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This guide provides background information on Environmental Impact Statements, and provides tools for locating statements and related documents.
Last Updated: Jun 18, 2015 URL: Print Guide RSS UpdatesEmail Alerts

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National Environmental Policy Act (NEPA) of 1969

This act required federal agencies to evaluate their activities “significantly affecting the quality of the human environment” by issuing an Environmental Impact Statement (EIS).  EISs are required for projects initiated, financed, or permitted by the federal government, with some exceptions (e.g., the USDA commodity support programs are exempt). 

There are three levels of evaluation, depending on the magnitude of impact on the environment.  Categorical exclusion allows projects meeting predetermined criteria for "no significant environmental impact" to be exempt from detailed evaluation. The second level is Environmental Assessment, or a brief statement of the impacts of an action and alternatives to such an action.  Based on results of the Environmental Assessment, the agency may issue a finding of no significant impact (FONSI), which may describe actions that will be taken to reduce potential impacts. The Environmental Assessment may be skipped if the agency expects in advance the project will not meet the standards for FONSI.  If there is no FONSI at the second level, the project moves to the third level of analysis, which is an Environmental Impact Statement (EIS).  The EIS process has multiple stages:

  1. Draft EIS for public comment
  2. Public hearings on the draft EIS
  3. Final EIS

The EIS is expected toaddress the environmental impact, unavoidable adverse environmental effects, alternatives to the proposal, short-term, long-term, and irreversible effects. Although NEPA mandates that adverse environmental impacts of proposed projects be identified and evaluated, NEPA does not mandate that projects with adverse impacts be stopped, or that impacts be eliminated, an interpretation upheld in 1989 by the U.S. Supreme Court.

NEPA was signed into Law on January 1, 1970 by President Richard Nixon.  The Law also established the Council on Environmental Quality in the executive office of the President of the United States.

Little NEPAs or State Environmental Policy / Environmental Quality Acts

Some states have enacted legislation patterned after NEPA which regulate the actions of state agencies, and also require EISs.  In Illinois, relevant state legislation includes the Illinois Environmental Protection Act.

Sources used

McGuire, Claire L. Emerging State Programs to Protect the Environment: “Little NEPA’s” and Beyond, 5   B.C. Envtl. Aff. L. Rev. 567 (1976), retrieved from on 7 December 2011.

The National Environmnental Policy Act of 1969, as Amended.  Retrieved from on 7 December 2011.

Cover Art
Environmental Encyclopedia - Gale Research Staff
ISBN: 0787654868
Publication Date: 2002-11-01
Donkin Teresa C. National Environmental Policy Act (1969). pp. 939-940 in Environmental Encyclopedia, vol. 2. 3rd ed. Detroit: Gale, 2003. (Available in the UIUC Online Collection).

Cover Art
Environmental Encyclopedia - Deirdre S. Blanchfield
ISBN: 9781414487366
Publication Date: 2011-06-10
Smith, Douglas. Environmental Impact Statement. pp. 590-591 in Environmental Encyclopedia, vol. 1. 4th ed. Detroit: Gale, 2011.
(Available in the UIUC Online Collection).

Guide Author

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Susan Braxton, Head Institute Librarian
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