By Gabrielle Gasser EBS STAFF
Editor’s Note: Some mentions of specific dates have been corrected.
GREAT FALLS – NorthWestern Energy staff said in a press conference this evening that a malfunctioning gate on the Hebgen Dam that caused flows to dramatically drop in the Madison River could be fixed tonight.
After the failure of a gate component on the dam caused river flows to drop to about a third of normal on Nov. 30, NorthWestern Energy personnel worked through the night to identify the issue and make a repair plan, according to Jeremy Clotfelter, director of hydro operations for NorthWestern Energy.
The dam malfunction and resulting low stream flows left fish stranded, an especially dire situation during the brown trout’s spawning season where spawning beds, or redds, were left exposed in dry channels.
According to Clotfelter, the failure occurred between 2 and 3 a.m. on Nov. 30 based on United States Geological Survey data that showed a sharp drop in flows at that time. Equipment at the site did not notify NorthWestern Energy of an issue at that time and Clotfelter said NorthWestern Energy became fully aware of the problem mid-morning Nov. 30.
“The indicating equipment worked as it’s designed to do,” Clotfelter said. “It’s just that the failure occurred in a matter that the indicating equipment would not pick up.”
NorthWestern Energy spent Nov. 30 trouble shooting the failure, according to Clotfelter, and a new gate component was fabricated overnight in Anaconda. This morning, contract divers were on site at Hebgen Dam and were able to support the gate from above to prevent it from closing any further.
to look at the component that failed on Hebgen Dam. PHOTO COURTESY OF NORTHWESTERN ENERGY
As of the 4 p.m. press conference, the replacement part was en route to the dam and Clotfelter was hopeful that the repair could be completed soon.
“If current efforts are successful, flow could be restored back this evening,” he said.
If the new part does not fix the issue, Clotfelter said NorthWestern Energy has the option to transfer flow to a different gate as an alternative solution.
As of 4:30 p.m. today, river flows were holding steady at approximately 250 cubic feet per second according to USGS data.
Moving forward, Clotfelter said NorthWestern Energy will focus on studying the failure as well as impacts to the Madison River and the fish.
“On the failure itself Federal Energy Regulatory Commission will be very involved in working with us to help identify the why and the how of the failure and to identify those corrective actions that we can implement to prevent reoccurrence,” he said. “And then on the resource side, certainly there will be efforts to understand the impact, and to see what could be done to help offset that going forward.”
