Wash. Rev. Code § 58.04.011
Any surveyor authorized by the court and the surveyor's employees may, without liability for trespass, enter upon any land or waters and remain there while performing the duties as required in RCW 58.04.001 through 58.04.007 and this section. The persons named in this section may, without liability for trespass, investigate, construct, or place a monument or reference monuments for the position of any land boundary mark or general land office corner or mark and subdivisional corners thereof. Persons entering lands under the authority of RCW 58.04.001 through 58.04.007 and this section must exercise due care not to damage property while on land or waters performing their duties, and are liable for property damage, if any, caused by their negligence or willful misconduct. Where practical, the persons named in this section must announce and identify themselves and their intention before entering upon private property in the performance of their duties.
RCW 58.04.011