Laguna Cachi (Costa Rica)

Cachí Lagoon Located in Central America , in the canton of Paradise , in the province of Cartago , in Costa Rica. It was created artificially by the reservoir of the Rio Reventazón , as it flows in a meandering course to the northeast, through a boxed valley. The main population that gives it its name is Cachí, located 1 kilometer from the eastern shore of the lake. It lies within the La Amista-Pacific Conservation Area at an altitude of 990 msnm (MINAE/SINAC-IUCN/ORMA, 1998).


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  • 1 Geographic location
    • 1 Description of the lagoon
    • 2 Represa de Cachí
    • 3 Comunidad Cachí
  • 2 Sources

Geographic location

This lagoon is located in the interior of the Central American country of Costa Rica, in the canton of Paraíso , province of Cartago, in one of the areas with the highest rainfall in the country, with an average annual rainfall between 1,200 and 8,000 millimeters.

Known as “Embalse Lago Cachí (Charrara-Cachí)” (MINAE/SINAC-UICN/ORMA, 1998), geographically it is located in Costa Rica, Cartographic Sheet 1: 50 000 of TAPANTI, at the geographical coordinates 09o 50′ 25” latitude north and 83° 48′ 10” west longitude.

PREPAC, for methodological purposes, used a glossary in which the classification of CACs may be different from how they are usually known in the country; According to the PREPAC Glossary classification, the CAC is classified as a reservoir, although officially the National Geographic Institute references it in the basic cartography, but without a name.

Description of the lagoon

Small artificial lagoon of around 3.24 km². The average water temperature is 22.4 (0m) and 17.7 (8m) degrees Celsius. Some water quality parameters are Hardness 39.86 (0 m) and 37.64 (8 m) mg CaCO3/l; transparency 1.0 m, dissolved oxygen (mg/l) 10.4 (0 m) and 7.6 (8 m); pH 7.65 (0 m) and 6.52 (8 m), and conductivity 0.1 (0 m) and 0.18 (8 m) µSi/cm.

It has a humidity of 87%, annual average. Its precipitation is 3230.8 mm, annual average. Prevailing winds, West-Southwest direction. With average speeds of 30 (from January to March) km/h. With an environmental temperature of 21 ºC, annual average.

It was created by the Cachí dam, which has an arch structural configuration (one of the thinnest in the world), and was built by the Costa Rican Institute of Electricity in 1966 for the production of hydroelectric energy . It was formed with the water flows of the Reventazon river .

It is located in a narrow alluvial plain with abundant contributions of poorly consolidated sedimentary materials, and surrounded by low-lying mountains with steep slopes.

The reservoir contains the Cachí dam (in the northeastern part of the lake), near the town of Ujarrás along National Highway 225 in the middle reaches of the Reventazón River, in the Ujarrás Valley.

The river has a total drainage area of ​​3,000 square kilometers, situated in an altitudinal range that varies from 3,432 meters above mean sea level at its highest point, to the lowest point at its mouth in the Caribbean Sea . The reservoir created by the Cachi dam intersects the 919 square kilometer upper basin.

The main rivers that supply the reservoir are the Grande de Orosi, Reventazón, Reventado and Navarro. Annual precipitation throughout the watershed ranges from 1,200-8,000 mm.

In 80% of the total area of ​​the basin, the relief varies clearly, with the mountains having slopes between 20 and 85 degrees. The average annual inflow of water into the reservoir is at the rate of 104 cubic meters per second. The reserve’s gross storage capacity is 51 million cubic meters.

The project’s flood discharge is 3,500 cubic meters per second. The reservoir has a water extension of 324 hectares (3.24 km²) with a very irregular shape. It extends over a length of 6 kilometers long by 1 kilometer wide on average, and with a maximum depth of 69 meters. 60% of the reservoir basin is covered with forest, the rest is agricultural land.

Represa de Cachí

Engineering work that was built by the Costa Rican Institute of Electricity (ICE) between the 1960s and 1970s, being one of the first hydroelectric projects in Costa Rica. It has an installed capacity of 102 MW with three units with a capacity of 34 MW each.

The project began with three stages: the first unit entered service in 1966, then continued with the second unit in 1967 and the third unit in 1978.6 The Reventazón River provides multiple benefits through the three dams built on it.

The dam was built with a slender double arch concrete structure (said to be one of the slenderest dams of its kind in the world), built to a height of 80 meters above its deepest base. It is located in a narrow gorge and has a crown length of 70 meters. The seizure has 51 million cubic meters of flows from the Reventazón River.

The project was planned, designed and executed by ICE, with the support and technical supervision of Dr. Serafín Laginha, a Portuguese consultant, to build the arch design used. The project was carried out after extensive explorations of the geological features that confirmed the suitability of the site.

During construction, two diversion tunnels with closed controls, designed for a flow rate of 600 cubic meters per second, were built to channel water away from the dam construction site.

It began in 2014 with the expansion of its electricity production capacity, building a new tunnel to conduct water to the powerhouse and installing a new power generation unit and replacing the two existing ones with more modern ones, since the that existed were around fifty years old. With this, the Costa Rican Institute of Electricity intends to reach 100% of clean electricity production, since up to now it is around 98%. Added to this is the Reventazón hydroelectric project in the Canton of Siquirres , Limón .

The species that have been reported to be present in the CAC are Oncorhynchus mykiss, trout; Oreochromis sp, tilapia. Crustaceans such as Procamburus clarkii, shrimp (crayfish) are reported. There is no information on mollusk species present in the CAC (Chinchilla, O. 2004 personal communication).

The Costa Rican Institute of Electricity with offices located in Cachí and the Costa Rican Institute of Tourism with offices located in Charrara, are institutions with a presence in the CAC.

Cachí Community

The small community of Cachi is located in the midst of the natural beauty of the Orosí Valley in the province of Cartago. Cachi is best known for the lake and dam of the same name in the community. This picturesque town is surrounded by lush forests , extensive coffee plantations , rivers, waterfalls, and other small communities, all of which encompass its deeply rooted customs and history.

Travelers interested in exploring true Costa Rican culture will enjoy the relaxed atmosphere of this city. However, despite the size, there are a large number of attractions and activities in the area.

The Cachi lake and dam provide power and prevent flood risks in the area. Although the structure of this city stands in stark contrast to the surrounding greenery, it is a surprisingly beautiful attraction to visit.

The total population of the Cachí district is 5,579, of which 51.03% are men and 48.97% are women (INEC, 2004). The minimum wage reported for the area is US$49.83 (INEC, 2003).

The communities of Cachí, Ujarrás, Ajenjal, and Loaiza have telephone services, drinking water, electricity, a paved road, a health post, and a school (Chinchilla, O. 2004, personal communication). There is no associativity information.


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