Balbina - The Disaster Grows in Size

Glenn Switkes

Balbina reservoir in satellite photo
Balbina reservoir in satellite photo
I was caught by surprise when I stumbled upon an official database on hydroelectric dams and reservoirs in Brazil - the System for Georeferenced Information on the Electric Sector (SIGEL), administered by the electrical energy regulatory agency, Aneel, and found an astounding fact about the Amazon's most catastrophic dam, Balbina.

Everyone knows that Balbina has been a disaster, flooding 2,360km2 of the rainforest including indigenous villages, while generating only 250 MW at full production. But, the SIGEL database confirms that Balbina's reservoir is actually 4,447 km2 in area, nearly twice its officially announced size. The discrepancy could be based on two factors - one is that the dam is apparently operating at a higher level than in its original design. Another may be that sedimentation over the 20 years of the dam's operation has extended the reservoir size.

This would make Balbina's black acidic pirana-infested waters, marked by forests of rotting tree trunks one of the world's ten largest man-made lakes. With Tucuruí's reservoir size also having increased - by 25% - since the dam began operation, also due to a higher operating level, perhaps the government's claims of "kinder, gentler dams" affecting relatively smaller areas of the forest should be afforded closer scrutiny, because they may very well flood much larger areas than advertised.