The mayor and city council of any city of the first class may, by resolution, direct and authorize the city treasurer to dispose of the surplus electric light, water, or natural gas distribution system funds, or the funds arising from the sale of electric light and water properties, by the payment of outstanding electric light, water, or natural gas distribution system warrants or bonds then due and by the payment of all current amounts required in any revenue bond ordinance in which any part of the earnings of the electric light or water utility or natural gas distribution system are pledged. The excess, if any, after such payments, may be transferred to the general fund of such city at the conclusion of the fiscal year.