Cal. Gov. Code § 6581
A joint county park board may designate the sheriff of any one of the counties as the park sheriff. The park sheriff shall be designated by a contract made by and between the board of supervisors of the county of the park sheriff and the joint county park board. The contract shall provide for the amount to be paid the county of the park sheriff for the services to be rendered by the park sheriff at the park, and the method and time of termination of the contract. The contract shall further provide that an amount equal to the funds received by the county of the park sheriff from the joint county park board during the term of the contract shall be expended during the term of the contract for the purposes of providing services at the park through the park sheriff. The contract shall not take effect until it has been executed by the parties to it and, in addition, has been approved in writing by the park sheriff and by duly adopted resolutions of each of the boards of supervisors of the counties.
Ca. Gov. Code § 6581