After a bond indebtedness has been authorized by the qualified electors of a district, the board of directors, instead of issuing bonds in the manner provided in this article, may enter into an obligation or contract with the United States for the construction or purchase of the necessary works under the provisions of an act of Congress entitled "An act appropriating the receipts from the sale and disposal of public lands in certain states and territories for the construction of irrigation works for the reclamation of arid lands," approved June 17, 1902, and all amendments thereto, or any other law of the United States enacted to aid the reclamation of arid lands, and the rules and regulations thereunder, or the board of directors may issue bonds for a portion of the amount of the indebtedness authorized by the bond election and enter into an obligation or contract with the United States to the extent of the remainder of such amount, and may obligate and bind the district for the payments to be made thereunder in the manner and at the time and places provided by the act of Congress and by the rules and regulations thereunder.