Embalse El Yeso, Mountain reservoir in Santiago Metropolitan Region, Chile

Embalse El Yeso is a reservoir in the Santiago Metropolitan Region of Chile, located at an altitude of 2,568 meters (8,425 feet) in the Andes. The body of water holds 250 million cubic meters and sits between rocky mountain slopes in a narrow valley.

Workers built on-site shelters in the 1950s to construct the reservoir as part of the water infrastructure for Santiago. The dam was completed in 1964 and has since supplied the river valley with water for farming and the city.

The reservoir takes its name from the Yeso River, whose name means gypsum in Spanish, after the mineral found in the valley. Its turquoise-green water, seen in the photographs, is fed by snowmelt from a catchment averaging 4,000 m in elevation. Fishing is the only water sport allowed; camping, hiking and mountain biking are permitted year-round.

Access requires permits from CONAF and certified guides for the drive into the mountains. The season typically runs from October through May but can shift depending on snowfall and weather.

The reservoir is operated by Aguas Andinas and forms part of a supply system that also includes the nearby Laguna Negra and Laguna Lo Encañado. In 2023 the company ran a preventive discharge test after the reservoir passed 90% of its capacity.