Cal. Pub. Util. Code § 70223

A retail transactions and use tax ordinance may be adopted by the board in accordance with Part 1.6 (commencing with Section 7251) of Division 2 of the Revenue and Taxation Code, if two-thirds of the electors voting on the measure vote to authorize its enactment at a special election called for that purpose by the board. Notwithstanding Sections 7261 and 7262 of the Revenue and Taxation Code, the retail transactions and use tax ordinance shall provide for imposition of a tax at a rate of one-half of 1 percent or at a lower rate specified in the ordinance.