If the electors of the district voting on the question of contracting bonded indebtedness approve the question, the board of the district may issue bonds of the district. [1971 c.513 §§40,41,42; 1981 c.94 §29; 1983 c.347 §25; 1983 c.350 §213; 1995 c.67 §31; 2007 c.783 §135]