Canterbury water quality poses risks

01:25, Nov 05 2012

More needs to be done to protect Canterbury's "precious" drinking water with quality in some areas already posing a serious health risk, Canterbury Medical Officer of Health Alistair Humphrey says.

Dr Humphrey said high nitrate levels in private and small water supplies in the Ashburton area were putting newborn babies at risk.

The high levels, generated by decades of intensive farming, could cause the potentially fatal disease methemoglobinemia- also known as blue-baby syndrome - in newborns aged up to three months.

There had been only one suspected case in New Zealand, but it was possible there had been more as it was not a notifiable disease and could be misdiagnosed as sudden infant death syndrome, Humphrey said.

"It is very rare . . . but increasingly, because of intensive agriculture, high nitrates are becoming an issue. I think one dead baby is one baby too many."

Ashburton's main water supply was fine, but many small and private water supplies near the mid-Canterbury town had nitrate levels deemed to be in the "red zone", and the affected areas were growing.


The Canterbury District Health Board was working to inform midwives and GPs of the health risk, but Humphrey said reducing the problem needed to be a priority in the Canterbury Water Management Strategy (CWMS) and the committees running it.

"It takes a long time to turn [nitrate levels] around. We've emphasised to them how important it is that they act now. It is an issue for the whole of Canterbury really.

"We must look after that precious resource; to date we have not done a very good job."

CDHB member Andy Dickerson said many of the water quality problems seen in Canterbury were "symptomatic" of a system that had not given priority to public health. "Powerful, well-resourced lobbies representing farming, business, Maori, environment and recreation interests continue to dominate this issue."

Changes to local government legislation had diminished the role of the medical officer of health in protecting drinking water quality and there was no specific health representation on the governance group of the CWMS or any of the regional zone committees, he said.

"The DHB is uniquely placed to contribute because we are not motivated by self interest. Our only concern is protecting public health."

David Caygill, the Environment Canterbury (ECan) commissioner with responsibility for water, said ECan worked closely with the district health board and believed they were "working on the same page".

"I don't think there is a person involved in [the CWMS] that does not regard the quality of drinking water and the health risk associated with that as anything other than extremely important.

"The issue here is not are the right people turning up to the right meetings - yes they are - the issue is that getting nitrates down to acceptable levels is not something that can be achieved in a matter of weeks or months."

The Press