Approval and Promulgation of Air Quality Implementation Plans; District of Columbia and State of Maryland1990 Base Year Emission Inventory for the Metropolitan Washington DC Area

EPA is approving revisions to the District of Columbia (DC) and the State of Maryland State Implementation Plans (SIPs) which pertain to the 1990 base year ozone emission inventories for the Washington DC-MD-VA Consolidated Metropolitan Statistical Area (CMSA) ozone nonattainment area. This area, commonly referred to as the Metropolitan Washington DC area, is classified as a serious ozone nonattainment area. The SIP revisions were prepared by the Metropolitan Washington Council of Governments and submitted by the District and the State of Maryland for the purpose of establishing the 1990 baseline of emissions contributing to ozone nonattainment problems in the Metropolitan Washington DC area. This rulemaking action is for Washington DC and Maryland portions of the area only. The approval of the SIP revision submitted by the Commonwealth of Virginia for its portion of the base year inventory of the Metropolitan Washington DC area was published on September 16, 1996 (61 FR 48632). This action is being taken under section 110 of the Clean Air Act.