RCW 90.48.270: Sewage drainage basins—Authority of department to delineate and establish.

The department shall have authority to delineate and establish sewage drainage basins in the state for the purpose of developing and/or adopting comprehensive plans for the control and abatement of water pollution within such basins. Basins may include, but are not limited to, rivers and their tributaries, streams, coastal waters, sounds, bays, lakes, and portions or combinations thereof, as well as the lands drained thereby.