Ariz. Rev. Stat. § 48-3093
Bonds deposited with or transferred to the United States may call for the payment of such interest not exceeding seven per cent per annum, may be of such denominations and call for the repayment of the principal at such times as may be agreed upon between the board and the secretary of the interior. The contract with the United States may likewise call for the payment of the amount or amounts to be paid by the district to the United States or any part thereof at such times and in such installments and with such interest charges not exceeding seven per cent per annum as may be agreed upon, and for assessment and levy therefor as provided in this article. The board on behalf of the district may accept appointment of the district as fiscal agent of the United States, or authorization of the district by the United States to make collection of monies for or on behalf of the United States in connection with any federal reclamation project, whereupon the district may so act and assume the duties and liabilities incident to such action, and the board may do any and all things required by the rules and regulations established by any department of the United States relating thereto.
A.R.S. § 48-3093