Whenever the commission determines upon investigation that sewage or other polluting matter from any city, village, town, county, borough, municipality or other entity, as defined in the compact, building, steamboat or other vessel, or any garbage, offal or any decomposable or putrescible matter of any kind is being discharged into any waters of the district, and whenever in the opinion of the commission such discharge is polluting such waters in a manner injurious to or so as to create a menace to public health, welfare and recreational purposes, or so as to create a public nuisance, or so as to be obnoxious, the commission shall give notice in writing of the discharge of such sewage or polluting matter to the Commissioner of Energy and Environmental Protection and to the Department of Public Health for such action as may be proper under the laws of the state of Connecticut. If, at the expiration of six months after the mailing of such notice, such discharge continues to pollute such waters in a manner injurious to or so as to create a menace to public health, welfare and recreational purposes, or so as to create a public nuisance, or so as to be obnoxious, such commission, upon a vote of at least three of the members from each state, may order the municipality, corporation or person so discharging sewage, refuse or other matter to show cause before it or its designated representative why such discharge should not be discontinued or why said commission should not issue an order regulating such pollution. A notice shall be served on the municipality, corporation or person so discharging sewage, refuse or other matter, directing such municipality, corporation or person to show cause before said commission on a date specified in such notice why an order should not be made directing the discontinuance of such discharge or otherwise regulating such pollution. Such notice shall specify the time when and place where a public hearing will be held by the commission or its delegated representative and shall be served personally or by mail at least fifteen days before such hearing and, in case of a municipality or a corporation, such service shall be upon an officer thereof. The person or persons presiding at such hearing shall take evidence and, after conducting such public hearing, the commission shall by order prescribe a reasonable date on or before which such municipality, corporation or person discharging sewage, refuse or other matter into the designated waters within the district shall cease to discharge such refuse or other matter and shall treat such sewage in accordance with the standards specified in the compact, and such order may prescribe that certain specific progress shall be made at definite times prior to the final date fixed in such order. The commission shall have authority to require from the officials and persons responsible for the execution of such orders satisfactory evidence at specified times of proper progress in the execution of such orders.