The Environmental Protection Agency (EPA) is approving State Implementation Plan (SIP) revisions submitted by the State of Montana on August 6, 2018. The revisions include an update to incorporate by reference the 2016 version of the Code of Federal Regulations (CFR) and 2015 version of the United States Code (U.S.C.) within the Administrative Rules of Montana (ARM) that are part of the Montana SIP. The revisions also include administrative changes that consolidate the ARM's references to the CFR and U.S.C. and remove two CFR exemptions from incorporation by reference into the ARM. Additional revisions remove incorporation by reference of certain EPA standards for which the State already has delegated authority from the EPA.