Itaipu opens spillway for the 3rd time this year to control reservoir level

The intense rains recorded in the Itaipu basin increased the flow of the rivers that flow into the reservoir and led to the scheduled opening of the plant's spillway, according to Itaipu Binacional.

The spillway at the Itaipu Plant was opened at 1:50 am this Sunday (13), for the third time this year, to control the reservoir level.

In 2026, before this Sunday's opening, there were two other operations: from June 28th to July 5th and on July 12th.

The left chute of the spillway was initially opened with a flow of 1,700 m³ per second. At 2:43 am, the amount of water released increased to 3,100 m³ per second. Itaipu's forecast is that the flow will reach 3,800 m³ per second in the afternoon and be reduced at the end of the day.

Spilling must continue until hydrological conditions return to a level that allows the spillway to be closed.

Why is the spillway open?

According to Itaipu, the opening depends mainly on the amount of water that reaches the plant and the conditions of energy generation and consumption.

The hydroelectric plant is of the “run-of-river” type and has little capacity to store water. Therefore, when the plant is unable to turbine or store the entire volume that reaches the reservoir, part of the water is released through the spillway.

Itaipu highlights that opening is a technical and routine procedure and cannot be directly associated with phenomena such as El Niño.

Iguaçu Falls walkway closed

The walkway near the Iguaçu Falls, on the Brazilian side, was closed preventively on Friday (11) due to the high flow of the Iguaçu River, according to the Iguaçu National Park advisory.

The normal flow of the Falls is around 1.5 million liters of water per second. This Sunday, the flow is above 8.5 million liters of water per second, according to automatic monitoring by Companhia Paranaense de Energia (Copel).

The reopening will depend on the reduction of water volume and safety conditions at the site.

The increase in flow is caused by rain along the Iguaçu River, which originates in the Metropolitan Region of Curitiba and runs through Paraná from east to west until reaching the Falls, on the border between Brazil and Argentina.