GRAY Wastewater Treatment Plant, Gray-la-Ville, Bourgogne-Franche-Comté

The GRAY wastewater treatment plant is located in Gray-la-Ville, a commune in the Haute-Saône department of the Bourgogne-Franche-Comté region in eastern France. The plant serves a population of about 14,960, classifying it as a medium-sized agglomeration under the EU Urban Waste Water Treatment Directive (UWWTD). As a French facility, it operates within the national regulatory framework that implements the EU directive, ensuring compliance with treatment standards for inland waters. Under the EU UWWTD, agglomerations with a population equivalent (PE) between 10,000 and 150,000 are required to have secondary treatment as a minimum. For plants discharging into sensitive areas, tertiary treatment may be mandated. It is expected to meet the secondary treatment standard applicable to its size category. The plant is part of the municipal wastewater infrastructure managed by the local authority. The treated effluent from the GRAY plant is discharged into a local watercourse, likely a tributary of the Saône River, which flows into the Rhône River and eventually reaches the Mediterranean Sea. The plant plays a key role in protecting the water quality of the Saône basin, supporting aquatic ecosystems and downstream communities. Its operation helps reduce nutrient and pollutant loads, contributing to the ecological health of the region.

The GRAY plant discharges into the local watershed that drains into the Saône River, a major tributary of the Rhône. The Saône basin supports diverse aquatic life and is important for regional biodiversity. Downstream, the Rhône flows into the Mediterranean Sea, making the plant's treatment performance critical for both freshwater and marine environments. The area is characterized by agricultural land use, which can contribute diffuse pollution, so the plant's nutrient removal is essential for preventing eutrophication in receiving waters.