36 C.F.R. § 801.6
The National Historic Preservation Act and the National Environmental Policy Act create separate and distinct responsibilities. The National Historic Preservation Act applies to those aspects of a project which may affect National Register properties and those which are eligible for listing in the National Register. The requirements for the National Environmental Policy Act apply to the effect that the project will have on the human environment. To the extent that the applicant finds it practicable to do so, the requirements of these two statutes should be integrated. Some projects, for reasons other than the effects on historic properties, may require an Environmental Impact Statement (EIS) subject to the time requirements for a draft and final EIS, in which case the applicant may choose to separately relate to the State Historic Preservation Officer, the Department of the Interior, and the Council for purposes of section 110(c) of the HCDA of 1980. In that event, information in the draft EIS should indicate that compliance with section 106 and these regulations is underway and the final EIS should reflect the results of this process. Applicants are directed to 36 CFR 800.9 , which describes in detail the manner in which the requirements of these two acts should be integrated and applies to all UDAG applicants under these regulations.
In those instances in which an Environmental Impact Statement will be prepared for the project, the applicant should consider phasing compliance with these procedures and the preparation of the Statement.
36 C.F.R. §801.6