EPA is taking direct final action approving State Implementation Plan (SIP) revisions submitted by the State of Montana on October 25, 2005. The revisions are to the Administrative Rules of Montana and update the citations and references to federal documents and addresses where copies of documents can be obtained, and delete three definitions. The intended effect of this action is to make federally enforceable those provisions that EPA is approving. This action is being taken under section 110 of the Clean Air Act.