The El Grado dam Historical milestone · El Grado, Somontano de Barbastro, Huesca The building of the dam on the Cinca, completed in 1969, closed the basin of the reservoir that regulates the irrigation of the Cinca and Aragon and Catalonia canals, and completely transformed the landscape and the economy of the valley below Mediano. 1969 Photo: McBodes (CC BY 3.0) What to see and do in El Grado