The Exceptional State Waters (ESW) Program is intended to identify and protect high quality waters for the benefit and enjoyment of future generations by prohibiting new or increased point source discharges to the designated waterbody. Tier III is another term used to refer to these protected waters. The equivalent regulatory terms are “Outstanding National Resource Waters” for EPA and “Exceptional State Waters” for Virginia.  The designation of a waterbody as an Exceptional State Water is a regulatory amendment to the Antidegradation Policy section of Virginia's Water Quality Standards regulation. Currently there are 30 waterways designated as ESW.

Citizens may submit a petition to designate a waterbody or a nomination may originate from within the agency. Exceptional State Waters are listed in the regulation.