Wash. Rev. Code § 36.33.130
The county lands assessment fund may be expended by the county commissioners to pay in full or in part, any assessment or installment of assessments of drainage improvement districts, diking improvement districts, or districts formed for the foregoing purposes, or assessments for road improvements, falling due against lands in the year when such lands are acquired by the county or while they are owned by the county, including lands acquired by the county for general purposes; also lands which have been acquired by the county by foreclosure of general taxes. Payment may be made of such assessments, or installments thereof, against such lands or classes of lands, and in such districts or classes of districts as the county commissioners deem advisable. No payment shall be made of any assessments or installments of assessments falling due prior to the year in which the lands were acquired by the county, nor shall any assessments be paid in advance of the time when they fall due. Assessments for maintenance and operation of dikes, drains, or other improvements of districts falling due upon such lands while owned by the county, may be paid without the payment of assessments or installments thereof for construction of the improvements, if the county commissioners elect so to do.
RCW 36.33.130