Document 2RjDOqeMeZ8K0D7bExO5jvJYL

NorthWestern Energy Delivering a Bright Future June 23, 2023 Via Federal eRukmaking Portal fregulations.goll Via Email fbenish.sarah(depa.goty Ms. Sarah Benish Sector Policies and Programs Division Office of Air Quality Planning and Standards U.S. Environmental Protection Agency Research Triangle Park, NC 27711 Re: NorthWestern Corporation Comments re: Proposal on National Emissions Standards for I lazardous Air Pollutants: Coal and Oil-Fired Electric Utility Steam Generating Units Review of the Residual Risk and Technology Review Docket ID No. EPA--HQ--OAR-2018-0794 Dear Ms. Benish: On behalf of NorthWestern Corporation d/b/a NorthWestern Energy ("NorthWestern"), I am commenting on thc U.S. Environmental Protection Agency's ("EPA's") proposed changes to thc National Emissions Standard for Hazardous Air Pollutants ("NESHAP") for the Coal- and Oil-fired Electric Utility Steam Electric Generating Units ("EGUs"), commonly known as the Mercury and Air Toxics Standard ("MATS"). The proposed changes were published in the Federal Register on April 24, 2023, at 88 Fed. Reg. 24,854 ("Proposed Rule"). As discussed herein, the Proposed Rule poses significant challenges for NorthWestern and its rate-paying customers in Montana, will likely have environmental and Environmental Justice impacts that are contrary to Administration policies, and is likely unlawful. NorthWestern agrees with and incorporates by reference thc concurrent comments submitted by Talen Montana, LLC ("Talen") as part owner and based on its knowledge as operator of Units 3 and 4 of the Colstrip Steam Electric Station ("Colstrip"). North Western. NorthWestern endeavors to minimize duplication of the Talen comments. These comments are organized into thc following sections: Summary of Comments; NorthWestern's commitment to environmental and climate responsibility; North Western's commitment to Environmental Justice; NorthWestern's energy portfolio and role in serving Montana electricity customers; 1 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000308- 00002 SC_EVERSPLIT0006139