Wash. Rev. Code § 35.56.090
Any person who has made objections to the assessment as equalized, shall have the right to appeal from the equalization as made by the city council or commission to the superior court of the county. The appeal shall be made by filing a written notice of appeal with the city clerk within ten days after the equalization of the assessments by the council or commission. The notice of appeal shall describe the property and the objections of such appellant to such assessment.
The appellant shall also file with the clerk of the superior court within ten days from the time of taking the appeal a copy of the notice of appeal together with a copy of the assessment roll and proceedings thereon, certified by the city clerk and a bond to the city conditioned to pay all costs that may be awarded against appellant in such sum not less than two hundred dollars, and with such security as shall be approved by the clerk of the court.
The case shall be docketed by the clerk of the court in the name of the person taking the appeal as plaintiff, and the city as defendant. The cause shall then be at issue and shall be tried immediately by the court as in the case of equitable causes; no further pleadings shall be necessary. The judgment of the court shall be either to confirm, modify or annul the assessment insofar as the same affects the property of the appellant. Appellate review of the superior court's decision may be sought as in other causes.
RCW 35.56.090
Severability-1988 c 202: See note following RCW 2.24.050.