Wash. Rev. Code § 89.12.060
Any or all of the provisions which may be required to be included in recordable contracts may be made covenants running with any tract of land covered by the contract by expressly so providing therein. Recordable contracts expressly providing that any or all of such provisions shall be covenants running with the land covered thereby shall not be destroyed or extinguished by any tax or assessment foreclosure or deed issued pursuant thereto.
Such of the limitations and provisions of RCW 89.12.050 as are included in the repayment contract between the district and the United States, shall govern all the lands within the district unless otherwise provided in such contract and shall govern notwithstanding any other provisions of the laws of this state.
RCW 89.12.060