Le Locle Wastewater Treatment Plant | Serving Le Locle, Neuchâtel, Switzerland

The Le Locle wastewater treatment plant is located in the municipality of Le Locle, in the canton of Neuchâtel, Switzerland. It serves a population of about 15,868 people, making it a medium-sized facility within the Swiss wastewater infrastructure. The plant is situated near the Col-des-Roches area, close to the French border. Switzerland's water protection legislation, particularly the Waters Protection Act (GSchG) and the Waters Protection Ordinance (GSchV), mandates that all wastewater treatment plants provide at least secondary treatment. For agglomerations of this size, tertiary treatment is often required to reduce nutrients and protect sensitive water bodies. The plant's treatment processes are designed to meet these stringent national standards. The treated effluent is discharged into the local watershed, which ultimately drains into the Doubs River, a tributary of the Saône, and then into the Rhône River before reaching the Mediterranean Sea. This downstream connection highlights the plant's role in protecting both local and regional water quality, supporting aquatic ecosystems and downstream communities.

The plant discharges into the Doubs River basin, which flows through the Jura region and joins the Saône River in France. The Saône then meets the Rhône, which empties into the Mediterranean Sea. This watershed supports diverse aquatic life, including fish species such as brown trout and grayling. The plant's treatment helps maintain water quality in this transboundary river system, which is ecologically sensitive due to its karst geology and seasonal flow variations.