Although no large bodies of water are found in the canton, numerous mountain lakes (above 800 m elevation) dot the landscape, some of them being used as reservoirs for hydroelectricity production. The largest natural lakes are Lake Sils, Lake Silvaplana, Lago di Poschiavo and Lake St. Moritz (all in Upper Engadin except that of Poschiavo). Artificial lakes are more numerous, the largest (over 100 ha) being Lago di Livigno, Lago di Lei, Lai da Sontga Maria, Zervreilasee, Lago Bianco, Lai da Marmorera and Lägh da l'Albigna. The total number of lakes has been estimated to 600. See list of mountain lakes of Switzerland for a more exhaustive list.