Detection of Giardia in sewage effluent.

Giardia sp. cysts were found at levels of 4,000-450,000/378,500 liters (100,000 gallons) in sewage effluents from three of seven sewage treatment plants in Sangamon County, Illinois, in June, July, and August 1981. Effluent from the positive plants is discharged into Lake Springfield (the present source of the city of Springfield's water supply) or the Sangamon River.