Carol Stream STP - Wastewater Treatment Plant in Carol Stream, Illinois

Carol Stream STP is a municipal wastewater treatment facility located in Carol Stream, Illinois, a suburb of Chicago. Serving a population of around 40,438, the plant is part of the region's infrastructure managed by local authorities under the U.S. Clean Water Act. However, for a community of this size in the United States, secondary treatment is typically required under the Clean Water Act, with permits issued by the Illinois Environmental Protection Agency. The plant likely employs conventional activated sludge or similar biological treatment. Treated effluent from the plant is discharged into local waterways that ultimately drain into the Mississippi River Basin. The plant plays a key role in protecting the downstream aquatic environment, including the Illinois River and the Gulf of Mexico, by reducing nutrient and pollutant loads.

The plant discharges into the DuPage River system, a tributary of the Illinois River, which flows into the Mississippi River and eventually the Gulf of Mexico. This watershed supports diverse aquatic life and is important for regional water quality. The plant's operations help mitigate nutrient pollution that can contribute to hypoxic zones in the Gulf.