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State’s largest electric utility asks regulators to weigh in on air toxics rule changes

A sign reading "NorthWestern Energy" in silver type against a tan woodgrain background.
Nora Saks
Montana Public Radio

NorthWestern Energy is requesting that Montana electric utility regulators to take a stand against a proposed rule that would increase restrictions for toxic air pollutants like mercury at coal and oil power plants.

Company representatives says the company is concerned about the viability of a power plant it considers vital to its electric generation portfolio.

NorthWestern Energy attorney Shannon Heim told the Montana Public Service Commission at its meeting this week that the rule would require pricey equipment installation at the Colstrip coal-fired power plant.

“The proposed rule that the EPA is currently considering, changing the Mercury and Air Toxic Standards or MATS, will have a material detrimental impact on NorthWestern and our Colstrip co-owners’ ability to continue to operate [the Colstrip Power Plant] absent incredibly expensive modifications,” said Heim.

NorthWestern Energy is asking commissioners to file a letter in the EPA docket against the changes, which include cutting limits for mercury, nickel, arsenic and other pollutants by about 70 percent. The Public Service Commission did not act on NorthWestern’s request at the meeting.

According to the Centers for Disease Control and Prevention, low levels of mercury vapor over a long period of time can cause neurological problems, kidney abnormalities and other health issues.

Comments on the proposed rule changes are due June 23.

Kayla writes about energy policy, the oil and gas industry and new electricity developments.