Twenty-eight years after the historic Boliden mining spill in Aznalcóllar, the image of the rivers surrounding the area is far from being that of a fully recovered environment. New images released by Greenpeace show leaks of turquoise blue water from the open-pit mine towards the Agrio and Guadiamar rivers, reconnecting this old problem with the lower course of the Guadalquivir.
Far from being an isolated incident, environmental organizations argue that the impact of the 1998 disaster is still very much present and could worsen if plans to reopen large mining operations in the basin succeed. The combination of unresolved mining liabilities, massive dumping projects, and an already heavily pressured estuary It has set off alarm bells among scientific and conservationist groups.
Acid seepage from the Aznalcóllar open pit
The new images presented in Seville show how the water impounded in the Aznalcóllar cut, where it is stored the toxic sludge from the 1998 spillIt seeps through the rock and reaches the Agrio and Guadiamar riverbeds. The water's characteristic turquoise color is, according to Greenpeace, a clear symptom of acid mine drainage with a high concentration of heavy metals.
These leaks are not entirely new, but they are a reminder that the problem is not solved. The environmental organization reports that water laden with heavy metals is reaching the Guadalquivir River.This poses a continued risk to river ecosystems and the economic uses associated with the estuary.
The recent series of storms that swept through Andalusia has worsened the situation. The heavy rains have increased the volume of water accumulated in the open pit and have facilitated the mobilization of contaminants, carrying some of these leachates into nearby rivers, as shown by the episodes of pollution in rivers. Extreme weather events act as a catalyst of a chronic problem that has remained latent since the late nineties.
Although the mine is not currently in operation, Greenpeace points out that The management of mining liabilities falls to the winning bidder. The company, Grupo México, operates the mine through Minera Los Frailes. The company maintains that its reopening project will include the remediation of these liabilities and will eliminate the source of pollution, but environmentalists are skeptical that the solution lies in expanding mining activity.
A mining model expanding in the heart of the Guadalquivir basin
The debate comes at a time when mining is once again gaining prominence in Andalusia. The Andalusian Regional Government has given the green light to the reopening of the Aznalcóllar mine in the hands of Grupo México and its subsidiary Los Frailes, in a context marked by the search for strategic raw materials for European industry.
According to the documentation criticized by environmentalists, the Aznalcóllar project contemplates the dumping of approximately 85.520 billion liters of water containing heavy metals over more than 18 years. These discharges would be carried out through a pipeline of about 30 kilometers that would flow into the Guadalquivir estuary, some of them coming from the emptying of the pits that store the sludge from the 1998 accident.
For Greenpeace, Ecologists in Action, Friends of the Earth and SEO/BirdLife, the plan represents a “environmental outrage” and suffers from serious legal and technical deficienciesThe organizations have filed an appeal requesting that the resolution authorizing the mining operation be annulled, arguing that the environmental impact statement is outdated and does not incorporate the best available scientific evidence.
The controversy is not limited to Aznalcóllar. Just a few kilometers away, the Las Cruces copper mine, which has operated as an open-pit mine since 2009, It plans to convert into an underground mining project.This change of model includes an additional discharge of some 32.760 billion liters of water containing heavy metals over 14 years, with a planned discharge point in La Algaba, also in the Guadalquivir area.
Greenpeace describes as "unacceptable recklessness" the support for the continuation of these projects based on an Environmental Impact Statement that is more than a decade old. The organization insists that a correlation between the activity of Cobre Las Cruces and the increase in toxicity has already been demonstrated. in the estuary, and warns that continuing down this path could turn the river into a “mining sewer”.
Synergistic effects on Doñana and the Natura 2000 Network
Beyond the figures for volume dumped, environmentalists focus on the sum of impacts. According to their calculations, The combination of the planned spills in Aznalcóllar and Cobre Las Cruces would leave the Guadalquivir River "mortally wounded"., as the synergistic effects of both projects on the same river system were not adequately taken into account.
The discharge points and areas of influence are linked to the Lower Guadalquivir Special Area of Conservation, integrated into the Natura 2000 Network. Habitats of community importance and protected species of the estuary and its surroundings would see increased pressureThis adds to the deterioration already suffered by the Doñana National Park due to the overexploitation of aquifers, intensive agriculture and the climate crisis.
In this context, the European Nature Restoration Regulation, approved in 2024, obliges Member States to restore at least 20% of ecosystems by 2030. Spain reaches this deadline with only 9% of its habitats in good condition, as the signatory organizations point out. The interpretation from environmental groups is clear: rather than accept new large-scale impactsThe principle of non-deterioration should be rigorously applied, and priority should be given to the recovery of already damaged areas.
From the perspective of environmental advocates, the current policy of granting discharge permits in the upper and middle Guadalquivir basin It does not fit with European ecological restoration objectives.The criticism extends to the way in which cumulative risks are being assessed, both for protected areas and for communities that depend on the river.
Contaminants in fish, shellfish and rice paddies
The warnings from Greenpeace and other groups are based on various scientific studies conducted by teams from the universities of Cádiz, Seville, and Granada. These studies have detected lead levels above European Union limits in slugs, a fish widely consumed in the riverside towns of the Guadalquivir and key to local fishing.
In the case of mantis shrimp, a crustacean highly prized in the gastronomy of the Andalusian coast, the analyses have confirmed presence of arsenic in values close to the maximum permitted due to European regulations. Researchers warn that, if the massive dumping plans materialize, the heavy metal load in the estuary could increase tenfold.
The consequences would not only affect these specific species. Scientific reports point to the need to also assess the status of other fishery resources of great economic and cultural importance, such as sole, red crab, prawns or king prawns that are captured at the mouth of the Guadalquivir River. The bioaccumulation of heavy metals in the food chain could have repercussions for human health and the reputation of local products.
The agricultural sector would not be left out either. The Guadalquivir marshes are home to the Spain's largest rice field, with more than 36.000 hectares crops that depend directly on river water; therefore the management of plant protection product containers This is crucial. Rice is particularly prone to accumulating arsenic in its tissues, so a sustained increase in this heavy metal in the river system could compromise both production and marketing.
For Greenpeace, the dumping permits granted by the Andalusian Regional Government do not adequately reflect this “critical scientific reality” and they overlook the medium and long-term risks to food security, agricultural employment and the economy of marshland villages.
A river that acts as a toxic waste dump
One of the keys to the problem lies in the very hydrological dynamics of the Guadalquivir, which requires measure microplastics in their riversFar from functioning as a simple canal that drains water into the Atlantic, The estuary behaves like a large reservoir where toxic substances accumulate.Several studies indicate that the Alcalá del Río dam acts as a "dead end" that slows the push of the tides inland.
This effect limits the circulation of water and forces many of the sediments loaded with heavy metals to settle and decant into the riverbed. This is compounded by the so-called "salt plug" at the river mouth, a natural barrier created by the meeting of fresh and salt water that further hinders the release of pollutants into the open sea.
The result is that heavy metals do not easily dilute and disperse in the ocean, but rather They adhere to suspended particles and eventually become integrated into the estuary mud.From there, they enter the food web and can be reactivated during flood events, drifting towards the Gulf of Cadiz and even the Alboran Sea.
When episodes of heavy rainfall or significant releases from the Alcalá del Río dam occur, Some of that contaminated sludge is removed and transported downstreamThis increases the exposure of marine fauna and fisheries resources. This dynamic makes any increase in heavy metal inputs a cumulative and difficult-to-reverse problem.
The weight of the 1998 disaster on the current debate
The discussion about new mining projects is inevitably marked by the memory of the Aznalcóllar accident of April 1998, considered one of the worst environmental disasters in recent Spanish history. The rupture of the Boliden-Apirsa waste pond released approximately seven million cubic meters of sludge and acidic water. that devastated the Guadiamar green corridor.
The spill affected about 80 kilometers of riverbed and contaminated around 4.600 hectares of crops, forcing the closure of fishing grounds and causing a serious socio-economic crisis in the region. Approximately 30 tons of dead wildlife were counted Aquifers with high levels of contamination were recorded, while thousands of people lost their jobs directly or indirectly.
Estimates at the time indicated economic losses of around eleven million euros, not counting long-term environmental costs or damage to the area's image. A significant portion of the sludge collected after the disaster It was precisely stored in the mining pits from Aznalcóllar, the same ones that today continue to be a source of acid drainage towards nearby rivers.
Organizations like Greenpeace insist that this precedent should be enough to exercise extreme caution with any new project in the basin. Their message is that the region cannot afford another episode of mass pollution and that prevention is much more effective —and cheaper— than repair after the fact.
Environmental demands and a call to mobilization
Given the scenario described, Greenpeace has demanded the immediate suspension of dumping permits related to Aznalcóllar and Cobre Las Cruces, as well as the declaration of a moratorium on new mining explorations that may affect the Guadalquivir basin.
The organization proposes the creation of a independent technical-scientific group that assesses the cumulative impact of the various projects, integrates the most recent scientific evidence and proposes alternatives that reconcile economic activity with the protection of river ecosystems.
The environmental movement also insists on the need to strengthen monitoring of water quality, sediments and fauna in the estuary, as well as to guarantee the transparency of information available to the public. Social groups and productive sectors linked to the river —such as fishing, nature tourism and the rice fields themselves— are identified as key players in demanding changes.
The figure of the Greenpeace coordinator in Andalusia, Luis Berraquero, has become relevant in this debate by giving voice to the request that society "learn from the mistakes of the past" and not repeat a development model that already demonstrated its limits almost three decades ago. Their appeal is directed to citizens, government agencies, and businesses alike., with the aim of opening a deep dialogue on what type of mining and water management is desired for the region.
The struggle between mining projects, environmental protection and the defense of traditional uses of the Guadalquivir River remains open almost thirty years after the Aznalcóllar disaster. The new leaks, the scientific data on heavy metals, and the large figures of spills expected They have brought to the forefront a conflict in which economic interests, European restoration obligations and the need to safeguard a river on which thousands of families in Andalusia depend intersect.
