Montastruc La Conseillere Wastewater Treatment Plant, Gragnague, Occitanie

Montastruc La Conseillere is a secondary wastewater treatment plant located in Gragnague, a commune in the Haute-Garonne department of Occitanie, southern France. The plant serves a population of approximately 2,805 residents and is part of the municipal wastewater infrastructure for the Toulouse metropolitan area. The plant provides secondary treatment, which typically involves biological processes to remove organic matter and suspended solids. With a designed capacity of 3,000 m³/day and a current discharge volume of 500.41 m³/day, the plant operates well below its capacity. As a French facility, it operates under the national regulations transposing the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations of this size. The treated effluent is discharged into local watercourses that ultimately drain into the Garonne River basin. The Garonne flows through southwestern France and into the Gironde estuary, supporting diverse aquatic ecosystems and agricultural water use. The plant's location inland, away from the coast, reduces direct marine impact.

The plant discharges into the Garonne River basin, which flows through the Occitanie region and eventually reaches the Atlantic Ocean via the Gironde estuary. The Garonne supports diverse aquatic life, including migratory fish species such as salmon and eels. The watershed is ecologically sensitive due to agricultural runoff and urban pressures from the Toulouse metropolitan area.