Deerfield STP and Coll System | Deerfield, Illinois Wastewater Treatment Plant

The Deerfield STP and Coll System is a municipal wastewater treatment facility serving the village of Deerfield, Illinois, a suburb north of Chicago in Lake County. The plant provides wastewater services to an estimated population of 21,078, reflecting a medium-sized agglomeration typical of suburban communities in the Chicago metropolitan area. As a US-based facility, the plant operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Illinois Environmental Protection Agency. For a plant of this scale, secondary treatment is the minimum standard, with potential additional requirements for nutrient removal to protect downstream waters. The plant's treated effluent ultimately drains to Lake Michigan via local tributaries such as the Chicago River or North Branch of the Chicago River. Lake Michigan is a vital freshwater resource providing drinking water to millions and supporting diverse aquatic life, including fish species like lake trout and whitefish. The plant plays a key role in protecting this ecosystem from nutrient pollution and pathogens.

The Deerfield STP discharges into the Lake Michigan watershed, a major Great Lake that serves as a drinking water source for over 10 million people. The lake supports a complex food web including alewife, salmon, and invasive species like zebra mussels. Nutrient loading from wastewater can contribute to algal blooms and hypoxia, making advanced treatment important for ecological health.