Wash. Rev. Code § 85.05.540
Where tide or other unsurveyed lands are reclaimed by a diking district and the owner of said lands shall desire to plat the same into lots, tracts or subdivisions, such plat shall specify and acknowledge the total benefits then a charge against each lot, tract or subdivision in said plat. Before a plat shall be approved or filed, same shall be submitted to the board of dike commissioners for their consideration. In case the owner and such board cannot agree as to the adjudged maximum benefits to be charged as the lien of the district and acknowledged to be such against each lot, tract or subdivision in such plat, any interested party may cause an action to be brought in the superior court of the county to have the just amount determined, and the decree of the court in such cause shall fix the amount of such lien and the same shall be conclusive and binding. In fixing the amount to be charged against the several lots, tracts and subdivisions, the adjudged benefits per acre, allowing credits for the benefits levied and paid at said time, shall be taken as the basis for determining the sum to be charged. The amount of adjudged benefits against property dedicated to the public for roads and highways in such plat shall be charged back against the abutting subdivisions and tracts in a just and equitable manner. All diking district assessments levied against the lands included in the plat shall be paid in full at the time said plat is approved. When approved such plat shall be filed with the county auditor of the county. Thereafter the lands within said plat shall be conveyed, assessed and taxed with reference to said plat.
RCW 85.05.540