If revenue bonds were issued pursuant to this chapter to make extensions, additions, or improvements to a utility previously owned by the municipality, then only the net income or revenues from such utility as so extended, added to, or improved can be pledged to the payment of such revenue bonds. The net income from the utility as extended, added to, or improved in such case shall be the excess of revenues or income remaining from time to time after first paying all reasonable and current expenses of maintenance, repairs, replacements, and operation including the interest on any general obligation bonds authorized to construct or acquire or improve such original utility and including the necessary debt service funds required to be provided for the retirement of said bond issues, and including the interest and debt service funds required annually to be paid or set aside on any refunding bonds issued to refund such general bonds issued for the original construction or acquisition or improvement of said utility, so extended, added to, or improved.

Source: SL 1931, ch 194, § 9; SDC 1939, § 45.2409; SL 1949, ch 191, § 4.