COUDES Wastewater Treatment Plant, Coudes, Auvergne-Rhône-Alpes, France

The COUDES wastewater treatment plant is located in the commune of Coudes, within the Puy-de-Dôme department of the Auvergne-Rhône-Alpes region in central France. It serves a population of approximately 2,655 residents, classifying it as a small agglomeration under French and EU regulations. The plant is situated along the Route du Rivage, near the Allier River. As a secondary treatment facility, COUDES meets the minimum requirements of the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The plant has a designed capacity of 2,700 m³/day and currently discharges an average volume of 473.65 m³/day, indicating significant spare capacity. The treatment process involves biological degradation of organic matter, followed by sedimentation to remove solids. The treated effluent is discharged into the Allier River, a major tributary of the Loire River. The Allier flows northward through the Massif Central and eventually joins the Loire, which drains into the Atlantic Ocean. The plant plays a key role in protecting the water quality of the Allier, which supports diverse aquatic life and is used for recreation and agriculture downstream.

The COUDES plant discharges into the Allier River, which flows through the Auvergne region and joins the Loire River, the longest river in France. The Allier is known for its dynamic gravel-bed morphology and supports a rich ecosystem, including migratory fish species such as Atlantic salmon and European eel. The river's watershed includes sensitive areas that benefit from the plant's secondary treatment, which reduces organic pollution and protects downstream water quality.