New EPA Regulations: Rollbacks, Repeals, and Budget Cuts

The new EPA regulations issued under Administrator Lee Zeldin amount to the largest deregulatory push in the agency’s history: since March 2025, the EPA has finalized or proposed dozens of rollbacks touching climate rules, power plant emissions, vehicle standards, chemical plant protections, drinking water limits for PFAS, refrigerant phasedowns, greenhouse gas reporting, and the agency’s own budget and workforce. Most of the finalized changes are already being challenged in federal court. What follows walks through what has changed, what it replaces, and where each piece stands.

The March 2025 Package

On March 12, 2025, Administrator Zeldin announced 31 deregulatory actions grouped under three themes: “Unleashing American Energy,” “Lowering the Cost of Living for American Families,” and “Advancing Cooperative Federalism.”¹ The list covered reconsideration of the Clean Power Plan 2.0, mercury and air toxics standards for coal plants, oil and gas methane rules, vehicle greenhouse gas standards, and particulate matter air quality standards, along with the termination of the agency’s environmental justice and diversity, equity, and inclusion programs and the closure of related offices. Most of the actions summarized below trace back to this package.

The Endangerment Finding and Vehicle Emissions

The single most consequential change is the rescission of the 2009 Endangerment Finding, the legal determination that greenhouse gases threaten public health and welfare. That finding had been the statutory foundation for regulating carbon dioxide, methane, and other greenhouse gases under the Clean Air Act. The EPA finalized the repeal on February 12, 2026, and the rule was published in the Federal Register on February 18, 2026.² The agency described it as the “single largest deregulatory action in U.S. history,” estimating total savings above $1.3 trillion.³

The rescission does not argue with climate science directly. It rests on three legal theories: that “air pollution” under Section 202(a) of the Clean Air Act refers only to local or regional harms rather than a global phenomenon; that under the major questions doctrine and the Supreme Court’s 2022 decision in West Virginia v. EPA, the agency lacks clear congressional authorization to regulate vehicle emissions for climate purposes; and that U.S. vehicle standards are “futile” because their projected effect on global temperatures is negligible, cited as 0.013°C by 2050.⁴ Analysts have flagged a direct tension with the Supreme Court’s 2007 decision in Massachusetts v. EPA, which held that the Clean Air Act “unambiguously” authorizes the agency to regulate greenhouse gases if it finds they contribute to climate change.⁵ The final rule also asserts that the Clean Air Act preempts state regulation of vehicle emissions, federal common law claims against greenhouse gas sources, and state common law claims aimed at out-of-state emissions.

Because the Endangerment Finding was the legal prerequisite for federal greenhouse gas standards on vehicles, its rescission automatically eliminated emission standards for light-duty, medium-duty, and heavy-duty vehicles and engines.² Zeldin said automakers are no longer under pressure to shift their fleets toward electric vehicles.³ The Biden administration’s multi-pollutant emissions standards for model years 2027 through 2032, finalized in April 2024, were effectively nullified as to their climate components.⁶ The EPA did not estimate the public health or environmental costs of the deregulation.⁷

Litigation began almost immediately. Seventeen organizations filed a petition for review in the U.S. Court of Appeals for the D.C. Circuit within days of the rule’s publication, and additional petitions have been consolidated.⁸ In June 2026, a coalition of 24 states, the District of Columbia, the U.S. Virgin Islands, 10 cities, and five counties filed a separate D.C. Circuit challenge, led by New York, Massachusetts, California, and Connecticut, arguing that the EPA abandoned a core government responsibility.⁹ A youth petitioner group asked the court in May 2026 to stay the rule pending review; no ruling has issued.

A parallel question about state-law climate suits is now before the Supreme Court. On February 23, 2026, the Court granted certiorari in Suncor Energy Inc. v. County Commissioners of Boulder County (No. 25-170), which asks whether federal law precludes state-law claims for injuries caused by greenhouse gas emissions’ effects on global climate.¹⁰ Argument is expected in the fall of 2026.

Power Plant Rules

The EPA has moved on three separate power-sector rules.

Greenhouse Gas Standards for Power Plants

On June 11, 2025, the EPA proposed a full repeal of all greenhouse gas emission standards for the power sector under Section 111 of the Clean Air Act, covering both the 2015 standards for new fossil fuel-fired plants and the 2024 standards for new and existing plants.¹¹ The proposal would make a legal finding that greenhouse gas emissions from power plants do not “contribute significantly to dangerous air pollution,” which would remove the statutory basis for regulating them.¹² The EPA estimated $19 billion in sector savings over two decades. The docket drew more than 127,000 comments, and the agency planned to submit a final action to the Office of Management and Budget in spring 2026.¹³

Mercury and Air Toxics Standards

On February 24, 2026, the EPA published a final rule repealing the 2024 amendments to the Mercury and Air Toxics Standards, reverting to the 2012 standards.¹⁴ Three strengthening measures were eliminated: a tighter filterable particulate matter standard for coal-fired units, which had dropped from 0.030 to 0.010 lb/MMBtu; stricter mercury limits for lignite-fired plants; and the requirement to use continuous emissions monitoring systems for particulate matter compliance.¹⁵ The EPA estimated the repeal would save the power sector about $120 million annually.¹¹

Petitions for review were filed in the D.C. Circuit in late March 2026, including Air Alliance Houston v. EPA and Illinois v. EPA, consolidated on April 1, 2026. Public interest groups also filed a petition for reconsideration with the EPA in April 2026, citing the agency’s cost analyses and its failure to account for health benefits.¹⁵ Separately, the NRDC and partners are challenging exemptions granted in spring 2025 that allowed nearly 70 coal-fired plants to bypass air pollution limits, increasing releases of mercury, arsenic, and benzene.¹⁶

New Gas-Fired Plants

On January 9, 2026, the EPA finalized nitrogen oxide standards for new gas-fired power plants and stationary turbines. The final rule was nearly 90% less stringent than the proposal the Biden administration issued in November 2024.¹⁷ The Biden proposal projected annual NOx reductions of 2,659 tons; the final rule projects reductions of only 296 tons by 2032.¹⁸ Selective catalytic reduction combined with combustion controls, which the Biden proposal identified as the best system of emissions reduction for most turbine categories, is now required only for large turbines operating above 45% capacity factor. The Clean Air Task Force called the final rule “far weaker” than the proposal.¹⁹ The Union of Concerned Scientists said the standards “open polluter loopholes” and “ignore public health harms,” and the NRDC and Public Citizen noted that the EPA declined to estimate the monetary benefits of reduced asthma and premature mortality, a decision environmental groups suggested could itself be grounds for legal challenge.

Oil and Gas Methane Rules

The 2024 regulations on methane and volatile organic compounds from oil and gas operations, known as the OOOOb and OOOOc rules, have been loosened in stages rather than repealed outright. A “comprehensive reconsideration” announced in March 2025 is ongoing, and the EPA has extended compliance deadlines and added time for flare monitoring and reporting through a sequence of interim and final rules.²⁰ On April 9, 2026, the EPA finalized a “technical reconsideration” of flaring and monitoring provisions, estimating $2.5 billion in industry savings from 2024 to 2038.

The mandatory phase-out of routine flaring of associated gas took effect May 7, 2026. Operators in the Williston, Bakken, and Permian basins warned they would have to shut in production at some well sites if flaring were not permitted, and on May 1, 2026, the EPA issued guidance allowing temporary flaring to continue past the deadline in limited circumstances deemed beyond operators’ control.²¹ The EPA is developing a further proposal to amend the 2024 rules, and compliance requirements suspended in November 2025 remain in flux.

Air Quality Programs

Fine Particulate Matter

In February 2024, the Biden EPA tightened the annual standard for fine particulate matter (PM 2.5) from 12.0 to 9.0 micrograms per cubic meter, citing effects including heart attacks, respiratory disease, and premature death.²² In November 2025, the EPA asked the D.C. Circuit to vacate the 2024 rule, arguing that the agency had failed to conduct a thorough review of air quality criteria and had unreasonably refused to consider the costs of the stricter standard.²³ The agency has indicated plans to propose a formal reconsideration that would effectively revert to the weaker 2020 standard. Previous EPA analyses had estimated the benefits of tightened PM 2.5 standards at between $3.6 billion and $9 billion.

Good Neighbor Plan

The federal Good Neighbor Plan, designed to limit nitrogen oxide emissions from upwind sources that contribute to smog in downwind states, has been dismantled. The Supreme Court stayed the plan in June 2024, and the EPA has since stayed it across all 23 covered states. In January 2026, the agency proposed a “phase 1” replacement approach that would approve individual state implementation plans rather than impose federal emission controls. The proposal covered plans from Alabama, Arizona, Kentucky, Minnesota, Mississippi, Nevada, New Mexico, and Tennessee.²⁴ The Clean Air Task Force called the approach a “get-out-of-jail-free card” for upwind polluters, arguing it allows them to avoid low-cost emission reductions while shifting compliance costs onto downwind states.²⁵

Regional Haze

The EPA has restructured the Regional Haze Program, which targets visibility in national parks and wilderness areas. In January 2026, the agency extended the deadline for states to submit third implementation period plans from July 2028 to July 2031.²⁶ A new “uniform rate of progress” policy grants states additional flexibility, and guidance tells states the agency does not support using “unconsented” power plant closures as a compliance mechanism. Environmental groups are challenging the uniform rate of progress policy in the Fourth and Sixth Circuits in National Parks Conservation Association v. EPA, arguing it is “contrary to the text of the Clean Air Act and is arbitrary.” Colorado filed a separate petition for review after the EPA fully disapproved the state’s plan revisions when a power plant reversed its planned closure.²⁷

Chemical Plants and Toxic Air Pollutants

The Biden EPA finalized a major strengthening of the Hazardous Organic NESHAP, known as the HON rule, in 2024. It required chemical manufacturing plants to cut air toxics emissions by 6,230 tons per year, reduce ethylene oxide and chloroprene emissions by 80%, and install fenceline monitoring for six carcinogens at large facilities. The agency estimated community cancer risk from air toxics at large facilities would drop by 96%.²⁸

The Trump EPA has proposed rescinding these regulations. If successful, the rescission would eliminate the requirement for 89 facilities to collectively cut ethylene oxide emissions by roughly 90%, leaving approximately 2.3 million people exposed to the gas. The administration argues that the Clean Air Act’s silence on additional “discretionary reviews” means the EPA lacks authority to strengthen hazardous air pollutant standards beyond the initial review cycle.²⁹ Experts at the Harvard Environmental and Energy Law Program say that if this legal interpretation is upheld, it would permanently restrict the EPA’s ability to update hazardous air pollutant standards based on new science. The administration has also used a “national security” provision to exempt roughly half of all commercial medical sterilizers from ethylene oxide standards, and the NRDC is suing to block those exemptions.

PFAS in Drinking Water

The 2024 PFAS drinking water rule capped PFOA and PFOS at 4.0 parts per trillion each and set limits for four other PFAS compounds.³⁰ On May 14, 2025, the EPA announced it would keep the PFOA and PFOS limits but intends to rescind the regulations for PFHxS, PFNA, HFPO-DA, and the associated hazard index mixture.

In May 2026, the EPA proposed a two-year compliance extension for the PFOA and PFOS standards, pushing the deadline for water systems from 2029 to April 2031. Under the proposal, systems granted an extension with contamination at or above 12 parts per trillion would still have to implement short-term mitigation.³¹ A separate rulemaking to rescind the standards for the other PFAS compounds is proceeding in parallel.

Hydrofluorocarbon Refrigerants

On May 26, 2026, the EPA finalized revisions to Biden-era rules governing hydrofluorocarbons under the American Innovation and Manufacturing Act. Compliance deadlines were extended by five to six years for transitioning to lower-warming-potential refrigerants in key sectors. Supermarket refrigeration systems and remote condensing units got an interim limit allowing refrigerants with a global warming potential up to 1,400 (compared with the previous 150 or 300) until January 1, 2032. Cold storage warehouses received a similar extension at an interim limit of 700.³² Semiconductor manufacturing compliance was pushed to 2030, and the installation deadline for legacy residential air conditioning systems was eliminated.

The White House estimated the combined changes at $2.4 billion in savings, including more than $800 million at supermarkets and up to $1.5 billion for transporters of refrigerated goods.³³ The EPA also proposed exempting all road and intermodal container transportation refrigeration units from leak repair requirements that had applied under the 2024 emissions reduction rule.

Greenhouse Gas Reporting

In September 2025, the EPA proposed eliminating greenhouse gas reporting requirements for the vast majority of major industrial polluters. The proposal would permanently remove reporting obligations for 46 source categories, including electricity generation, cement, iron and steel, petroleum refineries, and landfills, after reporting year 2024. Reporting for petroleum and natural gas systems would be suspended until 2034, aligning with the waste emissions charge delay in the One Big Beautiful Bill Act signed on July 4, 2025.³⁴

The proposal remains pending. The docket drew more than 53,000 comments.³⁵ The EPA estimates that finalizing it would save $303 million annually, totaling between $2 billion and $2.4 billion over ten years. The agency has also extended the reporting deadline for the 2025 reporting year.

Social Cost of Carbon

The administration has abandoned the practice of assigning a dollar value to the societal harms caused by greenhouse gas emissions, a figure the Biden EPA had set at $190 per metric ton of carbon dioxide in a November 2023 report.³⁶ On his first day in office, President Trump disbanded the Interagency Working Group on the Social Cost of Greenhouse Gases and withdrew all prior guidance. Federal agencies have been told to stop monetizing the impacts of greenhouse gas emissions in their regulatory analyses. Where monetization is required by law, agencies must consider only domestic effects and follow 2003-era guidance, a framework that predates most modern climate economics. OMB guidance states that the circumstances requiring monetization will be “few to none.”³⁷ Cost-benefit analyses for future regulations will minimize or exclude the climate benefits of pollution reduction, making it harder to justify environmental rules on economic grounds.

Waters of the United States

Which bodies of water receive federal protection under the Clean Water Act remains in flux, and the map is currently fractured. The Biden administration’s 2023 WOTUS rule is in effect in 24 states, while the EPA applies a pre-2015 definition in the other 26 states due to ongoing litigation.³⁸ On November 17, 2025, the EPA and the Army Corps of Engineers proposed a new rule to further narrow the definition and fully implement the Supreme Court’s 2023 decision in Sackett v. EPA. Under the proposal, “relatively permanent” waters would be those with standing or flowing water year-round or at least during the wet season, and a “continuous surface connection” would require surface water abutting a jurisdictional water at least during the wet season.³⁹ The comment period closed in January 2026 and no final rule has issued.

Coal Ash Disposal

The EPA has adjusted coal combustion residuals (CCR) rules through a series of steps. In February 2026, the agency extended compliance deadlines for CCR management units, giving facilities more time to complete groundwater monitoring and evaluations.⁴⁰ In April 2026, the EPA proposed broader amendments: exempting dewatering structures from certain requirements, establishing new site-specific compliance pathways for groundwater cleanup, allowing CCR extraction for beneficial use during post-closure care, and revising the definition of “beneficial use” to eliminate environmental demonstration requirements for placing large quantities of unencapsulated coal ash on land.⁴¹ The compliance deadline for certain large unlined surface impoundments would move from 2028 to 2031, in the interest of electric grid reliability.

Budget Cuts and Workforce Reductions

The EPA’s capacity to implement and enforce environmental law has shrunk significantly. Between January 2025 and January 2026, the agency lost more than 4,000 employees, a 24% reduction that brought headcount to 12,849, the lowest since the Reagan administration.⁴² The departures disproportionately affected team leaders, doctorate-holding scientists, and staff in health-related occupations. In July 2025, Administrator Zeldin announced elimination of the Office of Research and Development, the agency’s main scientific arm, claiming savings of nearly $750 million. Congress initially directed the EPA to halt the closure but ultimately passed appropriations language allowing the restructuring to proceed.

The administration’s fiscal year 2026 budget proposal called for a 54% funding cut, from $9.14 billion to $4.16 billion. Specific enforcement reductions included a 30% cut to civil enforcement, 49% to criminal enforcement, 35% to compliance monitoring, and complete elimination of environmental justice enforcement funding. Congress did not enact cuts of that magnitude but approved a 3% ($300 million) reduction to the EPA’s 2026 budget and rescinded some Inflation Reduction Act funding.⁴²

An Inspector General report found that staffing cuts left the agency’s grants workforce “overburdened.” The agency recommends that grant specialists oversee no more than 60 grants; by September 2025 the average had spiked to 180, and in one regional office project officers were managing 90 grants each.⁴³ Agency leadership responded that it does not intend to hire to close the gap because it expects grant spending to “contract dramatically.”

Where Challenges Get Filed

Where a lawsuit against the EPA lands can shape how it comes out, and the Supreme Court clarified the venue rules on June 18, 2025. In EPA v. Calumet, the Court ruled 7–2 that challenges to the EPA’s denial of small refinery exemptions from the renewable fuel program must be heard in the D.C. Circuit, because the agency relied on arguments applying generically to all refineries. In Oklahoma v. EPA, the Court reversed a transfer to the D.C. Circuit, holding that the EPA’s rejection of state emissions-control plans was based on fact-intensive, state-specific analysis and belonged in the regional circuit.⁴⁴ Together, the decisions narrowed the circumstances under which the EPA can funnel challenges to the D.C. Circuit and gave challengers more opportunity to litigate in regional courts. Given the volume of rules now being contested, that procedural shift may prove as consequential as any single rollback.

1
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U.S. EPA. PFAS Drinking Water Standards
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