National Environmental Policy Act (NEPA)

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National Environmental Policy Act or NEPA is a procedural law that requires that federal agencies complete a public analysis before making a decision that has "effects on the human environment". The level of analysis is based on a determination of "significance", were actions with a more significant effect requiring more detailed assessment. NEPA is a common basis for legal challenge to a federal action, under the claim that the action agency didn't sufficiently evaluate known effects, and is thus making an uninformed decision. NEPA doesn't regulate agency actions, but rather requires informed and disclosed decision making and consideration of alternatives.

NEPA information pages by federal agency:


  • NEPA is administered through at least three layers of policy.
  • Only actions with a Federal Nexus require NEPA analysis.
  • NEPA analysis begins with an Environmental Assessment (EA) which determines if an action is significant or not. If the EA reports a "Finding of No Significant Impact" *(a FONSI) then the decision may be made, and the agency obligation is complete. If the action is determined to have a significant impact, then a Environmental Impact Statement must be completed, requiring more steps and more public disclosure.
  • The "test of significance" involves considering 10 or 11 areas of concern around effects on the human environment.
  • Programmatic mechanisms are commonly used where an agency makes the same kind of decision over and over again. In a programmatic analysis a decision situation is analyzed, and a determination of significance is made, often considering the scale or scope of an action. Then when a decision is made, that individual decision is compared to the programmatic analysis. If the individual decision does not exceed the situation considered in the programmatic analysis, it is said to be "consistent with" the programmatic analysis, and the action is taken without public process, with a "letter to the file."
  • There is a tension within agencies between avoiding spending lots of labor on NEPA analysis, while still meeting NEPA requirements.
  • Agency-level NEPA implementation may shift between administrations, either reducing or increasing staff-level requirements and procedures. The level within an agency where a NEPA determination may be made (the "decision authority") may also change.