Zernez Wastewater Treatment Plant - Graubünden, Switzerland

The Zernez wastewater treatment plant is located in the municipality of Zernez, in the Engadin region of the canton of Graubünden, Switzerland. Situated in the Swiss Alps, the plant serves a small alpine community with a population of around 3,531. As part of Switzerland's decentralized wastewater infrastructure, it plays a key role in protecting local water quality in a mountainous environment. Switzerland's water protection legislation, particularly the Waters Protection Act (GSchG), requires all wastewater to be treated to a high standard. For small agglomerations like Zernez, secondary treatment with nutrient removal is typical to safeguard sensitive alpine waters. The plant's design capacity and treatment process are aligned with these national standards, ensuring compliance with stringent effluent limits. The treated effluent is discharged into the Inn River, which flows through the Engadin valley and eventually joins the Danube River basin. The Inn River supports diverse aquatic life and is an important corridor for fish migration. The plant's operation helps maintain the ecological integrity of this alpine river system, which is vital for tourism and local biodiversity.

The Zernez plant discharges into the Inn River, a major tributary of the Danube that flows through the Swiss Engadin region. The river supports a sensitive alpine ecosystem with species such as brown trout and grayling. Downstream, the Inn joins the Danube, which ultimately reaches the Black Sea. Protecting water quality in this headwater region is critical for the entire downstream river system.