The largest permanent lake in Spain's Doana national park, one of Europe's largest and most important wetlands, has shrunk to the size of a puddle as years of drought and overexploitation have taken their toll on the aquifer that supplies the area and supports millions of migrating birds.

The Santa Olalla lake, which is located in a Unesco world heritage site, dried up for the third time in 50 years, according to scientists from Spain's National Research Council (CSIC).

“The Santa Olalla lake, the largest permanent lake in Doñana and the last one that still had water in August, has dried up,” the CSIC said in a statement. “In recent days, it has been reduced to a small puddle at its center, where there are now no aquatic birds.”

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Water resources to Doana, whose marshes, woodlands, and dunes cover almost 130,000 hectares (320,000 acres) in the Andalucan provinces of Huelva, Seville, and Cádiz, have been dramatically reduced over the last 30 years due to climate change, farming, mining pollution, and marsh drainage.

Environmentalists have long advocated for the preservation of the area, which is also home to a significant population of endangered Iberian lynxes, arguing that illegal wells constructed to feed the region's numerous soft fruit farms were straining the aquifer.

The worst #drought in 500 years is hitting #Europe. Would this dangerous warning be enough for governments to act before it's too late?#ClimateCrisis pic.twitter.com/PTMTvWOUff

— Al Mayadeen English (@MayadeenEnglish) August 28, 2022

Their warnings, however, were ignored by rightwing MPs in the regional parliament, who voted earlier this year to "regulate" 1,461 hectares of land near the national park, allowing farmers who sank illegal wells and built illegal plantations on the site to legalize their operations.

“The continuous exploitation of the aquifer for intensive agriculture and human consumption – together with the dry years like this one – means that not only are the Doñana’s temporary lakes disappearing, its permanent ones are also under threat,” said the CSIC.

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According to the CSIC, the big yearly migration of summer visitors to the adjoining tourist resort of Matalascaas puts a significant strain on water resources. On August 31, a camera installed in the lake by the council revealed that it was "dry, parched, and cracked; reduced to a little puddle of water and sludge." But the next day, after many tourists had headed home, “a few springs were seen, suggesting the Doñana’s biggest permanent lake was being fed."

Revilla stated that water use in Matalascaas should be curtailed and restrictions enforced during drought years such as this one.

“You can’t keep watering the lawns in Matalascañas while the lakes of Doñana dry up completely,” he said.