On October 1, 2018, the California Air Resources Board (CARB) submitted its 2018 Infrastructure State Implementation Plan (SIP) for the 2015 0.070 ppm 8-hour ozone national ambient air quality standard (NAAQS) to the U.S. Environmental Protection Agency (EPA). The EPA approved most of CARB’s plan in 2021, but withheld approval for the Interstate Transport (or Good Neighbor) portion concerning California’s emissions that significantly contribute to air quality issues in downwind states. The Clean Air Act requires that states address interstate emissions that affect downwind states’ ability to attain and maintain the NAAQS; states must submit a plan to address these interstate emissions. In 2022, the EPA proposed disapproval of this section, finalizing it on February 2, 2023. Concurrently, the EPA proposed a nationwide Interstate Transport Federal Implementation Plan (FIP), which was finalized on June 5, 2023, and included California among other states. The FIP focused on large stationary sources and established emission standards for specific industries (e.g., cement and glass manufacturing).

CARB developed the 2024 Good Neighbor State Implementation Plan (SIP) to resolve the state implementation plan disapproval and replace the Interstate Transport FIP for California. A FIP may be replaced by an approvable SIP. As previously stated, the FIP focused on NO_x from stationary sources; however, mobile sources are the dominant driver of NO_x emissions in California. The Good Neighbor SIP exceeds the FIP emission reductions for California (10 tons per day NO_x) as it aims to achieve approximately 65 tons per day of NO_x reductions statewide by 2026, primarily through CARB’s recently adopted Clean Truck Check Program. California’s Clean Truck Check is a heavy-duty inspection and maintenance program. The program, which started in January 2023, is projected to reduce NO_x emissions by 68 tons per day by the 2026 ozone season and 81 tons per day by 2037 statewide, surpassing estimated NO_x reductions from California stationary sources in the FIP.

CARB developed the SIP in consultation with affected California Air Districts, aligning with their current rules and controls, and plans for stationary sources identified in the FIP. CARB also engaged with EPA headquarters and Region 9 staff to present the SIP and outline their strategy to address the FIP with a replacement SIP focusing on mobile source controls to achieve emissions reduction goals specified in the FIP. The SIP does not include stationary source emission reductions, as CARB has demonstrated that the mobile source reductions will be greater than those achieved by the FIP. Additionally, CARB evaluated the facilities subject to the FIP and determined that the majority of affected facilities already meet or exceed the standards in the FIP. Meaning, that the reductions expected to be realized from the FIP implementation may have been overestimated. If the Good Neighbor SIP is adopted and approved by EPA, the stationary source reductions outlined in the FIP will no longer apply to California facilities.

CARB will conduct a public meeting on July 25, 2024 to consider adoption of the proposed 2024 Good Neighbor SIP. If adopted, CARB will submit the 2024 Good Neighbor SIP to EPA for inclusion into the California SIP. CARB will accept written comments until July 15, 2024, as outlined in the public meeting notice.

If you would like to discuss the proposed adoption of the Good Neighbor SIP and how it may impact your California operations, please contact Trinity’s Sacramento Office or call 916.444.6666.