The Yesa swamp was inaugurated during Franco, in 1959, with 2,400 hectares of submerged farmland and favoring the depopulation of the localities of Tiermas, Ruesta and Escó. It has had safety problems from the very beginning, as the slope that supports the dam is geologically very unstable. Experts have been warning of these risks for years. However, the project to extend the reservoir was approved in 1985.

The initial project envisaged tripling the reservoir capacity, but a major social and judicial struggle has succeeded in reforming the project: they will double the volume of the reservoir from 490 cubic hectometers to 1,079. It was originally stated that the works would be completed by 2009, but the deadline has been delayed until they were consolidated in 2020. The works, which were initially awarded EUR 113 million, amounted to EUR 433 million, which means quadrupling the budget of the work. In addition, EUR 277 million should be earmarked for “complementary works”.

With regard to the effects, the increase in the dam will cause damage to the Special Conservation Areas and the Sites of Community Importance that make up the Natura 2000 ecological network and increase the likelihood of landslides. In addition, the waters will occupy the most fertile lands of the villages of Artieda, Mianos and Sigües. It will also affect the heritage of the Valley, as it will reduce the 22 kilometers of the Camino de Santiago.

No official movement and risk report

The geologist at the University of Zaragoza, Antonio Casas, is one of the experts who has researched Esa the most. Since 1990, warning of the risks of the reservoir began and the correctness of the forecasts in its reports has subsequently been verified. Last February, in the Parliament of Navarre, he stated that the situation on the right slope is "unsustainable", that it is moving some millimeters a month and that the movement has spread to areas not originally planned. In this sense, Casas assured that the situation "will be unsustainable" for the future of the crisis.

However, the Spanish Government and the Ebro Hydrographic Confederation (CHE) do not accept the investigations of Houses and other experts, and the Confederation does not provide any information in this regard. For years, therefore, citizens have been demanding that the Government of Navarre exercise its powers to request independent evaluation reports at international level in order to assess the risks involved. And after several negatives, they have finally received the yes: on 6 September, the Government of Navarra announced that it will be responsible for the opinion of international experts and that the costs of the report will be specified in the 2018 budgets.

They have also asked the central Government to halt the work until the report is produced. The intention has only been confirmed by the results of the investigation carried out by Government technicians, which was announced on 9 October: safety is not guaranteed in the expansion works of the Yesa reservoir and the Ebro Hydrographic Confederation is “underestimating” the risk.

The official objectives of enlargement, in doubt

José Luis Beaumont is a lawyer who has been on the Yesa swamp bench. He knows the CHE closely and has defined it as a “symbol of opacity”: “When problems are hidden or underestimated, this is no exception. In the Spanish State, large hydraulic works are accepted without prior geological studies, and then, when there are problems, public money is diverted”.

According to Beaumont, behind the expansion of the reservoir there is a hidden objective: according to the official version, the new concrete block that is being built will be based on the original prey, while he believes it will be the other way round, that is, to secure the original. “The CHE has never said so, because it should assume that the current reservoir is not safe and that it should be emptied until a solution is found,” he explained.

“The first project of the enlargement envisaged that the dams had a dimension of 1,225 cubic hectometers, and if they had been built in this way, it would not be possible to comply with the reservoir, even if the dam was closed for a whole year – this is not possible, because at least the ecological flow of the river should be left – as the contribution of the river Aragon is smaller,” the lawyer argues. In his view, the construction of a dam of these measures may have as its sole objective the maintenance of the old dam.

Similarities with the Vajont reservoir

The movements that are taking place are similar to those that experts detected in the Vajont reservoir (Pordenone, Italy). “Since the construction phase there were problems in Vajont, expert technicians insisted that if a slip occurred, if the reservoir was full or if the movement hurried, there could be a disaster like the one they say about Yesa. And as here, they didn’t listen to them there,” Beaumont said.

In particular, in October 1963 there was a significant slippage when the water level of the reservoir was high and a block of 260 cubic metres fell on the water, resulting in a wave of 200 metres high. The wave surpassed the prey, the people brought them before them and caused some 2,000 deaths. The lawyer has denounced that he was "sold" as if it were an "inevitable" accident caused by nature.

No tools against risks

Iker Aramendia is a resident of Sangüesa, one of the towns closest to the risk, and a member of the collective Esa+No. This group has repeatedly denounced that Che has not designed any emergency protocol to deal with an alleged disaster, even during the 2013 crisis. That year there were serious damage to the right wing and 60 housing units were evicted from the urbanizations of La Tranquillity and English. Some experts, including Houses, recommended the eviction of Sangüesa. “In the face of the danger we saw that we had no tools,” Aramendia said.

Since then, they have not stopped fighting and have managed to raise awareness: “It has not been easy for people to realize the situation, because the problem has been going on for many years, and suddenly saying that a whole people is in danger is going through a red line, you have to think about everyday life,” he said. It has been difficult for him to explain what it is to live with this concern: “When it rains here at night, you start to think about your ghosts and you can’t rule it out. Then go to the street and there, too, the theme comes out. And when there is no information, fears increase.”

However, Aramendia looks to the future with hope: “The majority of the Navarre Parliament is now in our favour, they have recognised the need to solve the problem and have put their competences in place. Furthermore, the European Commission is looking more at the environment and that may be an opportunity. A judge, with our case in hand, with the technical reports, will not be able to look elsewhere: he will have to stop, analyze it and seek a solution.”