Photos show the extent of change to the lagoon of Santa Olalla, at Donana National Park, Spain, between Nov 3, 2021 and Sept 2, 2022. (ESTACION BIOLOGICA DE DONANA(EBD-CSIC) / REUTERS VIA CHINADAILY.COM.CN)

The head of one of the leading wildlife conservation charities in Spain has accused the country of "environmental assault" after one of Europe's most important areas of wetlands all but dried up after years of drought and exploitation.

The Santa Olalla lake in the Donana National Park, in the southern province of Andalusia, was the last in the park to have had any water left following the punishing summer heat. But on Monday, experts from the Spanish National Research Council, or CSIC, confirmed that for the third time in 50 years, it was dry, "reduced to a small puddle at its center, where there are now no aquatic birds".

ALSO READ: 'Spanish Stonehenge' emerges from drought-hit dam

Juan Carlos del Olmo, president of WWF Spain, reacted angrily by saying that it had not dried up, but had been "plundered".

The Donana park was declared a UNESCO world heritage site in 1994, but the United Nations agency warned that this status was at risk nine years ago because of the amount of water that was being extracted from its 130,000 hectares of land, largely to supply nearby strawberry farms

"A real environmental assault carried out right before the authorities who are responsible and for which Spain has been convicted," he tweeted.

The Donana park was declared a UNESCO world heritage site in 1994, but the United Nations agency warned that this status was at risk nine years ago because of the amount of water that was being extracted from its 130,000 hectares of land, largely to supply nearby strawberry farms.

Lower than expected rainfall in the past decade has added to problems of pollution and exploitation.

Spanish newspaper El Pais reported that the annual average rainfall for Donana in the last 40 years has been 540 liters per square meter. But from September 2021 to May 2022, the figure was just 282 liters.

READ MORE:Dutch government declares water shortage due to drought

Other factors, such as mining pollution, marsh draining and climate-induced damage, have also taken their toll on the site, but the actions of right-wing members of the regional parliament, who had pushed through legislation allowing the sinking of illegal wells, have been cited as the most deliberate and avoidable contributory course of action.

"The continuous exploitation of the aquifer (a layer of rock allowing water to pass through) for intensive agriculture and human consumption-together with the dry years like this one-means that not only are the Donana's temporary lakes disappearing, its permanent ones are also under threat," a CSIC statement said.

READ MORE: EU agency: Europe facing worst drought in 500 years

Eloy Revilla, director of the Donana Biological Station, said what had happened to the wetlands this year should be a sign for related nearby sectors to start making changes.

julian@mail.chinadailyuk.com