Valle Grande Reservoir, Reservoir lake in Mendoza Province, Argentina

Valle Grande Reservoir is a body of water held back by the Valle Grande Dam, a 300-metre-long, 115-metre-high concrete structure of the Noetzli-Alcorta type, inaugurated in 1964. It lies at the end of the Atuel Canyon, about 30 km south of San Rafael, at an elevation of 834 metres. The dam's wall creates an emerald-green sheet of water used for swimming, diving, water skiing, rowing, catamaran rides, windsurfing and sport fishing.

The reservoir was created through dam construction on the Atuel River to manage water supply and produce electricity for the region. This infrastructure project transformed the local landscape and enabled economic development in southern Mendoza.

The dam's name, Valle Grande, is used for the reservoir and the surrounding area south of San Rafael. Near the dam stands a small Christian chapel that predates the later hydroelectric project, and a tunnel dug into the right bank for a planned power station now lies underwater, marked only by a seep of filtered water.

The reservoir is accessible via Provincial Route 173 from San Rafael, with lodging options near the water. Plan your visit during seasons with stable weather for the best conditions to enjoy activities on and around the lake.

The dam's foundations were excavated about 45 m deep, but the lake in front of the wall formed by filtration and shows only the remaining 70 m at the surface. A tunnel bored into the right bank for a planned powerhouse was abandoned and left underwater, betrayed only by a small spring seeping near a small Christian chapel that still stands.