Saint-Lys Wastewater Treatment Plant - Occitanie, France

The Saint-Lys wastewater treatment plant is located in the commune of Saint-Lys, within the Haute-Garonne department of Occitanie, France. It serves a population of approximately 5,868 people, classifying it as a small agglomeration under European Union regulations. As a French wastewater facility, the plant operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for discharges to freshwater and estuaries from agglomerations of this size. The directive also mandates appropriate treatment for sensitive areas, which may apply depending on the receiving water body's classification. The plant's treated effluent is discharged into the local watershed, which ultimately drains into the Garonne River via smaller tributaries. The Garonne flows through southwestern France and into the Gironde estuary, a major ecological corridor supporting diverse aquatic life and migratory fish species such as Atlantic salmon and European eel.

The Saint-Lys plant discharges into the Coulée Verte de l'Ayguebelle, a local watercourse that feeds into the Garonne River basin. The Garonne River flows through the Occitanie and Nouvelle-Aquitaine regions before reaching the Gironde estuary, a dynamic coastal ecosystem that supports diverse aquatic life and serves as an important migratory corridor for fish species. The watershed is influenced by both agricultural runoff and urban inputs, making effective wastewater treatment crucial for maintaining water quality in downstream environments.