chevron-down Created with Sketch Beta.

What is an Environmental Impact Statement?

By Tiffany Middleton

An EIS assesses the potential impact of actions “significantly affecting the quality of the human environment.”
CasarsaGuru/E+ via Getty Images

The environmental impact statement (EIS) is a government document that outlines the impact of a proposed project on its surrounding environment. In the United States, these statements are mandated by federal law for certain projects. Environmental impact statements are meant to inform the work and decisions of policymakers and community leaders. Here, Teaching Legal Docs will explore the EIS—what is it, who writes them and why, what parts and information are typically included, and why they are significant resources for teaching about the environment and environmental policy in the classroom.

A Purpose Under Law

In the United States at the federal level, an EIS is a report mandated by the National Environmental Policy Act of 1969 (NEPA), to assess the potential impact of actions “significantly affecting the quality of the human environment.” This requirement under NEPA does not prohibit harm to the environment, but rather requires advanced identification and disclosure of harm. Examples include building, clean-up, and infrastructure projects. But the NEPA mandate is broader. Development projects that constitute major federal action, as defined by law, including those that use federal land, federal tax dollars, or are under federal agency jurisdiction, are required to assess the impact of a proposed project on the physical, cultural, and human environments affected by the proposed project. The U.S. Bureau of Land Management submitted one of the earliest statements in February 1970, for the Trans-Alaska Pipeline project. The Alabama Trustee Implementation Group worked with several federal agencies in 2017 to produce an EIS in the wake of the Deepwater Horizon oil spill. Approximately 500 statements are prepared by federal agencies in the U.S. each year. An EIS outlines the status of the environment in the affected area, provides a baseline for understanding the potential consequences of the proposed project, identifies positive and negative effects for the environment, and offers alternative actions, including inaction, in relation to the proposed project.

Not all major federal projects that could affect the environment require an EIS. The EIS requirement is one of three possible environmental review categories under NEPA. Some projects require no review and earn a “categorical exclusion determination” (CATEX). The I-35W Saint Anthony Falls Bridge, which replaced the collapsed I-35W Mississippi River Bridge in Minnesota, for example, qualified for this exempt designation. Smaller projects might require an environmental assessment (EA), a simpler investigation of environmental impact. An evaluation of an EA could prompt a larger investigation and result in a full EIS, or result in a “finding of no significant impact” (FONSI), and proceed without further review. When the U.S. Department of Agriculture prepared an EA prior to building Willow Creek Cabins in Allegheny National Forest in 2005, for example, it resulted in a FONSI.

 Local Applications

Environmental impact statements often address local areas and projects that are tangible and potentially well-known, making them widely available and accessible. They are tools for informing the public about the development and engineering of the built environment, as well as windows into the civic planning that shapes communities. They reveal details about the environmental health and development of a specific area in a comprehensive report. An EIS helps to illustrate how federal legislation might be enforced, how federal agencies contribute to local projects and provide oversight through protocols, and how the public might engage with federal agencies as part of these processes.

Unpacking the Document as a Primary Source

The U.S. Environmental Protection Agency (EPA) maintains the Environmental Impact Database, which includes records of all statements filed since 1987, and PDF copies of all statements filed since 2012. The database is free and fully searchable. There are notes about what stage the statement is in the review process (i.e. draft, final), so it is clear where a proposed project is in the process, or what type of statement is available.
Each EIS in the database has a details page, which opens with one click in the database. The details page outlines basic information: title of the statement, which generally conveys the Proposed Action; the EIS Number, which includes the year the statement was submitted (example: 20180271); several notes about the document type, which details where the statement is in the review process; and contact details for the submitting federal agency. There are links to all of the PDF documents (including attachments) that have been submitted for the Proposed Action.

An EIS might have one or more authors. Federal agencies typically outsource the writing of an EIS to third party contractors (including lawyers, scientists, engineers) with expertise in their preparation and in relation to the proposed project. As a result, the EIS varies in appearance, as well as length and number of supplemental attachments. Notice the contrast between two example statements submitted by the U.S. Department of Agriculture (left) and on behalf of the Federal Highway Administration (right):

The table of contents in the statement provides the best guide for seeing and locating all of its parts. Many statements include an executive summary or other front matter, in addition to the formal introduction, which helps to provide an overview of the Proposed Action and navigate the sections.  

Standard Contents

The content of a federal EIS is regulated by the Council on Environmental Quality (CEQ), an office in the executive branch of the federal government tasked with enforcing the rules established by NEPA. A typical federal EIS includes the following four sections:

  • Section 1—Introduces the Proposed Action and its Purpose and Need
  • Section 2—Describes the Affected Environment, provides a baseline for understanding the current environmental situation in relation to the Proposed Action.
  • Section 3—Presents a Range of Alternatives to the Proposed Action—this is considered the “heart” of the EIS. There is always a No Action Alternative presented. Understanding how the environment would respond if no action were taken helps to evaluate the Proposed Action and Alternatives.
  • Section 4—Analyzes the environmental impact of each of the Proposed Actions and Range of Alternatives. The analysis include:
    • Impacts to threatened or endangered species
    • Air and water quality impacts
    • Impacts to historical and cultural sites, particularly sites of significance for indigenous peoples
    • Social and economical impacts to local communities, including housing stock, businesses, property values, and considerations of aesthetics and noise expected
    • Cost and schedule analysis for all of the actions and alternatives presented

The EIS may include additional topics not required for every project, including financial plans, environmental mitigation plans, and plans for complying with any additional required federal, state, or local permits.

With so much to address, the typical EIS is a lengthy document, often more than 100 pages. The table of contents, however, makes quick work identifying specific sections that might be most useful for a classroom discussion or civic action.

Beyond the Document

The EIS is meant to be a comprehensive decision-making tool for federal, state, and local policy makers, and to inform the public about proposed projects that could affect the environment. Beyond drafting the document itself, development of the EIS prompts a formal process of review to facilitate the decision-making process (see table). The process includes opportunities for members of the public to voice opinions and influence projects that affect their environment. In 1970, days after the Bureau of Land Management submitted their EIS for the Trans-Alaska Pipeline, three organizations raised concerns that the statement—at just eight pages—was inadequate given the complexities of the permafrost environment in Alaska. Ultimately, the report grew from eight pages to eight feet thick.

Each federal agency is required to develop its own protocols to implement the review process for environmental impact statements. Exact review processes vary across federal agencies, but all follow the 8-step process outlined in the chart. The Bureau of Prisons, for example, assigns specific staff to review statements. The National Oceanic and Atmospheric Administration involves their Office of the General Counsel for review. The Federal Highway Administration outlines an extensive review process that involves staff and project stakeholders. Thus, the EIS is an enforcement tool to ensure that federal agencies adhere to the goals outlined in NEPA.

Review Process for Federal Environmental Impact Statements

  • Scoping

First meetings are held and needs for work and research are assessed and delegated. Open to decision makers and those involved with the proposed project.

  • Notice

Public is notified that the relevant agency is preparing an EIS. An announcement is filed in the Federal Register, notices are sent to local media, letters are sent to individuals and groups that might be interested. Public may submit comments identifying issues that the EIS should address.

  • Draft EIS

Agency assembles all comments and prepares a draft statement.

  • Comment

Members of the public who are affected by the proposed action are welcome to provide feedback on the draft through written comments and public hearings over a 45-day period.

  • Final EIS and Proposed Action

The agency announces its Proposed Action, based on the feedback and analysis it received in earlier steps. A 30-day waiting period is required after comments close before announcing the Proposed Action.

  • Re-evaluation

Needed if changes are required to the Proposed Action, or if a length of time has passed between Final EIS and planned action.

  • Supplemental EIS

Prepared if new environmental impacts are discovered, or if the size and scope of the Proposed Action change.

  • Record of Decision

Final action prior to implementation of the Proposed Action. Any outstanding issues, including protests, are resolved. After this stage, protestors may sue the agency in federal court.

Environmental Impact Assessment Around the World

Since the mandate by the U.S government, the use of environmental impact statements has boomed. The International Association for Impact Assessment was established in 1981 to provide resources for professionals and persons interested in environmental assessment. Since then, individual states have also adopted similar requirements. California, for example, requires environmental assessments under the California Environmental Quality Act. Montana, Washington, D.C., and Puerto Rico have similar requirements. Internationally, the World Bank began including environmental assessment in its funding appraisals process in 1986. The United Nations adopted the EIS requirement for certain programs in 1987, and over 100 countries, including Australia, China, India, Nepal, and Ukraine, have adopted similar environmental assessment protocols. The EIS requirement in NEPA was a watershed development, fundamentally reshaping—and documenting—stakeholders’ work in the built environment.

Environmental Impact Assessment: Classroom Applications

  • Locate the EIS for a planned or completed local or regional project, if applicable. Allow students to read about the proposed action and the considered alternatives and discuss whether they think the proposed action is most appropriate.
  • Encourage students to submit comments on a draft EIS (during the comment period) concerning a local project, if applicable.


  • Ask students to research examples in state history where an EIS was challenged in federal court and the result.
  • Assign students to consider projects in their community that could require an EIS, and have them explain why. Invite a local expert (e.g. city manager, lawyer, engineer, forestry professional, park ranger) to discuss the students’ findings. They might bring examples of past EIS-worthy projects that have been completed in the community.