Dams and their associated structures are used for forming reservoirs for the storage of water or mud, and for holding back sediment, ice or snow. Reservoirs formed by dams are mainly used for energy production, water supply, irrigation, production of artificial snow, fish farms, reserves for fire-fighting operations and the regulation of water levels in lakes. They also play an increasingly important role during floods, since they limit the volume of water downstream and thus help reduce damage.
The Swiss Federal Office of Energy (SFOE) is the highest supervisory authority for all dams in Switzerland. Direct supervision is shared by the cantons and the federal government: the cantons are responsible for small dams, while the SFOE supervises large-scale facilities (205 reservoirs and 227 dams, 83 percent of which are used for hydropower production). 137 of these dams are in the form of concrete walls (80 gravity dams, 53 curved dams, 2 multiple-curve dams and 2 pierhead dams), while 83 are soil and stonefill constructions, and 7 are in the form of river weirs. 25 are higher than 100 metres, and 4 of these are over 200 metres high, namely the Grande Dixence gravity dam (285 metres), and the Mauvoisin (250 metres), Luzzone (225 metres) and Contra (220 metres) curved dams. Most of the large-scale dams are located in the Alps.