New Zealand’s love affair with Agrochemicals is often cited as proof that its 100% pure slogan has no factual basis. It’s extensive use of 1080 and pollution from its massive dairying industry is enough to discredit that credential.
Now we learn that the country’s extensive use of herbicides has resulted in traces of the chemical metsulfuron-methyl being found in two drinking water reservoirs in the Hunua Ranges. Twenty percent of Auckland’s drinking water supply is sourced from these dams. The chemical was used to control weeds in forestry areas in May and drained into the lakes when rain fell two days after spraying.
Note. No justification has been given for using chemicals within the catchment area of drinking water reservoirs, nor is there any indication if this is an acceptable practice. These areas should be pristine areas with stringent controls on the release of any substance which may potentially pollute the water, including run-off from road surfaces. But the NZ Herald doesn’t give its readers that information.
Details about the contamination were withheld from the public by Watercare and Auckland Council, until a whistleblower contacted the New Zealand Herald yesterday. But, in what reads like a Watercare PR release issued to control the story, the Herald (note how its article failed to give a concentration for the chemical, or comment on catchment safeguards) said:
Metsulfuron-methyl is a residual toxic herbicide used to kill broadleaf weeds and some annual grasses.
Watercare said the likely cause was run-off from surrounding blocks as a result of unexpected heavy rain two days after spraying. GPS tracking by helicopter confirmed spray was not applied to the lake areas…
Watercare said New Zealand drinking standards did not cover metsulfuron-methyl. But Australian guidelines said it would not be a health concern unless the concentration exceeded 0.2mg per litre.
Initial readings in both lakes were well below this level, Watercare said.
Dr Leo Schep, a toxicologist at the National Poisons Centre in Dunedin, said the Australian guidelines were robust, based on scientific data, and he would be happy with the Watercare figures if they were below the recommended guidelines.
He could not comment on the herbicide without looking it up.
Initial readings may have been acceptable, but what were they? What were subsequent readings like? The NZ Herald’s article omits the figures.
How long does this chemical persist in the lake’s sediments, and what happens when water is abstracted from the lake when it’s at low levels? Does it bio-accumulate?
To add insult to injury, Auckland Council decided last week it would use the inhumane poison 1080 for pest control in the Hunua Ranges National Park.
100% pure? No, not really.
If you live in Auckland you may think it wise to switch to bottled water in future.