The EPA is proposing three changes to the New Source Review (NSR) program for minor sources and minor modifications at major sources in Indian country, which we refer to as the “Tribal minor NSR program.” First, we propose to expand the list of emissions units and activities that are exempt from the Tribal minor NSR program by adding several types of low-emitting units and activities. Second, we propose to more clearly define the term “commence construction” and add the term “begin construction” to better reflect the regulatory requirements associated with construction activities. We believe both of these proposed changes would simplify the program, resulting in less burdensome implementation without detriment to air quality in Indian country. Lastly, we are reconsidering the advance notification period for relocation of a true minor source in response to a petition received on the final Tribal NSR rule from the American Petroleum Institute, the Independent Petroleum Association of America and America's Natural Gas Alliance.