OLNEY STP - Olney, Illinois Wastewater Treatment Plant

OLNEY STP is a municipal wastewater treatment plant located in Olney, Illinois, serving a population of about 8,968. The facility is situated in Richland County, within the interior of the United States, far from coastal influences. As a publicly owned treatment works (POTW), it plays a key role in managing the city's wastewater and protecting local water quality. Under the U.S. Clean Water Act, plants serving populations between 2,000 and 10,000 are typically required to provide secondary treatment, which involves biological processes to reduce organic matter and suspended solids. The plant is expected to meet effluent limitations set by the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Illinois Environmental Protection Agency. The treated effluent from OLNEY STP is discharged into a local waterway that ultimately drains into the Wabash River basin, a major tributary of the Ohio River and part of the Mississippi River system. This downstream connection supports diverse aquatic life and provides water resources for communities and ecosystems along the way.

The plant's discharge enters a local stream that flows into the Embarras River, a tributary of the Wabash River. The Wabash River then joins the Ohio River, which empties into the Mississippi River and eventually the Gulf of Mexico. This watershed supports a variety of fish and wildlife, including several species of freshwater mussels and migratory birds. The region's agricultural land use can contribute nutrient runoff, making effective wastewater treatment important for preventing eutrophication downstream.