38 M.R.S. § 495

It is recognized, owing to such variable factors as location, size, character and flow and the many varied uses of the waters subject to the terms of this compact, that no single standard of sewage and waste treatment and no single standard of quality of receiving waters is practical and that the degree of treatment of sewage and industrial wastes should take into account the classification of the receiving waters according to present and proposed highest use, such as for drinking water supply, industrial and agricultural uses, bathing and other recreational purposes, maintenance and propagation of fish life, shellfish culture, navigation and disposal of wastes.

The commission shall establish reasonable physical, chemical and bacteriological standards of water quality satisfactory for various classifications of use. It is agreed that each of the signatory states through appropriate agencies will prepare a classification of its interstate waters in entirety or by portions according to present and proposed highest use and for this purpose technical experts employed by state departments of health and state water pollution control agencies are authorized to confer on questions relating to classification of interstate waters affecting 2 or more states. Each signatory state agrees to submit its classification of its interstate waters to the commission for approval. It is agreed that after such approval, all signatory states through their appropriate state health departments and water pollution control agencies will work to establish programs of treatment of sewage and industrial wastes which will meet standards established by the commission for classified waters. The commission may from time to time make such changes in definitions of classifications and in standards as may be required by changed conditions or as may be necessary for uniformity.