Zervreilasee, Reservoir in the Valser Tal, Canton of the Grisons, Switzerland

Zervreilasee is a reservoir in the Canton of the Grisons situated at approximately 1900 meters elevation in an alpine valley surrounded by steep cliffs and forests. The clear water fills the valley between high peaks and is held back by a 151-meter-high concrete dam at its lower end.

The Zervreila dam, a 151-metre-high arch-gravity wall built by Motor-Columbus, was completed in 1957, flooding the village of Zervreila that gave the lake its name. The concession for the power plant was granted at the municipal assembly of 18 December 1948, and the plant was inaugurated with a two-day celebration on 4 and 5 September 1959. In 2018 the lake was almost completely emptied during a two-year refurbishment of the pressure pipeline.

The name Zervreilasee refers to the village of Zervreila that once stood here before the dam was built and now lies beneath the water. For local people, this reservoir represents the connection between their mountain heritage and the practical need to manage water resources in the region.

The lake is reachable from Vals by postal bus in about twenty minutes, and short paths from the parking area lead to the dam. A popular hiking route from Vals to the water takes about two and a half hours and passes through meadows and forests.

The lake serves as the starting point for an extended hiking circuit that connects all four lakes in the surrounding area - Zervreilasee, Guraletschsee, Ampervreilsee, and Selvasee - in a single tour lasting about six hours. This four-lake loop allows visitors to experience the full variety of the high alpine lake landscape in one outing.