Itaipu opens gates and releases up to 3,800 m³/s in the Paraná

The spillway opening operation took place on the left side of the structure and was triggered by the sharp increase in water inflows caused by the heavy rains recorded in the Paraná basin. According to Itaipu, the release will continue while hydrological conditions keep the reservoir level high and will be reduced when it is possible to close the gates again.

The water released by the dam flows directly into the Paraná River and continues downstream. However, the spillway opening alone does not guarantee an extraordinary flood in Misiones. The river level will also depend on the flow already carried, the contributions of its tributaries, and any further rainfall in the region.

The increased flow generated by Itaipu’s operation propagates downstream and can be altered by hydrological conditions encountered along the way. Currently, the Paraná and its main tributaries are experiencing a period of high water inflows, making the release a factor that must be monitored in the coming days.

Itaipu is a “run-of-the-river” hydroelectric plant with relatively limited storage capacity. When inflows rise and cannot be fully absorbed by generation and regulation, part of the water is diverted through the spillway—a normal operation that does not indicate an emergency situation.

This is the third spillway opening at Itaipu in 2026. The previous ones occurred between late June and early July, and again in July, also due to hydrological conditions that raised reservoir inflows.

For Misiones, the central focus will be to track the Paraná’s water level in the coming days. If rains decrease and upstream inflows start to decline, the effect of the release can be gradually absorbed. If high inflows persist, the river may show a new upward trend in sections downstream of Itaipu.

Source: Misiones Online