There is authorized to be appropriated to the Department of the Interior $600,000, through the end of fiscal year 1990, in addition to any other funds now available to the Department to discharge its duties to implement sections 1600b to 1600k of this title and section 4029 of title 42: Provided, That by mutual agreement, such funds shall be made available to the Federal Emergency Management Agency to discharge its duties under section 4029 of title 42: Provided further, That the provisions of sections 1600d and 1600e of this title shall not be affected by this section: And Provided further, in addition, Indian tribes may be eligible under Public Law 93–638 [25 U.S.C. 5301 et seq.] to contract for studies of Indian lands required under the provisions of this chapter.