A regional noxious weed control board comprising the area of two or more counties may be created as follows:
Either the county legislative authority, or the noxious weed control board, or both, of two or more counties may, upon a determination that the purpose of this chapter will be served by the creation of a regional noxious weed control board, adopt a resolution providing for a limited merger of the functions of their respective counties noxious weed control boards. The resolution becomes effective only when a similar resolution is adopted by the other county or counties comprising the proposed regional board.
RCW 17.10.110