In the situation of extreme drought, with no forecast of abundant rains in the short term and water reserves below minimums, the Department of Climate Action and the Catalan Water Agency (ACA) have initiated a plan to save the little water that remains in the Sau reservoir, which is currently at 10% of capacity, the lowest figure in recent decades. A plan that, apart from diverting volume from Sau to Susqueda, envisages removing as many fish as possible from the dam to prevent their death from lack of oxygen ending up contaminating the water and making it unusable for the use of mouth In the current situation, every drop counts.
The precious liquid still stored in the dam could supply a million inhabitants for three months. "The objective is to maintain the quality of the water in order to make the most of it", explained yesterday the director of the Implementation Area of the Catalan Water Agency (ACA), Elisabet Mas. In order to preserve its quality and guarantee the domestic demands of the Barcelona area and the regions of Girona as long as possible, water from the Sau reservoir has been diverted to the Susqueda for days. Both belong to the same basin, that of Ter Llobregat, which supplies drinking water to more than five million people.
Currently, 0.5 cubic hectometres are released per day, a transfer that would be stopped if a significant deterioration in water quality was detected or the oxygen in the lower layers of the reservoir was reduced. This situation could be accelerated by the current high temperatures combined with the unusually low volume of water in the swamp. They are only twenty meters deep. Experts point out that the reduction in the volume of water in Sau can lead to a decrease in oxygen in the water, a fact that could cause the death of fish if they are kept in high densities.
To reduce the fish density of the reservoir and avoid worsening the quality of the water resource, around two tons of fish per day will be removed, which will be slaughtered. The head of exotic species and conservation of the Climate Action department, Jordi Ruiz, indicated yesterday that there is no protected species or threatened habitat in this area. A study establishes ten species of fish present in the Sau reservoir and that 90% of them are exotic. In this group you would find catfish, carp, carp, sandra, alburn or sole fish, among others. Only one of the species that live in the swamp is not exotic, but it is also not typical of the Ter basin. This is the barb of the Ebro.
Ruiz explains that the legislation obliges the culling of exotic species and that the same will be done with the few barbs of the Ebro that are expected to be found there. "It is a matter of scientific coherence, moving fish from habitat where there has been a high mortality rate can cause health problems and affect other native fauna", points out Ruiz. If any native species is found, it would be moved to the section of river to which it corresponds.
Those who will take care of fishing will be two boats from the Blanes confraternity that will use a traditional system consisting of submerging the net to a certain depth to prevent it from washing away the bottom. Two pelican-type boats will be used to collect species on the surface in case of mortality in the reservoir. A fifth electric fishing boat, which was carrying out a survey yesterday to quantify the fish that the marsh can accommodate, will be used only in corners and very small spaces or as support for fishing boats and in some cases it could even opt for manual fishing. The extracted specimens will be treated by a company specialized in the treatment of biomass.
Yesterday, a crane lowered three of the boats that will start working tomorrow onto the surface of the water. It is estimated that the operation could last a month and a half.
