Wash. Rev. Code § 57.16.062
Whether an improvement district is initiated by petition or resolution, the board shall conduct a public hearing at the time and place designated in the notice to property owners. At this hearing the board shall hear objections from any person affected by the formation of the improvement district and may make such changes in the boundaries of the improvement district or such modifications in the plans for the proposed improvement as shall be deemed necessary. The board may not change the boundaries of the improvement district to include property not previously included in it without first passing a new resolution of intention and giving a new notice to property owners in the manner and form and within the time provided in this chapter for the original notice.
After the hearing and the expiration of the ten-day period for filing protests, the commissioners shall have jurisdiction to overrule protests and proceed with any such improvement district initiated by petition or resolution. The jurisdiction of the commissioners to proceed with any improvement district initiated by resolution shall be divested by protests filed with the secretary of the board within ten days after the public hearing, signed by the owners, according to the records of the applicable county auditor, of at least forty percent of the area of land within the proposed improvement district.
If the commissioners find that the improvement district should be formed, they shall by resolution form the improvement district and order the improvement. After execution of the resolution forming the improvement district, the secretary of the board of commissioners shall publish, in a legal publication that serves the area subject to the improvement district, a notice setting forth that a resolution has been passed forming the improvement district and that a lawsuit challenging the jurisdiction or authority of the district to proceed with the improvement and creating the improvement district must be filed, and notice to the district served, within thirty days of the publication of the notice. The notice shall set forth the nature of the appeal. Property owners bringing the appeal shall follow the procedures set forth under RCW 57.16.090. Whenever a resolution forming an improvement district has been adopted, the formation is conclusive in all things upon all parties, and cannot be contested or questioned in any manner in any proceeding whatsoever by any person not commencing a lawsuit in the manner and within the time provided in this section, except for lawsuits made under RCW 57.16.090.
Following an appeal, if it is unsuccessful or if no appeal is made under RCW 57.16.090, the commissioners may proceed with creating the improvement district, provide the improvement and provide the general funds of the district to be applied thereto, adopt detailed plans of the improvement district and declare the estimated cost thereof, acquire all necessary land therefor, pay all damages caused thereby, and commence in the name of the district such eminent domain proceedings as may be necessary to entitle the district to proceed with the improvements. The board shall thereupon proceed with the work and file with the county treasurer of the county in which the real property is located its roll levying special assessments in the amount to be paid by special assessment against the property situated within the improvement district in proportion to the special benefits to be derived by the property therein from the improvements.
RCW 57.16.062
Part headings not law-Effective date-1996 c 230: See notes following RCW 57.02.001.