Intermediate 
The view from the visitors centre at the southern edge of Donana National Park in southern Spain is an ornithologists dream: 200,000 hectares of wetlands vital for the birdlife of western Europe. Dozens of Britains most loved migratory birds rest here every year on their migrations from Africa. Donana is also home to some of Europes rarest birds, including the Spanish imperial eagle.
It is a glorious, vibrant landscape but it exists on a knife-edge. In 1998, almost two billion gallons of acidic water, mixed with waste metals, poured into the park from the Los Frailes mine 45km away. A toxic tsunami of waste poured down the Guadiamar river into the park. More than 25,000 kilos of dead  sh were collected afterwards and nearly 2,000 adult birds, chicks, eggs and nests were killed or destroyed.
It was Spains worst environmental disaster and the clean-up cost 90m. Suddenly aware of Donanas status as the nations most important natural site, Spain decided to spend a further 360m, some of it EU money, on restoring the landscape. In the 1950s and 60s, some parts of this landscape had been drained to create rice and cotton  elds. Some of this farmland is now being returned to its original wetland state.
It has been a costly but positive process. But Donana is still in trouble thanks to the increasing pressures of modern life. There are plans to build an oil pipeline through Donana and other developers want to build new hotels and golf courses, which would need enormous water supplies. Sand and soil washed from nearby farms is also blocking the channels that cross Donana.