Ariz. Rev. Stat. § 48-152
All proceeds received from the sale of the bonds, all fees, rents, tolls or other charges received by the district from any undertaking financed by the bonds, and all monies received from any source in connection therewith shall be paid to the district treasurer, or such depository as may be designated by the board of directors. The district treasurer or depository shall not commingle any money received under the terms of this article with any other monies, but the monies received under this article shall be deposited in a separate fund with the district treasurer or depository in the name of the district. The board of directors may by resolution provide that all deposits of such proceeds, fees, rents, tolls or other charges, and the monies received under this article, shall be secured by obligations of the United States or of this state of a market value equal at all times to the amount of the deposits, and all banks and trust companies are authorized to give such security for the deposits.
A.R.S. § 48-152