Yacyretá is a hydroelectric dam located in the Paraná River between Argentina and Paraguay. The dam is named for Yacyretá Island just upstream, much of which the dam submerged. The dam is 808 metres (2,651 ft) long and has 20 turbines with a power of 4050 MW that can produce 19 080 GWh. It is a joint project between Paraguay and Argentina.

The project generated controversy and criticism during its planning and construction because of the effects it had on local ecology, particularly the flooding of a unique environment causing the extinction in the wild of several species. The financial management of the project also had criticism, as it greatly exceeded its original budget, ultimately costing more than $11 billion.

The lake created by the dam displaced 40,000 people. The elevation of the water level also affected the road infrastructure and sewage of the region in a way that many studies undertaken prior to construction of the dam did not take into account.

Ecologically, it affected the environment by altering aquatic habitats via the elevation of the water level and the flooding of previously dry areas, producing chemical changes in the water, including a drop in water oxygen levels. The calm water behind the dam has also allowed the spread of waterborne diseases and disease vectors, such as schistosomiasis, dengue fever and malaria.

In 2014 Paraguay consumed almost 5 percent of its share of Yacyreta’s production, exporting the rest to Argentina.

More Info: en.wikipedia.org