ALEXIS STP - Advanced Wastewater Treatment Plant in Warren County, Illinois

ALEXIS STP is a municipal wastewater treatment facility located in Warren County, Illinois, United States. The plant serves a small population of 843 residents, reflecting its role as a local infrastructure asset in a rural area of the state. The plant employs advanced treatment processes, which go beyond the secondary treatment standard required by the U.S. Clean Water Act. With a designed capacity of 529.96 units and a discharge volume of 734.37 units, the facility operates under the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Illinois Environmental Protection Agency. The treated effluent is discharged into a local water body that ultimately drains into the Mississippi River basin, a major watershed supporting diverse aquatic life and regional water quality. The advanced treatment level helps protect downstream ecosystems and complies with federal and state water quality standards.

The plant discharges into a receiving water body within the Mississippi River basin, which flows into the Gulf of Mexico. This watershed supports a variety of fish and wildlife species and is an important migratory corridor for birds. The advanced treatment helps minimize nutrient and pollutant loading, reducing the risk of eutrophication in downstream waters.