Crest Hill STW East Wastewater Treatment Plant, Crest Hill, Illinois

Crest Hill STW East is a municipal wastewater treatment facility located in Crest Hill, Illinois, a community in Will County. The plant serves a population of about 10,861 residents, placing it in the small-to-medium agglomeration category for US wastewater infrastructure. As a US facility, Crest Hill STW East 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 plants of this scale, secondary treatment is the standard requirement, with additional nutrient removal potentially mandated depending on the receiving water body's sensitivity. The plant discharges treated effluent into the local watershed, which ultimately drains into the Des Plaines River and then to the Illinois River, a major tributary of the Mississippi River. This river system supports diverse aquatic life and provides drinking water for downstream communities, making effective treatment essential for water quality protection.

The plant's treated effluent flows into the Des Plaines River basin, which drains into the Illinois River and eventually the Mississippi River. This watershed supports a variety of fish and wildlife species and is used for recreation and drinking water supply. The Illinois River is a critical migratory corridor for waterfowl and supports commercial navigation, so maintaining low nutrient and pollutant loads is important for ecosystem health.