The existing waterworks system in its entirety, together with all additions, improvements and extensions thereto that may hereafter be made and the existing wastewater system in its entirety, together with all additions, improvements and extensions that may hereafter be made thereto by the city, are hereby declared to be a combined system, and said combined waterworks and sewerage system shall be maintained and operated as a single utility, and charges or rates shall be established for the use of such combined system, which shall be reasonable and commensurate with the services performed by said combined system, and shall be sufficient to maintain, operate, provide an adequate depreciation fund, and pay the principal and interest on any revenue bonds which may be issued, which by their terms are made payable from the revenues of such combined system. (Ord. 99-1208, 12-6-1999)