California Code, Health and Safety Code - HSC § 40100.7

(a) Section 40100.5 shall not apply to a county district if each city in the county consents, by the adoption of an ordinance or resolution, to the exclusion of the county district from the requirements of Section 40100.5.

(b) Within 60 days from the date of the adoption of an ordinance or resolution by all cities in the county to exclude the county district from the requirements of Section 40100.5, if requested by a majority of the cities in the county, the county district shall establish an advisory committee consisting of a mayor, or a city council member, from each city in the county. The members shall be selected by the city selection committee.

(c) Subdivision (a) shall become inapplicable, and Section 40100.5 shall apply, if, at any time after the condition prescribed in subdivision (a) has been met, a majority of the cities which contain a majority of the population in the incorporated areas of the county, as established by the most recent census data, have adopted resolutions requesting the application of Section 40100.5.