The El Yeso reservoir is an artificial reserve of water accumulated through a dam located in the Andes mountain range.

Location, ownership and function

The reservoir is located in the place called Boca del Valle, located 23 km upstream from the junction of the Yeso River with the Maipo River,1 at an altitude of 3000 meters above sea level, in the commune of San José de Maipo, Cordillera Province. , Santiago Metropolitan Region. It was built to provide security for the area's drinking water supply and irrigation.

Dam

The dam is an earth dam, with an inclined clay core with a length of 350 m, a height of 62 m, 6 m wide at its crest and a wall volume of 1,560,000 m³. The slope facing the water is protected by a layer of rockfill with a variable thickness of between 0.40 and 1.0 m, and downstream with rockfill one meter thick. The storage capacity of this reservoir is 250 million cubic meters.1​

Hydrology

The reservoir basin has an average elevation of 4000 meters above sea level and an area of ​​360 km², to which a snowy hydrology is attributed due to its high altitude. Its average annual flow entering the reservoir is 10 m³/s and its highest magnitudes occur between December and January.2​ Its storage capacity amounts to 250 hm³.

It is a short 10-minute tour where you can take photos and see the place where mine workers previously lived more than 200 years ago.

It is an abandoned place, however some families still live there.