(a) Generally. An agency may adopt a draft or final environmental impact statement, environmental assessment, or portion thereof, or categorical exclusion determination, consistent with this section.

(b) Environmental impact statements. An agency may adopt another agency's draft or final environmental impact statement, or portion thereof, provided that the adopting agency conducts an independent review of the statement and concludes that it meets the standards for an adequate statement, pursuant to the regulations in this subchapter and the adopting agency's NEPA procedures.

(1) If the actions covered by the original environmental impact statement and the proposed action are substantially the same, the adopting agency shall republish and file it as a final statement consistent with § 1506.9. If the actions are not substantially the same or the adopting agency determines that the statement may require supplementation consistent with § 1502.9 of this subchapter, the adopting agency shall treat the statement as a draft, supplement or reevaluate it as necessary, and republish and file it, consistent with § 1506.9.

(2) Notwithstanding paragraph (b)(1) of this section, if a cooperating agency does not issue a record of decision jointly or concurrently consistent with § 1505.2 of this subchapter, a cooperating agency may issue a record of decision adopting the environmental impact statement of a lead agency without republication.

(c) Environmental assessments. An agency may adopt another agency's environmental assessment, or portion thereof, if the actions covered by the original environmental assessment and the proposed action are substantially the same, and the assessment meets the standards for an adequate environmental assessment under the regulations in this subchapter and the adopting agency's NEPA procedures. If the actions are not substantially the same or the adopting agency determines that the environmental assessment may require supplementation consistent with § 1501.5(h) of this subchapter, the adopting agency may adopt and supplement or reevaluate the environmental assessment as necessary, issue its finding of no significant impact, and provide notice consistent with § 1501.6 of this subchapter.

(d) Categorical exclusion determinations. An agency may adopt another agency's determination that a categorical exclusion applies to a particular proposed action if the action covered by that determination and the adopting agency's proposed action are substantially the same. In such circumstances, the adopting agency shall:

(1) Document its adoption, including the determination that its proposed action is substantially the same as the action covered by the original categorical exclusion determination and that there are no extraordinary circumstances present that require the preparation of an environmental assessment or environmental impact statement; and

(2) Publish its adoption determination on an agency website or otherwise make it publicly available.

(e) Identification of certain circumstances. The adopting agency shall specify if one of the following circumstances is present:

(1) The agency is adopting an environmental assessment or environmental impact statement that is not final within the agency that prepared it.

(2) The action assessed in the environmental assessment or environmental impact statement is the subject of a referral under part 1504 of this subchapter.

(3) The environmental assessment or environmental impact statement's adequacy is the subject of a judicial action that is not final.