RCW 36.54.020

The board of county commissioners of any county may, severally or jointly with any other county, city or town, or the state of Washington, or any other state or any county, city or town of any other state, construct or acquire by purchase, gift, or condemnation, and operate any ferry necessary for continuation or connection of any county road across any navigable water. The procedure with respect to the exercise of the power herein granted shall be the same as provided for the joint erection or acquisition of bridges, trestles, or other structures. Any such ferries may be operated as free ferries or as toll ferries under the provisions of law of this state relating thereto.