Cal. Pub. Res. Code § 41721

The countywide siting element shall be approved by the county and by a majority of the cities within the county which contain a majority of the population of the incorporated area of the county except in those counties which have only two cities, in which case the element is subject to approval of the city which contains the majority of the population of the incorporated area of the county. Each city shall act upon the countywide siting element within 90 days after receipt of the siting element. If a city fails to act upon the siting element within 90 days after receiving the siting element, the city shall be deemed to have approved the siting element as submitted.