The water quality in Saginaw Bay has deteriorated from its natural Lake Huron character through man's overburdening use. Both the physical-chemical and biological characteristics indicate deteriorating conditions and trends. The intent of this report has been to compile and evaluate existing information on Saginaw Bay and document its present status. Water quality and trophic status have been evaluated with regard to physical, chemical, and biological parameters. Efforts were made to identify the community structure of aquatic plant and animal populations. Further emphasis has been placed on the identification and nature of water-quality variations and trends and the impact of contaminant sources on the system.