AUCH Lamothe Wastewater Treatment Plant, Roquelaure, Occitanie, France

AUCH Lamothe is a wastewater treatment plant located in Roquelaure, near Auch in the Occitanie region of France. The plant serves a population of approximately 31,500 people, classifying it as a medium-sized agglomeration under EU regulations. Its location in the Gers department places it within a rural and agricultural landscape. As a French facility, AUCH Lamothe operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations between 10,000 and 150,000 population equivalent. The directive also mandates more stringent treatment if the receiving waters are designated as sensitive areas. The plant's treatment processes and capacity are designed to meet these regulatory standards, ensuring compliance with national and European water quality objectives. The plant discharges treated effluent into the local watershed, which ultimately drains into the Garonne River basin. The Garonne flows northward through southwestern France before reaching the Gironde estuary and the Atlantic Ocean. This river system supports diverse aquatic life and is important for regional agriculture and water supply. The plant's operation helps protect downstream water quality and ecological health.

The treated effluent from AUCH Lamothe enters the local tributaries of the Gers River, a left-bank tributary of the Garonne. The Garonne River flows through the Aquitaine region and into the Gironde estuary, a major ecological zone supporting migratory fish species such as Atlantic salmon and European eel. The watershed is also used for irrigation and drinking water supply, making nutrient removal and pathogen control critical for maintaining water quality and ecosystem balance.