The Environmental Protection Agency (EPA) approves the Mashantucket Pequot Tribal Nation's (MPTN or the Tribe) Tribal Implementation Plan (TIP) under the Clean Air Act (CAA) to regulate air pollution within the exterior boundaries of the Tribe's reservation. The TIP is one of two CAA regulatory programs that comprise the Tribe's Clean Air Program (CAP). EPA approved the Tribe for treatment in the same manner as a State (Treatment as State or TAS) for purposes of administering New Source Review (NSR) and Title V operating permits under the CAA on July 10, 2008. In this action we act only on those portions of MPTN's CAP that constitute a TIP containing severable elements of an implementation plan under CAA section 110(a). The TIP includes permitting requirements for major and minor sources of air pollution. The purpose of the TIP is to enable the Tribe to attain and maintain the National Ambient Air Quality Standards (NAAQS) within the exterior boundaries of its reservation by establishing a federally enforceable preconstruction permitting program.