Yesterday saw Greenpeace protesters block natural gas operations near the UNESCO World Heritage Site, which is home to more than 4,000 species of vulnerable animals.
WWF have since made an appeal for the protected wetlands in Sevilla.
“Donaña is in very serious danger,” said Juan Carlos del Olmo, head of WWF Spain.
“We don’t want it to be put on the list of endangered sites, but soon there won’t be any other option.”
WWF says the wetlands now only receive a fifth of the water they need, in part due to illegal farming nearby.
They also say nearby mining, gas and dredging activities are causing further damage.
Utility company Gas Natural Fenosa, who has been given permission to use depleted natural gas reservoirs as underground storage sites, has been building pipelines in the fragile area.
Activists marched on the site on Tuesday, blocking the company’s lorries to prevent further pipeline construction.
Gas Natural Fenosa said: “We have worked near Donaña for close to 30 years with the utmost care for the surroundings.”