If the cost of the public utility works so far exceeds the revenues of the district derived from the operation of its public utilities, in addition to the other necessary expenses of the district, that it is necessary to incur a district bonded indebtedness, the board, at a regular meeting held within 60 days after the filing of the plans and estimates of cost and expected revenue, by ordinance shall submit the proposition as to whether bonded indebtedness shall be incurred for acquisition of the public utility works, to the electors of the district at a general district election or at a special district election called for the purpose.