Idaho Code § 43-1322
The board of county commissioners shall also enter an order dividing the new partitioned irrigation district into not less than three (3) nor more than seven (7) divisions of as nearly equal size as practical, which shall be numbered first, second, third, etc. One (1) director, who shall be an elector and resident in the division, shall be elected from each division of the district. Provided however, that in districts of three thousand (3,000) acres or less, the directors may be elected from qualified electors holding title or evidence of title to land in the district and residing in the county where some portion of the district is located. The number of divisions into which the district shall be divided shall be specified in the petition for the partition of the new irrigation district, and if not otherwise specified, shall be three (3). The board shall also enter an order dividing the remaining irrigation district after partition into the same number of divisions of as nearly equal size as practical as existed in the original irrigation district prior to partition.
Idaho Code § 43-1322