What is NEPA?

For more than 50 years, the National Environmental Policy Act (NEPA) has served as the foundation of reasonable, balanced and transparent protections for our environment. Our health, safety, and environment depend on it.

What is NEPA?

The National Environmental Policy Act (NEPA) is a critical law that empowers local communities to protect themselves and their environment from dangerous, rushed or poorly planned federal projects. We teach our children to “look before they leap.” NEPA requires our government to do the same.

Passed with overwhelming bipartisan support in Congress and signed into law by President Nixon on January 1, 1970, NEPA is the foundation of reasonable, balanced, and transparent protections for our environment. With the passage of NEPA, Congress recognized that government actions can have large-scale and profoundly detrimental effects on the environment and the health of local communities.

At its most basic level, NEPA requires government agencies to engage in a review process intended to discover any significant environmental and public health impacts before a decision is made and construction begins. For example, if the government wanted to build a toxic waste incinerator in a residential neighborhood, the NEPA environmental review process would likely discover significant long-term health risks to the local community. NEPA simply and sensibly ensures the federal government informs and is responsive to the public it serves.

Thanks to NEPA, millions of people have been given a voice in federal government decisions impacting their life they did not have before.

The three basic principles of NEPA are:


When the federal government wants to build or fund a project like a highway, bridge, dam or prison, it must first disclose its plans to the public. NEPA guarantees that the public is informed of these plans because, after all, the public will have to live with the project’s consequences.

Informed Decision-Making

As the federal government prepares to fund and build a project, it must conduct a detailed study that includes:

  • how the project will be built
  • the consequences of the project (good and bad) for surrounding communities
  • proposed project alternatives that still meet the government’s needs but better protect people and the environment
  • substantive measures that can be taken to lessen any harmful impacts of the project
Giving Voice to Local Communities

Before a project is started, the federal government must ask the public local communities included including – to voice concerns. They must also ask for local expertise regarding the project. In many cases, NEPA provides the only forum for citizens to engage on major federal actions that affect their health, communities, and environment. This is arguably the most important pillar of NEPA; it draws on our democratic values to ensure that projects are undertaken with the benefit of our communities in mind. Public input leads to better-developed projects with greater consensus and protections for our health and environment.


NEPA allowed these individuals to advocate for removing four dams on the lower Snake River to restore wild salmon runs. They are four of the more than 480,000 people who made their voices heard on this issue. Pictured, clockwise from the top left, are former Idaho Fish and Game biologist Steve Pettit, Executive Director of the Nez Perce Tribe Rebecca Miles, Earthjustice attorney Todd True and Nez Perce tribal member Elliott Moffett.

How does NEPA work?

The National Environmental Policy Act (NEPA) applies to all federal agencies and to most of the activities they approve or carry out. NEPA mandates Environmental Impact Statements (EISs) for all major projects — like power plants, roads, and bridges — that the federal government plans to undertake (except in emergency situations).

At the heart of this review process is the agencies’ obligation to consider alternatives to their original project designs, which forces the government to think outside the box and results in better projects that save money and reduce negative impacts. It also gives members of the public a voice in project design by letting them suggest alternatives, which promotes collaboration in planning and buy-in on final decisions. The bottom line is that the NEPA process is designed to ensure that the public has informed access and input into government decisions that could affect the human or natural environment.

The NEPA process begins when a federal agency develops a proposal to take a major federal action, typically for a construction project that uses federal resources. If it’s determined that the action is covered under NEPA, the federal agency is legally required to conduct an environmental review before construction begins.

The NEPA review process can involve three different levels of analysis:

Categorical Exclusions

The lowest level of analysis is given to Categorical Exclusions (CATEX). A Categorical Exclusion is a group of actions a federal agency has determined do not individually or cumulatively have a significant effect on the quality of the human environment (e.g., the reconstruction of a hiking trail in a National Parks).

In such cases, neither an Environmental Assessment (EA) nor an Environmental Impact Statement (EIS) is required.

Categorical Exclusions are based on an agency’s past experiences with a specific kind of action. The agency may have studied the action in previous environmental assessments and found no significant impact on public health or the environment. Agencies develop a list and the justification for each Categorical Exclusion when they develop or revise their NEPA implementing procedures.

Environmental Assessment/Finding of No Significant Impact

If there is uncertainty as to whether a proposed project will have significant effects on public health and the environment (often the case for minor projects), federal agencies prepare a concise, preliminary evaluation of potential consequences called an Environmental Assessment (EA).

The purpose of an Environmental Assessment (EA) is to determine the significance of the environmental effects and to examine alternative means to achieve a federal agency’s objectives. Generally, an Environmental Assessment must include a brief discussion of:

  • the need for the proposal
  • alternative courses of action for any proposal
  • the environmental impacts of the proposed action and alternatives
  • a listing of agencies and persons consulted

Often, the environmental assessment will identify ways in which the agency can revise the action to reduce environmental and social impacts.

If the initial assessment demonstrates no significant effects, the agency issues a Finding of No Significant Impact (FONSI) and proceeds with the action without further environmental analysis. Preparation of a detailed Environmental Impact Statement (EIS) is only required for actions where an initial finding indicates that the action “may significantly affect the quality of the human environment.”

Because of this tiering process, over 99% of federal projects are cleared with minimal environmental assessment. In total, the federal government undertakes approximately 50,000 actions every year that are subject to NEPA review, but only 500 draft Environmental Impact Statements are prepared annually. A Federal Highway Administration study found that from 1998 to 2004, no more than 3.5% percent of all proposed transportation projects required a detailed environmental study.

Environmental Assessments and Environmental Impact Statements serve fundamentally different purposes. An EA determines whether a specific threshold is crossed – the threshold of “significant” impact. In contrast, the job of an EIS is to provide an analysis of those “significant” impacts.

Environmental Impact Statements (EISs)

Federal agencies prepare an Environmental Impact Statement (EIS) if a proposed major federal action is determined to significantly affect the quality of the human environment. The regulatory requirements for an Environmental Impact Statement are more detailed and rigorous than the requirements for an Environmental Assessment.

The Environmental Impact Statement begins with the publication of a Notice of Intent (NOI) in the Federal Register, which informs the public of the upcoming environmental analysis, provides basic information about the proposed action and describes how the public can become involved in the EIS preparation.

This Notice of Intent starts the scoping process, which is the period in which the federal agency and the public collaborate to define the range of issues and possible alternatives to be addressed in the EIS. As part of the process, agencies are required to identify and invite the participation of interest persons (e.g., public hearings, video conferencing; formal hearings; workshops, etc.).

The Environmental Impact Statement must consider all reasonable projects alternatives. For all project alternatives that were eliminated, the EIS must briefly discuss the reasons why the alternative was eliminated from consideration. An EIS includes:

  • Summary: A summary of the EIS, including the major conclusions, areas of controversy, and the issues to be resolved.
  • Table of Contents: Assists the reader in navigating through the EIS.
  • Purpose and need statement: Explains the reason the agency is proposing the action and what the agency expects to achieve.
  • Alternatives: Consideration of a reasonable range of alternatives that can accomplish the purpose and need of the proposed action.
  • Affected environment: Describes the environment of the area to be affected by the alternatives under consideration.
  • Environmental consequences: A discussion of the direct and indirect environmental effects and their significance.
  • List of preparers: A list of the names and qualifications of the persons who were primarily responsible for preparing the EIS.
  • List of agencies, organizations, and persons to whom the EIS were sent.
  • Index: The index focuses on areas of reasonable interest to the reader.
  • Appendices (if required): Appendices provide background materials prepared in connection with the EIS.

Following publication of the initial Environmental Impact Statement, a comment period of no less than 45 days begins. A final report is then published in which the government is required to substantively respond to public comments. Publication of the final EIS begins the minimum 30-day “wait period,” in which agencies are generally required to wait 30 days before making a final decision on a proposed action.

The Environmental Impact Statement process ends with the issuance of the Record of Decision (ROD). The ROD:

  • explains the agency’s decision,
  • describes the alternatives the agency considered, and
  • discusses the agency’s plans for mitigation and monitoring, if necessary.

The EPA is then required to review and provide comments on the adequacy of the analysis and the project’s impact to the environment using a rating system. In the rare case that the EPA deems the Environmental Impact Statement’s analysis unsatisfactory, it is referred to the White House Council on Environmental Quality.

When is a supplement to the EIS required?

A supplement to a draft or final EIS is required when any of the following occurs:

  • An agency makes substantial changes to the proposed action that are relevant to its environmental concerns.
  • There are significant new circumstances or information relevant to the environmental effects that have bearing on the proposed action or its impacts.

If an agency decides to supplement its EIS, it prepares, circulates and files the supplemental EIS in the same fashion as a draft or final EIS.

Cinta KaipatTinian and Pågan:

“We will fight this fight without firing a shot. The military will sit up and take notice and hear our voices.”

Cinta Kaipat is a resident of Saipan who has been fighting to return to her home island of Pågan. Pågan was evacuated years ago due to a volcanic eruption, but now former residents are prevented from returning. The U.S. military wants to turn Pågan—and the nearby island of Tinian—into a live-fire training area. Kaipat is a client in an Earthjustice lawsuit that is using NEPA to protect Pågan and Tinian.

PRIME FARMLAND, fisheries, beaches, forests and coral reefs—now at risk in the North Pacific—are also benefiting from the defensive power of NEPA. The U.S. government wants to conduct destructive war games on two islands, Tinian and Pågan, in the Commonwealth of the Northern Mariana Islands. There, mostly indigenous and low-income U.S. citizens are using NEPA to compel the U.S. Navy to consider the devastating effects that artillery, rockets and bombardment could have on their tropical homeland and sacred sites. Training could make it impossible for formerly displaced families to return to Pågan and could also disrupt access to vital emergency medical care.

If it weren’t for NEPA, low-income families and community leaders in the Northern Marianas would have little chance to protect their lands and livelihoods.

Pictured, clockwise from the top left: Gus Castro on Apå’an Santatti Beach on Pågan. The beach is one site where the U.S. military wants to do live-fire training and practice amphibious landings. A Japanese bomber lies near the airstrip on Pågan. Relics from WWII litter the island. Guma Taga, an archeological site on the island. The site is filled with lattes, ancient stone supports that were used in construction. Earthjustice attorney David Henkin speaks with a client on Pågan.

How do you benefit from NEPA?

For nearly 50 years, the United States has had an empowering legal tool that allows communities to defend themselves against harmful government and industry actions.

Simply put, NEPA ensures that the federal government makes the best decision based on the best information while engaging and informing the public it serves. We teach our children to “look before they leap.” NEPA simply and sensibly requires the government to do the same.

The Partnership Project's NEPA campaign is a registered 501 (c) (3) non-profit organization.