New Lenox STP 2 Wastewater Treatment Plant, Illinois

New Lenox STP 2 is a municipal wastewater treatment plant located at 2085 Sanford Avenue in New Lenox, Illinois, within Will County. The facility serves a population of approximately 7,500 people, placing it in the small-to-medium agglomeration category for US wastewater infrastructure. As a US-based plant, New Lenox STP 2 operates under the Clean Water Act, administered through the National Pollutant Discharge Elimination System (NPDES) permit program. The Illinois Environmental Protection Agency (IEPA) issues and enforces permits for facilities of this scale, typically requiring secondary treatment as a minimum standard. The plant's treatment processes and capacity details are not publicly available, but regulatory compliance ensures protection of local water quality. The plant discharges treated effluent into the local watershed, which ultimately drains to the Des Plaines River and then to the Illinois River, a major tributary of the Mississippi River. This drainage network supports diverse aquatic habitats and provides drinking water for downstream communities. The plant's operation is critical for maintaining water quality in this densely populated region of northeastern Illinois.

The plant's treated effluent enters the local stream network, flowing into the Des Plaines River and then the Illinois River, which joins the Mississippi River. This watershed supports a variety of fish and wildlife species, including migratory waterfowl along the Mississippi Flyway. The Illinois River is ecologically significant as a large river system that provides habitat for mussels, fish, and riparian vegetation. Protecting water quality in this basin is essential for both ecological health and human uses such as recreation and drinking water supply.