Wash. Rev. Code § 36.94.270
If any portion of the system after its installation in such local district is not adequate for the purpose for which it was intended, or that for any reason changes, alterations, or betterments are necessary in any portion of the system after its installation, then such district, with boundaries which may include one or more existing local districts, may be created in the same manner as is provided herein for the creation of local districts. Upon the organization of such local district as provided for in this section the plan of the improvement and the payment of the cost of the improvement shall be carried out in the same manner as is provided herein for the carrying out of and the paying for the improvement in the utility local improvement districts or local improvement districts previously provided for in this chapter.
RCW 36.94.270
Severability-1981 c 313: See note following RCW 36.94.020.