Yacyretá Dam: A Comprehensive Overview
Yacyretá Dam: Location
Geographic Location
The Yacyretá Dam is situated 1,000 kilometers north of Buenos Aires and 300 kilometers from Asunción, in the vicinity of the Yacyretá, Apipé Grande, and Talavera Islands. It extends up to the cities of Ituzaingó and Ayolas, 80 kilometers downstream from Posadas and Encarnación, adjacent to the main branch of the Paraná River. The structure spans 808 meters in length and approximately 80 meters in width.
The dam lies on a stretch of the Paraná River flowing from east to west, in the southeast of Paraguay and northeast of Argentina. The powerhouse is near the cities of Ayolas (Misiones, Paraguay) and Ituzaingó (Corrientes, Argentina). It is 1,470 navigable kilometers from Buenos Aires and 310 kilometers by road from Asunción. The nearest provincial capital is Posadas, Argentina, 90 kilometers to the northeast.
Description of the Hydroelectric Power Plant
Construction commenced on December 3, 1983. On April 26, 1989, an Exchange of Notes defined the final layout of the protection areas in the tributary stream valleys on the right (Paraguayan) margin. The main section of the river was closed in June of the same year. On May 19 of the following year, the second arm of the Paraná River (Ana-Cua) was closed with a landfill and 16 radial gates. Together with the main spillway, these gates can discharge up to 95,000 m3/s. A navigation lock was built on the Argentine side of the main arm to bridge the height difference, ensuring continuous river navigation. This lock became operational before the reservoir was filled. The first hydropower unit began operating between June 1, 1993, and September 2, 1994. All 20 units were fully operational by July 7, 1998.
The plant has a total installed capacity of 3,200 MW, with an expansion project planned to nearly double this capacity, potentially supplying 15% of Argentina’s total electricity demand.
Each turbine can process 2,630 million liters of water per hour. The 20 turbines combined can process the equivalent of Asunción’s 13-day drinking water supply or Buenos Aires’ 2-day supply every hour. The annual energy production is 19,000 GWh, equivalent to 65% of the combined power generation of Paraguay and Argentina.
Yacyretá is a run-of-the-river power plant that harnesses the Paraná River’s flow for continuous energy production. The powerhouse, housing the 20 hydraulic units, measures 70 meters high, 80 meters wide, and 816 meters long—comparable to a 20-story building spanning eight blocks. The construction of the 20 hydraulic units used more steel than 40,000 large cars.
Powerful cranes operate the gates and perform maintenance. Four fish transfer systems at both ends of the powerhouse maintain biological continuity between the river and the reservoir. A navigation lock accommodates vessels up to 3,600 cubic meters (12 feet).
Despite its benefits, the project faced criticism regarding its environmental impact, including the flooding of a unique biome and the extinction of endemic species. Management of the project also drew criticism due to budget overruns (reaching $11.5 billion) and allegations of corruption.
Dam Structure and Reservoir
The dam is a low-rise, loose material structure extending approximately 65 kilometers, with 28 kilometers on the Paraguayan side and 17 kilometers on the Argentine side. The remaining 20 kilometers are on Yacyretá Island, also home to the concrete structures of the two landfills and the powerhouse. As of February 2009, the dam’s height was 18 meters, with plans to add 5 meters by mid-2011.
The Paraná River basin covers 970,000 km2, mostly in Brazilian territory.
Fish Transfer Facilities
The powerhouse has four fish lifts at each end to facilitate fish passage between the river and the reservoir. These lifts are large, square buckets (4m x 4m) that are filled with water and fish and then lifted to the reservoir level. The fish are then released through special channels. Temporary “descenders” prevent fish from falling from the channel outlets, which will eventually be submerged in the reservoir.
These facilities operate continuously, managed by personnel supervised by biologists. The frequency of operation varies seasonally and depends on fish behavior.
The fish transfer system includes intakes downstream near units 7 and 14, connected to the fish facilities at the plant’s ends. Fish are drawn into the intakes by pumps, concentrated, lifted, and discharged into the reservoir.