Finding of Failure To Attain and Reclassification of Tribal Portions of the Greater Connecticut Ozone Nonattainment Area as Serious for the 2015 Ozone National Ambient Air Quality Standards

The Environmental Protection Agency (EPA) previously granted the State of Connecticut's request to reclassify the Greater Connecticut ozone nonattainment area from Moderate to Serious under the 2015 ozone National Ambient Air Quality Standards (NAAQS). That request, however, did not include areas governed by the Mashantucket Pequot Tribal Nation and the Mohegan Indian Tribe that are located within this nonattainment area. Given that ozone monitoring data indicate that the Greater Connecticut area failed to attain the 2015 ozone NAAQS by the applicable attainment date, we are proposing to find that these tribal portions of the area did not attain the standards by the attainment date and to reclassify those portions of the area by operation of law to Serious nonattainment for the 2015 ozone NAAQS. This action, if finalized as proposed, would fulfill the EPA's statutory obligation to determine whether the Mashantucket Pequot Tribal Nation and the Mohegan Indian Tribe portions of the Greater Connecticut area attained the NAAQS by the attainment date. This action also solicits public comment on EPA's prior action on CT DEEP's request to exclude event-influenced air quality monitoring data from regulatory decisions. EPA is required to provide an opportunity for public comment on the claimed exceptional events and all supporting data. This proposed action provides the public with an opportunity to comment on the claimed exceptional events, all supporting documents, and the EPA's July 22, 2024 concurrence and nonconcurrence with CT DEEP's request.