Banned in 2019, chlorothalonil, a fungicide approved in the 1970s, has long been one of the best-selling pesticides in Charente-Maritime. One of its metabolites, chlorothalonil R471811, resulting from its breakdown, is now found in drinking water, as well as elsewhere in France. The agglomeration of La Rochelle (Charente-Maritime) has just made a radical decision: to close all fifteen of its catchments located on the Onis Plain.
This summer, all of these drillings identified chlorothalonil R471811. If the level is above 3 micrograms per liter (the drinking threshold), you can no longer drink the water. The La Rochelle results showed levels of chlorothalonil R471811 between 1.4 and 2.9 micrograms per litre. After treatment, tap water still contained between 0.1 and 1.9 micrograms per liter.
The water remains potable
If La Rochelle’s water can still be consumed, “including by vulnerable people”, the inter-community has nevertheless decided to “temporarily switch off” these fifteen catchments. Winter and spring rains can actually further leach the soil and potentially increase the concentration of this metabolite in groundwater, said Guillaume Crabal, the intercommunity’s vice president in charge of drinking water. Jean-François Fontaine, its president, wanted to reassure: the water remains potable and complies with the regulations of the Regional Health Agency (ARS) in New Aquitaine and Anse (National Agency for Food Safety, Environment and Work).
There is currently no effective method for filtering chlorothalonil R471811. Its very danger remains unknown. In these circumstances, the metropolitan area of La Rochelle prefers to apply the precautionary principle. “We applaud this decision and the quick response from elected officials. Our association and citizens have been demanding this precautionary principle for a long time,” commented Franck Rinchet-Girollet, one of the representatives of Avenir Santé Environnement, an organization that advocates a transition to agriculture and an end to the use of synthetic pesticides.
“This is a parenthesis”
A third of the inhabitants of the La Rochelle region have so far been supplied by these 15 watersheds located along the Onis plain. By the end of October, they will all be connected to the water of the Charente River, treated by the drinking water plant in Coulonges. Chlorothalonil R471811 was also found in this river, but in proportions close to the threshold of good quality, emphasized Guillaume Crabal. This measure will come into force by the end of October, when the time has come for the necessary connections to be established.
No quantitative restrictions accompany this highly political decision taken by the La Rochelle metropolitan area in the name of “transparency.” New samples will be taken regularly. A progress report will be prepared before the summer season, which annually affects the flow of the Charente River. What about the fifteen catchments and their future? We do not put an end to these watersheds, this is just a bracket. We must not give up,” insisted Guillaume Crabal. In recent years, the La Rochelle region has acquired 100 hectares of agricultural land around the watersheds to better protect them. The total catchment area of these same catchments exceeds 23,000 hectares.
Source: Le Parisien
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