Assumption STP Wastewater Treatment Plant, Assumption, Illinois

Assumption STP is a municipal wastewater treatment facility located in Assumption, Christian County, Illinois. The plant serves a population of approximately 1,511 residents, classifying it as a small-scale treatment facility under U.S. EPA guidelines. The plant provides secondary treatment, which is the standard level required by the U.S. Clean Water Act for municipal wastewater plants. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The plant's designed capacity is 1,476.31 thousand gallons per day, with an actual discharge volume of 794.94 thousand gallons per day, indicating operational capacity below design limits. The treated effluent is discharged into local waterways that ultimately drain into the Mississippi River basin. The plant plays a key role in protecting local water quality and downstream ecosystems, including the Mississippi River and the Gulf of Mexico.

The plant discharges into receiving waters that flow into the Kaskaskia River, a tributary of the Mississippi River. The Mississippi River basin supports diverse aquatic life and is a major migratory corridor for birds and fish. The plant's secondary treatment helps reduce nutrient loading, which is critical for mitigating hypoxia in the Gulf of Mexico.