The Environmental Protection Agency (EPA) is promulgating amendments to the New Source Review (NSR) Prevention of Significant Deterioration (PSD) program that amend certain outdated language that limited the EPA's ability to delegate the federal PSD program to interested Indian tribes. This final action provides consistency with the current federal PSD regulatory requirements by allowing the EPA to delegate the PSD program to interested tribes for their attainment areas. The EPA regulations already provide for the administrative delegation of the PSD program to state and local governments for their attainment areas and administrative delegation of the nonattainment NSR program to states, tribes and local governments. This final rule deletes a restriction on tribes' ability to take delegation of the PSD program and includes tribes, along with state and local governments, to make it clear that tribes, as well as states and local governments, may voluntarily request and assume direct delegation of the NSR program in areas that are currently attaining the national ambient air quality standards (NAAQS). This final rule does not create any new requirements.