A vast area in the marshy lowlands of Las Marismas, around southwestern Spain’s Guadalquivir River, was designated as a wildlife refuge and national park in 1963. Donana National Park became a UNESCO World Heritage Site in 1994, but not before suffering persistent threats to its unique ecosystem caused by water extraction for agricultural irrigation and burgeoning coastal tourist facilities.
Four years on, this unique area faced an even more severe threat – a massive spill of mining waste from a storage lagoon at the Los Frailes lead-zinc mine operated by the Swedish-Canadian Boliden company at nearby Aznalcollar. A dam wall collapsed, sending millions of cubic meters of concentrated zinc, lead and cadmium sludge into the River Guadiamar, a tributary of the Guadalquivir that flowed through Donana National Park. This toxic cocktail polluted a 60 km (37 mi) stretch of the river, killing all aquatic life, depositing lethal heavy-metal waste in wetlands, polluting wells, permeating ground water, ruining farmland and destroying standing crops.
Boliden inevitably claimed that the disaster could not have been foreseen, though it probably happened because pollution fines were so low in Spain that it was cheaper to let things happen than take expensive remedial action. This theory is supported by the fact that a report commissioned by the company two years earlier identified the failed dam’s weakness. After the event, contributory factors such as unsuitable subsoil and blasting at the opencast mine were identified. But whatever the cause, its effects were disastrous and despite a 250 million euro clean-up it will take four decades for the polluted area to recover fully.
However, there was a silver lining. The rapid construction of an emergency dam across the River Guadiamar prevented any toxic waste contaminating Donana National Park’s fragile ecology, which therefore remained undamaged by this avoidable disaster.
When: April 25 1998
Where: Andalucia, Spain
Toll: Long-term environmental damage.
You should know: In 2000, without giving any advance warning, Boliden abruptly abandoned its mining activities in Spain, before filing for bankruptcy later that same year to avoid paying a hefty fine imposed by the out-of-pocket Spanish government.