California Code, Government Code - GOV § 67970

(a) A retail transactions and use tax ordinance applicable within the boundaries of the authority may be imposed by the authority in accordance with this chapter and Part 1.6 (commencing with Section 7251) of Division 2 of the Revenue and Taxation Code, if all of the following occur:

(b) The retail transactions and use tax shall remain in effect for not longer than 30 years, or any lesser period of time specified in the tax ordinance.  The tax may be continued in effect, or reimposed, by a tax ordinance adopted by a majority vote of the authority, if the reimposition of the tax is approved by a two-thirds vote of the voters.