Funds from the endowment referred to in subsection (a) shall be expended exclusively as the Woodstock Foundation, or its successors and assigns, in consultation with the Secretary, may designate for the preservation and maintenance of the Marsh-Billings-Rockefeller Mansion and its immediate surrounding property.

No expenditure shall be made pursuant to this section unless the Secretary determines that such expenditure is consistent with the purposes of this subchapter.