Proposed rule · 2026-17502

Air Plan Approval; Kentucky; Cincinnati-Hamilton Area Limited Maintenance Plan for the 1997 8-Hour Ozone NAAQS

The U.S. Environmental Protection Agency (EPA or Agency) is proposing to approve a State Implementation Plan (SIP) revision submitted by the Commonwealth of Kentucky through the Energy and Environment Cabinet (Cabinet), Division of Air Quality (Division), on July 23, 2024. The SIP revision consists of a Limited Maintenance Plan (LMP) for the Kentucky portion of the tri-state Cincinnati-Hamilton 1997 8-hour ozone nonattainment area (the "tri-state Cincinnati-Hamilton Area"). The Kentucky portion of the tri-state Cincinnati-Hamilton Area is composed of Boone, Campbell, and Kenton Counties in Kentucky (hereinafter also referred to as the "Northern Kentucky Area"). The EPA is proposing to approve Kentucky's LMP for the Northern Kentucky Area because it provides for the maintenance of the 1997 8-hour ozone National Ambient Air Quality Standards (NAAQS) within the tri-state Cincinnati-Hamilton Area through the end of the second 10-year portion of the maintenance period. The effect of this proposed action would be to make certain commitments related to maintenance of the 1997 8-hour ozone NAAQS in the Northern Kentucky Area federally enforceable as part of the Kentucky SIP.