40 C.F.R. § 1506.3 : Protection of Environment — COUNCIL ON ENVIRONMENTAL QUALITY — NATIONAL ENVIRONMENTAL POLICY ACT IMPLEMENTING REGULATIONS — OTHER REQUIREMENTS OF NEPA — Adoption

(a) Generally. An agency may adopt a Federal draft or final environmental impact statement, environmental assessment, or portion thereof, or categorical exclusion determination provided that the statement, assessment, portion thereof, or determination meets the standards for an adequate statement, assessment, or determination under the regulations in this subchapter.
(b) Environmental impact statements.
(1) If the actions covered by the original environmental impact statement and the proposed action are substantially the same, the adopting agency shall republish it as a final statement consistent with § 1506.10. If the actions are not substantially the same, the adopting agency shall treat the statement as a draft and republish it, consistent with § 1506.10.
(2) Notwithstanding paragraph (b)(1) of this section, a cooperating agency may adopt in its record of decision without republishing the environmental impact statement of a lead agency when, after an independent review of the statement, the cooperating agency concludes that its comments and suggestions have been satisfied.
(c) Environmental assessments. If the actions covered by the original environmental assessment and the proposed action are substantially the same, the adopting agency may adopt the environmental assessment in its finding of no significant impact and provide notice consistent with § 1501.6 of this chapter.
(d) Categorical exclusions. An agency may adopt another agency's determination that a categorical exclusion applies to a proposed action if the action covered by the original categorical exclusion determination and the adopting agency's proposed action are substantially the same. The agency shall document the adoption.
(e) Identification of certain circumstances. The adopting agency shall specify if one of the following circumstances is present:
(1) The agency is adopting an assessment or statement that is not final within the agency that prepared it.
(2) The action assessed in the assessment or statement is the subject of a referral under part 1504 of this chapter.
(3) The assessment or statement's adequacy is the subject of a judicial action that is not final.

40 C.F.R. §1506.3

85 FR 43370, 9/14/2020