Wash. Rev. Code § 90.64.200
The director of agriculture may enter at all reasonable times in or upon dairy farms for the purpose of inspecting and investigating conditions relating to the pollution of any waters of the state.
If the director of agriculture or the director's duly appointed agent is denied access to a dairy farm, he or she may apply to a court of competent jurisdiction for a search warrant authorizing access to the property and facilities at a reasonable time for purposes of conducting tests and inspections, taking samples, and examining records. To show that access is denied, the director of agriculture shall file with the court an affidavit or declarations containing a description of his or her attempts to notify and locate the owner or the owner's agent and to secure consent. Upon application, the court may issue a search warrant for the purposes requested.
RCW 90.64.200