There are some 2,250 hydroelectric installations of various sizes in Metropolitan France whose power varies from 1,000 watts to several hundred megawatts. 436 of them are operated by EDF. Out of the total installed capacity of 25.4 gigawatts nationwide, EDF produces no less than 20 gigawatts or 13% of the company's total energy production.A smallish watercourse 70 km long whose source is in the commune of Gentioux-Pigerolles (Creuse department) and mouth at Saint-Léonard-de-Noblat (Haut-Vienne department) where it flows into the River Vienne is the River Maulde on which EDF operates six dams with a combined power output of 18 megawatts. Located at Martinex, Fleix, Langleret, Villejoubert and Lartige, the six gravity dams, most of them Ambursen type dams, roughly16m high, have buttresses spaced at intervals and are of identical design.