When a formation petition is presented to it, the board of supervisors shall make an order dividing the proposed district into five divisions in such manner as to equalize, as nearly as practicable, the population in the respective divisions. The board of supervisors shall use for this purpose the population as estimated by it from the register of voters used at the last general election.
The divisions of the district shall be numbered first, second, third, fourth, and fifth.
Ca. Water Code § 71160