Reservoir of a Fervenza Nature · Mazaricos, Xallas, A Coruña The largest reservoir in the Xallas, built in 1966 to supply a hydroelectric plant today operated by Ferroatlántica; it stores 103 cubic hectometres over around 1,250 hectares spread across four municipalities, and its dam, raised on the boundary between Dumbría and Mazaricos, is 27 metres high by 127 metres long. It takes its name from the Castelo da Fervenza, one of the mountains forming the gorge where it sits. Its construction flooded valleys and farmland and altered the comarca's climate, increasing humidity and fog; the dolmen da Gándara de Baíñas was left beneath its waters, visible only when the water level drops a great deal. In 2007 its draining to maximise electricity output caused an ecological disaster with the death of thousands of fish. It is today a notable birdwatching spot. Photo: luscofusco (CC BY 2.0) What to see and do in Mazaricos