Washington Revised Code Title 58. Boundaries and Plats § 58.04.007. Affected landowners may resolve dispute over location of a point or line--Procedures

(1) If all of the affected landowners agree to a description and marking of a point or line determining a boundary, they shall document the agreement in a written instrument, using appropriate legal descriptions and including a survey map, filed in accordance with chapter 58.09 RCW. The written instrument shall be signed and acknowledged by each party in the manner required for a conveyance of real property. The agreement is binding upon the parties, their successors, assigns, heirs and devisees and runs with the land. The agreement shall be recorded with the real estate records in the county or counties in which the affected parcels of real estate or any portion of them is located;

(2) If all of the affected landowners cannot agree to a point or line determining the boundary between two or more parcels of real estate, any one of them may bring suit for determination as provided in RCW 58.04.020.