Zernez Susch Wastewater Treatment Plant - Susch, Graubünden, Switzerland

The Zernez Susch wastewater treatment plant is located in the village of Susch, within the municipality of Zernez in the Engadin region of Graubünden, Switzerland. This small-scale facility serves a population of 303 residents, reflecting the rural and alpine character of the area. The plant provides secondary treatment, which is the standard biological treatment stage required under Swiss wastewater regulations for communities of this size. Swiss federal law mandates that all wastewater undergo at least secondary treatment before discharge, with more advanced treatment required in sensitive watersheds. The plant's designed capacity of 938.00 m³/day significantly exceeds the current discharge volume of 137.54 m³/day, indicating ample reserve capacity for future growth or seasonal tourist fluctuations. The treated effluent is discharged into the local hydrological network, ultimately flowing into the Inn River, which is a major tributary of the Danube. The Inn River originates in the Swiss Alps and flows through Austria and Germany before joining the Danube. The plant's operation helps protect the sensitive alpine aquatic ecosystems of the Engadin region, which support diverse fish populations and are important for regional biodiversity.

The Zernez Susch plant discharges into the Inn River basin, which drains the Engadin valley and flows into the Danube River system. The alpine watershed is ecologically sensitive, supporting cold-water fish species such as brown trout and grayling. Downstream, the Inn River passes through the Swiss National Park region, an area of high conservation value. The plant's secondary treatment helps maintain water quality in this pristine mountain environment.