West Monroe Regional STP | Wastewater Treatment Plant in Ouachita Parish, Louisiana

West Monroe Regional STP is a municipal wastewater treatment facility located in Ouachita Parish, Louisiana, serving an estimated population of 37,996. The plant is part of the region's wastewater infrastructure, handling domestic and industrial flows from the West Monroe area. As a US facility, the plant operates under the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Louisiana Department of Environmental Quality. For a plant serving nearly 38,000 people, secondary treatment is the minimum standard under the Clean Water Act, with potential additional requirements for nutrient removal or disinfection depending on the receiving water body. The plant's treated effluent discharges into the Ouachita River basin, which flows south through Louisiana to the Mississippi River and ultimately the Gulf of Mexico. The Ouachita River supports diverse aquatic life and is an important ecological corridor in the region. The plant's location inland, over 50 km from the coast, reduces direct marine impact but contributes to the nutrient load in the Mississippi River watershed.

The plant discharges into the Ouachita River, a major tributary of the Mississippi River system. The river flows through the Mississippi Alluvial Plain, supporting wetlands and bottomland hardwood forests that provide critical habitat for fish, birds, and other wildlife. Downstream, the Mississippi River delivers treated effluent to the Gulf of Mexico, where nutrient inputs can contribute to hypoxic zones. The plant's inland location and regulatory oversight help manage its environmental footprint.