MAZERES Wastewater Treatment Plant, Mazères, Occitanie, France

The MAZERES wastewater treatment plant is located in Mazères, a commune in the Ariège department of Occitanie, southern France. It serves a population of approximately 3,546 residents, placing it in the small agglomeration category under French regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 2,700 m³/day and a reported discharge volume of 632.6 m³/day, the facility operates well within its capacity, ensuring effective treatment of municipal wastewater. The treated effluent is discharged into the local watershed, which ultimately drains into the Ariège River and then the Garonne River, flowing toward the Atlantic Ocean. The plant plays a key role in protecting the water quality of these rivers and supporting the ecological health of the Garonne basin.

The plant discharges into the Ariège River, a tributary of the Garonne River, which flows through southwestern France to the Gironde estuary and the Atlantic Ocean. The Garonne basin supports diverse aquatic life, including migratory fish species such as salmon and eels. Advanced treatment at this plant helps reduce nutrient and pollutant loads, safeguarding downstream water quality and ecosystem health.