Banned pesticide found near drinking water area in dunes

Last year, high concentrations of the agricultural toxin dinoterb, banned since 1998, were measured in Heemskerk, not far from where the water supplier PWN purifies the water in the dunes. The Hollands Noorderkwartier Water Board is investigating whether the limit values were exceeded and is including the data in its ongoing investigation into the source of the pollution.

The pesticide was also measured above the standard of 30 nanograms per liter at ten other measuring points in Noord-Holland last year, including in the Natura 2000 area of Het Zwanenwater near Callantsoog. "This poses a serious threat to biodiversity in this area and to the health of local residents," said the environmental organization Mobilization for the Environment (MOB). About 443.8 nanograms were measured in the water near Heemskerk.

PWN said it is aware of this. "We are shocked every time by what we find, you wouldn't expect it to be a banned substance," said a spokesperson of the water company. "Dinoterb has been detected in the surface water near one of our buildings in Heemskerk but not in the dunes and drinking water. We cannot find any measurable concentrations in the laboratory. We cannot explain how this is possible. As far as drinking water is concerned, there is no reason to worry about this substance.

The water board recently reported that the standard was exceeded in surface water at 12 locations in the north of Noord-Holland until 2022, as was the case last year. "Dinoterb does not belong in the water. We also want to know the cause, hence the investigation of the source," the water board said.

MOB suspects that dinoterb was used illegally in ornamental flower cultivation, but according to the authority, it is unknown when, how or why the substance entered the surface water. Comprehensive investigations in the coming months, coordinated with the Dutch Food and Consumer Product Safety Authority (NVWA) and the environmental services, should provide a clear answer.

Due to the "alarming figures," the action group is once again pushing for stricter enforcement of the regulations, as the pesticide has been banned since 1998. The water board stressed that monitoring and enforcement capacity is primarily deployed in areas where active substances are found in surface water but said it can only enforce the regulations if a potential polluter is involved. "We are now focusing on investigating the source, that is the priority," a spokesperson for the water board said. The first measurement data for 2024 will also be published later this year.