LA CHAUX Wastewater Treatment Plant, La Chaux (Cossonay), Vaud, Switzerland

LA CHAUX is an advanced wastewater treatment plant located in La Chaux (Cossonay), a municipality in the district of Morges, Vaud, Switzerland. The plant serves a small population of 267 residents, reflecting its role in a rural or peri-urban setting. Its location in the Swiss Plateau region places it within a landscape of rolling hills and agricultural land, with proximity to the Jura mountains to the north. The plant employs advanced treatment processes, which go beyond secondary treatment to remove nutrients such as nitrogen and phosphorus. This level of treatment is typical for Swiss plants discharging into sensitive water bodies, in line with the Swiss Water Protection Act (Gewässerschutzgesetz). The plant's designed capacity of 625.00 m³/day indicates headroom for future growth or seasonal peaks, while the current discharge volume of 121.20 m³/day shows it operates well below capacity. The treated effluent is discharged into local watercourses that eventually drain into the Rhone River basin via the Venoge River or other tributaries of Lake Geneva (Lac Léman). Lake Geneva is a large, deep alpine lake that supports diverse aquatic life and serves as a drinking water source for the region. The advanced treatment helps protect downstream ecosystems, including the lake's sensitive oligotrophic conditions, from nutrient pollution.

The plant discharges into local streams that flow into the Venoge River, a tributary of Lake Geneva (Lac Léman). Lake Geneva is a large oligotrophic lake that supports a diverse ecosystem, including endemic fish species and migratory birds. The advanced treatment ensures minimal nutrient loading, helping to prevent eutrophication and maintain water quality for downstream communities and habitats.