Sterling Elkhorn Crk STP - Wastewater Treatment Plant in Sterling, Illinois

Sterling Elkhorn Crk STP is a municipal wastewater treatment facility located in Sterling, Illinois, within Whiteside County. The plant serves a population of about 18,678 people, placing it in the medium agglomeration category for U.S. wastewater systems. As an inland facility, it treats wastewater from residential and commercial sources in the Sterling area. Under the U.S. Clean Water Act, plants of this scale are typically required to meet secondary treatment standards through National Pollutant Discharge Elimination System (NPDES) permits issued by the Illinois Environmental Protection Agency. These permits set effluent limits for biochemical oxygen demand, total suspended solids, and other pollutants to protect water quality. The treated effluent from Sterling Elkhorn Crk STP is discharged into a local waterway that ultimately drains into the Mississippi River basin. The Mississippi River system supports diverse aquatic life and provides drinking water for millions downstream. Proper treatment at this facility helps maintain water quality in the region's streams and rivers, which are important for recreation and ecosystem health.

The plant discharges into a tributary of the Rock River, which flows into the Mississippi River near the Quad Cities. The Mississippi River basin is a major ecological corridor supporting over 260 fish species and numerous migratory birds. Downstream waters are used for drinking water, agriculture, and recreation, making effective wastewater treatment critical for maintaining water quality and aquatic habitat in this extensive river system.