Guillestre Wastewater Treatment Plant, Guillestre, France

The Guillestre wastewater treatment plant is located in the commune of Guillestre, within the Hautes-Alpes department of the Provence-Alpes-Côte d'Azur region in southeastern France. The facility serves a population of approximately 17,260, placing it in the medium agglomeration category under EU classification. As a French plant serving between 10,000 and 100,000 people, it is subject to the EU Urban Waste Water Treatment Directive 91/271/EEC, which requires secondary treatment as a minimum standard. The directive also mandates more stringent treatment if the receiving waters are designated as sensitive areas, such as those prone to eutrophication. The plant's location in a mountainous alpine region may influence its design and operational considerations. The treated effluent is discharged into the local watershed, which ultimately drains into the Durance River, a major tributary of the Rhône River. The Rhône flows into the Mediterranean Sea. The plant plays a key role in protecting the water quality of the Durance River and downstream ecosystems, including the Camargue delta, a region of high ecological importance for migratory birds and aquatic life.

The Guillestre plant discharges into the Durance River basin, which flows into the Rhône River and then the Mediterranean Sea. The Durance is a dynamic alpine river that supports diverse aquatic habitats and is important for regional water supply and irrigation. Downstream, the Rhône delta and the Camargue region are ecologically sensitive areas that depend on good water quality to sustain wetland ecosystems and migratory bird populations.