The governing body of a local government issuing revenue refunding bonds pursuant to this part and part 1 of this chapter shall prescribe and collect reasonable rates, fees or charges for the services, facilities and commodities of the enterprise, and shall revise such rates, fees or charges from time to time whenever necessary so that the enterprise shall be and always remain self-supporting. The rates, fees or charges prescribed shall be at least sufficient to produce revenue to:
(1) Provide for all expenses of operation and maintenance of the enterprise, including reasonable reserves therefor; and
(2) Pay when due all bonds and interest thereon, for the payment of which such revenue is or shall have been pledged, charged or otherwise encumbered, including reasonable reserves therefor.