In carrying out the provisions of the said reclamation Act, and Acts amendatory thereof or supplementary thereto, the Secretary of the Interior is authorized, upon such terms as may be agreed upon, to cooperate with irrigation districts, water-users' associations, corporations, entrymen, or water users for the construction or use of such reservoirs, canals, or ditches as may be advantageously used by the Government and irrigation districts, water-users' associations, corporations, entrymen, or water users for impounding, delivering, and carrying water for irrigation purposes: Provided, That the title to and management of the works so constructed shall be subject to the provisions of section 498 of this title: Provided further, That water shall not be furnished from any such reservoir or delivered through any such canal or ditch to any one landowner in excess of an amount sufficient to irrigate one hundred and sixty acres: Provided, That nothing contained in sections 523 to 525 of this title shall be held or construed as enlarging or attempting to enlarge the right of the United States, under existing law, to control the waters of any stream in any State.