Wash. Rev. Code § 89.08.100
After the hearing, if the commission finds that the public health, safety, and welfare warrant the creation of the district, it shall enter an order to that effect and define the boundaries thereof by metes and bounds or by legal subdivisions.
In making its findings the commission shall consider the topography of the particular area and of the state generally; the composition of the soil; the distribution of erosion; the prevailing land use practices; the effects upon and benefits to the land proposed to be included; the relation of the area to existing watersheds and agricultural regions and to other similar districts organized or proposed; and consider such other physical, geographical, and economic factors as are relevant.
If the commission finds there is no need for the district, it shall enter an order denying the petition, and no petition covering the same or substantially the same area may be filed within six months thereafter.
RCW 89.08.100