Itaipu opens its spillway and the high Paraná backs up the Iguazú mouth at Puerto Iguazú

Itaipu Binacional opened its spillway gates and began releasing about 4,800 m³/s, according to the dam's statement quoted by the Argentine press. The move responds to the water reaching the reservoir after heavy rain in the basin: Brazil's grid operator ONS recorded an inflow of 16,735 m³/s on 11 October, with 4,215 m³/s spilled and 9,666 m³/s through the turbines.

Why it shows up in Puerto Iguazú

Itaipu sits on the Paraná River, 14 km upstream of the point where the Iguazú flows into it, by the Three Frontiers Landmark. With the Paraná running high, the Iguazú's mouth is backed up: its water drains more slowly and the level rises along the river's last stretch. That is the rise port workers in Puerto Iguazú describe, visible to the naked eye. Port activity remains under monitoring.

According to the dam, the releases should continue through the long weekend and may run into the first days of the week.

What we measure

• Paraná River, ANA gauge 7.5 km upstream of the Friendship Bridge: the highest level in our series, covered in Paraná River rises 5 meters in 24 hours.
• Iguazú River, at the Falls: a peak of 11,831 m³/s at 5 am on 12 October, the highest in our series, already falling by the afternoon.

Both readings are on border weather.

Source: De la Tribuna, with ONS and ANA data.