Wash. Rev. Code § 85.05.365
Whenever any diking district assessments levied under this act shall remain unpaid for a period of four years from the date when such assessment becomes due and payable, the diking district, which levied said assessment or assessments is hereby empowered and authorized, through its board of commissioners, to make application to the county treasurer of the county in which said diking district is located, for a certificate of delinquency to be issued to it for said delinquent assessments and delinquent interest thereon. And the county treasurer shall issue to said diking district a certificate of delinquency in the same manner and form as to an individual: PROVIDED, HOWEVER, That it shall not be necessary or required for said diking district to pay to said county treasurer any part or portion of said delinquent assessments or interest thereon, but payment of general taxes and interest due upon said general taxes, upon said diked lands will be sufficient payment by said diking district to entitle it to have said certificate of delinquency issued to it. Said diking district shall be empowered to foreclose said certificate or certificates and take title in said district the same as delinquent tax certificates are foreclosed by individuals. After acquiring title to any such lands through such foreclosure proceedings, the diking district, through its commissioners, may offer for sale and sell all, or any part, of such lands, in the same manner as counties are authorized to offer for sale and sell lands acquired by counties through delinquent tax foreclosure sales; and to issue a deed of conveyance therefor to the purchaser, executed by the commissioners of the diking district in behalf of the district, and attested by the clerk of the district. All revenue derived by the diking district from the sale of any such lands shall be first used for the redemption of any bonds and interest outstanding against said diking district which is due and payable, and the remainder thereof, if any, shall be applied to the payment of maintenance warrants, or other indebtedness, of the district, which is due and owing, in the priority deemed best by the board of diking commissioners.
RCW 85.05.365