California Code, Health and Safety Code - HSC § 14831

The board of supervisors of a county that has a population of 400,000 or more on or after January 1, 1985, may, by ordinance, regulate the formation and continued existence of fire companies. The board of supervisors may authorize the formation of any new fire company within the county where it determines that a reasonable level of fire services does not already exist and where the provision of supplemental or competing fire services by any other entity would not result in the mismanagement of emergencies or in confusion to those seeking aid.

The board of supervisors may order that any fire companies formed pursuant to this part may continue to exist upon making the determination that the circumstances stated above exist. The board of supervisors may, by ordinance, establish additional regulations and criteria for the establishment and ongoing operation of fire companies organized pursuant to this part.