The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) revision submitted by the State of Maine. This revision amends the definition of ``Ozone Transport Region'' in the State's Chapter 100 Definitions Regulation and revises language in the State's Chapter 113 Growth Offset Regulation regarding applicability of Nonattainment New Source Review in areas that, at a future date, may not be within the Ozone Transport Region. The intended effect of this action is to approve the submittal into the Maine SIP. This action is being taken under the Clean Air Act (CAA).