Finding of No Significant Impact ( FONSI) Law and Legal Definition

A Finding of No Significant Impact (FONSI) presents the reasons why an action will not have a significant effect on the human environment. It must include the Environment Assessment(EA) or summary of the EA that supports the FONSI determination.

A FONSI is issued when environmental analysis and interagency review during the EA process find a project to have no significant impacts on the quality of the environment. The FONSI document is the EA modified to reflect all applicable comments and responses. If it was not done in the EA, the FONSI must include the project sponsor's recommendation or selected alternative. No formal public circulation of the FONSI is required, but the state clearinghouse must be notified of the availability of the FONSI.

The following is an example from a case law, where FONSI was discussed:

In the Ass'n of Citizens to Protect & Pres. the Env’t of the Oak Grove Cmty. v. FAA, 287 Fed. Appx. 764, 766 (11th Cir. Ala. 2008), The plaintiff argued that the district court had subject matter jurisdiction because the FAA's Finding of No Significant Impact (FONSI) with respect to the proposed expansion project at a municipal airport was not a final order. The court held that “FONSI was a final order, and the district court lacked subject matter jurisdiction.”