Cal. Public Resources Code § 41721.5

(a) Any amendments to 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 amendment is subject to approval of the city which contains the majority of the population of the incorporated area of the county. (b) Any person or public agency proposing the development of a solid waste disposal or transformation facility may initiate an amendment to the countywide siting element by submitting a site identification and description to the county board of supervisors. (c) The county shall submit the site identification and description to the cities within the county within 20 days after the site identification and description is submitted to the county board of supervisors. Each city shall act upon the proposed amendment within 90 days after receipt of the proposed amendment. If a city fails to act upon the proposed amendment within 90 days after receiving the amendment, the city shall be deemed to have approved the proposed amendment as submitted. (d) If the county or a city disapproves the proposed amendment, the county or city shall mail notice of its decision by first-class mail to the person or public agency proposing the amendment within 10 days of the disapproval, stating its reasons for the disapproval. (e) No county or city shall disapprove a proposed amendment unless it determines, based on substantial evidence in the record, that the amendment would cause one or more significant adverse impacts within its boundaries from the proposed project. (f) Within 45 days after the date of disapproval by the county or a city of a proposed amendment, or a decision by the board not to concur in the issuance, modification, or revision of a solid waste facilities permit pursuant to Section 44009, any person may file with the superior court a writ of mandate for review of the disapproval or the decision. The evidence before the court shall consist of the record before the county or city which disapproved the proposed amendment or the record before the board in its determination not to concur in issuance, modification, or revision of the solid waste facilities permit. Section 1094.5 of the Code of Civil Procedure shall govern the proceedings conducted pursuant to this subdivision.