Alqueva.
The Alqueva Dam, with a reservoir surface measuring 250 km² and more than 1100 km of banks, is the largest artificial lake in Europe. It covers 5 municipalities in Alentejo: Portel, Moura, Reguengos de Monsaraz, Mourão and Alandroal, and also the regional municipalities of Olivença, Cheles, Alconchel and Villanueva del Fresno.
The Alqueva Dam is today the largest water reserve in this country. Electrical production capacity started at 260MW, enough to supply the Beja district, with power being doubled in 2012 to 520MW.