Wash. Rev. Code § 35.27.310
The town clerk shall keep a book marked "ordinances" into which he or she shall copy all town ordinances, with his or her certificate annexed to said copy stating that the foregoing ordinance is a true and correct copy of an ordinance of the town, and giving the number and title of the ordinance, and stating that it has been published or posted according to law. Such record copy, with the clerk's certificate, shall be prima facie evidence of the contents of the ordinance and of its passage and publication, and shall be admissible as such in any court or proceeding. Such record shall not be filed in any case but shall be returned to the custody of the clerk. Nothing herein shall be construed to prevent the proof of the passage and publication of ordinances in the usual way. The book of ordinances shall have a general index sufficiently comprehensive to enable a person readily to ascertain matters contained therein.
RCW 35.27.310