Jersey Water’s application to allow the pesticide oxadixyl to exceed the legal limit in the island’s mains water has been granted.

The dispensation, involving a key reservoir that was brought back into service this month, has been approved by Jersey’s environment minister Steve Luce.

The regulatory limit for oxadixyl in treated water is 0.1ug/l which is equivalent to one part in 10 billion. The new temporary limit has been set at 0.3ug/l, 100 times lower than the already prudent health-based limit of 30ug/l.

Jersey Water said it has so far been able to keep the levels below the regulatory limit but may need to rely on the dispensation in the event that oxadixyl levels increase over the summer. The dispensation will remain in place for up to three years while the company researches and implements a long-term treatment solution to the oxadixyl problem.

The company brought Val de la Mare reservoir back in to service at the beginning of June after five months, following the discovery in February of pesticide oxadixyl in streams feeding the reservoir. To enable the water from Val de la Mare to be used over the summer, the company applied for a temporary dispensation under the Water (Jersey) Law 1972 allowing it to exceed the regulatory limits.

Jersey Water chief executive Helier Smith said: “The need for a dispensation in this instance is principally a legal and regulatory compliance matter rather than a health-based issue. The water that we supply will remain safe to drink.

“The presence of oxadixyl in Val de la Mare reservoir and elsewhere is historic and has arisen due to factors outside of the company’s control. We are working hard to find a way to remove oxadixyl through treatment but in the meantime will work to complying with the lower regulatory limit where it is practical for us to do so.”

Val de la Mare Reservoir represents 35 per cent of the company’s water storage capacity.

A version of this article first appeared on wwtonline