Odor Studies of Three Illinois Impoundments

Weekly threshold odor numbers (TONs) were determined in the waters of three impoundments and the finished water produced by treatment at each impoundment site during a two year period. The magnitude of taste and odor in the three impoundments are a seasonal function. High TONs generally occur during the period May through October, the period of anoxic conditions in bottom waters of impoundments. Regardless of the magnitude of TONs in the raw waters, the TONs in the three finished waters range from 3 to 10 about 95 percent of the time. The likely causes of each excessive TONs are discussed. Based on the seasonal and overall data, the 20 commonly measured biological, chemical, and physical parameters were not correlated to the TONs.