At the end of September, the cantons of Geneva, Vaud and Valais announced the detection of 1,2,4-triazole in drinking water from Lake Geneva. This chemical compound, used in the production of certain pesticides, was found in low concentration, levels considered safe for human health according to current knowledge.
But beyond the immediate health issue, the ASL is concerned about potential environmental impacts of such a pollutant in Lake Geneva and the Rhône. Visit Syngenta chemical site in Monthey has been identified as the main source of this contamination, which is not linked to a one-off incident, but probably to a long-standing practice of discharging into the Rhône.
The ASL has sent a letter to the Department of the Environment (SEN) of the canton of Valais in order to obtain details on the monitoring, origin and extent of these discharges, and calls for reinforced monitoring of the Rhône and Léman rivers. It also asked to be informed of results of the evaluation entrusted to SCAHT, and whether other steps have been taken to gain a better understanding of the toxicity of this substance in the aquatic environment.
To follow interventions and positions taken by the ASL with the authorities, go to Lake surveillance on our website.
