Cal. Health and Safety Code § 25149.1

(a) No city, county, or city and county, whether general law or chartered, which has issued a conditional use permit for a hazardous waste facility shall thereafter adopt an ordinance, rule, or regulation, or issue or amend any permit, which adoption, issuance, or amendment imposes additional restrictions on the types of hazardous waste which previously have been authorized to be accepted for disposal, treatment, or storage under the terms and conditions of any previously issued conditional use permit for that facility. (b) This section does not apply to a modification or revocation of a use permit which is necessary to enforce the terms and conditions of the use permit, or to abate a nuisance, or to prevent an immediate threat to the public health or safety. Modification or revocation of an existing use permit may only occur after the city, county, or city and county orders the facility operator to abate the nuisance or correct the threat to the public health or safety, the facility operator has been afforded adequate opportunity to abate the nuisance or correct the threat to the public health or safety, and the facility operator has failed to comply with the enforcement or abatement order. (c) This section does not apply to an existing hazardous waste facility, as defined in Section 25148.