Designation of Areas for Air Quality Planning Purposes; Redesignation of Particulate Matter Unclassifiable Areas; Redesignation of Hydrographic Area 61 for Particulate Matter, Sulfur Dioxide, and Nitrogen Dioxide; State of Nevada

In this document, EPA is approving a request from the State of Nevada, pursuant to section 107(d) of the Clean Air Act (Act), to redesignate the current single unclassifiable area for particulate matter with an aerodynamic diameter less than or equal to 10 micrometers (PM-10) into numerous individual areas to be consistent with the area definitions for other pollutants. EPA is also approving a State-requested subdivision of one of those individual areas, referred to as hydrographic area 61 (Boulder Flat), into two areas. EPA's approval of these requests establishes hydrographic areas as the section 107(d) unclassifiable areas for PM-10 and replaces hydrographic area 61 with two new section 107(d) areas for PM-10, sulfur dioxide (SO<INF>2</INF>), and nitrogen dioxide (NO<INF>2</INF>): upper area 61 and lower area 61. In this action, EPA is also deleting certain total suspended particulate (TSP) area designations that are no longer necessary. EPA proposed these actions in the Federal Register on April 30, 2002 (67 FR 21194). EPA received comments from several commenters on our proposed actions. After carefully reviewing and considering the issues raised by the commenters, EPA is finalizing our actions as proposed.