Wash. Rev. Code § 35.56.100
From and after the equalization of the roll, the several assessments therein shall become a lien upon the real estate described therein and shall remain a lien until paid. The assessment lien shall take precedence of all other liens against such property, except the lien of general taxes. The assessments shall be collected by the same officers and enforced in the same manner as provided by law for the collection and enforcement of local assessments for street improvements. All of the provisions of laws and ordinances relative to the guaranty, enforcement, and collection of local assessments for street improvements, including foreclosure in case of delinquency, shall be applicable to these assessments.
RCW 35.56.100
Assessments for local improvements, collection and foreclosure: Chapters 35.49, 35.50 RCW.