Wash. Rev. Code § 35.92.265
Each and all of the respective areas of land heretofore organized into local improvement assessment districts for irrigation or domestic water supply purposes including all areas annexed thereto, under the provisions of chapter 112, Laws of 1915, codified as RCW 35.92.220 - 35.92.260, whether organized by or within a city or town other than a city of the first class or by or within a city of the first class, are hereby validated and declared to be duly existing local improvement districts having the respective boundaries set forth in their organization or annexation proceedings as shown by the files in the office of the clerk of the city or town in which formed. All debts, contracts and obligations heretofore made or incurred by or in favor of any such local improvement district and any and all assessments or levies and all other things and proceedings done or taken by the city or town within, and by which such districts were organized, under or in pursuance of such organization, and under or in pursuance of the levy and collection of special assessments by the city or town to pay the whole or any part of the cost and expense or upkeep, repair, reconstruction, operation and maintenance of such local improvement districts and any expense incident to said purposes are hereby declared legal and valid and in full force and effect.
RCW 35.92.265