The Cavallers reservoir or the Tor lakes can be found on the Noguera de Tor river, a tributary of the Noguera Ribagorzana. The dam is located in the municipality of Valle de Bohí, in the region of Alta Ribagorza, in Lérida, Catalonia, Spain. Until 1996, the municipality received the name of Barruera. The dam was built in 1960, on the bed of a lake, that of Cavallers, at an altitude of 1,780 m, in the Pyrenees of Lérida, in a granitic zone where there are hardly any trees, dominated by rocks, in a valley that Discurring from north to south. The dam is built by means of a series of buttresses anchored to the rock. It has a free spillway at the coronation, which allows the water to slip through four of the buttresses to its base.1 In this place the river Noguera de Tor is born. In the last 10 years, the average storage has been 14 hm3, 93.1% of its capacity. The reservoir, fed in turn by the Black Lake, at 2100 m of altitude, provides water to the Caldas de Bohí hydroelectric power station, next to the La Farga residence. The plant is 4108 meters from the dam and 1300 meters above sea level. The jump is 438.35 m and is located at the junction of Noguera de Tor with the Sant Nicolau valley, which provides water from Serradé lakes through the Sant Esperit dam.2 The installed capacity is 45 800 kw.3 There is a car park at the base of the dam at 1697 m, which is accessed by the road from Caldas de Bohí. This swamp is one of the accesses to the National Park of Aiguas Tortas and Lake of San Mauricio. It is located 154 km north of Lleida.