It's been one dam story after another in South America in the past week or so.
The 2,750 Mw HidroAysén dam in southern Chile got the green light from an appeals court after a three-month suspension to review objections from environmentalists.
The on-again-off-again Belo Monte dam in Brazil is off again, at least for the moment. A judge suspended construction because of the likely impact on fish stocks and local communities that depend on fisheries. The dam would also flood an area occupied by indigenous people.
But flooding - with the related methane emissions, as Philip Fearnside of Brazil's Amazonian Research Institute has pointed out - is not the only environmental impact of a dam like Belo Monte. As with most megaprojects, people flock to the area looking for work ... and tend to stay, clearing land and putting even more pressure on natural resources.
The Belo Monte project is not one dam, but a series of dams planned for the Xingú River. Upstream dams can be used to control the flow of water to hydroelectric plants further downstream. That is why plans for the Inambari dam in southeastern Peru are probably not dead yet, even though government officials insist that it is not on the table. Besides generating some 2,000 Mw of electricity - mainly for export to Brazil, because Peru doesn't need that amount of additional energy right now - the Inambari dam would be used to control the flow of water downstream to a series of dams on the Madeira River in Brazil.
Planners tend to look at hydroelectric dams in terms of kilowatt hours and flow control. But a river is more than a conduit for water - it's an entire complex ecosystem, as Ernesto Raez of the Center for Environmental Sustainability at Cayetano Heredia University in Lima points out. This animated video from the center is an excellent introduction to Amazonian river ecosystems and the impact of dams.
Inambari is only one of a number of hydroelectric projects on the drawing board for the Peruvian Amazon, and Brazil is the country most interested in seeing them built. Many would flood indigenous communities - which means they will face local consultation processes under the new "prior consultation law" signed by Peruvian President Ollanta Humala in September 2011. Most would be located on the steep eastern slope of the Andes mountains - a steeply inclined area with a lot of rivers, but also one of the most unexplored regions on the continent.
Because it's the place where the Andean and Amazonian ecosystems meet, the cloud forest is one of the hottest of the world's biodiversity hot spots. Ecuador's Yasuní Biosphere Reserve is usually cited as one of the most biodiverse places on the planet, but tropical ecologist Greg Asner of the Carnegie Institution for Science at Stanford University says that is probably because most of the rest of the cloud forest in Ecuador and Peru hasn't been explored, as the area is very remote and access is difficult.
So there's no real base line against which to compare the impact of a dam , a highway or any other "development" project that will bring people into an unstudied ecosystem. No one can say for certain what will be lost, because no one really knows what's there. And a two-week - or two-month - environmental impact study would not even scratch the surface.
It is ironic that the resurgence of interest in major hydroelectric projects in South America comes just as the United States is ditching dams and restoring rivers to their natural state. A World Bank energy expert told me a couple of years ago that the new hydroelectric projects in Latin America would be kinder, gentler dams, but the Belo Monte, Madeira and Inambari projects look like the big dams of the past. There's no question that Latin American countries will have to meet increasing demand for energy as their economies continue to grow, but instead of rushing to clog the western Amazon basin with dams, each country should perform a realistic projection of future needs and an honest assessment of its options - and their economic, environmental and social impact - with full transparency and public participation.
Barbara Fraser is a freelance journalist based in Lima, Peru. With 20 years of experience in Latin America, she puts a human face on current events and public policy. She offers research, writing, editing and photography services, with particular expertise in Latin American, environmental, public health and social issues.