Wash. Rev. Code § 86.09.496
On or before the thirty-first day of December of each year, the county treasurer of the county in which the land is located shall cause to be posted the delinquency list which must contain the names of persons to whom the property is assessed and a description of the property delinquent and the amount of the assessment and costs due, opposite each name and description.
He or she must append to and post with the delinquency list a notice that unless the assessments delinquent, together with costs and accrued interest, are paid, the real property upon which such assessments are a lien will be sold at public auction. The said notice and delinquent list shall be posted at least twenty days prior to the time of sale. Concurrent as nearly as possible with the date of the posting aforesaid, the said county treasurer shall publish the location of the place where said notice is posted and in connection therewith a notice that unless delinquent assessments together with costs and accrued interest are paid, the real property upon which such assessments are a lien will be sold at public auction. Such notice must be published once a week for three successive weeks in a newspaper of general circulation published in the county within which the land is located; but said notice of publication need not comprise the delinquent list where the same is posted as herein provided. Both notices must designate the time and place of sale. The time of sale must not be less than twenty-one nor more than twenty-eight days from the date of posting and from the date of the first publication of the notice thereof, and the place must be at some point designated by the treasurer.
RCW 86.09.496