Document 2NNx5jMR0B973BMBGx936B4eL

NorthWestern Energy Delivering a Bright Future Transmission limitations on the ability to import power; Inability to close Colstrip prior to 2035 without constructing replacement thermal bascload capacity; Costs of installing additional controls on Colstrip; Colstrip and NorthWesteni portfolio scenarios; Cost and safety hazards of closing Colstrip prior to 2036 without constructing replacement thermal baseload capacity; Consequences of diverting capital from other beneficial projects to comply with the Proposed Rule Prejudice to NorthWestern of the Proposed Rule; Statutory and Administrative Procedure Act deficiencies with the Proposed Rule; and, Requests. Each of these subjects is addressed below. 1. Summary of Comments The Proposed Rule, if finalized in its current form, is deeply harmful to thc residents of Montana and will work in contradiction to the President's environmental objectives in Executive Order 13990, and Executive Order 12898, as most recently amended by the President on April 23, 2023. This is a result of the specific history and current electrical generation and grid limitations of NorthWestern and Montana. As EPA is aware, Colstrip is in full compliance with the current MATS standards, which EPA does not dispute meet the statutory objectives of the Clean Air Act. However, as EPA also acknowledges and Talon explains in detail, Colstrip cannot come into compliance with either of the candidate standards set forth thc Proposed Rule without extensive supplementation of existing pollution controls -- the venturi wet scrubbers currently in use cannot meet the proposed standards. As detailed by Talcn, upgrading Colstrip to comply with the Proposed Rule is cost-prohibitive, resulting in at least $350,000,000 in capital costs, plus an additional $15 million annual operating costs. See Talcn Comments, Attachment C. NorthWesteni and residents of Montana would bear the majority of these costs. Colstrip is thc only facility identified by EPA as facing this predicament. In addition, if Colstrip is closed in the near term, North Western cannot provide adequate and reliable electrical service for its Montana customers without new replacement baseload capacity. Colstrip currently plays an essential role in baseload capacity for North Western, and thcrc arc no near-term feasible means to replace Colstrip's capacity with other existing North Western capacity or market purchases from in-state or out-of- 2 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000308- 00003 SC_EVERSPLIT0006140