The El Chocón Dam (Spanish: Represa El Chocón Cerros Colorados) is the fourth of the five dams on the Limay River in the northwestern Argentine Patagonia (the Comahue region), at 381 metres (1,250 ft) above mean sea level. El Chocón Cerros Colorados is on the Limay River at about 80 km (50 mi) upstream of its confluence with the Neuquén River.

El Chocón Cerros Colorados is used to regulate the flow of the Limay River, for irrigation, and for the generation of hydroelectricity. Its power station is the largest hydroelectric power plant in Patagonia, with a capacity of 1,260 megawatts (1,690,000 hp). It was built by the state-owned company Hidronor (Hidroeléctrica Norpatagónica). It started operating in 1973 and achieved full capacity in 1978. In the period 1974–1995, it produced an annual average of 2,700 gigawatt-hours (9,700 TJ). In 1993 it was privatized, with an exploitation concession granted to Hidroeléctrica El Chocón S. A.

While the formal name of the project is Embalse Ezequiel Ramos Mexía, in common use it ended up acquiring the name of the settlement that served as the construction's base of operations, Villa El Chocón (a small town, population 957, as of 2001).

El Chocón is part of a larger engineering scheme that also includes the Cerros Colorados Complex, on the Neuquén River. The Hydroelectric Complex which holds El Chocón and Arroyito Hydroelectric Power Plants, is located in the region known as Comahue, which is formed by the Argentine provinces of Río Negro and Neuquén and the southern area of the Buenos Aires and La Pampa provinces.

The dam is made of earth, with a concrete spillway. About 13,000,000 cubic metres (460,000,000 cu ft) of materials were used. It measures 2,500 metres (8,200 ft) in length. Its maximum height over the river bed is 87 metres (285 ft).

The reservoir has a maximum area of 860 km (332 sq mi), a mean depth of 24.7 metres (81 ft) (maximum 60 metres (200 ft)), and a maximum volume of 206,000,000,000 cubic metres (7.3×10 cu ft). It is used for sailing, sport fishing and other forms of recreation by locals and tourists.

The power plant has six vertical Francis turbines, with a nominal power of 210 megawatts (280,000 hp) each, which rotate at 88 rpm. The apparent powers are 200 MVA for each generator and 180 MVA for each transformer.

Material: Hidroeléctrica El Chocón S.A.

• List of power stations in Argentina

• Structural specifications of the dam
• Hydroelectric dams of Argentina
• Fact Sheet on El Chocon Hydroelectric Power Plant from Global Energy Observatory