Walnut Ridge Wastewater Treatment Plant, Jefferson County, Missouri

Walnut Ridge is a wastewater treatment plant located in Jefferson County, Missouri, United States. It serves a small population of 59 residents and is situated in the High Ridge Township area. The plant operates under the regulatory framework of the US Clean Water Act, which requires National Pollutant Discharge Elimination System (NPDES) permits for all discharges into surface waters. The plant provides advanced treatment, which goes beyond secondary treatment to remove additional nutrients and contaminants. Its designed capacity is 53.00 million gallons per day, and it currently discharges 18.93 million gallons per day. Advanced treatment typically includes biological nutrient removal or tertiary filtration. The treated effluent is discharged into a local water body that ultimately drains into the Mississippi River basin. The plant plays a key role in protecting downstream water quality in the Meramec River watershed, which supports diverse aquatic life and recreational uses. Its advanced treatment helps reduce nutrient loading to the Gulf of Mexico, contributing to efforts to mitigate the hypoxic zone.

The plant discharges into a tributary of the Meramec River, which flows into the Mississippi River and eventually reaches the Gulf of Mexico. The Meramec River watershed is ecologically sensitive, supporting diverse fish and mussel populations. Advanced treatment at this plant helps reduce nutrient and pollutant loads, protecting downstream aquatic habitats and recreational waters.