(1) Except as otherwise provided in subsections (2) and (3) of this section, the county board shall make an order dividing the irrigation district into three divisions as nearly equal in size as may be practicable, which shall be numbered first, second, and third, and one director shall be elected for each division.

(2) After formation of an irrigation district, in districts comprising over twenty-five thousand acres, the electors thereof may determine by a majority vote to increase the number of directors in any multiple of three up to nine, whereupon the district may be divided into as many divisions as there are directors agreed upon. One-third of the number of directors so elected shall retire each year, and the order of their retirement may be agreed upon by the directors of the district, and successors shall be elected in the manner provided for the election of directors in other districts. The election for the increased number of directors shall be called upon a petition signed by twenty percent of the electors of the district presented to the then board of directors.

(3) After formation of an irrigation district, in districts comprising less than fifteen thousand acres, upon the majority vote of the board of directors, the question of whether the divisions in the irrigation district may be eliminated and the subsequent election of the directors conducted on an at-large basis may be submitted to the electors. The divisions in the district shall be eliminated and the directors elected on an at-large basis only upon the affirmative vote of two-thirds of the electors of the district.