Latin America depends in a very significant way on rivers and dams to supply the lion's share of the region's electrical power needs. According to the International Energy Annual, about 70% of the electrical power produced in Central and South America comes from hydroelectric facilities. Brazil, Colombia, Paraguay, and Venezuela, are the among the world's top 15 producers of hydroelectric energy. And Brazil ranks third, surpassed only by China and Canada.

 

While the hydroelectric dams have supplied the power needs of Latin Americans for decades, the construction of the large projects came at the expense of the environment and local rural populations, including indigenous communities.

 

Large-scale hydroelectric dams, praised for decades as a clean, reliable source of energy, have gone a long way toward helping meet the electricity needs of a large segment of the population in the region. But these facilities have come under increasing scrutiny in recent years by environmental groups that contend that the dams alter both upstream ecosystems, by flooding river basins, and downstream environments, by cutting the natural flow of water. Big dams often have a steep social cost as well, as they displace rural populations, including local indigenous communities.

 

Still, the push continues in the region for more hydroelectric dams, creating new controversies in countries like Brazil, Chile, and even Nicaragua.

 

In Chile, the polemic revolves around a plan by the country's leading electricity producers to construct five dams on the glacier-fed Baker and Pascua rivers. Critics say the projects not only would cause environmental damage but are unnecessary.

 

In Nicaragua, a country with an overtaxed electricity grid that relies on petroleum-burning plants for 80% of its electricity, the government has proposed a huge hydroelectric facility on the Rio Grande de Matagalpa, the country's second-largest river. The project is expected to displace about 1,000 residents.

 

The biggest controversies by far are in Brazil, where the government is strongly backing projects like the Belo Monte Dam despite the objections of local residents, environmental groups, and the Roman Catholic Church.

 

Existing facilities have also created conflicts, such as a dispute over revenues from the massive binational Itaipú dam, the world's largest hydroelectric dam located along the Brazil-Paraguay border. Paraguay has to sell unused electricity to Brazil at avery low prices, and the dispute could end up with international arbitrators.

 

But the regional needs have also led to cooperation efforts, such as the Central American countries' proposal to create a regionally integrated system of electricity generation and distribution.

 

There are other problems associated with hydroelectric power, such as reduced flow. This was the case recently in Venezuela, where an extended drought lowered water levels on the Rio Caroni, greatly cutting output on the Guri Dam, the world's third-largest hydroelectric facility.

 

With few alternatives immediately available, the region is expected to continue to rely heavily on hydroelectric power. But global warming might influence policy. Leaders are going to have to determine whether drought is going to be a recurring problem and, if so, what alternatives (other than fossil fuels) are available.