70 ILCS 2605/7e
The sanitary district shall carry into effect all lawful orders issued under the provisions of "An Act to establish a Sanitary Water Board and to control, prevent, and abate pollution of the streams, lakes, ponds, and other surface and underground waters in the State, and to repeal an Act named therein", approved July 12, 1951, as heretofore or hereafter amended, and the "Environmental Protection Act", enacted by the 76th General Assembly.
If the sanitary district causes or allows the discharge of any raw sewage or waste which may cause or tend to cause the pollution of Illinois river waters it shall immediately so notify the Environmental Protection Agency and each municipality that uses Illinois river waters as its primary or implemental source of supply. Each municipality that uses the Illinois river waters as its primary or implemental source of supply shall so notify the sanitary district.
70 ILCS 2605/7e