The dam dates back to 1968, when the hydroelectric power station was also built, both of which are owned by Unión Fenosa. It is located on the Ulla river, between the municipalities of Arzúa (A Coruña) and Vila de Cruces (Pontevedra). The turbine area and the substation are both located underground. The most remarkable feature of this construction is the use of rubble instead of concrete in the dam wall, which is 91 metres high. The reservoir has a capacity of 297 cubic hectometres, with a maximum capacity of 252 and a minimum of 220. 

One of the negative consequences of the reservoir, from a historical-artistic point of view, was the disappearance of several villages and, alongside these, the loss of numerous cultural heritage assets. This fact caused great alterations in the daily life of the neighbourhood. 

Currently, there is a recreational area and a river beach in the area surrounding the reservoir. It furthermore enjoys a special fishing regime. The reservoir and its surroundings offer an ideal place for water sports (sailing, canoeing...), hiking and cycling routes. 

You can visit "Enredo do Abelleiro", an unusual thematic museum dedicated to honey and beekeeping.