In an Opinion piece published in the New York Times, Dr. Philip Fearnside, an ecologist at the National Institute for Research in Amazonia in Brazil, “one-fifth of all of the water that runs off the surface of the Earth ends up in” the Amazon basin. This area has been called a “hot spot for future hydropower expansion” since “The flows of these rivers can generate a lot of electricity…At least 158 dams are either operating or under construction now in the river basin, according to a study last year in the journal Nature Communications, and an additional 351 have been proposed.”
Brazil, Peru, Bolivia and Ecuador “have big plans for Amazonian dams.” Unfortunately, “plans for these big, disruptive projects are often shrouded in secrecy.” Mega dam building in the Amazon region is “driven by the country’s agricultural and heavy industrial interests, is being carried out with little regard to the impacts on Indigenous people and the environment, is proceeding with little effort to capitalize on the nation’s vast renewable energy potential, and is often fueled by corruption.”
Dr. Fearnside reports that the negative environmental impacts of megadams include:
—”some lowland dams in the Amazon actually may exceed the carbon emissions rates of fossil fuel plants.”
—”Dams can block annual fish migrations… after Brazil built one dam on the Madeira, in 2011, and another in 2013, fish catches in what had been the world’s second greatest riverine fishery plummeted in Brazil, Bolivia and Peru.”
—”nutrient-rich sediments carried by these rivers are trapped behind dams rather than carried downstream and deposited on flood plains, where they are essential for agriculture. “
—”forests…drown in the sprawling reservoirs behind them and are cut down to make way for the accompanying development and to clear paths for transmission lines strung across vast distances”
—”Mercury that occurs naturally in the soil as well as in runoff from gold mining operations that can often be found upriver of dams can be transformed into highly poisonous methylmercury through a chemical reaction at the bottom of reservoirs, where there is almost no oxygen in the water”
—”the lack of oxygen at the bottom of these reservoirs also causes another chemical reaction that produces methane, a highly potent greenhouse gas”
—”A 2014 study in the journal Energy Policy warned that “in most countries large hydropower dams will be too costly in absolute terms and take too long to build” to make sense.”
You can read the entire Opinion piece here. Translation into Spanish and Portuguese is also available.