Wash. Rev. Code § 85.32.010
The maintenance of drainage districts is essential to the economy of the state. The influx of population and changes in land use since many such districts were formed, has made obsolete and unjust the method used under existing law to provide funds for the operation of such districts and for the maintenance and expansion of its drainage systems. Also, in many instances, properties lying outside of the territorial limits of such districts, have been and are being developed in such a manner that waters therefrom, through artificial rather than natural processes, are accumulated and discharged for outlet upon lands within such districts, and the facilities of such district are used without charge to furnish service and benefit to such lands. To furnish remedy for such situations where they are found to exist the state declares that it has an interest therein and this chapter is passed.
RCW 85.32.010