Mequinenza Dam (Spanish: Presa de Mequinenza) is a concrete gravity dam in the province of Zaragoza, Spain.

It impounds the Ebro creating a large reservoir, which is called Mar de Aragón.

Empresa Nacional Hidroeléctrica del Ribagorzana S.A. (ENHER) was mandated in 1955[2][3] by Instituto Nacional de Industria (INI) to build two dams on the Ebro near Mequinenza and Ribarroja.

the reservoir has a surface area of 75.4 km2, a total capacity of 1.53 billion m3 and a length of almost 110[2][3] km.

The turbines, generators and transformers were refurbished from 2007 until 2010 raising the capacity of the new machines to 96 MW each.