Section 153.13 - Application of revenues(1) All revenues derived from any water supply system, water system improvement, sewage disposal system or sewer improvements for either of which a single issue of water revenue bonds or sewer revenue bonds shall be issued, except such part thereof as may be required to pay the cost of maintaining, repairing and operating such system or systems and to provide reserves therefor as may be provided in the resolution authorizing the issuance of such water revenue bonds or sewer revenue bonds, shall be set aside at such regular intervals as may be provided in such resolution and deposited for the credit of the following separate funds for the following purposes:(a) Sinking fund for the payment of interest on and the principal of such water revenue bonds and/or sewer revenue bonds as the same shall become due, necessary charges of paying agents for paying such interest and principal, and any premium upon bonds retired by call or purchase before their maturity or respective maturities, including the accumulation of reserves for such purposes; and(b) A fund for anticipated renewals and replacements and extraordinary repairs.(2) The use and disposition of moneys to the credit of such sinking fund shall be subject to such regulations as may be provided in the resolution authorizing the issuance of the water revenue bonds and/or sewer revenue bonds and, except as may otherwise be provided in such resolution, such sinking fund shall be a fund for the benefit of all bonds without distinction or priority of one over the other.(3) The county commission shall at the close of each fiscal year make or cause to be made a comprehensive report of its operations of the water supply system or systems and sewage disposal system or systems under its control during the preceding fiscal year, including all matters relating to rates, revenues, expenses for maintenance, repair and operation and of replacements and extensions, principal and interest retirements and the status of all funds, and there shall be set forth in such report the budget recommended by the commission for the current fiscal year. A copy of such annual report shall be filed with the clerk of the circuit court in the county and shall be open to the inspection of all interested persons. Any surplus of the gross revenues remaining at the end of any fiscal year after making the required deposits for the credit of the separate funds set forth above, and not appropriated in the budget for the then-current fiscal year, shall be paid into the sinking fund.