Document G6r083Y2ogR26J2GnYKrbDm3Y

USCA Case #24-1190 Document #2062093 Filed: 06/27/2024 Page 4 of 92 7. Talen Montana is the operator of Units 3 and 4 at the Colstrip Steam Electric Station, commonly referred to as Colstrip Power Plant ("Colstrip"), in Rosebud County, Montana. Talen Montana also has a 15 percent economic interest in these units, which currently consist of two active coal-fired generating units capable of producing up to 1,480 net MW of electricity that have been operating for approximately 38 years. K. Each of the units has approximately 740 MW of net generating capacity, and the adjacent Rosebud coal mine supplies Colstrip's low-sulfur subbituminous coal. Units 3 and 4 are the only remaining active units at Colstrip, as Units 1 and 2 recently retired in 2020. Units 3 and 4 have a useful life of at least another two decades, provided investments continue to be made for equipment maintenance and replacement as necessary. 9. Colstrip is one of the largest coal-fired electric generating facilities west of the Mississippi River, supplying electricity throughout Montana and the Pacific Northwest. Colstrip plays an integral role in maintaining operation of the NorthWestern Balancing Authority in Montana, especially during peak electricity demand events. 10. The MATS Final Rule sets forth aggressive compliance timelines for demonstration of compliance with EPA's new and more stringent filterable particulate matter ("tPM") emission limit requiring that these upgrades be made at 3 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000309-00004 SC_EVERSPLIT0006167