In its regulatory agenda published in the Official Gazette of the Union (DOU) on December 23rd, the National Water and Sanitation Agency (ANA) included priority items that are likely to directly impact the interests of two large companies in the national electricity sector. The objective is to establish new operating conditions for the reservoirs of the Paraná and Pardo River water systems.
The measures to be adopted by the regulatory agency for the Paraná River affect the Jupiá hydroelectric plant (UHE Engenheiro Souza Dias), controlled by the Chinese company CTG Brasil, and the Porto Primavera hydroelectric plant (UHE Engenheiro Sérgio Motta), under concession to Auren Energia, which is also responsible for the Limoeiro, Caconde, and Euclides da Cunha plants, located on the Pardo River.
Both companies are closely monitoring developments, as minimum flow restrictions could limit operational flexibility during peak profitability hours, directly impacting plant revenue.
Parana River
The Jupiá and Porto Primavera hydroelectric plants play an important geographical role because they are the last ones on the Paraná River before the waters flow into Paraguayan and Argentinian territory to supply the Itaipu hydroelectric plant. Unlike other reservoirs with large storage capacities, these units operate on a "run-of-river" system, meaning they do not accumulate large volumes for the long term.
The new ANA regulation aims to discipline the use of these waters to ensure that the electricity sector maintains a constant minimum flow. The objective is to prevent energy generation from completely interrupting flows during water crises or periods of low demand, which harms the multiple uses of water downstream.
Regulatory Innovations
According to the discussions of Public Consultation No. 10/2025ANA intends to establish strict limits for minimum instantaneous outflow rates. Jupiá must maintain a minimum of 3.300 m³/s, while Porto Primavera will need to provide a minimum of 3.900 m³/s.
These values were calculated to ensure the navigability of the river and the preservation of aquatic life, even when energy generation is not at its maximum capacity. An important innovation of this model is the linking of the operation of Jupiá and Porto Primavera to the level of the so-called "headwater" reservoirs, located at the top of the basin, such as Furnas, Emborcação and Nova Ponte.
If these upper reservoirs have a usable volume of less than 30%, ANA (National Water Agency) will have the prerogative to declare a situation of scarcity. In these circumstances, the flow regulations for Jupiá and Porto Primavera may be temporarily revised to conserve water throughout the entire water system.
Conflict resolution
In the case of the Tietê-Paraná Waterway, maintaining minimum flow rates is essential to avoid the closure of navigation. In previous drought periods, the low river level paralyzed the transport of crops, resulting in losses in the billions.
Another important issue concerns social conflicts. Regions like Castilho (SP) and Três Lagoas (MS) depend on tourism. Inns, marinas, and fishing suffer from abrupt variations in the river level, which can dry up the banks in a few hours due to fluctuations in energy generation.
In the case of energy generation, the idea is to offer the ONS (National System Operator) greater predictability regarding the region's actual water availability. The expectation is that the final resolution, after analyzing the contributions submitted by CTG Brasil and Auren Energia, will be published in early 2026, taking effect for the next drought cycle.
Rio Pardo
In the Rio Pardo region, which runs through the states of Minas Gerais and São Paulo, the regulatory challenge focuses on balancing energy generation with economic activities such as irrigation and public water supply. The basin has a system of cascading power plants, operated mainly by Auren Energia (formerly AES Brasil), whose management has historically sought coordination of the electricity sector through the ONS (National System Operator).
However, the region has faced periods of severe water scarcity, generating direct conflicts with irrigators, who have a strong economic presence in the area. Unlike a simple mandatory regulation, the process in the Rio Pardo region requires a Negotiated Water Allocation, involving a complex coordination between the ANA (National Water Agency), ANEEL (National Electric Energy Agency), ONS, CBH-Pardo (Rio Pardo Hydrographic Basin Committee) and the generating companies.
The new short- and long-term operating rules will define: minimum and maximum safety levels for reservoirs at different times of the year; mandatory minimum remaining flows to ensure service to downstream users and environmental health; and prioritization criteria for cuts or restrictions during drought alerts.
For rural producers of crops such as coffee and sugarcane, in municipalities like Casa Branca, Mococa, and São José do Rio Pardo, regulation is seen as a milestone in legal security. Without these rules, irrigators would remain vulnerable to level variations caused by energy generation during peak hours, when electricity demand and energy costs are highest.
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