Lake Carucedo Nature · Carucedo, El Bierzo, León A barrier lake born of the alluvium of waste that the Roman mining of Las Médulas washed down the valley, a singular case of a wetland created by human hand. Ringed by poplar groves and reed beds, it is today a refuge for waterbirds. Photo: Manupucelano (CC BY-SA 3.0) What to see and do in Carucedo