Viewpoint – Decision Making on Amazon Dams: Politics Trumps Uncertainty in the Madeira River Sediments Controversy

The Madeira River, an Amazon tributary draining parts of Bolivia, Peru and Brazil, has one of the highest sediment loads in the world. The questions of how these sediments would affect the Santo Antônio and Jirau hydroelectric dams, now under construction in Brazil, and how the dams would affect sediment flows, have been the subject of an extended controversy associated with the environmental licensing of the dams. Shortly before licensing the dams, the official scenario changed completely from one in which sediments would accumulate rapidly but could be contained without damage to dam operation, to one in which there would be no accumulation of sediments at all. The uncertainty of this scenario is very high. Under political pressure, the technical staff of the licensing department was overridden and the dams were licensed and built without resolving a variety of controversies, including the question of sediments. Valuable lessons from the Madeira River sediment controversy could contribute to improving decision making on dams and other major development projects in Brazil and in many other countries