On March 15, 2023, EPA released its final “good neighbor” plan for the 2015 ozone National Ambient Air Quality Standard (NAAQS). The Clean Air Act’s good neighbor provision requires each State Implementation Plan (SIP) to prohibit emissions that will significantly contribute to nonattainment of a NAAQS, or interfere with maintenance of a NAAQS, in a downwind state. The Act requires EPA to backstop state action by promulgating Federal Implementation Plans (FIPs) if a state fails to submit, or EPA disapproves, a good neighbor SIP. Wisconsin electric generation units (EGUs) have been subject to good neighbor SIP obligations for various pollutants since 2017.
In March 2022, EPA released a proposed version of this good neighbor transport rule designed to reduce interstate transport of nitrogen oxide pollution, a precursor to the formation of ozone. A summary of the rule proposal can be found here. The proposal would have created new NOx emission limitations for large industrial sources located in 23 states, including Wisconsin. The regulated sources categories included paper and paperboard facilities, cement kilns, boilers and furnaces at iron and steel mills, reciprocating internal combustion engines used to move natural gas through pipelines, furnaces located at glass and glass-product manufacturing facilities, basic chemical manufacturing, petroleum, and coal products manufacturing. The proposed rule would have significantly impacted many Wisconsin industrial facilities.
In a significant departure from the proposal, the final rule excludes from regulation non-EGU industrial sources in Wisconsin, Minnesota, and Alabama. These sectors provided information to EPA demonstrating that the facilities in these states were inconsequential to pollution transport in their respect regions.
The following map details the states subject to the final rule.
The ostensible purpose of this final rule is to reduce ozone levels in areas of the country that do not meet the 2015 ozone NAAQS. This is accomplished by forcing NOx emission reductions in upwind states to mitigate their significant contribution to ozone exceedances in downwind states. The technical support documents in the rulemaking docket demonstrate that many states will experience lower ozone concentrations under this proposal. However, several areas will remain burdened by significant upwind ozone contributions even after implementing the required controls.
Legally, the final rule is intended to resolve the “good neighbor” obligations of the covered states. However, the underlying technical support documents associated with the final rule demonstrate that Illinois and Indiana will remain the largest contributors to Wisconsin’s ozone nonattainment areas after full rule implementation in 2026. Sheboygan County and Southeast Wisconsin counties are particularly susceptible to ozone pollution caused by emissions emanating from Illinois and Indiana, and these counties’ modeled compliance margins in 2026 are extremely narrow. This has been an ongoing criticism of the EPA’s suite of pollution transport rules and today’s rule may not resolve those concerns.
A copy of the rule can be found here.