The National Environmental Policy Act (NEPA) [42 U.S.C. 4321 et seq.] was signed into law on January 1, 1970. The Act establishes national environmental policy and goals for the protection, maintenance, and enhancement of the environment, and it provides a process for implementing these goals within the federal agencies.  The Act also establishes the Council on Environmental Quality (CEQ).  The complete text of the law is available for review at NEPAnet.

Title I of NEPA contains a Declaration of National Environmental Policy.  Section 101 states that it is the responsibility of the federal government to “use all practicable means, consistent with other essential considerations of national policy” to promote certain environmental goals, including “fulfill[ing] the responsibilities of each generation as trustee of the environment for succeeding generations.”

Section 102 requires all federal agencies are to prepare detailed statements assessing the environmental impact of and alternatives to major federal actions significantly affecting the environment. These statements are commonly referred to as environmental impact statements (EISs). Section 102 also requires federal agencies to lend appropriate support to initiatives and programs designed to anticipate and prevent a decline in the quality of mankind's world environment.

Title II of NEPA establishes the Council on Environmental Quality (CEQ). While NEPA established the basic framework for integrating environmental considerations into Federal decisionmaking, it did not provide the details of the process for which it would be accomplished. Federal implementation of NEPA was the charge of the CEQ, which interpreted the law and addressed NEPA's action forcing provisions in the form of regulations and guidance. In 1978, CEQ issued Regulations for Implementing the Procedural Provisions of the National Environmental Policy Act (40 CFR §§ 1500 -1508). In 1980, CEQ issued the guidance document, Forty Questions and Answers on the CEQ Regulations. Since that time, CEQ has issued additional guidance and other information covering a variety of issues relevant to the NEPA process. This information is available at CEQ NEPAnet.

The Environmental Protection Agency (EPA) has a unique responsibility in the NEPA review process. Under Section 309 of the Clean Air Act [PDF 12kb], EPA is required to review and publicly comment on the environmental impacts of major federal actions including actions that are the subject of EISs.  If EPA determines that the action is environmentally unsatisfactory, it is required by Section 309 to refer the matter to the Council on Environmental Quality (CEQ). (See also EPA Section 309 Review of NEPA Documents.)

There are three levels of analysis depending on whether or not an undertaking could significantly affect the environment.  These three levels include: categorical exclusion determination; preparation of an environmental assessment/finding of no significant impact (EA/FONSI); and preparation of an environmental impact statement (EIS).

At the first level, an undertaking may be categorically excluded from a detailed environmental analysis if it meets certain criteria, which a federal agency has previously determined as having no significant environmental impact.  A number of agencies have developed lists of actions that are normally categorically excluded from environmental evaluation under their NEPA regulations. At the second level of analysis, a federal agency prepares a written environmental assessment (EA) to determine whether or not a federal undertaking would significantly affect the environment.  If the answer is no, the agency issues a finding of no significant impact (FONSI).  The FONSI may address measures that an agency will take to reduce (mitigate) potentially significant impacts. If the EA determines that the environmental consequences of a proposed federal undertaking may be significant, an EIS 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 and then comment on the draft EIS when it is completed. If a federal agency anticipates 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 having to first prepare an EA. After a final EIS is prepared and at the time of its decision, a 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. Additional explanation on the basics of the NEPA process is available on the EPA Compliance and Enforcement Office’s NEPA site.

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There are three levels of analysis depending on whether or not an undertaking could significantly affect the environment.  These three levels include: a categorical exclusion determination; preparation of an environmental assessment/finding of no significant impact (EA); and preparation of an environmental impact statement (EIS).

CE. At the first level, an undertaking may be categorically excluded from a detailed environmental analysis if it meets certain criteria, which a federal agency has previously determined as having no significant environmental impact.  A number of agencies have developed lists of actions that are normally categorically excluded from environmental evaluation under their NEPA regulations.

EA. At the second level of analysis, a federal agency prepares a written environmental assessment (EA) to determine whether or not a federal undertaking would significantly affect the environment.  If the answer is no, the agency issues a finding of no significant impact (FONSI).  The FONSI may address measures that an agency will take to reduce (mitigate) potentially significant impacts. If the EA determines that the environmental consequences of a proposed federal undertaking may be significant, an EIS is prepared.  

EIS. 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 and then comment on the draft EIS when it is completed. If a federal agency anticipates 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 having to first prepare an EA. After a final EIS is prepared and at the time of its decision, a 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. Additional explanation on the basics of the NEPA process is available on the EPA Compliance and Enforcement Office’s NEPA site.

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For transportation projects, NEPA requires the Federal Highway Administration (FHWA) and other transportation agencies to consider potential impacts to the social and natural environment. In addition to evaluating the potential environmental effects, FHWA must take into account the transportation needs of the public in reaching a decision that is in the best overall public interest.

To address the NEPA responsibilities established by CEQ, the Federal Highway Administration (FHWA) issued regulations (23 CFR § 771), Environmental Impact and Related Procedures. The FHWA guidance complementing the regulations were issued in the form of a Technical Advisory (T.6640.8a), Guidance for Preparing and Processing Environmental and Section 4(f) Documents. The Technical Advisory provides detailed information on the contents and processing of environmental documents. Additional guidance and information on the NEPA process and other environmental requirements are found in the FHWA Environmental Guidebook and on FHWA's SAFETEA-LU Environmental Review Provisions web site.

More details about the NEPA process and transportation are available on the FHWA NEPA Project Development web site. Also see FHWA's Re:NEPA Community of Practice web site.

Section 6002 of the  Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) established new procedures that must be followed when preparing an environmental impact statement for a highway or transit project. The law updates the environmental review process to include a new category of "participating agencies" that have an interest in the project. It also requires that the lead agency establish a coordination plan for agency and public participation and comment and that the participating agencies and the public have the opportunity to comment on the purpose and need and range of alternatives for a project. The law also establishes a 180-day time limit on legal challenges to federal agency approvals for projects, which is triggered by publication of a notice of environmental decisions for the project in the Federal Register. More information on Section 6002 and its implementation is available in FHWA's SAFETEA-LU Environmental Review Process Final Guidance, issued in November 2006.

For more information on transportation project delivery and environmental streamlining, please link to Project Delivery/Streamlining section of this site.

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