STEP SECO Wastewater Treatment Plant, Damphreux-Lugnez, Jura, Switzerland

STEP SECO is a municipal wastewater treatment plant located in Damphreux-Lugnez, in the Jura canton of Switzerland. It serves a population of approximately 1,017 residents, reflecting its role as a small-scale facility in a rural setting. The plant is situated near the border with France, in the Ajoie region, and is part of Switzerland's decentralized wastewater infrastructure. The plant provides secondary treatment, which is the standard required under Swiss regulations for agglomerations of this size. Switzerland's Water Protection Act mandates that all wastewater receive appropriate treatment before discharge, with secondary treatment being the minimum for most inland plants. The plant has a designed capacity of 1,700 m³ per day and currently treats an average daily volume of about 462 m³, indicating ample capacity for future growth. The treated effluent is discharged into local streams that eventually flow into the Allaine River, a tributary of the Doubs River, which forms part of the Rhône basin. The Doubs River is known for its diverse aquatic life and supports a rich ecosystem. The plant's operation helps protect the water quality of these downstream water bodies, which are important for both ecological health and recreational use in the region.

The treated effluent from STEP SECO enters small watercourses in the Ajoie region, which drain into the Allaine River. The Allaine flows into the Doubs River, a major tributary of the Saône, which ultimately joins the Rhône River and discharges into the Mediterranean Sea. The Doubs River supports diverse fish populations, including brown trout and grayling, and its riparian zones provide habitat for various bird species. The plant's secondary treatment helps maintain the ecological integrity of these waters by reducing organic pollutants and nutrients.