California Code, Government Code - GOV § 23210

(a) Not later than 30 days after the conclusion of the hearing, if a proposed boundary change has not been abandoned pursuant to Section 23209, the board of supervisors of each affected county shall adopt substantially similar ordinances approving the proposed boundary change.

(b) The ordinances shall declare that the proposal meets each of the conditions of Section 23202.  The ordinances shall specify any terms and conditions to which the boundary change is subject, including, but not limited to, a division of any county debt or property.  In addition, the ordinances shall state the effective date of the boundary change.  The ordinances shall be adopted by majority vote of each board of supervisors.

(c) If, in the case of inhabited territory, more than 25 percent, but not more than 50 percent, of the resident-voters in the affected territory have filed and have not withdrawn written protests before the conclusion of the hearing, the board of supervisors of each affected county shall provide that their ordinances are subject to confirmation by the voters in the affected territory.  The election shall be conducted in accordance with the procedures of the Elections Code relating to county referendum elections regarding the qualifications of voters, the manner of voting, the form of the ballot, the duties of precinct and election officers, the canvassing of returns, and all other particulars.

(d) After the canvass of the returns of any election on the proposed boundary change conducted pursuant to subdivision (c), the board of supervisors of the conducting county shall declare by resolution the total number of votes cast in the election and the number of votes cast for and against the proposed boundary change.  If a majority of the votes were cast against the proposed boundary change, then the ordinances adopted pursuant to subdivision (a) shall not take effect.  If a majority of the votes were cast in favor of the proposed boundary change, then the ordinances shall take effect, as provided.