Skip to main content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
What They Are and Where to Find Them
The National Environmental Policy Act (42 U.S.C. §4321 et seq) requires federal agencies to assess the environmental impact of all major federal actions significantly affecting the quality of the human environment. An environmental assessment provides evidence for determining whether a proposed agency action would require preparation of an Environmental Impact Statement (EIS) or a finding of no significant impact. If an EIS is required:
- The agency prepares a Draft EIS with a full description of the affected environment, a reasonable range of alternatives, and an analysis of the impacts of each alternative.
- Based on comments on the Draft EIS, the agency prepares a Final EIS and announces its Proposed Action.
- If new environmental impacts not considered in the original EIS are discovered, the agency re-evaluates its initial decision, considers new alternatives to avoid or mitigate the new impacts, and prepares a Supplemental EIS.
Environmental Impact Statements often are available on the websites of the U.S. government agencies that prepared them. But more comprehensive collections are readily available, specifically the EPA Environmental Impact Statement Database and the Northwestern University Transportation Library.