The canoe trip could have been magical. Majestic mangroves have their roots in the tropical mangroves of Abidjan, competing for center stage with raffia and rattan palms. But instead of peaceful, nurturing water, the spectacle of an ocean of plastics, shoes, cans, bags swollen with putrefaction and unidentified floating objects jumps to mind. And the smell. Sometimes unbearable because of the smell of excrement. Supposed to be the lung of the Ivorian economic capital, the Ebrié lagoon is suffocated by domestic and industrial waste and eaten away by invasive plants.
Only a few descents into the water of large hotels, Ivorian and international institutions and residences under construction of ministers are protected by rows of buoys of these tons of rubbish adrift. The lagoon, which covers 560 km2 and has around ten arms, is not impacted evenly. Marine movements favor the dilution of certain pollutants. But the pollution is such that “the pearl of the lagoons” is now nicknamed “the trash can”.
For researchers, its condition is due to strong anthropogenic and urban pressure. Abidjan has seen its population triple in twenty years according to World Bank data, exceeding 6 million inhabitants in 2021. “I am sure that our capital exceeds 7 million inhabitants”, even declared Ivorian President Alassane Ouattara at the inauguration of the cable-stayed bridge bearing his name on August 12. The economic metropolis, originally built on 422 km2, now covers 2,119 km2 and has a fifth of the country’s population. Like all African megacities, it is still set to grow.
But the former political capital is growing faster than its sanitation infrastructure. While the network has around 60 pumping stations, 60% of Abidjan residents are not connected to mains drainage, according to the National Office for Sanitation and Drainage (ONAD). Wastewater from the 40% connected to the national network of the Water Distribution Company of Côte d’Ivoire (Sodeci) reaches the Koumassi reprocessing station, formerly faulty but now rehabilitated, which discharges it into the sea after passing through a deodorization unit.
But where does the dirty water of two-thirds of the unconnected inhabitants go? In septic tanks whose sludge is emptied by trucks and treated within four stations in the district: Anyama, Yopougon Songon-Kassemblé, Bingerville and Vitré 2. The latter was designed to methanize sludge and eventually produce energy which will supply the Koumassi station.
To catch up, the country, which has six other wastewater treatment plants for the main large cities, has launched an ambitious construction site for fourteen new plants that will equip eleven medium-sized municipalities. A program that is part of the government’s “Water for All” plan to cover the needs of all Ivorians by 2030.
Untreated industrial water discharges
But in Abidjan, despite the investments, the pollution still trickles into the lagoon waters. Bouaké Fofana, the minister of hydraulics, sanitation and safety, admitted, the day before the inauguration of the bridge over the emblematic bay of Cocody, that “thirty inlets of waste water” had been identified and that a study was underway to neutralize them. “The lagoon will regain its former quality,” he promised. “Demographic pressure and industrial concentration will further increase the volume of discharges, however, warns the Ivorian geoscientist Sylvain Mondé. All these infrastructures will have to be calibrated and redeveloped in order to respond to the high flow of water to be treated. »
Samples taken by Le Monde Afrique and submitted to Flandres-Analyses, a Dunkirk laboratory specializing in waste water, revealed that “without being of too critical a quality, the water from the Ebrié lagoon resulting from the samples can be considered of mediocre quality “. The samples present “contents of indicator parameters, synonymous with the presence of insufficiently, even untreated domestic wastewater and therefore diluted in the mass, explains Emmanuel Dupré, the head of the analysis laboratory. But this pollution does not mean that the lagoon is an open sewer outlet. These traces rather tend to designate discharges of non-reprocessed industrial water.
Results that do not surprise Professor Bernard Yapo, deputy director of the Ivorian Antipollution Center (Ciapol), attached to the Ministry of the Environment, which has been monitoring the body of water with its meager resources for around thirty years. years. To better understand, head to the lagoon areas of the Plateau and Yopougon municipalities. In this rainy season, the wastewater from many industries and the most modest households flows into the gutters before flowing directly into the inlets already congested by constructions, sometimes anarchic, and wild dumps of garbage. , construction waste, earth fill.
“It is the agri-food industries, very numerous in Abidjan, which pollute the waters the most and have caused the very advanced degradation of the lagoon”, says Mr. Yapo, passing on foot oil and soap companies in the industrial zone of Yopougon. From the second street, at the exit of a tobacco factory, a whitish stream with a large flow flows on the side. “Many industries do not treat their water or are not up to standard,” reveals the professor. Further on, three small streams – green, brown and sparkling – meet in the same collective gutter, before also ending up in the lagoon.
Fines, formal notices and penalties up to and including imprisonment are provided for in the event of non-compliance with the standards. “It happened a few times, assures Bernard Yapo. The companies then brought themselves up to standard. But this remains too rare and the ministry’s brigade lacks the means and vehicles to carry out sufficient checks. “And let’s face it, like in all countries, ‘friendships’ and corruption don’t help,” he continues.
Despite the state of the Ebrié lagoon, some fishermen still cast their nets in the middle of its troubled waters to try to enrich the daily attiéké, a dish of cassava semolina essential to Ivorian gastronomy. But fishing is far from miraculous. Pollution causes many fish to migrate offshore or renders the remaining species unfit for consumption. In 2022, the country imported 90% of the fish it consumes.