Arenal reservoir exceeds the level scheduled for the last quarter of 2024 and increases the country's energy reserves

The following is a machine translation of an ICE release

After facing one of the driest years on record in the basins that feed the country's hydroelectric plants, the National Electric System (SEN) is showing a recovery in Arenal, its largest and most important reservoir.

To date ( see graph ), it exceeds 539 meters above sea level ( masl ), which increases energy reserves for the summer of 2025. In January of this year, the maximum level reached 538 masl for a few days.

The recovery of the reservoir has two basic components. The first is the increase in rainfall in the North and Caribbean areas, where most of the water currents that reach Arenal originate and travel. According to the Costa Rican Institute of Electricity (ICE), this body of water collects the resources of four main rivers: Arenal, Caño Negro, Chiquito and Piedras.

The second is the optimization of resources and management measures implemented by ICE, which managed SEN resources to protect the reservoir while continuing to meet the country's demand. In this management, it is necessary to highlight that ICE must guarantee water to the Arenal-Tempisque Irrigation District.

“Why is it so important that Arenal exceeds the programmed level? Our only multi-year reservoir is essential to face the summer and guarantee the satisfaction of demand throughout the year, always seeking to reduce the use of thermal backup to the minimum possible. Compared to January 2024, we already have an additional meter, and we hope that for the remaining weeks of the rainy season it will continue to grow,” said Marco Acuña, president of Grupo ICE.

“Currently, all the plants in the national generation park are operating normally and responding to the needs of the SEN itself. We project that next year will show more favorable conditions for the production of electric energy, but this does not imply neglecting the risks of a renewable matrix such as the Costa Rican one,” he added.

Last May, Arenal reached its lowest point in recent years: 531 meters above sea level. However, in the last five months it has risen by almost 8 meters – a height that is 4 meters higher than estimated. The reservoir supplies the water resource for three plants that operate in cascade: Arenal, Dengo and Sandillal.