Thursday 2 February
An extremely low level of the herbicide Hexazinone was
detected in the water produced by the Warkworth Water Treatment Plant – which
serves the local Warkworth community – during routine testing carried out by
A recent test
detected Hexazinone at a level of 0.0005mg/L in the water produced at the plant.
This level is 800-times below the Ministry of Health’s
maximum allowable value (MAV) of 0.4mg/L, as defined in the Drinking Water
Standards of New Zealand 2005 (Revised 2008).
Watercare general manager service delivery Shayne Cunis says
the company is committed to the delivery of a safe water supply and therefore carries
out extensive testing and treatment.
“We have adjusted the operation of the Warkworth Water
Treatment Plant to prevent this substance from entering the drinking water
supply,” says Cunis.
“Our staff have notified the Auckland Regional Public Health
Service (ARPHS) and the Medical Officer of Health David Sinclair. ARPHS have
confirmed that they are satisfied with our actions and response to this result.”
Further water samples have been taken and the test results
are expected tomorrow.
Hexazinone is a broad spectrum herbicide that is often
applied to control woody/herbaceous, annual and perennial weeds. It is known to
be soluble in water, highly mobile and can leach from the soil. Watercare has
notified Auckland Council’s pollution response team which is the entity
responsible for investigating reports of environmental pollution.
In Warkworth, water is sourced from the Mahurangi River.
Watercare publishes detailed water quality reports for all
of its water treatment plants each year on its website.