Cal. Wat. Code § 41028
The final election roll shall be used for all purposes relating to elections, until subsequently modified in accordance with the procedures set forth in this chapter, or until the board elects at least 84 days prior to a general election to use the most recent county assessment roll. The board may at any time cause a revised preliminary election roll to be prepared in accordance with Section 41026. Upon written petition filed by the holders of title to land with at least 10 percent of the votes based on the last finalized election roll, at least 150 days before any general or special election, the board shall prepare a new preliminary election roll and follow the procedures provided for in Section 41027. At least 84 days prior to an election, the district shall update the names listed as the holder of title to land of each parcel on the election roll and may rely on the most recent county assessment roll for determining ownership.
Ca. Water Code § 41028