McLain POTW - Secondary Wastewater Treatment Plant in McLain, Mississippi

McLain POTW is a publicly owned treatment works located on Turtle Lake Road in McLain, Greene County, Mississippi. The plant serves a small population of 603 residents, reflecting the rural character of the area. As a secondary treatment facility, it provides biological treatment to reduce organic pollutants and suspended solids before discharge. The plant operates under the U.S. Clean Water Act, which requires secondary treatment for municipal wastewater plants. With a designed capacity of 136.27 million gallons per day and an average discharge volume of 37.85 million gallons per day, the facility has capacity to accommodate future growth. The regulatory framework ensures compliance with National Pollutant Discharge Elimination System (NPDES) permits issued by the Mississippi Department of Environmental Quality. The treated effluent is discharged into local streams that drain into the Pascagoula River basin, one of the last free-flowing river systems in the contiguous United States. This watershed supports diverse aquatic life, including several species of freshwater mussels and fish. The plant's inland location, more than 50 km from the coast, reduces direct marine impact, but its discharge contributes to the overall water quality of the Pascagoula River and eventually the Gulf of Mexico.

The plant's discharge enters local tributaries of the Pascagoula River, which flows into the Mississippi Sound and the Gulf of Mexico. The Pascagoula River basin is ecologically significant as one of the largest unimpeded river systems in the lower 48 states, supporting a rich diversity of fish, mussels, and migratory birds. The secondary treatment process helps protect downstream water quality by reducing biochemical oxygen demand and suspended solids, which is critical for maintaining the health of this sensitive aquatic ecosystem.