2015 Ozone NAAQS Infrastructure and Transport SIPs

Under the Clean Air Act (CAA) sections 110(a)(1) and 110(a)(2), each state is required to submit a state implementation plan (SIP) that provides for the implementation, maintenance, and enforcement of a revised primary or secondary NAAQS (National Ambient Air Quality Standard). CAA section 110(a)(1) and section 110(a)(2) require each state to make this new SIP submission within three years after the Environmental Protection Agency (EPA) promulgates a new or revised NAAQS. On October 26, 2015, EPA revised the eight-hour primary and secondary standards for ozone from seventy-five parts per million (ppm) to seventy ppm (80 FR 65292).

On October 10, 2019, the Department of Energy and Environment, Division of Environmental Quality (DEQ), submitted a SIP to EPA that lays out DEQ's strategy for ensuring that Arkansans are protected from unhealthy levels of ozone pollution. The SIP also addresses interstate transport of ozone precursors and visibility impairing pollutants to ensure that Arkansas is a good neighbor to downwind states.

DEQ proposed the plan in two parts concurrent with an Arkansas Pollution Control and Ecology Commission (APC&EC) rulemaking to adopt the 2015 ozone NAAQS into APC&EC Regulation No. 19. The first part addresses Clean Air Act ozone requirements for air quality monitoring, modeling, control strategy, and emissions inventory. The second part addresses Clean Air Act ozone good neighbor requirements. Both parts of the SIP and the rulemaking were subject to public comment and hearing. The changes to Regulation No. 19 were adopted on September 27, 2019. The final SIP combines both parts with changes made in response to public comment.

Final 2015 Ozone NAAQS Infrastructure and Transport SIP

EPA Action on the 2015 Ozone NAAQS Infrastructure and Transport SIP

On February 12, 2021, EPA approved portions of the October 25, 2018, Arkansas Infrastructure SIP submittal for the 2015 Ozone NAAQS, including Interstate Transport "Prong 3."

On March 22, 2021, EPA finalized approval of the Arkansas Regional Haze Phase III SIP revision submitted by DEQ on August 13, 2019, including Interstate Transport "Prong 4" for the 2015 Ozone NAAQS.