RCW 85.28.080: Service by publication.

In case any person interested in any of the lands to be crossed by such ditch, as aforesaid, does not reside in the county, or cannot be found therein, or conceals himself or herself so that personal service cannot be had upon him or her, upon proof thereof being made satisfactorily to appear to said court, said summons may be served by publication, in the same manner and with like effect as is done in civil actions: PROVIDED, That no other or different form of summons shall be required for publication than is required for personal service.