The Secretary of the Interior is authorized and directed to, and he shall, promulgate charges, or the basis of computation thereof, for electrical energy generated at Hoover Dam beginning , computed to be sufficient, together with other net revenues from the project, to accomplish the following purposes:

((a)) To meet the cost of operation and maintenance, and to provide for replacements, of the project beginning ;

((b)) To repay to the Treasury, with interest, the advances to the Colorado River Dam Fund for the project made prior to , within fifty years from that date (excluding advances allocated to flood control by , which shall be repayable as provided in ), and such advances made on and after , over fifty-year periods;

((c)) To provide $600,000 for each of the years and for the purposes specified in ;

((d)) To provide $500,000 for each of the years and for the purposes specified in ; and

((e)) To provide, by application of the increments to rates specified in section 403(c)(2) of the Colorado River Basin Project Act of 1968, as amended and supplemented [], revenues, from and after , for application to the purposes there specified.