A statement that the National Environmental Policy Act (NEPA) requires federal agencies to file before taking an action "significantly affecting the quality of the human environment." An EIS describes a proposed agency action's negative and positive effects on the environment and offers alternatives. An EIS's stated purpose is to help collect relevant private and public information in a single place to help decision makers remain fully informed. Several states require their agencies to file an EIS under state-specific "little NEPA" statutes.

For more information, see Practice Note, Environmental Law: Overview.