El Chocón Dam
| The El Chocón Dam | |
|---|---|
The El Chocón Reservoir, as seen from the International Space Station. The dam is located on the bottom part of the picture. | |
Interactive map of The El Chocón Dam | |
| Official name | Embalse Ezequiel Ramos Mexía |
| Location | Villa El Chocón, Neuquén, Argentina |
| Coordinates | 39°15′57″S 68°45′23″W / 39.26583°S 68.75639°W |
| Construction began | 1968 (assembly of workshops and accessories) |
| Opening date | First unit: December 22, 1972; complete closure: 1977 |
| Construction cost | World Bank financing (~USD 82 million + parallel loans); repair: ~USD 50 million |
| Owners | Hidronor S.A. (initial state-owned); currently Enel Generación El Chocón |
| Dam and spillways | |
| Type of dam | loose material dam |
| Impounds | Limay River, Neuquen |
| Height | 94 m (308 ft) |
| Length | 2,500 m (8,200 ft) |
| Width (base) | 2,250 meters |
| Spillway type | Surface with sector gates |
| Spillway capacity | 8,000 m³/s |
| Reservoir | |
| Creates | Ezequiel Ramos Mexía Reservoir |
| Total capacity | ~20,155 million m³ (20,155 Hm³) |
| Catchment area | Limay River basin (~54,749 km²) |
| Surface area | ~816 km² |
| Maximum water depth | 60–64 m. |
| Power Station | |
| Operator | Enel Generación El Chocón S.A. (concession since 1993) |
| Commission date | Started in 1973; full capacity in 1978. |
| Decommission date | Has not occurred; remains in operation. |
| Turbines | 6 × 210 MW vertical Francis turbines |
| Installed capacity | 1,260 MW |
| Annual generation | 2,700 GWh (historical average); ~3,350 GWh in project design |
| Website https://www.enel.com.ar/es/enel-generacion-el-chocon.html | |
The El Chocón Dam (officially the El Chocón–Cerros Colorados Complex) is one of the most iconic engineering works in Patagonia and the Argentine Republic. Located on the Limay River, in the northwestern region of Patagonia known as Comahue, it is 381 meters above sea level and approximately 80 kilometers upstream from the confluence of the Limay and Neuquén Rivers.
Conceived as part of a strategic hydroelectric development and water regulation plan, El Chocón performs vital functions: regulating the flow of the Limay River, ensuring irrigation water in large areas of the Upper and Middle Valleys, and, above all, generating large-scale hydroelectric power. Its plant is the largest in Patagonia and one of the most important in Argentina, with an installed capacity of 1,260 MW.
The dam's construction was carried out by the state-owned company Hidronor (Hidroeléctrica Norpatagónica S.A.), and it marked a milestone in the history of Argentine public works. The first generator began operating in 1972, and the dam reached full generating capacity in 1977. During the period 1974–1995, the plant produced an annual average of 2,700 GWh, becoming a pillar of the national energy supply.
As of 2025, the engineering project formally known as the Ezequiel Ramos Mexía Reservoir is still commonly referred to by the name of the settlement that served as the basis for its construction, Villa El Chocón. Although small, this town has grown since the 2001 census, and according to the 2022 census, its population is 1,180.
El Chocón is part of a larger hydroelectric project that also includes the Cerros Colorados Complex, located on the Neuquén River. The Hydroelectric Complex, which encompasses the El Chocón and Arroyito plants, is located in the region known as Comahue. This area encompasses the provinces of Río Negro and Neuquén.