California Code, Public Utilities Code - PUC § 142250

(a) A retail transactions and use tax ordinance, applicable in the incorporated and unincorporated territory of the county may be imposed by the authority in accordance with Section 142262 of this code and 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 approve the imposition of the tax at an election which shall be called for that purpose by resolution of the board of supervisors.

(b) The election shall be held in the November 2002 or a subsequent general election.

(c) The tax ordinance shall become operative as set forth in Section 142253.  The tax ordinance shall specify the period, not to exceed 30 years, during which the tax is to be imposed.  The tax may be terminated earlier if the conditions of Sections 142255, 142256, 142257, and 142260 have been met.