California Code, Government Code - GOV § 25826

The board of supervisors may fix and collect a fee from each camper or party of two or more campers for the privilege of using for camping purposes, any land owned by the State, the county, or any land owned by any city or the United States, to the extent that it has jurisdiction over that land for the purpose of levying such a fee.  City-owned land located in the county within which the city is situated and regularly established city-owned camps having sanitary facilities are not subject to the provisions of this section.  Money so collected shall be used solely for sanitary measures in the area and to acquire, construct, reconstruct, alter, enlarge, repair, operate and maintain sanitary facilities therein for campers.

The board of supervisors may enter into a cooperative agreement with the United States or any agency thereof for the purpose of carrying out the provisions of this section.