Water groups file federal complaint over Hebgen Dam failure

Orgs: NorthWestern should pay for investigation into ecological impact

By: - January 5, 2022 6:32 pm

The Madison River near Ennis, Montana (Photo via Flickr | CC-BY-SA 2.0).

A group of Montana environmental organizations is calling for an outside, independent investigation into the ecological impacts of a gate failure at Hebgen Dam in November that resulted in plummeting water levels in a stretch of the upper Madison River, stranding some fish to die and dewatering spawning areas.

Upper Missouri Waterkeeper, the Montana Environmental Information Center and the Madison River Foundation filed a citizens’ complaint Wednesday asking the Federal Energy Regulatory Commission to require that dam operator NorthWestern Energy pay for a third-party study into the impacts of the dewatering on “aquatic resources” downstream, and guided by the results of that analysis, administer a fund to restore affected habitat and provide financial assistance to affected community and business interests. Any entity, under federal law, can complain of a violation by a licensed utility.

“We’re looking for a formal process where everyone has a seat at the table —  NorthWestern, federal and state agencies, and affected stakeholders,” said Guy Alsentzer, executive director of Upper Missouri Waterkeeper. “And we’re asking NorthWestern to pay the cost to make downstream communities whole again.”

Around 2 a.m., Nov.30, a part on the dam gate failed, causing it to drop and cut water flow from 648 cubic feet per second to 279 — an almost 60% reduction – in 15 minutes, the power company reported to FERC in December. NorthWestern’s didn’t identify any issues at first, as the failure occurred beneath the dam’s monitoring instrumentation. It took an angler in the area to raise alarms about the water levels, which weren’t restored in some areas until Dec. 2.

Just downstream from the dam, fish, including rainbow and brown trout, were left high and dry, either dying or stranded in shallow pools separate from the main channel of the Madison River until they could be moved by volunteers. Spawning habitat in the shallows where brown trout had recently laid eggs were also exposed.

Many of those side channels and key habitat for spawning were dried out,” Alsentzer said. “Nobody has a qualitative understanding of how big this was.” 

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The company has acknowledged violating two provisions in its license: one requiring a continuous water flow of 600 cfs as measured by a U.S. Geological Survey gauge near Kirby Ranch, and another requiring NorthWestern to limit changes in outflow to 10 percent per day. However, in December, FERC said in a letter to NorthWestern it would wait to decide whether the dewatering violated license conditions until the company submitted a root cause analysis to the commission.

As far as the fish are concerned, NorthWestern has said the extent of the impact to the fishery may take years to understand.

Part of the reason for the complaint is to trigger a transparent process to discern that impact as quickly as possible, Alsentzer said — not just to the habitat, but also to businesses that rely on the Madison River’s status as a top destination for trout fishing.

“The flow-based conditions of the license are explicit for good reason, and not solely due to Hebgen’s water storage functions,” the complaint to FERC reads. “Successful natural reproduction of wild fish and restrictive fishing regulations has resulted in the river downstream of Hebgen becoming one of the premiere trout fisheries in the Nation. Unfortunately, Licensee’s violations created a dewatering event that occurred at an ecologically sensitive time period for brown trout recruitment.”

A spokesman for Northwestern said an investigation into the gate failure is underway. In the December correspondence, FERC told NorthWestern it must make permanent repairs to the dam, and recommended improving monitoring systems to ensure that the company can act on a potential future malfunction more quickly.

“NorthWestern Energy submitted reports to the Federal Energy Regulatory Commission about the failure and together with our federal regulatory agency and others, are taking purposeful steps to ensure a thorough analysis of the gate component,” company spokeswoman Jo Dee Black said. “The analysis, based on sound engineering principles, will be used to understand why this relatively new part failed and to establish corrective actions. NorthWestern Energy will also be working with resource agency biologists and others to develop scientific studies to assess effects on the fishery.”

Alsentzser acknowledged that these processes were underway, but said there needs to be an investigation that details the potential ecological impact, not just how the relevant parts failed.

A spokesperson for FERC acknowledged receiving the complaint but had no further comment.

Greg Lemon, a spokesman for the Montana Department of Fish, Wildlife and Parks, said the agency is continuing to work with NorthWestern, but won’t be able to tell much about the impact of the dewatering on the fishery for years, potentially.

“What I’m hearing from my staff is it’s concerning that the incident happened, but I’m not hearing that anybody’s certain about what’s going to happen in the future,” Lemon said.

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Arren Kimbel-Sannit
Arren Kimbel-Sannit

Arren Kimbel-Sannit is an Arizona-bred journalist who has covered politics, policy and power building at every level of government. Before getting his dose of northern exposure, Arren worked as a reporter in all manner of Arizona newsrooms, for the Dallas Morning News and for POLITICO in Washington, D.C. He has a special interest in how land-use decisions affect working-class people, which he displayed through reporting on the epidemic of pedestrian deaths in the U.S. for the Los Angeles Times and PBS Newshour. He's also covered housing, agriculture, the Trump presidency and more.