Mattmark dam is a reservoir in the Saas Valley of the Canton of Valais, Switzerland. The Mattmark dam was built from 1960 to 1965. The lakes 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).
