Banned Pesticide at 2,000 Times Limit in Flemish Stream

A highly toxic, EU-banned pesticide has been detected in a stream in Reningelst, West Flanders, at concentrations approximately 2,000 times the legal limit for surface water intended for drinking water production. While authorities confirm there is no immediate danger to public drinking water supplies, the discovery has intensified concerns about pesticide enforcement and water quality in the region.

The Discovery

Water samples collected on April 27 from the Grote Kemmelbeek stream in Reningelst, a village in the municipality of Poperinge, revealed oxamyl levels of 232 micrograms per liter — far exceeding the allowable limit of 0.12 micrograms per liter, according to VRT NWS. The results were not made public for nearly three weeks.

Oxamyl is a carbamate pesticide that was banned for professional agricultural use across the European Union in 2023. It had already been prohibited for private use prior to that. The substance is highly toxic to humans and animals and was previously used to protect potatoes, vegetables, and ornamental plants against nematodes.

Official Response

Flemish Environment Minister Jo Brouns (CD&V) has ordered an accelerated investigation to identify the source of the contamination. “This is completely unacceptable. A banned pesticide does not belong in our waterways. This must be investigated to the bone,” Brouns said, as reported by Nieuwsblad. “If a perpetrator is identified, they must be held accountable and punished.”

According to HLN, Brouns emphasized the need for a systemic shift: “We must not wait until banned substances appear in our waterways or ultimately in our drinking water. We must measure faster, intervene faster, and act harder against those who use or discharge banned products.”

Drinking Water Safety

Despite the alarming concentration, De Watergroep — the Flemish water company — has confirmed there is no risk to public drinking water. Spokesperson Kathleen De Schepper explained that the contaminated water undergoes significant dilution in the IJzer basin before reaching the De Blankaart water production center in Diksmuide, which supplies approximately 363,000 people.

“Before the water reaches our reservoir, there is significant dilution in the IJzer basin and the catchment area towards De Blankaart,” De Schepper said. “We have been investigating this substance since 2018.”

Environmental and Transparency Concerns

Lieven Stubbe of Natuurpunt De Bron and Groen Ieper expressed alarm at both the contamination levels and the communication process. “My great fear is that we are systematically and increasingly absorbing — albeit small — amounts of such substances into our drinking water,” Stubbe told VRT NWS. He questioned why only farmers were informed of the contamination via an urgent flash message, while the general public was not notified for nearly three weeks.

Bart Naeyaert, Deputy for the Province of West Flanders (CD&V), defended the response: “This is unacceptable. We did respond quickly with a message to growers and contract sprayers in the area, so they are warned.”

Miguel Gheysens, Alderman for Water Policy in Ieper, suggested the contamination could have been accidental rather than deliberate. “Hopefully the product was not deliberately discharged, but ended up in nature accidentally, for example through a knocked-over bottle,” he said.

Broader Context

The discovery comes just days after the Flemish government approved its long-awaited Strategic Drinking Water Plan on May 4, which addresses the ongoing crisis of pesticide contamination in West Flemish drinking water. The De Blankaart facility has been struggling with elevated levels of 1,2,4-triazoles — breakdown products of fungicidal pesticides — since early 2024. The new plan grants a temporary three-year extension of relaxed norms for these substances while phasing out more than 30 crop protection products.

What’s Next

The accelerated investigation ordered by Minister Brouns will aim to determine whether the oxamyl contamination resulted from illegal use or an accidental spill. The distinction carries significant implications for legal consequences and future prevention strategies. Meanwhile, the incident has further eroded public trust in tap water quality in the Westhoek region, where many residents have already switched to bottled water amid ongoing concerns about pesticide contamination.

Oxamyl is highly soluble in water and cannot be physically removed from the stream; it must break down naturally over time, posing a threat to aquatic life in the immediate vicinity.