Mattmark Dam. Saas Valley, Valais, The Alps, Switzerland. Royalty-Free Stock Photography

Mattmark dam is a reservoir in the Saas Valley of the Canton of Valais, Switzerland. The Mattmark dam was built from 1960-1965. The lake's surface area is 1.76 km². The lake lies at a height of 2,197 metres above sea level, between the massifs of the Rimpfischhorn and Stellihorn. The highest peak visible from the lake is the Strahlhorn (4,190 m).