Approval and Promulgation of Air Quality Implementation Plans; Designation of Areas for Air Quality Planning Purposes; Arizona; Miami Sulfur Dioxide State Implementation Plan and Request for Redesignation to Attainment; Correction of Boundary of Miami Sulfur Dioxide Nonattainment Area

EPA is taking direct final action under the Clean Air Act to approve the Miami Sulfur Dioxide Nonattainment Area State Implementation and Maintenance Plan as a revision to the Arizona state implementation plan. The Arizona Department of Environmental Quality developed this plan to maintain the sulfur dioxide national ambient air quality standards in the Miami (Gila County) area. The maintenance plan contains various elements, including contingency provisions that will be implemented if measured ambient concentrations of sulfur dioxide are above certain trigger levels. EPA is also approving the State of Arizona's request for redesignation of the Miami area from nonattainment to attainment for the sulfur dioxide standards. Lastly, EPA is correcting the boundary of the Miami sulfur dioxide nonattainment area to exclude a noncontiguous township that was erroneously included in the description of the area and to fix a transcription error in the listing of one of the other townships. EPA is taking these actions consistent with provisions in the Clean Air Act that obligate the Agency to approve or disapprove submittals of revisions to state implementation plans and requests for redesignation. The intended effect is to redesignate the Miami, Arizona sulfur dioxide nonattainment area to attainment, provide for maintenance of the standard for the ten-year period following redesignation, and correct long-standing errors in the codified description of the area.