Provision shall be made by the governing body of such city for the payment of said bonds, by fixing rates and charges for the use of and the services to be rendered by such property and facilities, which rates and charges so fixed shall be sufficient to pay all expenses of the city in connection therewith and cover the cost of operation and repairs, pay all interest charges upon all indebtedness created for the purpose of improving, constructing, reconstructing, repairing or improving of such public levee and the improvements and facilities thereon for which such revenue bonds were issued to so improve, construct, reconstruct or repair and to provide a sinking fund sufficient to pay off such indebtedness at maturity.