Grand'Combe-Châteleu Wastewater Treatment Plant, Bourgogne-Franche-Comté, France

The Grand'Combe-Châteleu wastewater treatment plant is located in the commune of Grand'Combe-Châteleu in the Doubs department of Bourgogne-Franche-Comté, France. It serves a population of approximately 2,700 people, classifying it as a small agglomeration under French regulations. As a secondary treatment facility, the plant meets the minimum treatment requirements set by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The directive mandates secondary treatment for discharges into freshwater and estuaries, ensuring organic matter and suspended solids are reduced to acceptable levels. The treated effluent is discharged into local watercourses that flow into the Doubs River, a tributary of the Saône, which ultimately joins the Rhône River and drains into the Mediterranean Sea. The plant plays a key role in protecting the Doubs River basin from nutrient pollution and maintaining water quality for downstream ecosystems.

The plant discharges into the Doubs River watershed, which flows through the Jura Mountains and into the Saône River, a major tributary of the Rhône. The Rhône then empties into the Mediterranean Sea. The Doubs River supports diverse aquatic life, including fish species such as brown trout and grayling, and its water quality is critical for both ecological health and human uses like drinking water and recreation.