The Yesa reservoir was built in the Pyrenees in 1959 and it is located in an area called Prepirineo. The dam is located in Navarra, but the reservoir extends through the community of Aragon, more specifically through the province of Zaragoza. It occupies a total of 2089 hectares and receives water from the dam of the Aragón river. As the Periódico de Aragón coined it in 2004, “the history of Yesa is a story of obstacles.”

The reservoir was created to supply water to different towns and for irrigation. The water accumulated in the reservoir is also used for electricity generation. These same waters have managed to create a total of 81107.64 hectares of irrigated land, most of which is in Aragon. The reservoir supplies the city of Zaragoza and more than 35 municipalities.

Far from its impressive volume, the reservoir is marked by continuous problems that have haunted it from its very first day. The decision alone to locate it where it is currently located caused the flooding of several villages and the eviction of many others, causing more than 1,500 people to leave their homes. Villages such as Ruesta, Tiermas and Escó were abandoned because they were totally flooded or became uninhabitable due to the proximity of the water. It also affected villages upstream, such as Acín de Gacipollera, but this time due to the need to plant a pine forest to prevent the massive dragging of sediments by the rains. Even 2048 hectares of farmland were flooded, a thousand of which were of very good agricultural quality.

The inconveniences continued, as the structure itself has not ceased to give headaches.

From the “Yesa no” web page, a group of neighbors and activists assure that the Yesa area is not capable of supporting this kind infrastructure. In fact, the dam has suffered landslides and has had cracks for many years. When all this was already happening, a plan to increase the height of the dam was approved, which ended up outraging those people who were suffering from the dam’s problems.

This project was intended to triple the volume of Yesa, but the works have not gone as expected. In June 2021 the following headline was published on the Diario de Noticias website: “The State assures that it will raise Yesa even though it does not even have the safety guarantee it demanded”. Just as a few years earlier they had published another headline related to the reservoir: “A study on Yesa shows that the force supporting the dam is equal to that of a potential collapse”. There was even a “Yesa Case”, where the court ruled in favor of the defendants.

Since the works began, there have been up to three displacements and the cracks have increased. Due to these situations, the towns located beyond the dam have been forced to take preventive measures in the event of a possible rupture of the dam. Sangüesa is one of these municipalities that would be affected by such a big problem as the outflow of water from the reservoir.

Testimonies

Alicia Aisa and Igor Martínez, two neighbors from Aesa, have agreed to answer some questions on this subject.

What was the cause of the problems with the Yesa reservoir? Firstly, these problems were already anounced when the dam was built and the engineer René Petit had wrote that the dam could not be raised. Secondly, the works involve slope movements, which are causing problems such as evictions of a housing development in Yesa due to cracks and landslides on roads and homes.

What problems are those affected by the reservoir dealing with? The eviction of their homes and the imminent danger due to movements of the slopes that would entail the breakdown of the current dam that would depopulate a few municipalities without time to evacuate.

What measures have been put in place by the local and regional institutions? The only measure has been to maintain these slopes that are costing the region four times over what was budgeted at the time to do this work, insisting on finishing something that will not be viable and endangering many people, such as Sangüesa, among many other municipalities.

Would you like to send a message to the institutions? We could stop this work, since it entails more risk than benefit. There is no need to increase the size of the dam.

What is the current problem with the dam? As of today, the works continue without providing any security, evacuation plan, or notification of movements that we can count on to know what situation we are in. Some alarms have been placed in Sangüesa, but the population is unaware of their sound. There is no information about the evacuation plan, and it is well known that there would not be enough time to evacuate. There have even been people who have moved to other towns of Navarra because of fear.

What are the alternatives or solutions to these problems? The solution is to stop the expansion of the dam and stop the ongoing work.

Neighbors are angry because this situation is a result of the bad actions of people in power. For this reason, different initiatives have been created against the reservoir and its enlargement and, in the face of the flight forward of the directors of a certain project with the works, demonstrations have taken place to make themselves heard.

The idea of creating a reservoir to supply water for drinking and irrigation in many municipalities and lands initially appealed to all those who were going to benefit from its creation, but it is the disadvantages already mentioned.