Cal. Pub. Util. Code § 180305

(a)
1. (1) An ordinance and corresponding expenditure plan may be imposed by the authority in a geographic area that comprises less than the total area of the County of Sacramento, including its incorporated cities, subject to the guidelines set forth in subdivision (c).
2. (2) An ordinance and expenditure plan described in paragraph (1) shall be adopted by at least a two-thirds vote of the total membership of the governing board.
3. (3) An ordinance described in paragraph (1) shall be subject to voter approval by the electors in the area to which the tax applies.
(b) Notwithstanding Section 180102, if an ordinance and expenditure plan for a portion of the County of Sacramento are approved pursuant to the process set forth in Chapter 5 (commencing with Section 180200), all subsequent governing board decisions and actions related to implementation of that ordinance and expenditure plan, including an action to amend the expenditure plan pursuant to Section 180207, shall be made by a majority of both of the following:
1. (1) Those members representing the city or cities subject to the ordinance, if any.
2. (2) All members appointed from the board of supervisors.
(c) The governing board shall determine the area to which the tax would apply before the electors vote on the measure. If the tax only applies to a portion of the county, all of the following shall apply:
1. (1) The incorporated area of a city within the county shall be either wholly included or wholly excluded from the area to be taxed.
2. (2) The unincorporated area of the county shall either be wholly included or wholly excluded from the area to be taxed.
3. (3) The area to be taxed shall include at least the incorporated area from two cities or the incorporated area from one city and the unincorporated area from the county.
(d) All revenues derived from the tax shall be expended for the primary benefit of the portion of the county in which the tax is imposed. Expenditures made within that portion of the county are deemed to confer a primary benefit. The authority shall, as part of the expenditure plan, adopt objective eligibility guidelines that define primary benefit. The expenditure plan, including those guidelines, shall be made readily accessible to voters in the manner required by Section 180203. Any revenues derived from the tax shall supplement, and not supplant, other transportation revenues available to the portion of the county to which the tax applies.
(e) Notwithstanding subdivision (b) of Section 180206, an expenditure plan applicable to a portion of the county shall not be adopted until it has received the approval of the board of supervisors and of the city councils representing both a majority of the cities included within the area subject to the tax and a majority of the population residing in the incorporated areas subject to the tax.
(f) Unless otherwise stated in this chapter, the other provisions of this division that apply to an ordinance and expenditure plan shall also apply to an ordinance and expenditure plan applicable to a portion of the county, including the authority to issue bonds pursuant to Chapter 6 (commencing with Section 180250).
(g) The term “district,” as defined and used in Sections 7252, 7261, and 7262 of the Revenue and Taxation Code, shall not be interpreted to preclude the authority from imposing a transactions and use tax in accordance with the Transactions and Use Tax Law (Part 1.6 (commencing with Section 7251) of Division 2 of the Revenue and Taxation Code) in an area that comprises less than the total geographic jurisdiction of the authority, so long as all other applicable requirements of that law are complied with.