There are three types of environmental reviews an agency can require for a proposed major federal action: an environmental assessment, an environmental impact statement, or a categorical exclusion. These reviews are designed to make an agency consider the environmental consequences of the proposed action, alternative actions the agency could take in lieu of the proposed action, the expected environmental impacts of those alternative actions, and the agency’s rationale for selecting its preferred approach.
An environmental assessment (EA) is a preliminary step to determine if the action will significantly affect the quality of the environment. If the agency determines that there will be a significant impact, then it must prepare an environmental impact statement (EIS). An environmental impact statement is an in-depth analysis of the proposed action’s environmental consequences and can take years to finalize. If the agency determines that there will not be a significant impact on the environment, then the agency makes a Finding of No Significant Impact (FONSI) and does not need to prepare an environmental impact statement.
Agencies can also adopt categorical exclusions (CEs), which are classes of actions that the agency determines do not generally have a significant effect on the human environment, and therefore do not require an EA or an EIS. Agencies often use categorical exclusions for actions such as routine maintenance, operational activities, and authorization of regularly-occurring actions. An agency’s internal procedures may only require administrative approval to use a categorical exclusion or it may require a documented explanation as to why the proposed action does not require an environmental assessment. Congress amended NEPA in 2023 to also allow an agency to adopt another agency’s CE. See 42 U.S.C. § 4336c.
CEQ’s Regulations Implementing NEPA
The Council of Environmental Quality (CEQ), a small agency within the Executive Office of the President, historically issued implementing regulations for NEPA that outlined how federal agencies should comply with the statute. CEQ’s NEPA implementing regulations created a single framework for environmental reviews, but were designed to provide flexibility to each agency consistent with its mandate and activities.
In February 2025, the District Court for the District of North Dakota vacated CEQ’s 2024 NEPA regulations (the Phase II rule), holding that CEQ lacked the authority to issue binding NEPA regulations. Shortly after, CEQ revoked all its NEPA rules and issued guidance requiring each federal agency to revise its NEPA regulations consistent with the 2023 amendments, using CEQ’s 2020 rule as a model and incorporating specific policy priorities.
Other Federal Agencies’ Rules Implementing NEPA
Federal agencies continue to be bound by their own NEPA implementing regulations. According to CEQ’s Feb. 19, 2025 guidance, federal agencies will continue with pending and ongoing NEPA analyses while they revise their rules. As of early July, 2025, several agencies have issued interim final rules and adopted new rules or new non-binding guidance documents that will now govern their NEPA implementation.
Other agencies continue to operate under rules that are decades-old and inconsistent with NEPA as amended. Where agency rules are inconsistent with NEPA, CEQ’s guidance urged agencies to make “any adjustments needed” though the guidance does not state whether those adjustments will be subject to public notice and comment.
Regulatory Trackers
