Public Utilities Code § 28750.6

28750.6.

If, at any time between each federal decennial census, the district annexes territory, pursuant to Chapter 9 (commencing with Section 29500), the board, within 90 days after completion of the annexation proceedings, shall, by resolution, adjust the boundaries of the election districts so that the district shall be as nearly equal in population as practicable, considering the factors specified in Section 28745.6.