16 U.S.C. § 691c

The Secretary of the Interior may do all things and make all expenditures necessary to secure the safe title in the United States to the areas which may be acquired under section 691 of this title , including purchase of options when deemed necessary by the Secretary of the Interior, and expenses incident to the location, examination, and survey of such areas and the acquisition of title thereto, but no payment shall be made for any such areas until the title thereto shall be satisfactory to the Attorney General. That the acquisition of such areas by the United States shall in no case be defeated because of rights-of-way, easements, and reservations which from their nature will in the opinion of the Secretary of the Interior in no manner interfere with the use of the areas so encumbered for the purpose of section 691a of this title .