Wash. Rev. Code § 35.27.030
Whenever a petition is presented to the council of any incorporated town in this state, signed by not less than five electors of such town, setting forth that in the belief of the petitioners, the boundaries of said town are indefinite and uncertain and that on account of such indefiniteness and uncertainty the legality of the taxes levied within such town are in danger of being affected, and setting forth the particular causes or reasons of such alleged indefiniteness or uncertainty, it shall be the duty of the town council to cause the petition to be filed and recorded by the clerk, and to cause a copy of the same to be made and certified by the clerk and the corporate seal of such town to be attached to said certificate, and the mayor of such town shall forthwith present said certified copy of the petition to the board of county commissioners of the county wherein said town is situated, with a written request to be signed by him or her as such mayor that the said board of county commissioners proceed to examine the boundaries of such town or city, and make the same definite and certain.
RCW 35.27.030