When any improvement district revenue producing utility is taken over by the city annexing such improvement district, and no contract is entered into between such improvement district and the city as set out in Kan. Stat. Ann. § 19-2786e, then in that event the board of directors of the improvement district shall have the power to distribute any cash on hand to the subscribers or customers of such revenue producing utility on a pro rata basis based upon the amount of money spent with such improvement district revenue producing utility by each customer during the twelve months period immediately preceding such annexation or acquisition of such revenue producing utility by the city, whichever event occurs later.