The provisions of Section 2 B [73-18-2 B NMSA 1978] and Section 3 to Section 25 N.M. Stat. Ann. § 73-18-3 to 73-18-24, inclusive, of this act shall apply only to conservancy districts heretofore or hereafter organized or existing under the Conservancy Act and which heretofore or hereafter shall have entered into a contract with the United States under the reclamation law.