drop by 10% in a 24 hour period. The other was for a drop in minimum flows further downstream at the Kirby Ranch U.S. Geological Survey gauge.

Though Quake Lake helped to stymie some of the decrease, flows at the gauge dropped to 395 CFS. That drop was well below the required level of 600 CFS at the Kirby Ranch gauge.

Those violations, and concerns for possible damage to the fishery, led to the creation of a monitoring and mitigation plan by the utility company with partner agencies, like FWP and the U.S. Forest Service.

Andy Welch, the manager of hydropower license compliance for NWE, said that the focus was to address the area of highest impact in the plan, the reach between the dam and Quake Lake, and the effect exposure to the elements had on spawning redds in that area.

In early January of this year, non profit groups Upper Missouri Waterkeeper, the Madison River Foundation and the Montana Environmental Information Center filed complaints with FERC to request an independent investigation into the dam’s malfunction, and to address potential economic and environmental impacts.

A diver prepares for work underwater at Hebgen Dam. Photos courtesy of NorthWestern Energy

Guy Alsentzer, the executive director of Upper Missouri Waterkeeper, said the petition was meant to create instructions for an accountability mechanism for NWE.

“We have to make sure that somebody is on the hook to do the necessary science-based research to find out the next steps,” Alsenzter said.

The main concern was the dewatering of the Madison River system, said Malovich, the executive director of the Madison River Foundation.

“As the organization dedicated to protecting the Madison River, we wanted to make sure NWE was held accountable for the mishap,” Malovich said.

Welch said the methodology for crafting the plans were mainly investigative. The group looked at tributaries, channels and channel margins in the area where redds are usually dug by brown trout.

That work included electrofishing the Pine Butte section of the river to get more information on the species ratios and to track cohorts of fish, electrofishing side channels and margins to look for young-of-year salmonids, electrofishing between Hebgen and Quake lakes, and to do redd counts between the lakes.

The mitigation plan aimed to continue monitoring to get more data from the stretch of river below the dam to Quake Lake and to bolster the survivability of spawning redds.

That preventative work would include working with landowners to see if there are cattle impacts on the waterway, to use fencing to reduce possible cattle impacts and mechanically change channel dimensions to improve spawning gravel for redds.

Welch said the federal agency approved the plans, and that NWE was not fined. The agency looked at the petition sent in by the non profits, and determined that the plans “encapsulated most of the elements,” Alsentzer said.

Despite plans in place to unpack the past and prepare for the future, the overall effect on the fishery is still unknown.

People collect trout from a drying channel of the upper Madison River, before transported it and other fish into the main channel of the river below Hebgen Dam on Wednesday, Dec. 1, 2021. A malfunction at Hebgen Dam caused flows in the upper Madison River to drop suddenly Tuesday morning, leaving parts of the river dry and prompting state officials to order a full fishing closure for the upper river.Samuel Wilson/Chronicle/Report for America


Stranded fish and exposed spawning redds were the primary concerns for people who responded to the dewatering event last year.

The monitoring and mitigation plans can only go as far as historical data allows them to, and there is a lack of data for the hardest hit section of the river below the dam.

Welch said that after stepping back from the chaos of the incident, the impact to spawning redds and young-of-year fish did not appear to be catastrophic.

“We decided that yes there has been an impact, but the magnitude and severity of that impact is kind of unknown,” Welch said.

Matt Jaeger, hydropower program director for FWP, said that multiple years of data will need to be collected to put any possible loss into context. Side channels were hardest hit by the incident.

Monitoring in those channels was done in the spring to look for fish that at the time of the incident would have been most vulnerable, he said. The monitoring was designed to look at whether a whole cohort of fish was wiped out.

Jaeger said that’s not what they saw. They saw some fish in the one and two year old age class — the groups that could have been most impacted by the sudden drop in flows.

He added that the fish are resilient, and that there were redds that weren’t dewatered completely in other areas.

“It would have been more surprising to see an entire cohort missing than what we saw,” Jaeger said.

The plan released by the NWE concluded that “effects may be evident for the next four years, but not fully realized until 2025.”

Malovich said that as far as dam failures go, the incident last year was “as good of a situation that you could probably hope for.”

Alsentzer was optimistic about the situation, and approved of the plans put forth by NWE and its partner agencies.

His hope is that the utility company will be a “good neighbor” in the coming years and continue work to bolster the fishery.

“Waterkeeper’s hope is that we dodged a bullet, but at the same time, if science indicates some serious future impacts, right the wrong,” Alsentzer said.

Water leaves Hebgen Dam and flows out of a culvert and into the upper Madison River on Dec. 15, 2022. In late November 2021, a malfunction at the dam caused flows to drop suddenly, leaving parts of the river dry.Rachel Leathe/Chronicle