California Code, Water Code - WAT § 75971

If, on the date set by the board for the final action on the annexation petition, there is presented to the board of the annexing district written protests signed by 3 percent, or 1,000, or more, of the electors of the annexing district, the board shall call and provide for an election at which there shall be submitted to the electors of the annexing district the question as to whether or not the petitioning district shall be annexed upon the terms set forth in the annexation petition.

If sufficient protests are not presented the board may adopt an order annexing the petitioning district, or may, in its discretion, submit the question to the electors of the district as though sufficient protests had been presented.