California Code, Public Utilities Code - PUC § 101265

(a) The district may cause to be levied and collected taxes for any lawful purpose, subject to a maximum limit of fifteen cents ($0.15) per one hundred dollars ($100) of assessed valuation.

(b) The maximum limit may be increased to twenty-five cents ($0.25) per one hundred dollars ($100) of assessed valuation, if approval is first obtained from the city council of each city lying entirely within the boundaries of the district and the board of supervisors.

(c) The maximum limit may be increased above the maximum limits as specified in subdivisions (a) and (b), if such a maximum limit is first approved by the majority of the voters voting at any general or special election on the proposition establishing such a maximum limit.