In addition to the powers granted in RCW 35.30.040 and 35.30.050, any such city, through its council may borrow money or contract indebtedness not exceeding in amount the amount of indebtedness authorized by chapter 39.36 RCW, as now or hereafter amended, for the purpose of supplying the city with water, artificial light, or sewers, when the plants used therefor are owned and controlled by the city, whenever three-fifths of the voters assent thereto at an election to be held for that purpose, according to the provisions of RCW 35.30.050.