Wash. Rev. Code § 36.22.020
It shall be the duty of the county auditor of each county, within fifteen days after the adjournment of each regular session, to publish a summary of the proceedings of the legislative authority at such term, in any newspaper published in the county or having a general circulation therein, or the auditor may post copies of such proceedings in three of the most public places in the county. The seal of the county commissioners for each county, used by the county auditor as clerk to attest the proceedings of the legislative authority, shall be and remain in the custody of the county auditor, and the auditor is hereby authorized to use such seal in attestation of all official acts, whether as clerk of the legislative authority, as auditor or recorder of deeds; and all certificates, exemplifications of records, or other acts performed as county auditor, certified under the seal of the county commissioners, pursuant to this section, in this state, shall be as valid and legally binding as though attested by a seal of office of the county auditor.
RCW 36.22.020