Approval and Promulgation of State Implementation Plans; State of Colorado; Interstate Transport of Pollution Revisions for the 1997 PM2.5 and 8-Hour Ozone NAAQS: “Significant Contribution,” “Interference With Maintenance,” and “Interference With Prevention of Significant Deterioration” Requirements; Revisions to Regulation No. 3

EPA is approving portions of a State Implementation Plan (SIP) revision submitted by the State of Colorado for the purpose of addressing the "good neighbor" provisions of Clean Air Act ("Act" or "CAA") section 110(a)(2)(D)(i) for the 1997 8-hour ozone National Ambient Air Quality Standards ("NAAQS" or "standards") and the 1997 fine particulate matter ("PM<INF>2.5</INF>") NAAQS. This SIP revision addresses the requirement that the State of Colorado's SIP ("Interstate Transport SIP") have adequate provisions to prohibit air emissions from adversely affecting another state's air quality through interstate transport. In this action, EPA is approving the Colorado Interstate Transport SIP provisions that address the requirement of section 110(a)(2)(D)(i) that emissions from Colorado sources do not significantly contribute to nonattainment of the 1997 PM<INF>2.5</INF> NAAQS in any other state, interfere with maintenance of the 1997 PM<INF>2.5</INF> NAAQS by any other state, or interfere with any other state's required measures to prevent significant deterioration of air quality for the 1997 PM<INF>2.5</INF> and 8-hour ozone NAAQS. EPA is also approving certain revisions to Colorado Regulation No. 3 submitted by the State of Colorado in separate prior submissions. This action is being taken under section 110 of the CAA.