The end of a wonder
Before 1982, the Paraná River contained the Guaíra Falls, or Sete Quedas. This series of 18 waterfalls was a large natural wonder. By total volume of falling water, it was the largest waterfall on Earth. Its constant roar could be heard from 32 kilometers away. The falls marked a sharp ecological boundary, separating the fish species of the upper and lower Paraná River basins. This unique environment, sustained by the constant mist and tumultuous water, supported species found nowhere else.
The construction of the Itaipu Dam, a massive hydroelectric project between Brazil and Paraguay, spelled the end for Sete Quedas. In October 1982, the dam's floodgates were closed, and it took only 14 days for the rising waters of the Itaipu reservoir to completely submerge the falls. The Sete Quedas National Park was officially dissolved by the Brazilian government. The inundation of 1,350 square kilometers of land destroyed the falls and also vast tracts of forest and agricultural areas, forever altering the region's environment and biodiversity. The natural barrier that had separated aquatic ecosystems for millennia was gone, leading to a massive invasion of fish species into the upper Paraná basin.