What is known as the “dry stretch” of 100 km between the dam and the main powerhouse includes two indigenous reserves, plus a population of traditional Amazonian riverside dwellers. Since the impact on these people is not the normal one of being flooded by a reservoir, they were not classified as “directly impacted” in the environmental study and have not had the consultations and compensations to which directly impacted people are entitled. The human rights commission of the Organization of American States (OAS) considered the lack of consultation with the indigenous people a violation of the international accords to which Brazil is a signatory, and Brazil retaliated by cutting off its dues payments to the OAS. The dam will also have more familiar impacts by flooding about one fourth of the city of Altamira, as well as the populated rural areas that will be flooded by the reservoir.What is most extraordinary is the project’s potential impact on vast areas of indigenous land and tropical rainforest upstream of the reservoir, but the environmental impact studies and licensing have been conducted in such a way as to avoid any consideration of these impacts. The original plan for the Xingu River called for five additional dams upstream of Belo Monte. These dams, especially the 6,140 square kilometer Babaquara Dam (now renamed the “Altamira” Dam), would store water that could be released during the Xingu River’s low-flow period to keep the turbines at Belo Monte running.The Xingu has a large annual oscillation in water flow, with as much as 60 times more water in the high-flow as compared to the low-flow period. During the low-flow period the unregulated flow of the river is insufficient to turn even one of the turbines in Belo Monte’s 11,000 MW main powerhouse. Since the Belo Monte Dam itself will be essentially ‘run-of-the-river’, without storing water in its relatively small reservoir, economic analysis suggests that the dam by itself won’t be economically viable.

The official scenario for the Xingu River changed in July 2008 when Brazil’s National Council for Energy Policy (CNPE) declared that Belo Monte would be the only dam on the Xingu River. However, the council is free to reverse this decision at any time. Top electrical officials considered the CNPE decision a political move that is technically irrational. Brazil’s current president blocked creation of an extractive reserve upstream of Belo Monte on the grounds that it would hamper building “dams in addition to Belo Monte”. The fact that the Brazilian government and various companies are willing to invest large sums in Belo Monte may be an indication that they do not expect history to follow the official scenario of only one dam.

In addition to their impacts on tropical forests and indigenous peoples, these dams would make the Xingu a source of greenhouse-gas emissions, especially methane (CH4) which forms when dead plants decay on the bottom of a reservoir where the water contains no oxygen. The Babaquara Dam’s 23m vertical variation in water level, annually exposing and flooding a 3,580 square kilometer drawdown zone would make the complex a virtual ‘methane factory’. The reservoir’s flooding of soft vegetation growing in the drawdown zone converts carbon from CO2 removed from the atmosphere by photosynthesis into CH4, with a much higher impact on global warming.