South Pekin STP - Secondary Wastewater Treatment in Tazewell County, Illinois

South Pekin STP is a municipal wastewater treatment facility located in Tazewell County, Illinois, serving a population of 1,251. The plant provides secondary treatment, a standard level for small communities in the United States, ensuring compliance with federal and state regulations. The plant has a designed capacity of 567.81 million gallons per year and discharges approximately 473.18 million gallons of treated wastewater annually. As a US facility, it operates under the National Pollutant Discharge Elimination System (NPDES) permit program, which sets effluent limits to protect water quality. The treated effluent is discharged into a local waterway that ultimately drains into the Illinois River basin, a major tributary of the Mississippi River. This watershed supports diverse aquatic life and provides drinking water for downstream communities, making effective treatment essential for environmental and public health.

The plant discharges into a tributary of the Illinois River, which flows into the Mississippi River and eventually the Gulf of Mexico. The Illinois River basin supports a variety of fish and wildlife, including migratory birds and endangered species. Effective secondary treatment helps reduce nutrient loads that could contribute to hypoxia in the Gulf.