National Environmental Policy Act (NEPA)

National Environmental Policy Act (NEPA)

The National Environmental Policy Act (NEPA) of 1969 established an environmental policy with the goal of protecting, maintaining, and enhancing the human environment. NEPA brought environmental concerns to the forefront of federal decision-making, creating a process for evaluating the impacts of federal actions. In implementing NEPA, the federal agency responsible for a proposed project is required to coordinate with all branches of government that may have jurisdiction over the resources impacted by the project.

Depending on expected project impacts, the NEPA process follows one of three paths:

  • Categorical Exclusion (CE)
  • Environmental Assessment (EA)
  • Environmental Impact Statement (EIS)

The simplest form of NEPA evaluation is the categorical exclusion. A project may be categorically excluded from detailed environmental analysis if it falls within a defined project type that the lead federal agency has previously evaluated for impacts. Agencies have developed lists of actions which typically do not require detailed analysis if certain criteria are met.

If a proposed action is not categorically excluded from further NEPA evaluation, the lead federal agency may prepare an environmental assessment to determine if the action would significantly affect the human environment. If no significant adverse effects are expected, the agency may issue a Finding of No Significant Impact (FONSI.) The FONSI may include mitigation measures which an agency will require a project proponent to complete to ensure significant impacts do not occur.

If an EA determines that the environmental effects of a proposed federal undertaking may be significant, an environmental impact statement is prepared. An EIS is a more detailed evaluation of the proposed action and alternatives. The public, other federal agencies and outside parties may provide input into the preparation of an EIS throughout its development. If a federal agency expects that an undertaking may significantly impact the environment, or if a project is environmentally controversial, a federal agency may choose to prepare an EIS without first preparing an EA.

After a final EIS is prepared, the lead federal agency will prepare a public record of its decision addressing how the findings of the EIS, including consideration of alternatives, were incorporated into the agency's decision-making process.

Environmental Assessment

Many federal actions requiring NEPA review are completed through the development of an environmental assessment. An EA is intended to analyze the impacts a project may have on the environment in a more streamlined fashion than does an EIS. The findings of an EA determine whether significant impacts to the environment are expected as a result of a project. If significant impacts are expected, an EIS may be required; if an EA shows that no significant impacts are likely, then the agency can release a FONSI and the project can move forward.

EAs are described in Section 1508.9 of the Council on Environmental Quality's NEPA regulations. Generally, an EA includes discussions of the purpose and need for a proposed action, an analysis of alternatives, the environmental impacts of the proposed action and alternatives, and a listing of agencies and persons consulted during EA preparation.

Environmental Impact Statement

NEPA requires that all federal undertakings with the potential to significantly affect the quality of the human environment complete an EIS to analyze and disclose project effects. Used as a tool for decision-making, an EIS describes the positive and negative environmental effects of a proposed action as well as alternative actions. Several states have adopted laws similar to NEPA requiring environmental review of projects with a state agency nexus.

For more information, see:

Full Text of NEPA (PDF file, 9 pages, 39K)

EPA's NEPA Website