The rains had been monumental throughout April 2014. By early May, the operators of the 219 MW Cachoeira Caldeirão dam being built in Brazil’s remote Amapá state knew that levels on the Araguari river were dangerously high. If some water was not released fast, the whole thing might collapse. There would be no danger to people because any run-off would be absorbed by two other dams downstream, the hydropower company thought.

But communications failed and no one warned the small town of Ferreira Gomes, nestled on the banks of the Araguari nearly 50km away.

On 7 May, seven hours after millions of gallons of water rushed out of the temporary coffer dam, the Araguari rose by 17 feet. Ferreira Gomes was swamped; public buildings were swept away, more than 1,000 homes and other buildings were flooded and thousands of people were forced to evacuate.

There is little evidence of that flood today in Ferreira Gomes and, seen from the air, the dam’s 30 sq km reservoir, surrounded by lush equatorial rainforest, looks quite natural. But the accident proved to Moroni Remuyna and many others in the town that big dams are dangerous to people and the environment, and that they do not bring development. “The history of dam-building has been one of incompetence, greed, illegality and callousness,” says Remuyna.

He works with Dam Affected People (Movimento dos Atingidos por Barragens), a grassroots Brazilian NGO that opposes inappropriate dams. He says that the first dam built on the Araguari was also the first in the Amazon basin. “It was 1979. People were promised compensation when they were made to move, but no one got anything.

“In 2010 they built a second, bigger dam on the river. There was more deforestation and a massive die-off of fish. More people were forced to move and the river has never recovered ecologically. We are now worse off than before,” Remuyna told the Guardian earlier this year.

“The authorities said only 350 people were affected in Ferreira Gomes but it was thousands. Many people never got any compensation after the flooding. The government promised us economic development but they destroyed livelihoods.”

The rush for energy

Brazil is home to three of the world’s largest dams, including the Itaipu project on the Paraná river. Photograph: Bloomberg via Getty Images

The damage done by dam-building to the environment and communities living along the Araguari has been more or less repeated across Latin America over the past 40 years, as countries have rushed to industrialise and generate electricity for cities.

With 256 large dams built or planned, Brazil generates nearly 65% of its electricity from hydropower [pdf]. The country is home to three of the world’s largest dams, including the mighty 14,000MW Itaipu project on the Paraná river, on the border with Paraguay.

Other countries are catching up. Of the 412 dams built, under construction or proposed in the Amazon basin in 2015, 77 were in Peru, 55 in Ecuador, 14 in Bolivia, six in Venezuela and two in Guyana. Meanwhile, Chile, Argentina, Bolivia, Costa Rica, Nicaragua, Panama, El Salvador and Honduras are all building large dams.

The benefits of dams are proven, according to the London-based International Hydropower Association (IHA), which says dams now account for roughly 65% of all electricity generated in the continent. Together, South American countries installed around 10GW of hydropower in 2016, nearly as much as China.

“Over 1,200GW of renewable hydro energy is now operating in South America – enough to supply clean electricity to more than one billion people. But the potential is there to develop three times as much,” says the association’s latest report on the state of the worlds hydropower [pdf].

“We need more hydropower on the grid, as it plays a role as a flexible, sustainable generation source. We also need it to play the often unrecognised role of energy storage,” said IHA president Ken Adams at a meeting of governments and dam builders in Addis Ababa in early May.

“Better hydro is an important way to meet the goal of sustainable energy agreed on by all countries, and the ambition of the Paris climate agreement. It offers affordable, cleaner, reliable energy as well as storage,” said Rachel Kyte, former World Bank climate chief and now CEO of Sustainable Energy for All (SE4All).

Big dams in South America have long been seen as symbols of national pride, and evidence of economic progress. Politicians, such as Ecuador’s Rafael Correa, point out that 50 years of construction have reduced poverty, helped meet an insatiable demand for electricity and clean water, and allowed countries to industrialise and urbanise rapidly and cheaply. Remote areas of the continent have been opened up to mining and farming, and clean hydro-electricity is the most efficient way to provide energy security, store critically needed water and control the flow of rivers.

Monuments of social inequity

Environmentalists shout slogans in front of riot policemen during a rally against a hydropower dam proposed for the southern Chilean Patagonia, in Santiago in 2011. Photograph: Victor Ruiz Caballero/Reuters

But in an intense and polarised debate that has raged on for more than 25 years, critics of big dams in Latin America argue that many of them are monuments of injustice, political corruption and social inequity.

Critics, including Bianca Jagger, say that an unaccountable industry, encouraged by governments to steamroll over environmental and human rights laws, and sweep aside evidence of ecological damage, has worked with dictators and corrupt governments to destroy vast swaths of forest and ruin livelihoods, penalising people who live in the world’s untouched regions where rivers are most suitable to be dammed.

Far from providing clean energy, dams increase climate emissions by drowning forests and lead to corruption, says International Rivers, the world’s most vocal river protection group.

“Rivers are seen by governments only as a resource, not as a source of livelihoods,” says Kate Horner, the group’s director. “Vast money is involved in these mega-projects and there are often implications of corruption. Seldom is anyone held responsible for the violence and intimidation that often accompanies dam building.

“The displacement of people has been vast, comparable to conflict-induced displacement. But there is not the same humanitarian response. Compensation is often not paid. States and governments have responsibility, but companies should not be allowed to benefit.”

Dam-building has been strongly implicated in Brazil’s ongoing corruption scandal. Last year, senior executives of one of the country’s largest construction firms testified to the existence of a cartel of major companies, influential politicians and high-level government bureaucrats who had rigged bids, engaged in bribery and offered kickbacks on major dam projects.

Elsewhere, Chinese companies have built dozens of large dams for Latin American governments in return for oil and access to minerals and food. But, say critics, the deals are opaque, the companies are unaccountable and operators are often given loopholes to bypass requirements to protect fish, wildlife and water quality.

Dam builders on the back foot

Worldwide opposition to big dams peaked in the 1990s when giant Chinese and Latin American projects, such as the Three Gorges, the Narmada and the Yacyretá dams – became the targets of international environmentalists. This led to an exhaustive World Bank-led study, which concluded in 2000 that while big dams were important for development, “in too many cases an unacceptable and often unnecessary price had been paid to secure those benefits”. Since then, builders have reframed dams as a climate change panacea and a way to meet the energy storage challenge.

The Yangtze river runs through the discharging dam of the Three Gorges hydropower project. Worldwide opposition to big dams peaked in the 1990s. Photograph: Andrew K/EPA

A new wave of building and opposition has now begun across Latin America, but human rights abuses and the murder of activists, such as Goldman prize winner Berta Caceres, has again focused attention on how dams can affect indigenous groups.



Brazil’s determination to develop a series of huge linked dams on the Xingu, Teles Pires and Juruena rivers has become an international issue. Others on the Araguaia and Tocantins rivers would impact 11 ethnic groups.

“Few indigenous people ever recover from the economic and psychological disruption caused by dislocation,” says William Fisher, professor of international development at Clark University. “Displacement severs often strong spiritual and cultural attachments to land and threatens the communal bonds and cultural practices which hold these societies together.”

Dam builders are increasingly on the back foot. Climate change increases the need for renewables, but because hydropower is widely used to cool power stations, any reduction in river flow caused by droughts only adds to the energy crisis. Once built, solar plants are cheaper than thermal power stations to operate.



In 2014, Chile cancelled five dams in the Patagonia region under strong public pressure, and approved 700MW of new solar and wind farms. Work on the Belo Monte dam in Brazil has been halted and major projects in Peru and Honduras have been abandoned after protests.



The era of big dam-building is not over, but technological progress and economies of scale now offer governments alternatives that did not exist 20 years ago. In places such as Patagonia and the Atacama desert, South America has some of the best wind and solar sites in the world. Better-designed smaller dams and geothermal and marine energy are now being discussed.



There are few remaining wild rivers in Latin America and many that have already been dammed are likely to be impounded again and again. Back in Amapá state, the people of Ferreiro Gomes fear that the Araguari will be further diminished. “There are proposals to build another, possible two more dams on the Araguari,” says Remuyna. “This would mean the end of the river and fishing as we know it. Where will it end?”

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