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-Tocantins-Araguaia moist forests many smaller blackwater rivers including the Pacajá and Anapu tributaries of the Amazon River, the Bacajá and Fresco tributaries of the Xingu, and the Parauapebas and Catete tributaries of the Tocantins. The ecoregion is in the neotropic ecozone and the tropical and subtropical moist broadleaf forests biome. The Köppen climate classification is "Am": equatorial, monsoonal. Temperatures are fairly steady throughout the year, slightly higher in April and slightly lower in July. Average temperatures range from , with a mean of . The region is drier than the ecoregions further to the west. In the middle Xingu annual rainfall is .