The Secretary of the Army is authorized, out of any money available for carrying out the provisions of sections 702a, 702b to 702d, 702e to 702g, 702h, 702i, 702j, 702k, 702l, 702m, and 704 of this title, to purchase from, or to reimburse States or local levee districts for the cost of, any levee rights-of-way or easements for the building of levees in the Mississippi Valley for which the United States was or is under obligation to pay under the provisions of said sections regardless of whether said States or local levee districts have furnished such rights-of-way in the past and regardless of the conditions under which such levee rights-of-way were furnished, or may be furnished in the future: Provided, That after careful investigation the prices are found to be reasonable: And provided further, That payments or reimbursements for levee rights-of-way or easements conveying the privilege of building levees may be made as soon as they have been acquired in conformity with local custom or legal procedure in such matters and to the satisfaction of the Chief of Engineers.