WELSH STP - Advanced Wastewater Treatment Plant in Welsh, Louisiana

WELSH STP is an advanced wastewater treatment plant located in Welsh, Louisiana, United States. The facility serves a population of approximately 3,380 residents in the Jefferson Davis Parish area. The plant provides advanced treatment, which goes beyond secondary treatment to remove additional pollutants such as nutrients. With a designed capacity of 2649.78 and a discharge volume of 855.50, the plant operates under the U.S. Clean Water Act, which requires NPDES permits for discharges into surface waters. Advanced treatment is typical for plants in sensitive watersheds or those requiring high effluent quality. The treated effluent is discharged into local waterways that drain into the Gulf of Mexico via the Mermentau River basin. This region supports diverse aquatic life and is part of the larger Mississippi River watershed, which ultimately empties into the Gulf of Mexico.

The plant discharges into the Mermentau River basin, which flows into the Gulf of Mexico. This coastal watershed supports important fisheries and wetland ecosystems. Advanced treatment helps protect downstream water quality by reducing nutrient loads that could contribute to hypoxia in the Gulf.