Innerthal Wastewater Treatment Plant, Innerthal, Schwyz, Switzerland

The Innerthal wastewater treatment plant is located in the village of Innerthal, part of the March district in the canton of Schwyz, Switzerland. This small-scale facility serves a population of 100 residents, reflecting the rural character of the alpine community. The plant provides secondary biological treatment, which is the standard required under Swiss water protection legislation for small agglomerations. With a designed capacity of 233 cubic meters per day and an actual discharge volume of 45.39 cubic meters per day, the plant operates well within its capacity. The treated effluent is discharged into local watercourses that ultimately drain into the Wägitalersee, a lake in the Schwyz region, and then via the Wägitaler Aa into the Linth canal and Lake Zurich. This watershed is part of the Rhine basin, which flows into the North Sea. The plant plays a key role in protecting the sensitive alpine aquatic environment from nutrient pollution.

The plant discharges into small streams that feed the Wägitalersee, a lake in the canton of Schwyz. The lake is part of the Wägitaler Aa-Linth system, which flows into Lake Zurich and eventually the Rhine River. The alpine watershed supports diverse aquatic life and is sensitive to nutrient inputs, making effective wastewater treatment essential for maintaining water quality in this ecologically valuable region.