Wash. Rev. Code § 91.08.150
In case the land or other property sought to be taken or damaged is state land, the summons and copy of petition shall be served upon the commissioner of public lands; if it is county land it shall be served upon the county auditor, and if school land, upon the county auditor and the chair of the board of directors of the school district. Service upon other parties defendant, public or private, shall be made in the same manner as is or shall be provided by law for service of summons in other civil actions. If the state is made a defendant the attorney general shall represent it. If the county is a defendant the court shall appoint an attorney to represent it at all stages of the proceedings, and may allow him or her compensation for his or her services as costs of the proceeding.
RCW 91.08.150
Civil procedure-Commencement of actions: Chapter 4.28 RCW.
Department of natural resources to exercise powers and duties-Indemnification of private parties: RCW 43.30.411.
Eminent domain where state land is involved: RCW 8.28.010.
Public lands treated as private lands: RCW 91.08.570.