Los Caracoles

San Juan

Historically, the province of San Juan has made great efforts to ensure the water supply because its dry climate and low rainfall requires the optimization of water resources. For this reason, the systematization of the river has always been a key aspect of local development to regulate its unpredictable water flow. In this sense, the Los Caracoles Hydroelectric power plant was designed to secure and expand regional irrigation capacity improving the quality of farmland and contributing to the expansion of the energy sector.

A project for energy and irrigation

125 MW

Potencia instalada

17.000 ha

Reserva de agua para riego

8.735.335 m3

Movimiento de suelos

213.735 m3



Los Caracoles hydroelectric power plant


EPSE (Energía Provincial Sociedad del Estado


The dam at Los Caracoles is made of loose materials with a concrete face and a volume of 10.35 billion cubic meters of compacted filler material, forming a reservoir with a capacity of 565 cubic hectometres and a surface area of 1,290 hectares. The dam rises 136 meters above the riverbed and has a crown of 620 meters in length.

Inside, the dam has monitoring instruments that provide information about its behavior throughout its lifetime.

The flood spillway is designed for a maximum flow of 3,200 cubic meters per second. It is located on the left bank of the dam and consists of an outflow with two radial gates measuring 9.5 meters x 17.8 meters. This is followed by two tunnels of 330 meters long, with an initial gooseneck-shaped tranche at an angle of 60 °, then a straight section with a 10% gradient, and finally the outflow itself, which has a ski jump followed by a stilling.

The powerhouse is a reinforced concrete structure of 30 meters in height, containing a bridge crane with a 110 ton-capacity, used to assemble the turbines and generators. Currently, it is used for operations and maintenance.

The headrace tunnel is 1,526 meters long. At its top end in the reservoir there is an intake tower in reinforced concrete which is 14 meters high and equipped with metal bars and a well where the operation and maintenance floodgates are housed. At the other end, the gallery has a 80 meter-high surge chamber, fully excavated in rock and covered in reinforced concrete.

The reservoir water reaches the hydroelectric plant, dropping the last 100 meters through a penstock which is 5.50 meters in diameter to begin with, narrowing to 4.30 and finally forking off to reach each turbine with 3 meter-diameter branches.

The energy produced by the hydroelectric power station is transported to the city of San Juan along a high voltage 132 KV line which is 47.9 kilometers long.

El agua del embalse llega a la central hidroeléctrica, descendiendo los últimos 100 metros a través de una tubería forzada que se inicia con 5,50 metros de diámetro, luego se reduce a 4,30 y, finalmente, se bifurca para llegar a cada turbina, con ramales de 3 metros de diámetro.

La energía producida por la central hidroeléctrica es transportada hasta la ciudad de San Juan mediante una línea de alta tensión de 132 kilovolts y de 47,9 kilómetros de longitud.

2.778 m

Longitud de túneles

11.466.379 m3


1.290 ha


620 m

Longitud de coronamiento presa