California Code, Streets and Highways Code - SHC § 35568

In the exercise of its power to operate, manage, and control parking places, the commission may lease any or all parking places to any person for the sole purpose of the operation of public parking facilities on them by such person, or may make a contract with any person for such purpose.  The consideration to be paid by the operator for any lease or under any contract may be a fixed sum or a percentage of gross rentals, fees, or charges collected by the operator, or any other consideration.