Amazon river dolphin widespread river dolphins. They are present in six countries in South America: Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela, in an area covering about . The boundaries are set by waterfalls, such as the Xingu and Tapajós rivers in Brazil, as well as very shallow water. A series of rapids and waterfalls in the Madeira River have isolated one population, recognized as the subspecies "I. g. boliviensis", in the southern part of the Amazon basin in Bolivia. They are also distributed in the basin of the Orinoco River, except the Caroni River and the upper Caura River in Venezuela. The
Xingu River extracting from the river most of what they need for food and water. The Brazilian government is building the Belo Monte Dam, which will be the world's third-largest hydroelectric dam, on the Lower Xingu. Construction of this dam is under legal challenge by environment and indigenous groups, who assert the dam would have negative environmental and social impacts along with reducing the flow by up to 80% along a stretch known as the Volta Grande ("Big Bend"). The river flow in this stretch is highly complex and includes major sections of rapids. More than 450 fish species have been documented