Les Risouls Wastewater Treatment Plant, Chorges, France

Les Risouls is a wastewater treatment plant located in Chorges, within the Provence-Alpes-Cote d'Azur region of France. It serves a population of approximately 3,800 residents, classifying it as a small agglomeration under French and EU regulations. The plant is situated near the Durance River basin, an important watercourse in the region. The plant operates with secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for inland freshwater discharges from agglomerations of this size. Its designed capacity is 2,150 m³/day, and it currently treats an average daily flow of 677.91 m³/day, indicating significant spare capacity. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into the local watershed, which ultimately drains into the Durance River and then to the Rhone River, flowing into the Mediterranean Sea. The plant plays a key role in protecting the Durance River ecosystem, which supports diverse aquatic life and is used for irrigation and recreation. By meeting EU standards, Les Risouls helps maintain water quality in this sensitive alpine-to-Mediterranean transition zone.

The plant discharges into the Durance River basin, a major tributary of the Rhone River, which flows into the Mediterranean Sea. The Durance supports a diverse aquatic ecosystem, including fish species like the endemic Rhone streber, and provides water for agriculture and hydropower. The region's Mediterranean climate and mountainous terrain make the river sensitive to pollution, so secondary treatment is essential to protect downstream water quality and biodiversity.