Wash. Rev. Code § 85.20.050
The board of commissioners of the drainage or diking district shall constitute the board of supervisors of the reorganized district. From the entry of an order under RCW 85.20.030 reorganizing the district, such reorganized district, and its board of supervisors, shall have all the rights and powers of and be subject to all laws applicable to a diking or drainage improvement district, and such district so reorganized shall be dissolved without any further proceedings therefor. Notwithstanding such dissolution and reorganization, none of the outstanding bonds, warrants or other indebtedness of the district, shall be affected thereby; and all lands liable to be assessed to pay any of such bonds, warrants or other indebtedness shall remain liable to the same extent as if such reorganization had not been made, and any and all assessments theretofore levied or made against any such lands shall be and remain unimpaired and shall be collected in the same manner as if no such reorganization had been had. The legislative authority of the county in which such reorganized district is situated shall have all the powers possessed at the time of the reorganization by the board of commissioners of such district to levy, assess, and cause to be collected any and all assessments or charges against any of the lands within such district that may be necessary or required to provide funds for the payment of all the bonds, warrants and other indebtedness thereof.
RCW 85.20.050