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Drought and overexploitation of aquifers dry up the last permanent lagoon in Spain’s Doñana National Park

The Santa Olalla lagoon, the largest permanent lagoon in Doñana National Park and the last one to hold water in August, has finally dried up. The lagoon have been reduced to a small puddle in the centre, where waterfowls no longer gather. This is the third time this happened since the Doñana Biological Station – CSIC began to record data on the park in the 1970s. 

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 whole summer, offering refuge to the first wader birds that migrate south after breeding in northern Europe. In addition, they also provide habitats for a good number of aquatic species of flora and fauna. Rice fields also offer an important refuge. "But things have changed. Doñana no longer has permanent lagoons while the area of rice planted this year is three times less than usual, due to the water scarcity", explains Eloy Revilla, director of the Doñana Biological Station – CSIC.

An intense period of drought

The drought that Europe is suffering, especially intense in the Iberian Peninsula, is ravaging the natural park. However, the most worrying thing is that this started a long time ago. "It has not rained normally for years now. Doñana has had below-average rainfall levels for ten years in a row", comments Revilla. Wetlands and species depending on them, such as waterfowls, are especially affected and they are forced to move in the search of areas with available water in the worst periods of the dry season.

Santa Olalla lagoon is the last one remaining with permanent water of a group of big lagoons (the peridunare lagoons) formed in the lee of the dune ridge that separates the marshes from the Atlantic Ocean. Its origin lies in the water of the aquifer, which creates an explosion of life. This and other natural values have made Doñana had been considered a National Park and a Biosphere Reserve. However, the continuos exploitation of the aquifer for the intensive agriculture and human consumption, also in dry years such as this, makes that not only the temporary lagoons in Doñana have disappeared, but also the permanent lagoons are threatened.

Vista del último charco de agua de la laguna de Santa Olalla el día 31 de agosto. Banco de Imágenes EBD-CSIC

The overexploitation of the aquifer

These peridunare lagoons are mainly affected by water intakes of the town of Matalascañas town, whose water consumption increases exponentially with the arrival of tourist in summer, making population grow from a few thousand inhabitants to about 100,000 people. The effect of water consumption by tourists is so intense that piezometers -soundings measuring the depth of the water level in the aquifer- detect the differences between weekdays and weekends, when consumption is much higher. Even they can identify the difference between day and night, when people are sleeping and spend less water.

"This is the third time that the Santa Olalla lagoon dries up completely since we have records. It also happened in 1982 and 1995, in both cases also coinciding with periods of intense drought", explained Eloy Revilla. "We know, from the previous times that has happened, that it is not only the drought that has caused the permanent lagoons in Doñana to have dissapeared. The overexploitation of the aquifer is also responsible". An aquifer is over exploited when more water is extracted than replenished when it rains, something that is happening for several years in Doñana.

The Unique Scientific and Technical Infrastructures – Doñana Biological Reserve, depending on the Doñana Biological Station – CSIC, has installed a monitoring camera in the lagoon to watch the evolution in the next days. On August 31st, Santa Olalla was dried up, parched and cracked, reduced to a tiny puddle of water and mud. Surprisingly, on September 1, after many people have already returned home, some springs that nourishes the biggest permanent lagoon in Doñana have came up again.

Nuevas entradas de agua en la Laguna de Santa Olalla. Banco de imágenes EBD-CSIC

Given the severe situation that the Santa Olalla lagoon is facing, the director of the Doñana Biological Station – CSIC is calling for measures to end the extraction of groundwater from Matalascañas to be accelerated and, in the meantime, to impose restrictions on the use of water for urbanisation, at least in years when the lagoons face extreme situations as this. "You can't keep watering the lawns in Matalascañas while the lagoons of Doñana dry up completely", he concluded.