The last permanent lagoon in Doñana dries up

The drought and the overexploitation of the aquifers have dried up the last permanent lagoon in Doñana.

This is the Santa Olalla lagoon, the largest permanent lagoon in Doñana and the last one to hold water in August. These days, it has been reduced to a small puddle in the center, where waterfowl no longer come. This is the third time that it has happened since the Doñana Biological Station (EBD), dependent on the Higher Council for Scientific Research (CSIC) in Spain, began to record data on the natural space in the 70s of the last century.

Doñana has historically been a refuge for fauna. It has an important system of lagoons, of which only a few remain with water throughout the summer, offering refuge to the first wading birds that migrate south after breeding in northern Europe, and also constitute the habitats of a good number of strictly aquatic flora and fauna species. In addition, in summer the rice fields also offer an important refuge. “But things have changed. Doñana no longer has any permanent lagoons, while the area of ​​rice fields planted this year is a third of normal due to lack of water”, explains Eloy Revilla, director of the Doñana-CSIC Biological Station.

An intense period of drought

The drought that Europe is suffering, especially intense in the Iberian Peninsula, is wreaking havoc in the natural space. However, the most worrying thing is that this comes from afar. “It’s been years since it rained normally. Doñana has had precipitation levels below average for ten consecutive years”, says Revilla. Wetlands and the species that depend on them, such as waterfowl, are especially affected and are forced to move in search of areas that maintain available water in the harshest times of the dry season.

The Santa Olalla lagoon is the only one that was maintained with permanent water from a rosary of large lagoons (lagoons peridunares) that form in the lee of the impressive chain of dunes that separates the marsh from the Atlantic Ocean. Its origin is in the discharge of water from the Doñana aquifer in this area, which generates an explosion of life. These and other natural values ​​have made Doñana considered a National Park and Biosphere Reserve. However, the continuous exploitation of the aquifer by intensive agriculture and extraction for human consumption, also in years as dry as this one, means that not only the temporary lagoons have disappeared from Doñana, but also the permanent ones are threatened. .

Aerial view of the Santa Olalla lagoon on September 2. (Photo: Image bank of the EBD / CSIC)

The overexploitation of the aquifer, the main problem

It is known that the peridunares lagoons are mainly affected by the water withdrawals of the town of Matalascañas, which in summer increases its water consumption exponentially with the arrival of tens of thousands of tourists and that makes the population exceed a few thousand inhabitants to about one hundred thousand people. The effect of water consumption by tourists is so intense that piezometers -the wells that measure the depth of the aquifer’s water level- detect the differences between weekdays and weekends, when the consumption is much higher. They even identify the difference between day and night, when people sleep and use less water.

“This is the third time that the Santa Olalla lagoon has dried up completely since we have records. It also happened in 1983 and 1995, in both cases also coinciding with periods of intense drought”, explains Revilla. “We know, from the times it has happened before, that the drought is not the only reason why the permanent lagoons in Doñana have disappeared. The overexploitation of the Doñana aquifer is also responsible”. An aquifer is overexploited when more water is extracted from it than is recharged when it rains, something that has been happening in Doñana for many years.

The Technological and Singular Scientific Infrastructure – Doñana Biological Reserve, dependent on the Doñana Biological Station, has installed a monitoring camera in the lagoon to see its evolution in the coming days. On August 31, Santa Olalla was dry, parched and cracked, reduced to a tiny puddle of water and mud. Surprisingly, on September 1, after many people have already returned to their homes, it is observed that some springs and springs sprout from which the largest permanent lagoon in Doñana is nourished.

Faced with this serious situation in which the Santa Olalla lagoon finds itself, the director of the Doñana Biological Station asks that the measures be accelerated to eliminate the underground water catchments of Matalascañas, and that, in the meantime, restrictions be imposed on the use of water in urbanization, at least in years in which the lagoons are in situations as extreme as this one. “It cannot be that while the grass in Matalascañas continues to be watered, the Doñana lagoons dry up completely,” he concludes. (Source: CSIC)