All operation and maintenance charges upon projects existing prior to , shall become due and payable on the date fixed for each project by the Secretary of the Interior, and if such charge is paid on or before the date when due there shall be a discount of 5 per centum of such charge.December 5, 19241924-12-05

All contracts providing for new projects and new divisions of projects approved after , shall require that all operation and maintenance charges shall be payable in advance. In each case where the care, operation, and maintenance of a project or division of a project are transferred to the water users the contract shall require the payment of operation and maintenance charges in advance. Whenever an adjustment of water charges is made under sections 371, 376, 377, 412, 417, 433, 438, 462, 463, 466, 467, 473, 474, 478, 493, 494, 500, 501 and 526 of this title the adjustment contract shall provide that thereafter all operation and maintenance charges shall be payable in advance.11111December 5, 19241924-12-05