COMMELLE Wastewater Treatment Plant, Porte-des-Bonnevaux, France

The COMMELLE wastewater treatment plant is located in the commune of Porte-des-Bonnevaux, within the Isère department of the Auvergne-Rhône-Alpes region in southeastern France. It serves a population of approximately 740 residents, classifying it as a small agglomeration under French and EU regulations. The plant provides secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. Its designed capacity is 900 m³/day, with an average daily discharge volume of about 132 m³, indicating ample reserve capacity for future growth or seasonal peaks. The treated effluent is discharged into the local watershed, which ultimately drains into the Rhône River basin. The Rhône is one of Europe's major rivers, flowing into the Mediterranean Sea. The plant's operation helps protect downstream water quality and aquatic ecosystems in the Rhône corridor, a region of significant ecological and economic importance.

The plant's discharge enters a tributary of the Rhône River, which flows southward through the Rhône Valley into the Mediterranean Sea. The Rhône basin supports diverse aquatic life and is an important migratory corridor for fish species. The secondary treatment provided by the plant reduces organic pollutants and suspended solids, helping to maintain the ecological health of the downstream river system and the coastal waters of the Gulf of Lion.