Advocates of huge hydroelectric dam projects on the Amazon, Congo, and Mekong rivers often overestimate economic benefits and underestimate far-reaching effects on biodiversity, according to an article in Science by a cadre of scientists representing 30 academic, government, and conservation organizations in eight countries. “These three river basins hold roughly one-third of the world’s freshwater fish species,” said lead author Kirk Winemiller of Texas A&M University. “The 450 additional dams being planned or under construction in these basins put many unique fishes at risk.”

Impacts of the proposed Amazon dams include forced relocation of human populations and expanding deforestation. “Even when environmental impact assessments are mandated, millions of dollars may be spent on studies that have no actual influence on design parameters, sometimes because they are completed after construction is underway,” explained Assistant Professor Leandro Castello, a co-author, who studies how global change affects the ecology and conservation of fish and fisheries. “A lack of transparency during dam approval raises doubts about whether funders and the public are aware of the risks and impacts on millions of people.”

There is a better way, according to the researchers. For the first time, spatial data on biodiversity and ecosystem services are adequate to support sophisticated analyses that balance the costs and benefits of hydropower.

Read the full press release.

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