Cal. PRC § 5080.19

(a) In order to assure the best possible return from concessions, the department shall periodically survey, and obtain advice and information from professional property managers regarding, the commercial rental market for public and private properties in areas where concessions exist or are expected to be authorized and compile information therefrom, and shall use that information for the purposes of Section 5080.06 and subdivision (b) of this section.

(b) Rent and other returns received from concessions shall reflect current commercial rental market conditions, except in instances when the director has determined that a particular service or facility needs to be furnished to the public and that service or facility cannot be furnished except at less than a fair market value rate of return to the state.

(c) Rental terms of concessions that operate seasonally shall reflect the seasonal characteristics of those concessions.

(d) Rent shall be paid on the basis of the higher of a flat monthly amount or a percentage of gross sales, except in those instances in which part of the compensation paid by a concessionaire consists of the value assigned to services performed by the concessionaire on behalf of the department and those services are of a type normally performed by departmental personnel.