The history of Itaipú begins with an old shared aspiration: to harness the enormous hydroelectric potential of the Paraná River on the stretch separating Paraguay from Brazil. The Paraná, one of the mightiest rivers in the world, offered exceptional conditions in that area for generating energy on a large scale, but its exploitation required an agreement between the two countries that share its waters.
After years of negotiations, not without diplomatic tensions —among them, the dispute over the Salto del Guairá area—, Paraguay and Brazil signed the Itaipú Treaty in 1973, which laid the legal foundations of the future plant. The agreement created the binational entity Itaipú, owned in equal parts by both states, and established the regime of construction, financing, operation and sharing of the generated energy. It was a milestone of South American diplomacy and integration, though its clauses —especially those referring to the sale of Paraguay's surplus energy to Brazil— would generate debates that continue to this day.
The treaty reflected the context of its era: two authoritarian regimes (Stroessner's in Paraguay and the Brazilian military dictatorship) driving a pharaonic work as a symbol of progress and cooperation. Itaipú was thus born not only as an engineering project, but as a first-rate geopolitical piece in the Southern Cone.
The construction of Itaipú was one of the greatest civil-engineering undertakings in history. Begun in the 1970s, it mobilized tens of thousands of workers —peaks of several tens of thousands of simultaneous laborers are cited— and consumed colossal amounts of concrete, iron and machinery. The magnitude of the work gave rise to famous comparisons: the amount of concrete used and the iron and steel employed are usually equated with those of several dozen large stadiums or the Eiffel Tower multiplied many times.
One of the most spectacular challenges was diverting the course of the Paraná River itself in order to build the main wall in the dry. To do this, an enormous diversion channel was excavated and millions of cubic meters of earth and rock were removed, in one of the largest earth-moving operations ever carried out. Once the river was diverted, the gigantic concrete dam was built, which combines different types of structure along its nearly 8 kilometers of extension.
The work completely transformed the region. Camps and cities for the workers sprang up, roads and services were built, and the flow of people and money spurred the explosive growth of Ciudad del Este and Foz do Iguaçu. It was an undertaking that, beyond the figures, marked a generation of Paraguayans and Brazilians and was etched as a symbol of the effort and ambition of an entire era.
In 1982, after years of works, came one of the decisive moments: the filling of the reservoir. When the dam was closed, the waters of the Paraná began to accumulate and flood a vast territory upstream, forming an enormous artificial lake that stretches along the boundary between Paraguay and Brazil. The reservoir, of great surface area, forced the relocation of numerous populations and the relocation of wildlife and flora in one of the largest environmental-rescue operations of the era.
The filling had a consequence of great symbolic charge: under the waters of the reservoir were submerged the Saltos del Guairá (known in Portuguese as Sete Quedas), a set of falls that ranked among the mightiest in the world and that was a natural site of enormous beauty and value for both countries. Their disappearance under the lake generated controversy and nostalgia, and even today it's remembered as the natural price the construction of the dam had.
The wildlife rescue during the filling —the so-called 'Operation Mymba Kuera', in Guaraní— became a famous episode: teams worked to save animals trapped by the rising waters. The reservoir, once stabilized, would not only feed the plant's turbines, but would give rise to new activities, protected areas and biological refuges on its shores, in an attempt to balance the impact of the work with conservation.
In 1984 the first generating unit of Itaipú came into operation, and from then on, year after year, turbines were added until completing the plant's total units. Each turbine and its associated generator are gigantic pieces, and the whole gave Itaipú a colossal installed capacity, which for a long time made it the largest hydroelectric plant in the world.
For decades, Itaipú held the absolute record and supplied an enormous portion of the electric energy of Paraguay and a very significant part of Brazil's. Although in terms of installed capacity it was surpassed by China's Three Gorges dam, Itaipú kept breaking world records for annual energy generation, thanks to the constant and abundant flow of the Paraná River, remaining one of the two largest plants on the planet and, in several years, the one with the greatest actual production.
For Paraguay, Itaipú has a particular dimension: the country consumes only a fraction of the energy that corresponds to it and, according to the treaty, cedes the surplus to Brazil. This has made the dam a central issue of Paraguayan economy and politics, with recurring debates about the price of that energy and about the future of the binational agreement, especially as the scheduled review deadlines are met. Itaipú is, thus, much more than an engineering work: it's a key piece of energy sovereignty and of the relationship between the two countries.
More than four decades after coming into operation, Itaipú is a central institution in the life of Paraguay and Brazil. It continues to generate an immense amount of clean and renewable energy, sustains much of the electric matrix of both countries and employs thousands of people. Its binational management, with Paraguayan and Brazilian sectors in parity, makes it an uncommon case of joint administration of a strategic resource between two nations.
Itaipú's relationship with its surroundings also changed over time. After criticism over the environmental impact of the work, the entity developed important programs of nature protection, reforestation and creation of biological refuges around the reservoir, in an effort to recover fragments of the threatened Alto Paraná Atlantic Forest. It also promoted social, educational and development projects in the region.
Today, besides its energy function, Itaipú is one of the great tourist destinations of Paraguay. Hundreds of thousands of visitors tour the complex each year: the panoramic tour, the technical circuits, the nighttime illumination and the natural areas. The dam was recognized as one of the Seven Wonders of the Modern World of engineering, and seeing it up close helps to understand the scale of the human effort, the weight of energy in modern life and the recent history of the integration between two countries that decided, together, to tame one of the most powerful rivers on the planet.