La. Stat. tit. 45 § 1144
When any such political subdivision has issued bonds and pledged the revenues of any utility in whole or in part for the payment thereof, it shall impose and collect fees and charges for the products, commodities and services furnished by such utility, including those furnished to the subdivision itself and its various agencies and departments, in amounts and at rates as shall be sufficient at all times to pay the expenses of operating and maintaining the utility; provide a sinking fund sufficient to assure the prompt payment of principal of and interest on the bonds as each falls due; provide such reasonable fund for contingencies as may be required by the resolution authorizing the bonds and provide an adequate depreciation fund for those repairs, extensions and improvements to the utility as may be necessary to assure adequate and efficient service to the public. No board or commission other than the governing body of the political subdivision shall have authority to fix or supervise the making of such fees and charges.
La. R.S. § 45:1144