Smithton WWTP - Secondary Treatment Plant in Smithton, Illinois

Smithton WWTP is a municipal wastewater treatment facility located on Press Road in Smithton, Saint Clair County, Illinois. The plant serves a population of approximately 3,700 residents and operates under the regulatory framework of the US Clean Water Act, which requires secondary treatment for municipal discharges. The plant provides secondary treatment, a standard level that removes about 85% of organic matter and suspended solids. With a designed capacity of 3,596.13 thousand gallons per day and an actual discharge volume of 908.50 thousand gallons per day, the facility operates well below its capacity, indicating room for future growth. The treated effluent is discharged into a local waterway that ultimately drains into the Mississippi River basin. The plant plays a key role in protecting downstream water quality in the Mississippi River system, which supports diverse aquatic life and provides drinking water for millions.

The plant discharges into a tributary of the Mississippi River, which flows into the Gulf of Mexico. The Mississippi River basin is ecologically significant, supporting a wide range of fish and wildlife species. Downstream, the river contributes to the Gulf of Mexico's hypoxic zone, making nutrient removal an important consideration for wastewater treatment in this region.