EPA Acts on Interstate Transport Requirements for Ozone Under State Implementation Plans

On Tuesday, January 31, EPA Administrator Michael Regan finalized EPA’s disapproval of State Implementation Plan (SIP) submissions for 19 states regarding the interstate transport of ozone under the 2015 eight-hour ozone national ambient air quality standards (NAAQS) of 70 parts per billion. Under the Clean Air Act, states were required to submit SIPs for the 2015 eight-hour ozone standard by October 1, 2018. The Clean Air Act required the SIPs to include “good neighbor” provisions, which prohibit emissions that either significantly contribute to nonattainment in a neighboring state or interfere with maintenance of the NAAQS in a neighboring state.

According to EPA, the agency based its disapprovals on an assessment of the information and analyses provided by states in their individual SIP submissions, comments received, and an EPA air quality analysis projecting ozone air quality and contributions in 2023. As a result of the disapproval, these 19 states have two years to obtain EPA approval of updated SIP submissions or be subject to a Federal Implementation Plan — a plan that EPA proposed in April 2022 and that the agency has said it plans to finalize by March 15, 2023, although the plan has not yet been sent to the Office of Management and Budget for interagency review.

The states subject to this action are Alabama, Arkansas, California, Illinois, Indiana, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nevada, New Jersey, New York, Ohio, Oklahoma, Texas, Utah, West Virginia, and Wisconsin (with SIP submissions from Minnesota and Wisconsin only partially disapproved). EPA will address similar SIP submissions from Tennessee and Wyoming in a separate action.

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