RCW 84.08.040

The department of revenue shall secure, tabulate, and keep records of valuations of all classes of property throughout the state, and for that purpose, shall have access to all records and files of state offices and departments and county and municipal offices and shall require all public officers and employees whose duties make it possible to ascertain valuations, including valuations of property of public service corporations for rate making purposes to file reports with the department of revenue, giving such information as to such valuation and the source thereof: PROVIDED, That the nature and kind of the tabulations, records of valuation and requirements from public officers, as stated herein, shall be in such form, and cover such valuations, as the department of revenue shall prescribe.