Arenal reservoir reaches highest level in the last 20 years

The following is a machine translation of an ICE release

The Arenal Reservoir –located between the provinces of Alajuela and Guanacaste– reached its highest level in the last 20 years this week, reaching 546.87 meters above sea level ( masl ). This is the most important energy reserve in the country, and is essential to face the conditions of the dry season.

December 2024 was one of the months with the highest rainfall in the reservoir area, according to the records of the Costa Rican Institute of Electricity (ICE), which began in 1958. The phenomenon, combined with efficient operational management and cold thrusts, places Arenal at its highest level since 2005, when it reached 546.78 meters above sea level.

The operating range of this reservoir is between 529 and 546 meters above sea level. Achieving high storage levels guarantees the availability of energy in the summer, since Arenal is the only multi-year reserve of the National Electric System (SEN); that is, it stores water from one year to be used in the next.

“Compared to the conditions we face in 2024, this year is favouring us in the energy sector. The state of our reservoirs guarantees reserves for the coming months, so there is no risk of rationing for 2025,” said Marco Acuña, president of Grupo ICE.

José Joaquín Granados, head of Generation at the Institute, explained that “what is happening these days is historic. We do not have to be alarmed by these levels, as it is a natural situation typical of a reservoir. The water stored in Arenal during these months will be used in the coming summer.”

With 87 square kilometers and 45 years of operation, Arenal also plays a fundamental role in the incorporation of other renewable sources, such as wind and solar. Its firmness allows it to regulate the high variability of these resources, while facilitating the development of scenic and visitor tourism in the area.