In the humid heart of South America, on the border between Brazil and Paraguay, thunder once echoed louder than anywhere else on Earth.
It wasn’t war.
It wasn’t industry.
It was water — crashing, tumbling, roaring.
This was Guara Falls, a monumental natural marvel made up of 18 colossal waterfalls, whose combined roar could be heard over 30 kilometers away. Its flow was twice the volume of Niagara Falls, and every hour of every day, a rainbow arched above its misty plume like a crown on a forgotten king.
But in 1982, it vanished — not through erosion, not by drought — but by deliberate destruction. The Brazilian military obliterated it, leveling its ancient bedrock and swallowing it beneath a man-made sea. What replaced it wasn’t a natural wonder, but an engineered one: Itaipu Dam, the second-largest hydroelectric facility in the world. A monument to human ambition, and a cautionary tale for the planet.
This is the story of how a river was tamed, how a natural paradise was sacrificed, and how an energy megastructure now looms as both savior and villain.
Paradise Drowned
Before its death, Guara Falls wasn’t just beautiful — it was profitable. Tourists came in droves, lured by its raw power, its permanent rainbow, and its proximity to the more famous but less intense Iguazu Falls. Locals spoke of its voice — a constant thunder that rolled across the valley. But beneath the spectacle lay tension.
Brazil’s economy was booming in the 1960s, growing at nearly 10% per year, and the population was exploding. Energy shortages loomed. The solution? Tap into the Piranha River, South America’s second-longest, which cut through ancient rock along the Brazil-Paraguay border. There, a narrow gorge named Itaipu offered the perfect bottleneck for a dam.
Only one problem: Paraguay.
Still nursing scars from the catastrophic War of the Triple Alliance (1864–1870), Paraguay had lost much of its land and population to Brazil and Argentina. A border dispute, colonial resentment, and a failed river-diversion attempt in the 1960s meant any joint project was politically radioactive.
But necessity is a potent motivator. By the early 1970s, diplomatic pressure and military occupation by Brazil convinced Paraguay to come to the table. In 1973, they signed the Itaipu Treaty, creating a binational company — Itaipu Binacional — and splitting power output 50/50. Though in practice, the split was anything but equal.
A River Rerouted
The first challenge: reroute the river. Not metaphorically. Literally.
To build the dam, engineers had to divert the Piranha’s centuries-old path. A diversion channel was dug — 2 kilometers long, 150 meters wide, 90 meters deep — the largest ever attempted. It took three years, 50 million tons of rock and earth, and enough explosives to shake the valley. On October 30, 1978, dynamite blew open the channel. The river obeyed.
To keep the construction site dry, engineers built coffer dams, colossal embankments that stood between the workers and the watery chaos waiting to return. With the river temporarily tamed, construction began.
But rerouting a river was child’s play compared to what came next: flooding a world.
Submerging the Past
To generate power year-round, the dam required a reservoir the size of a small nation — 1,350 square kilometers, or nearly twice the size of Chicago. It would reach depths of 100 meters, swallowing whole forests, villages, and ecosystems.
The task of evaluating what would be lost was gargantuan. Military helicopters flew photo missions. Surveyors documented every farm, home, and tree. The result: 8,500 homes bought, 40,000 people displaced, $500 million spent on real estate alone — and the complete annihilation of Guara Falls.
Wildlife rescue? Just 17 people, mostly volunteers. A gesture more than a plan. When the floods came in 1982, they moved fast. 14 days to erase millennia.
An Engineering Goliath Rises
Itaipu is not just a dam. It’s a civilization in concrete.
At its core is a gravity dam weighing 61 million tons — the mass of 6,000 Eiffel Towers. The dam is segmented into 18 massive concrete blocks, each taller than Big Ben and cooled by giant freezer systems to avoid cracking under South America’s sun.
To mix this much concrete, six massive plants worked day and night, pouring 12.3 million cubic meters. Meanwhile, massive rock-crushing facilities pulverized 2,430 tons per hour, and seven aerial cableways ferried materials across the construction site in a never-ending ballet of motion.
By 1982, the final sluices were shut. In weeks, the waters surged, and Guara Falls disappeared beneath them — dynamited, flattened, erased.
Death and Power
Tragedy struck just before the flood. On January 18, 1982, an overloaded footbridge near the falls collapsed, sending 40 people to their deaths, visitors desperate for one last look.
During the flooding, a desperate rescue effort tried to save 30,000 stranded animals. Most died. And entire communities watched as their homes — some for indigenous Avá Guaraní families — vanished underwater. 688 families, gone.
But the dam delivered what it promised: power. Turbines the size of buildings, weighing 6,600 tons each, were installed between 1984 and 2007. Each turbine generates 700 megawatts, and Itaipu now delivers 14,000 megawatts total — nearly 20% of Brazil’s and 90% of Paraguay’s energy.
The total output? Enough to power the world for 43 days straight.
Politics, Profit, and Parity
Under the original deal, Paraguay was required to sell its unused energy to Brazil at cost — sometimes as little as $10 per megawatt-hour, while Brazil resold it for six times more. The arrangement fueled decades of political tension.
Between 1985 and 2012, Brazil consumed 93% of Itaipu’s output, essentially subsidizing its industries with cheap energy. Paraguay? It received minimal revenue and couldn’t sell its power on the open market.
Until recently.
In 2023, Paraguay fully repaid its debt and began renegotiating treaty terms. It now has the right to sell directly to Brazil’s private sector — or elsewhere. By 2026, this could net $600 million a year in new revenue. For a small country, this is seismic.
The newfound wealth is transforming Paraguay. With the highest GDP growth rate in Latin America in 2024, it’s leveraging Itaipu’s energy for tech-driven industries like green hydrogen and crypto mining.
Legacy and the Future
So what now?
Environmentally, the cost was immense: forests lost, species extinct, entire cultures erased. But Itaipu prevented the burning of hundreds of millions of tons of fossil fuels, offering a clean energy model for a region still hooked on hydrocarbons.
Large-scale reforestation efforts are underway, particularly to restore indigenous lands and preserve the dam’s water quality. But critics say these efforts only exist because they benefit the dam — not because of moral reckoning.
Still, Itaipu is here to stay. It’s counted among the Seven Engineering Wonders of the Modern World. It fuels two nations, and its output helps fight climate change. But it’s also a paradox — a monument to destruction in service of survival.
What was lost can’t be recovered.
But what was gained may yet shape the future of an entire continent.
FAQ: Itaipu Dam and the Lost Guara Falls
What were Guara Falls?
Guara Falls was a cluster of 18 massive waterfalls on the Brazil-Paraguay border, twice as powerful as Niagara and a major natural attraction until destroyed in 1982.
Why was Guara Falls destroyed?
To build Itaipu Dam, a massive hydroelectric project that required flooding the falls’ location for the creation of a reservoir.
How large is the Itaipu Dam?
It stretches 8 km across the Piranha River, with a total generating capacity of 14,000 MW, making it one of the largest in the world.
Who owns Itaipu Dam?
It is jointly owned by Brazil and Paraguay under a binational treaty established in 1973.
Why is there political tension over the dam?
Paraguay was historically required to sell excess electricity to Brazil at reduced rates, leading to disputes over fairness and sovereignty.
How much power does it generate?
Since 1984, Itaipu has generated over 3 billion gigawatt-hours — the most of any hydro plant globally.
What happened to local communities?
Over 40,000 people, including indigenous groups, were displaced. Many communities were permanently flooded.
Are there environmental consequences?
Yes. Vast forests were lost, wildlife perished, and ecosystems collapsed — though some reforestation has since occurred.
Can Paraguay now sell energy to other countries?
Yes, thanks to recent treaty renegotiations, Paraguay can sell directly to private markets, increasing its revenue and energy independence.
