32 CFR 651.12 - Determining appropriate level of NEPA analysis.
(a) The flow chart shown in Figure 1 summarizes the process for determining documentation requirements, as follows:
(2) If the proposed action is adequately covered within an existing EA or EIS, a REC is prepared to that effect. The REC should state the applicable EA or EIS title and date, and identify where it may be reviewed ( § 651.19, Figure 3). The REC is then attached to the proponent's record copy of that EA or EIS.
(3) If the proposed action is within the general scope of an existing EA or EIS, but requires additional information, a supplement is prepared, considering the new, modified, or missing information. Existing documents are incorporated by reference and conclusions are published as either a FNSI or NOI to supplement the EIS.
(4) If the proposed action is not covered adequately in any existing EA or EIS, or is of a significantly larger scope than that described in the existing document, an EA is prepared, followed by either a FNSI or NOI to prepare an EIS. Initiation of an EIS may proceed without first preparing an EA, if deemed appropriate by the proponent.
(5) If the proposed action is not within the scope of any existing EA or EIS, then the proponent must begin the preparation of a new EA or EIS, as appropriate.
(b) The proponent of a proposed action may adopt appropriate environmental documents (EAs or EISs) prepared by another agency ( 40 CFR 1500.4(n) and 1506.3). In such cases, the proponent will document their use in a REC FNSI, or ROD.