If you dive one day in the Calanques National Park, off Marseille (Bouches-du-Rhône), you may have the chance to admire seahorses dancing in front of your mask, to observe a diadem sea urchin darting its spines 10 cm long or photograph impressive colonies of red coral.
This reserve is so exceptional that one can come across no less than sixty species, including the fin whale, the loggerhead turtle and the famous large mother-of-pearl, the largest shell in the Mediterranean.
It's hard to imagine that this treasure of biodiversity has suffered for almost half a century one of the worst marine pollution in France.
And this, in full knowledge of the facts.
30 million tonnes spilled
For decades, the Alteo alumina plant, located inland at Gardanne, 30 km from Marseille, threw off, 320 m deep, in the heart of the Calanques park, 30 million tonnes of sludge. red.
After stopping these "solid" discharges five years ago, the company has just announced that it now complies with all legal environmental standards concerning its "liquid" discharges.
"Alteo started up the last water treatment unit, during the summer as planned, to achieve the water quality objectives required by the deadline of August 30, 2020," said a spokesperson for the factory, currently looking for buyers.
The company, which was placed in receivership following a sudden drop in its orders, claims to have invested more than 36 million euros in the treatment of its "effluents".
"Thanks to the mobilization of associations, we have succeeded in bringing this industrialist to meet standards by installing three levels of filtration", welcomes the Vice-President of the Calanques National Park Pierre Aplincourt.
In addition, a member of France Nature Environnement, he has not forgotten that "for nearly half a century, millions of tonnes of red mud were thrown into the sea from this factory" in what today constitutes the heart. Calanques and "today line part of the Cassidaigne pit".
Red dust loaded with arsenic and mercury
This canyon, located off Cassis, plunges to nearly 1,000 m deep.
"This submarine dump could in the future become a time bomb", worries the environmental association Robin des Bois which points to another pollution, terrestrial this one.
Nearly two million tonnes of powdery and toxic residues are stored in the open on the landfill of Mange-Garri, near Marseille.
Environmental associations denounce the flight of red dust laden with arsenic and mercury.
A judicial investigation was opened in March 2019 concerning this onshore storage of bauxite residues, the raw material of alumina.
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"None of the buyers (
Editor's note: of the Alteo industrial site
) will have the financial means and the legal responsibility to monitor, and if necessary secure, the underwater landfill and ensure the maintenance, stability and safety of the terrestrial stock of dehydrated red mud, estimates the NGO Robin des Bois.
This double burden will have to be ensured by the State for decades with the support of communities.
"
Since the beginning of June, the company has received eight offers, most of which foresee in the more or less long term the abandonment of the processing of bauxite on the site.