Wash. Rev. Code § 36.88.050
In case any such road improvement shall be initiated by petition, such petition shall set forth the nature and territorial extent of such proposed improvement, and the fact that the signers thereof are the owners, according to the records of the county auditor of property to an aggregate amount of a majority of the lineal frontage upon the improvement to be made and of the area within the limits of the assessment district to be created therefor.
Upon the filing of such petition the board shall determine whether the same shall be sufficient and whether the property within the proposed district shall be sufficiently developed and if the board shall find the district to be sufficiently developed and the petition to be sufficient, it shall proceed to adopt a resolution setting forth the nature and territorial extent of the improvement petitioned for, designating the number of the proposed improvement district and describing the boundaries thereof, stating the estimated cost and expense of the improvement and the proportionate amount thereof which will be borne by the property within the proposed district, notifying the owners of property therein to appear at a meeting of the board at the time specified in such resolution, and directing the county road engineer to submit to the board at or prior to the date fixed for such hearing a diagram or print showing thereon the lots, tracts and parcels of land and other property which will be specially benefited thereby and the estimated amount of the cost and expense of such improvement to be borne by each lot, tract or parcel of land or other property, and also designating thereon all property which is being purchased under contract from the county. The resolution of intention shall be published in at least two consecutive issues of a newspaper of general circulation in such county, the date of the first publication to be at least fifteen days prior to the date fixed by such resolution for hearing before the board of county commissioners.
Notice of the adoption of the resolution of intention shall be given each owner or reputed owner of any lot, tract or parcel of land or other property within the proposed improvement district by mailing said notice to the owner or reputed owner of the property as shown on the tax rolls of the county treasurer at the address shown thereon at least fifteen days before the date fixed for the public hearing. The notice shall refer to the resolution of intention and designate the proposed improvement district by number. Said notice shall also set forth the nature of the proposed improvement, the total estimated cost, the proportion of total cost to be borne by assessments, the estimated amount of the cost and expense of such improvement to be borne by the particular lot, tract or parcel, the date and place of the hearing before the board of county commissioners, and the fact that property owners may withdraw their names from the petition or add their names thereto at any time prior to five o'clock p.m. of the day before the hearing.
RCW 36.88.050