Within the boundaries of the Park the Secretary of the Interior (hereinafter referred to as the “Secretary”) is authorized to acquire lands, waters, and other property, or any interest therein, by donation, purchase with donated or appropriated funds, exchange, or otherwise. The Indiana Dunes State Park may be acquired only by donation of the State of Indiana, and the Secretary is hereby directed to negotiate with the State for the acquisition of said park. In exercising his authority to acquire property by exchange for the purposes of this subchapter, the Secretary may accept title to non-Federal property located within the area described in section 460u of this title and convey to the grantor of such property any federally owned property under the jurisdiction of the Secretary which he classifies as suitable for exchange or other disposal within the State of Indiana or Illinois. Properties so exchanged shall be approximately equal in fair market value, as determined by the Secretary who may, in his discretion, base his determination on an independent appraisal obtained by him: Provided, That the Secretary may accept cash from or pay cash to the grantor in such an exchange in order to equalize the values of the properties exchanged. The Secretary is expressly authorized to acquire by donation, purchase with donated or appropriated funds, or exchange, lands or interests therein which are owned for school or educational purposes by a State or a political subdivision thereof.

In exercising his authority to acquire property under subsection (a) of this section, the Secretary may enter into contracts requiring the expenditure, when appropriated, of funds authorized to be appropriated by section 460u–9 of this title, but the liability of the United States under any such contract shall be contingent on the appropriation of funds sufficient to fulfill the obligations thereby incurred.