The EPA is approving revisions to the State Implementation Plan (SIP) submitted by the Governor of Montana on December 8, 1997, May 28, 2003, and August 25, 2004. The December 8, 1997 submittal revised the Administrative Rules of Montana (ARM) chapter 8, subchapter 3, section 17.8.316 (Incinerators) by adding subsection (6). ARM 17.8.316(6) excludes incinerators from having to comply with the other provisions of ARM 17.8.316, including the particulate matter emissions standard of 0.10 grains per cubic foot and the 10% opacity standard, if these sources have been issued a Montana air quality permit under 75-2- 215, Montana Code Annotated (MCA), and ARM 17.8.770, which pertain to permitting of solid or hazardous waste incinerators. The August 25, 2004 submittal made a minor editorial revision to ARM 17.8.316(5). The May 28, 2003 submittal made minor editorial revisions to ARM 17.8.316(6). In a December 12, 2007 Notice of Proposed Rulemaking (72 FR 70540), we proposed to approve these revisions to the Montana State Implementation Plan (SIP). This action is being taken under section 110 of the Clean Air Act (CAA).