Biologist Carmen Diaz steps onto cracked mud. The lagoon in the heart of Spain's Donana nature reserve is a puddle. The park called "the crown jewel of Spain" may be dying.

Farming and tourism had already drained the aquifer feeding Donana. Then climate change hit Spain with record-high temperatures and a prolonged drought this year. The disappearance of Donana's Santa Olalla lagoon's in August makes Diaz, 66, fear that the ecosystem she has studied for four decades may have vanished for good.

"Seeing this last bit of water makes me think that the entire park is dry," Diaz said.

Donana's Santa Olalla lagoon was the biggest of the handful of lagoons that maintained some water year-round, providing a summer reservoir of aquatic plants and animals.

Sitting on an estuary where the Guadalquivir River meets the Atlantic Ocean, Donana covers 74,000 hectares (182,000 acres). The reserve was founded in the 1960s with help from environmental group WWF. A UNESCO World Heritage Site and Biosphere Reserve, Donana is a wintering site for a half-million waterfowl and a stopover spot for millions more birds that migrate from Africa to northern Europe. Home to five threatened bird species, including the endangered Spanish imperial eagle, Donana also hosts a breeding-and-rescue center for the endangered Iberian lynx.

"The solution should have come at least 20 years ago but nothing was done. The environment always loses against the economy," said Diaz, a researcher for the Spanish National Research Council. "Donana has been the crown jewel of Spain because it is an emblematic park, and we are letting it slip away."

Donana encompasses two large ecosystems. Besides the wooded dunes, there are marshlands along the Guadalquivir.

Spanish galleons once brought silver back from Spain's American colonies here on their way upstream to Seville. Then, scientists and conservationists came from all over the world. Now Donana is a case study in how humans destroy natural resources.

Eight mating pairs of imperial eagles have produced only two chicks in 2022, said Carlos Davila, who works in Donana for environmental group SEO Birdlife.

"It has been a disastrous year for the imperial eagle," he said.

When Donana's aquifer fills from rain, lagoons emerge in the swallow depressions between the dunes, creating refuges for turtles, frogs, and aquatic plants. From atop a dune inside the reserve, the 360-degree view of low-lying trees and sand is only broken by a tightly packed mass of buildings seen when one turns to the Atlantic.

They are in Matalascanas, a former fishing village that developed into a beach resort town, complete with hotels, swimming pools and a now-defunct golf course. The water for Matalascanas comes from wells that pull from the aquifer. The European Court of Justice cited Matalascanas as making some of Donana's once-permanent lagoons go dry. Spain's government has approved a plan to reroute water from another area to supply Matalascanas.

"The biggest problem is that this development draws from the aquifer using wells that are very close to the lagoons," Diaz said. "This forms a cone of depression that hurts the closest lagoons, which are the best ones, since they are the biggest."

A two-hour drive south of Seville, one enters Huelva, a rural province including the Donana reserve. Like other areas near Spain's coast, Huelva has worked hard to become one of Europe's major agricultural areas. Strawberries, raspberries, blueberries and blackberries replaced olives, cereals and potatoes in the 1980s. European customers pay far more for the berries, but the crop needs much more water than olives do.

In 2004, authorities divided the farmland into areas eligible for irrigation and those that could only grow crops with rainwater. But with the berry trade booming, some farmers whose lands were left out of irrigation areas drilled wells anyway. WWF says there are between 1,000 and 2,000 illegal wells used to irrigate some 2,000 hectares (4,900 acres) of berries outside the reserve.

Outside the reserve's limits, roadside signs warn drivers to be on the lookout for lynx. Greenhouses hold mostly berries.

"Perhaps 50% of (damage done to the park) is due to drought and lack of rain, but the other 50% of the blame goes to the lack of governance in the area, the cutting off of tributaries, and illegal wells," WWF's Felipe Fuentelsaz told the AP.

Authorities have managed to close over 400 wells and purchased some farmland to remove crops, but far from being discouraged, many farmers are pushing authorities to reclassify their terrain as irrigable.

One group represents 1,500 farmers who feel that they were unfairly left out of the 2004 irrigation plans. Spokesman Julio Diaz said many families have the right to water and should be able to use it.

"What we are going to do is ensure that these farmers recover their historic rights, which they used to have," Diaz said. "Nothing will be increased, but we must recover what they once had."

Spain's central government is concerned that expanding water use could earn a hefty fine from the Europoean Union.

The government plans to reroute water from rivers that lie further west toward Donana to relieve pressure on the aquifer. The group represented by Julio Diaz wants that water to come to them. But other farmers who have been using legal wells on lands declared irrigable say not so fast.

Manuel Delgado, spokesman for 300 farmers in the town of Almonte, said that his group believes that any new water should go to those farmers who already have water rights, so they can close their legal wells and protect the aquifer.

"If there is new terrain declared eligible for irrigation, we won't be able to replace the legal wells with the surface water," he said. "There won't be water for everyone."