Wash. Rev. Code § 85.24.140
Any person who feels aggrieved by the final assessment made against any lot, block, or parcel of land owned by him or her, may appeal therefrom to the superior court of the county in which the land is situated. Such appeal shall be taken within the time and substantially in the manner prescribed by the laws of this state for appeals from justices' courts. All notice of appeal shall be filed with the said board, and shall be served upon the prosecuting attorney of the county in which the action is brought. The secretary of the board shall, at appellant's expense, certify to the superior court so much of the record as appellant may request, and the cause shall be tried in the superior court de novo.
Any person aggrieved by any final order or judgment made by the superior court concerning any assessment authorized by this chapter, may seek appellate review of the order or judgment as in other civil cases.
RCW 85.24.140
Severability-1988 c 202: See note following RCW 2.24.050.