What EPA’s Recission of the Endangerment Finding Means for Your Project

On February 18, 2026, the Environmental Protection Agency (EPA) published a final rule rescinding the 2009 “findings of contribution and endangerment” for greenhouse gases (GHGs) under the Clean Air Act (CAA) and repealing all associated GHG emission standards for on-road motor vehicles and engines. EPA states that the action reflects its “best reading” of the CAA following the President’s Executive Order directing a reevaluation of the 2009 finding. Although the rule directly addresses motor vehicle emissions, it may signal EPA’s willingness to reconsider GHG regulations for stationary sources and other sectors. Such actions would require separate rulemakings.

What is the Endangerment Finding?

EPA’s 2009 Endangerment Finding concluded that GHG emissions from new motor vehicles contribute to air pollution that endangers public health and welfare and are therefore subject to regulation under the CAA. The finding followed the Supreme Court’s 2007 decision in Massachusetts v. EPA, which held that GHGs qualify as “air pollutants.” For more background, refer to our September 2025 article.

Following the 2009 finding, EPA promulgated GHG standards for mobile and stationary sources, power plants, oil and gas methane emissions, and hydrofluorocarbons. The Endangerment Finding served as the legal and scientific foundation for EPA’s GHG regulatory framework. Although industry groups repeatedly challenged the finding, courts consistently upheld EPA’s authority.

The February 2026 decision nullifies the 2009 Endangerment Finding and repeals all federal vehicle GHG standards. EPA says this is “the single largest deregulatory action in U.S. history” and that it will “save Americans over $1.3 trillion.”

What Is California Doing in Response?

California’s current posture is best understood as litigation plus regulatory backstopping. California Attorney General Rob Bonta publicly denounced the repeal and stated California will challenge EPA in court. Separately, public health and environmental groups have already filed a challenge in the D.C. Circuit. Congress has also previously used the Congressional Review Act (CRA) to disapprove EPA waivers tied to California vehicle standards, and California (with other states) filed suit challenging those CRA resolutions.

This matters because it reinforces the “two-track” reality: California is simultaneously defending its ability to regulate mobile-source emissions while preparing for reduced federal ambition. Even where federal standards retreat, California climate planning has a built-in expectation that state programs or policies can substitute for lost mobile-source reductions if federal/other conditions change.

We’ll be keeping track of whether litigation produces a stay before the rule’s effective date or specifies a longer period of regulatory divergence, where federal standards lapse but state programs continue.

What Does this Mean for Developers and CEQA Practitioners?

The repeal represents a significant shift in federal climate regulatory policy. However, the ultimate durability and scope of that shift will depend on the outcome of litigation and potential future administrative or legislative action, such as repealing GHG regulations for stationary sources.

For most project applicants, the immediate issue is not “Does my project become exempt from GHG analysis?” It’s whether the assumptions used to estimate future mobile source emissions and the feasibility narrative for mitigation need to be updated. Project applicants should consider the following:

1. Near-term project impacts are limited, but modeling assumptions may shift. EPA is repealing federal vehicle GHG standards, but the federal fuel economy program—the National Highway Traffic Safety Administration’s (NHTSA’s) Corporate Average Fuel Economy (CAFE)—remains. EPA expressly states that it is not revising provisions necessary for NHTSA’s program or its co-administration framework. So fleet transformation may continue for multiple reasons (fuel economy rules, state rules, market), but there is new uncertainty around the “federal tailpipe” trajectory that many CEQA/NEPA forecasts include.

2. Expect a period of “dual-baseline” arguments in environmental review. If you’re a project applicant relying on forecasts that assume increasingly stringent federal tailpipe standards, agencies and commenters may ask, “Is that still a reasonably foreseeable regulatory setting?” or “Should a sensitivity case be disclosed?” The answer doesn’t need to be perfect—it needs to be transparent and defensible.

3. Federal permit projects may see less consistency in what agencies expect. With the Council on Environmental Quality’s NEPA regulations having been rescinded and federal climate guidance withdrawn, agencies may diverge on how they treat GHG analysis, even before EPA’s endangerment repeal is factored in.

4. Your CEQA mitigation strategy should include mobile source emission reductions. For transportation/infrastructure applicants, measures that tend to remain valuable across policy scenarios include construction emissions reductions (equipment standards, electrification where feasible), operational efficiency and vehicle miles traveled (VMT)-reduction design elements (when applicable), and electric vehicle–ready infrastructure where it aligns with local/state requirements and utility planning.

Our Takeaway: Build project documentation that can survive either federal outcome by (1) clearly stating assumptions, (2) adding a modest sensitivity analysis where fleet standards drive results, (3) aligning your NEPA analysis with agency guidance and local nuance, and (4) favoring mitigation that remains beneficial under state and local frameworks.

ESA Is Ready to Support Your Project

In the short term (i.e., next 30–90 days), we recommend that you clarify your vehicle modeling assumptions and discuss regulatory uncertainty. In the medium term (i.e., next 90–180 days), we recommend that you conduct sensitivity tests or model multiple scenarios to balance flexibility with uncertainty. In the longer term (i.e., next 180+ days), we recommend that you consider a two-track compliance strategy and analyze Climate Action Plan target attainment for multiple scenarios and strengthen monitoring and adaptive management.

ESA’s air quality and GHG/climate experts keep up to date on regulatory changes and provide strategic guidance and airtight technical analyses for your projects to meet rigorous environmental review standards. Contact ESA’s Air Quality, Climate, and Acoustics leads Brian Schuster and Alan Sako, LEED, AP BD+C, for more information, and be sure to subscribe to our newsletter and follow ESA on LinkedIn for timely regulatory updates.