Wash. Rev. Code § 85.38.110
A list of presumed eligible voters shall be prepared and maintained by each special district. The list shall include the assessor's tax number for each lot or parcel in the district, the name or the names of the owners of such lots and parcels and their mailing address, the extent of the ownership interest of such persons, and if such persons are natural persons, whether they are known to be registered voters in the state of Washington. Whenever such a list is prepared, the district shall attempt to notify each owner of the requirements necessary to establish voting authority to vote. Whenever lots or parcels in the district are sold, the district shall attempt to notify the purchasers of the requirements necessary to establish voting authority. Each special district shall provide a copy of this list, and any revised list, to the auditor of the county within which all or the largest portion of the special district is located. The special district must compile the list of eligible voters and provide it to the county auditor by the first day of November preceding the special district general election. In the event the special district does not provide the county auditor with the list of qualified voters by this date, the county auditor shall compile the list and charge the special district for the costs required for its preparation. The county auditor shall not be held responsible for any errors in the list.
RCW 85.38.110