Wash. Rev. Code § 88.32.100
The final assessment shall be a lien, paramount to all other liens, except liens for taxes and other special assessments, upon the property assessed, from the time the assessment roll shall be approved by said board of county commissioners and placed in the hands of the county treasurer, as collector. After said roll shall have been delivered to the county treasurer for collection, he or she shall proceed to collect the same, in the manner as other taxes are collected: PROVIDED, That such treasurer shall give at least ten days' notice in the official newspaper (and shall mail a copy of such notice to the owner of the property assessed, when the post office address of such owner is known, but failure to mail such notice shall not be fatal when publication thereof is made), that such roll has been certified to him or her for collection, and that unless payment be made within thirty days from the date of such notice, that the sum charged against each lot or parcel of land shall be paid in not more than ten equal annual payments, with interest upon the whole sum so charged at a rate not to exceed seven percent per annum. Said interest shall be paid semiannually, and the county treasurer shall proceed to collect the amount due each year by the publication of notice as hereinabove provided.
RCW 88.32.100