California Code, Public Resources Code - PRC § 4129

The board of supervisors of any county may provide by ordinance that the county elects to assume responsibility for the prevention and suppression of all fires on all land in the county, including lands within state responsibility areas when the Director of Forestry and Fire Protection concurs in accordance with criteria adopted by the State Board of Forestry and Fire Protection, but not including lands owned or controlled by the federal government or any agency of the federal government or lands within the exterior boundaries of any city.  After the effective date of the contract referred to in Section 4133, the county shall exercise for the duration of the contract all the duty, power, authority, and responsibility for the prevention and suppression of all fires on all land in the county for which the county is authorized by this section to elect to assume responsibility.