A conference was held in the matter of pollution of the waters of Lake Michigan and its trinbutary basin (Illinois-Indiana-Michigan-Wisconsin). The report prepared for the information of the conference and other interested parties, and for use by the conferees in their consideration of actions needed to improve and preserve the quality of waters. The report is based on studies and investigations by the Federal Water Pollution Control Administration, paralleling investigations made through cooperative agreements by other agencies of the Department of the Interior, and information obtained from other Federal agencies, agencies of the four Lake Michigan States, municipalities, universities, and others. (Author Modified Abstract)