All green waters, that could make a pretty picture, if it weren’t for the danger that accompanies this funny fluorescent color. At Lake Saint-Mandé, located in the Bois de Vincennes in Paris, the waters have changed appearance in recent weeks under the probable effect of cyanobacteria, as well as at Lake Daumesnil. This is dangerous pollution for humans and animals, warn local residents and an association, who ask the town hall to put up an information panel.
It was Denise (her first name has been changed, for fear, according to her, of “retaliations”), a passionate nature walker who does wildlife photography, who first sounded the alarm, in August. On her way, she saw these dog-killing bacteria proliferate in the water, to the point of completely covering them. In humans, they can cause diarrhea and vomiting, irritation of the skin, nose or throat, and fever if you come into contact with infested water. So Denise quickly notified a manager at the Bois de Vincennes on August 4, as well as an on-site gardener.
Works that dry up the lakes
More than a month later, the bacteria are still there, but no information has been released, and Denise is moved: “I consider that there must be information on the health risks because people do not know not. I’ve seen nannies splashing little ones in the water. I also see children going to fetch water to make sand pies. », worries the walker.
The cause according to her: the water supply to Lake Saint-Mandé “cut off for three weeks”. In a response to a letter dated July, the Head of the Bois de Vincennes Division explains that “following work on the non-potable water network of the City of Paris which supplies the lakes and rivers of the Bois de Vincennes Vincennes” there would be “a reduction in the supply capacities of the lakes and rivers of the Bois de Vincennes”. However, it is known that cyanobacteria develop when watercourses are at their lowest.
“Consequence of climate change”
On September 5, Marie-Noëlle Bernard, of the National Tree Surveillance Group, alerted the Bois de Vincennes Division: “It is obvious that there is a health emergency,” she noted. But still no information for local residents.
Contacted, the town hall of the 12th arrondissement affirms that the cyanobacteria pollution is due to the “strong heat of recent weeks” which would have “resulted in an increase in the temperature of the bodies of water in the Bois de Vincennes which is conducive to the development of cyanobacteria”. “This is in no way linked to maintenance or management choices for these bodies of water but rather a consequence of climate change,” she defends. According to several researchers contacted by 20 minutes in a previous article, “the division rate of cyanobacteria increases with temperature. But temperature alone is not enough. »
Eau de Paris took samples last Thursday, according to our information. “The services are exercising extreme vigilance while awaiting the results,” explains the town hall of the 12th, which aims to be reassuring: “The ecological situation of the bodies of water is monitored very closely by the Bois de Vincennes agents and by associations for the protection of aquatic environments. No mortality of fish, birds or other animals has been observed. » “Only lies”, retorts the GNSA, which claims to have collected testimonies concerning the deaths of two geese and several fish and calls into question the management of the lake.