24 C.F.R. § 58.52
The responsible entity may adopt a draft or final EIS prepared by another agency provided that the EIS was prepared in accordance with 40 CFR parts 1500 through 1508. If the responsible entity adopts an EIS prepared by another agency, the procedure in 40 CFR 1506.3 shall be followed. An adopted EIS may have to be revised and modified to adapt it to the particular environmental conditions and circumstances of the project if these are different from the project reviewed in the EIS. In such cases the responsible entity must prepare, circulate, and file a supplemental draft EIS in the manner prescribed in § 58.60(d) and otherwise comply with the clearance and time requirements of the EIS process, except that scoping requirements under 40 CFR 1501.7 shall not apply. The agency that prepared the original EIS should be informed that the responsible entity intends to amend and adopt the EIS. The responsible entity may adopt an EIS when it acts as a cooperating agency in its preparation under 40 CFR 1506.3 . The responsible entity is not required to re-circulate or file the EIS, but must complete the clearance process for the RROF. The decision to adopt an EIS shall be made a part of the project ERR.
24 C.F.R. §58.52