Clean Air Act Approval and Promulgation of State Implementation Plans; Prevention of Significant Deterioration; Designation of Areas for Air Quality Planning Purposes; Montana, North Dakota, South Dakota, Utah, and Wyoming

In this document, EPA is approving revisions to the prevention of significant deterioration (PSD) permitting regulations which were submitted as revisions to the State Implementation Plans (SIPs) for Montana, North Dakota, Utah, and Wyoming. The revisions were submitted mainly to address the replacement of the total suspended particulate (TSP) increments with increments for PM-10 (particulate matter 10 micrometers or less in diameter). Also, North Dakota and Wyoming submitted PSD program revisions to incorporate changes in the Federal PSD regulations for utility pollution control projects. All of the States except Montana made other minor revisions to their PSD programs. EPA is approving the SIP revisions because they are consistent with the corresponding Federal regulations. EPA is also removing the TSP area designation tables and revising and/or adding PM-10 area designation tables in 40 CFR part 81 for these States as well as for the State of South Dakota (which has been delegated authority to implement the Federal PSD regulations in 40 CFR 52.21). With the PM-10 increments becoming effective in these areas, the TSP area designations no longer serve any useful purpose relative to PSD.