19 Apr 2012: 151 Planned Dams Threatens
Balance of Andean Amazon, Study Says

A new study warns that 151 hydroelectric dams planned along six major rivers in the Amazon basin over the next two decades, including dozens of so-called mega-dams, could significantly disrupt the region’s ecological connectivity. Writing in the online journal PLoS ONE, researchers say 60 percent of the dams currently being planned would cause the first major break in river connectivity between the Andean headwaters and the lowland Amazon, possibly threatening the free flow of several Andean-Amazon rivers. The Andes provide most of the sediment, nutrients, and organic matter to the species-rich Amazonian floodplain, a vast region that spans Bolivia, Brazil, Colombia, Ecuador, and Peru. Many fish species spawn only in rivers fed by the Andes. In addition, the study found that the majority of the projects would cause increased forest loss because of new roads and transmission lines. “There appears to be no strategic planning regarding possible consequences to the disruption of an ecological connection that has existed for millions of years,” said Matt Finer of the U.S.-based Center for International Environmental Law and lead author of the study. If built, the planned projects would increase the number of dams in the region by 300 percent. More than half would be large dams generating more than 100 megawatts; about 40 percent are already in advanced stages of planning.