Cotonou suffers from a longstanding problem of uncontrolled waste disposal and resulting environmental contamination. Most of the city’s waste ends up at informal dumpsites across the city or in the waters of Lake Nokoué, the lagoon, and the sea, where the shores are now widely covered with garbage. Waste overflows have led to severe pollution and health risks, including an increase in water-borne diseases, damages to fisheries and biodiversity, and the clogging of sewers with solid waste. Especially slum areas of the city, such for example Vèdeko, have been become increasingly converted into dumpsites. New slums are informally built at some of the wastelands along the lagoon and the Ouémé River.  Water is contaminated by leachate from waste that has increasingly piled up over the last three decades, decomposing organic waste, and toxic and even radioactive substances and heavy metals (such as lead, mercury, iron, zinc, and copper) from electronic waste and discarded batteries. The contamination has caused the spread of illnesses and epidemics, entered the food chain, and also led to a drastic decline in fish in Lake Nokoué, where the amount of fish has almost halved within just a couple of years, making it no longer possible for many fishers to make a living. Much of the waste also stems from Dantokpa Market, one of the largest markets in West Africa and trading point for all sorts of goods. Although the dumping of waste is officially prohibited, merchants say they have nowhere else to discard the waste.