Approval and Promulgation of Implementation Plans Indiana: Revised Mobile Source Inventories and Motor Vehicle Emissions Budgets for 2005 and 2007 Using MOBILE6

EPA is approving Indiana's August 6, 2004, submittal of revised mobile emission inventories and 2005 and 2007 motor vehicle emissions budgets (MVEBs) which have been developed using MOBILE6, an updated model for calculating mobile emissions of ozone precursors. These inventories and associated motor vehicle emissions budgets are part of the 1-hour ozone attainment plan approved for the Northwest Indiana area. The Northwest Indiana area consists of Lake and Porter Counties in Indiana. The State's submittal meets a commitment by the State of Indiana to revise and resubmit the MVEBs using MOBILE6 methods within two years following EPA's release of MOBILE6, provided that transportation conformity is not determined without adequate MOBILE6- based MVEBs during the second year. The lack of approved motor vehicle emissions budgets has resulted in an administrative freeze on transportation conformity in this area. The approval of these budgets will allow transportation conformity determinations to be made in Northwest Indiana.