Wash. Rev. Code § 85.08.820
Whenever the department of ecology shall have purchased and the state of Washington owns the entire issue of any series of bonds of any county in the state, the payment of which is to be made from and is secured by assessments upon the property included within any drainage improvement district organized and existing in such county, and it shall appear to the satisfaction of the director of ecology that owing to and by reason of the nature of the soil within and the topography of such drainage improvement district the lands contained therein were not or will not be drained sufficiently to permit the cultivation thereof within the time when assessments for the payment of the interest on said bonds and to constitute a sinking fund to retire said bonds as provided by law became or will become due, and that by reason thereof the owners of said lands were or will be unable to meet said assessment, the director of ecology shall have the power and he or she is hereby authorized under such terms and conditions as he or she shall deem advisable to enter into a contract in writing with the board of county commissioners of the county issuing such bonds, waiving the payment of interest upon such bonds from the date of their issue for not to exceed five years, and extending the time of payment of said bonds for not to exceed five years; and upon the execution of said contract the board of county commissioners of said county shall have the power and is hereby authorized to cancel all assessments made upon the lands included within such drainage improvement district for the payment of principal and/or interest on said bonds prior to the date of said contract, and to omit the levy of any assessments for said purposes until the expiration of the time of the waiver of interest payments upon said bonds specified in said contract.
RCW 85.08.820