About Alcantara Dam

Alcántara dam sits on the Tajo (Tagus) river in the province of Cáceres, Extremadura, just upstream of the historic Roman bridge of Alcántara — one of the finest surviving examples of Roman engineering. Completed in 1969, the gravity dam is 130 metres tall and impounds 3,160 million cubic metres, making it the second-largest reservoir in Spain. Alcántara is primarily a hydroelectric facility, housing one of Spain's largest hydropower plants. The reservoir occupies a deep, narrow gorge carved by the Tagus through the granite bedrock of western Extremadura, creating a long, sinuous lake that extends upstream for over 90 kilometres. The Tagus is the longest river in the Iberian Peninsula, and Alcántara's position near the Portuguese border makes it a key element in the international management of the river's flow. Water released from Alcántara flows downstream into Portugal, where it feeds additional reservoirs before reaching the Atlantic at Lisbon. The dam's operation is therefore coordinated under the Albufeira Convention, the bilateral water-sharing agreement between Spain and Portugal.