Wash. Rev. Code § 87.03.550
The board of directors of an included district shall before the expiration of their term of office cause to be prepared and filed with the board of directors of the consolidated district a statement of all property of such included district, and upon the organization of such consolidated district, the property, of such included district shall, subject to the rights of the holders of the bonds or other obligations of such district, become the property of such consolidated district, and the board of directors of such consolidated district shall in making assessments for such consolidated district cause equitable credit to be given to the lands of such included district for such property received as is of value and benefit to the consolidated district.
RCW 87.03.550