Wash. Rev. Code § 87.03.540
The board of directors of each included district shall hold office until the board of directors of the consolidated district shall have been elected and shall have qualified, and thereupon the term of office of the directors of such included district shall terminate, and the board of directors of such consolidated district shall have and exercise all the powers and duties in regard to such included district as were vested in the board of directors of such district. Each organized district included in a consolidated district shall either retain its corporate existence so far as necessary for the purpose of carrying out all contracts of such district, and until its indebtedness has been paid in full, or the board of directors of the consolidated district may constitute each such included district a local improvement district for the purpose of carrying out the obligations of, such included district and shall have all the power possessed by the board of directors of such included district to carry out all contracts of such included district to levy, assess and cause to be collected any and all assessments or charges against all of the land within such local improvement district that may be necessary or required to provide for the payment of all the bonds, warrants, and other indebtedness thereof, and to provide for the construction, reconstruction, betterment, improvement, maintenance and operation of all such work as are for the special benefit of the land in such local improvement district. Until such assessments shall have been collected and all indebtedness of the respective included districts paid, separate funds shall be maintained for each such district as were maintained in such included districts prior to the consolidation. A petition shall not be required for the establishment of the lands of such included districts as local improvement districts.
RCW 87.03.540
Board's powers and duties generally: RCW 87.03.140.