Wash. Rev. Code § 47.68.130
In operating an airport or air navigation facility owned or controlled by the state, the department may enter into contracts, leases, and other arrangements for a term not exceeding twenty-five years with any persons. The department may grant the privilege of using or improving the airport or air navigation facility or any portion or facility thereof or space therein for commercial purposes, confer the privilege of supplying goods, commodities, things, services, or facilities at the airport or air navigation facility, or make available services to be furnished by the department or its agents at the airport or air navigation facility. In each case the department may establish the terms and conditions and fix the charges, rentals, or fees for the privileges or services, which shall be reasonable and uniform for the same class of privilege or service and shall be established with due regard to the property and improvements used and the cost of operation to the state. In no case shall the public be deprived of its rightful, equal, and uniform use of the airport, air navigation facility, or portion or facility thereof.
RCW 47.68.130