It was created by the construction of a concrete dam 54 meters high at the junction of the Charadros and Varnava Torrents. Construction began in 1925 and the project began its operation in 1931. The reservoir has a surface area of 2,4 square kilometers, a watershed of 132 square kilometers, a maximum capacity of 41 million m3 of water and an operational volume of 34 million m3. The reservoir operates as a backup source for the water supply system of the greater Attica region and as a primary regulating reservoir.