The interest derived from the investments referred to in Section 3.04.010, shall become a part of the funds invested; provided, that the interest derived from the investment of money raised by any bonded indebtedness may be applied at the discretion of such utility service board and upon its direction through the transfer of such interest to the appropriate redemption, bond or interest fund and where meter deposit funds of the municipal water utility are invested so as to earn interest, such portion of the fund representing interest earned may at the discretion of such  utility service board and upon its direction be transferred to and used in the operating or depreciation fund of such utility. (Prior code § 7-2)