Wash. Rev. Code § 47.52.139
Upon receipt of the findings and order adopting a plan, the county, city, or town may notify the department of transportation of its approval of such plan in writing, in which event such plan shall be final.
In the event that a county, city, or town does not approve the plan, the county, city, or town shall file its disapproval in writing with the secretary of transportation within thirty days after the mailing thereof to such mayor or county commissioner. Along with the written disapproval shall be filed a written request for a hearing before a board of review, hereinafter referred to as the board. The request for hearing shall set forth the portions of the plan of the department to which the county, city, or town objects, and shall include every issue to be considered by the board. The hearing before a board of review shall be governed by RCW 47.52.150 through 47.52.190, as now or hereafter amended.
RCW 47.52.139