Standards of Performance for Existing Sources

Under Clean Air Act section 111(d), EPA issues guidelines to states on how to establish standards of performance for existing source of air pollutants that, if new, would otherwise be subject to new source performance standards. States must develop and submit state plans that establish and provide for implementation and enforcement of the standards of performance.

Emission Guidelines for Oil and Natural Gas Sector

On November 15, 2021, EPA proposed a rule (Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review) that would expand and strengthen emissions reduction requirements for new, modified and reconstructed oil and natural gas sources, and would require states to reduce methane emissions from these sources. On December 6, 2022, EPA issued a supplemental proposal to the initial proposed rule, to update, strengthen, and expand the standards proposed in the November 2021 proposal. Arkansas Department of Energy and Environment Division of Environmental Quality provided comments on the proposal to EPA on February 13, 2023. On March 8, 2024, EPA issued finalized New Source Performance Standards, emission guidelines and provisions related to optical gas imaging. On January 15, 2025, EPA proposed amendments to the final rule in response to petitions for reconsideration.

New Source Performance Standards for Greenhouse Gas Emissions From New, Modified, and Reconstructed Fossil Fuel-Fired Electric Generating Units; Emission Guidelines for Greenhouse Gas Emissions From Existing Fossil Fuel-Fired Electric Generating Units; and Repeal of the Affordable Clean Energy Rule

On May 23, 2023, EPA proposed five separate actions under Clean Air Act Section 111(d) to address greenhouse gas (GHG) emissions from fossil fuel-fired electric generating units (EGUs). EPA is proposing revised new source performance standards (NSPS), first for GHG emissions from new fossil fuel-fired stationary combustion turbine EGUs and second for GHG emissions from fossil fuel-fired steam generating units that undertake a large modification, based upon the 8-year review required by the CAA. Third, EPA is proposing emission guidelines for GHG emissions from existing fossil fuel-fired steam generating EGUs, which include both coal-fired and oil/gas-fired steam generating EGUs. Fourth, EPA is proposing emission guidelines for GHG emissions from the largest, most frequently operated existing stationary combustion turbines and is soliciting comment on approaches for emission guidelines for GHG emissions for the remainder of the existing combustion turbine category. Finally, EPA is proposing to repeal the Affordable Clean Energy (ACE) Rule. On January 15, 2025, EPA provided notice that it was denying or partially denying two petitioners request for reconsideration to the final rule.

Emission Guidelines for Municipal Solid Waste Landfills

In 2016, EPA issued guidelines for reducing emissions from existing municipal solid waste landfills. In 2017, EPA announced that the agency was reconsidering certain aspects of the emission guidelines. In August 2019, EPA issued revisions to the emission guidelines to align state plan timing with requirements under the updated Clean Air Act section 111(d) implementing regulations finalized on July 8, 2019.

On May 21, 2021, EPA published a final rule in the Federal Register that established a federal implementation plan (FIP) for states that had not yet submitted state plans. On July 31, 2021, Arkansas Department of Energy and Environment Division of Environmental Quality (DEQ) proposed revisions to the state 111(d) plan to address new requirements for municipal solid waste landfills, and to update 111(d) plans for kraft pulp mills and sulfuric acid plants. The public comment period ended on September 30, 2021. On June 20, 2022, DEQ submitted the 111(d) plan revisions to EPA for approval. EPA published final approval of the 111(d) plan revision on December 29, 2022, which became effective on January 30, 2023.

Implementing Regulations under Clean Air Act Section 111(d)

On December 23, 2022 EPA proposed a rule to update the implementing regulations under Clean Air Act Section 111(d). Arkansas Department of Energy and Environment Division of Environmental Quality provided comments on the proposal to EPA on February 27, 2023. EPA published a final rule to adopt changes November 17, 2023. The final action revised the timing of certain actions related to state plans and federal implementation plans, and finalized requirements related to public participation, "remaining useful life and other factor" (RULOF) consideration, and electronic submission of state plans. With this action, EPA introduced partial/conditional approvals of state 111(d) plans and parallel processing options for states submitting 111(d)plans. EPA also revised definitions for "standard of performance," "meaningful engagement," and "pertinent stakeholders."

On July 31, 2021, Arkansas Department of Energy and Environment Division of Environmental Quality (DEQ) proposed revisions to the state 111(d) plan to address new requirements for municipal solid waste landfills, and to update 111(d) plans for kraft pulp mills and sulfuric acid plants. The public comment period ended on September 30, 2021. On June 20, 2022, DEQ submitted the 111(d) plan revisions to EPA for approval. The final SIP package can be accessed below. EPA published final approval of the 111(d) plan revision on December 29, 2022, which became effective on January 30, 2023.