Lorraine Williamson
The Guadalquivir River, lifeline of Andalucia, hides a problem few want to confront: its sludge is laced with metals. A new study by the universities of Seville and Cádiz reveals that while Spain regulates contamination in water, it has no rules for polluted riverbeds — leaving nature exposed to long-term risks.
The research team analysed samples from 15 points along the Guadalquivir between 2022 and 2023. The findings showed elevated concentrations of metals, particularly in the upper basin near the Cobre Las Cruces mine, but also at the river’s mouth close to Doñana National Park. Most of the pollutants are trapped in the sludge, or sediment, that settles on the riverbed.
Unlike water, this sludge is not covered by strict European or Spanish environmental limits. That regulatory blind spot means contamination can sit unnoticed for years, slowly leaching into ecosystems. Areas of slower water flow act as collection points where harmful substances accumulate, increasing the risk for plants and animals.
Why Doñana stands in the firing line
The Guadalquivir estuary is directly linked to Doñana, Europe’s most important wetland reserve and a UNESCO World Heritage site. Thousands of migratory birds, rare lynx, and countless plant species depend on its delicate balance of fresh and saltwater. Even indirect contamination — when metals from sludge work their way into the food chain — could undermine decades of conservation efforts.
Researchers warn that without examining water, sludge, and wildlife together, early signs of damage will be missed.
History repeating itself?
Spain has been here before. In 1998, the Aznalcóllar mining disaster released five million cubic metres of toxic sludge into the Guadiamar River, devastating landscapes just upstream from Doñana. Although safeguards were promised, new mining projects in Andalucia raise concerns that lessons have not been fully learned.
Agriculture and industry add further pressure, feeding the Guadalquivir with chemicals that slowly sink into its riverbed. Without rules to govern sediment quality, regulators cannot guarantee that nature is safe — even when the water itself meets official standards.
Protests over Guadalvuivir mining waste
A call for urgent regulation
Environmental scientists say the situation exposes a glaring gap in EU and Spanish law. As climate change intensifies droughts and floods, sediments may be stirred up more often, redistributing pollution across wider areas. This makes the absence of regulation even more dangerous.
Calls are growing for authorities to extend environmental controls to cover river sludge, not just water. Without this, monitoring remains incomplete, enforcement is patchy, and protected areas like Doñana remain vulnerable to contamination hiding in plain sight.
Source: EuropaPress