Canterbury water plan 'risks health'

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Canterbury's top health watchdog is warning of potentially huge health effects if the proposed Central Plains Water (CPW) scheme goes ahead in its current form.

These could include an explosion in the incidence of the crippling and potentially fatal water-borne diseases campylobacter and cryptosporidium, he says.

Medical officer of health Dr Alistair Humphrey said "downstream" social and health concerns were being largely overlooked in the haste to move the $350 million irrigation scheme forward.

"I think the consideration has been relatively superficial at this point," Humphrey said.

"It needs far more detail as to what is going to happen."

Zoologist Wally Clark, a professor emeritus at the University of Canterbury, said water was a big concern, especially where dairying was concerned. Campylobacter and cryptosporidium, previously little-known diseases here, had become commonplace in Canterbury with the growth of dairying, he said.

"They're really bad now and they're increasing," Clark said. "There's a real need to look at the incidence of these diseases and the means of transmission very closely." Clark said.

South Canterbury had the highest rates of campylobacter in the world.

Humphrey said he wanted to see a comprehensive assessment, similar to the Greater Christchurch Urban Development Strategy, a long-term planning document for future growth.

He wanted it to look at long-term water supply and the potential degradation of aquifers serving residents of Christchurch.

He said it should also consider residual social health impacts related to construction and transportation – for example road accidents and housing supply and cost.

The CPW scheme plans to irrigate 60,000ha of farmland between the Waimakariri and Rakaia rivers.

Once in operation, 40 cubic metres of water a second (cumecs) would be drawn from the rivers.

Humphrey said the implications extended "far beyond water".

His office had already put forward a request for an assessment and wanted to see it carried out in advance of consent hearings scheduled for February.

Pat Morrison, chairman of the CPW project, said yesterday he understood a team of 28 experts was already looking into such issues.

"They've all been raised, they've got very detailed technical reports on all those issues," Morrison said.

"Non-economic concerns have to be taken into account to get the consents."

Humphrey maintained that health impacts had not comprehensively been dealt with.

"We haven't passed judgment on this project but this is something that needs to be done and the sooner the better, so we're clear about where we are going with this."

Clark said water quality in Canterbury had already suffered as a result of increased dairying – an industry that would prosper further with the CPW project.

Both campylobacter and cryptosporidium, which can cause severe diarrhoea and can be fatal, are spread to humans through contaminated water. Cows and calves are natural carriers for the diseases and pass the bug through faeces.

Irrigation systems spread the disease by sweeping faecal matter into the watershed and through ground absorption.

"Does the right to take water to irrigate pasture also confer the right to pollute human supplies?" Clark said.

"It's a bold ask, but there have been a good number of reports of campylobacter in our community and private wells. So I don't think I'm dreaming."

Expensive water treatment plants would help minimise contamination of supplies but would not protect those who drew water from private wells.

- © Fairfax NZ News