Riversdale nitrate levels cause concern

Testing … Riversdale resident Hilary Riordan gives a sample of tap water taken from her house to Greenpeace Aotearoa spectrometer operator Charlotte Noble for testing. PHOTO: SANDY EGGLESTON

Riversdale residents concerned about the levels of nitrates in their bore water are considering their options after water testing carried out in the town on Sunday.

Greenpeace Aotearoa staff tested the water of 28 bores in the town using a spectrometer and found levels ranging from 5.19mg/litre to 8.88mg/litre.

The maximum level allowed in New Zealand is 11.3mg/litre, the level set by the World Health Organisation as the limit necessary to avoid blue baby syndrome.

Resident Hilary Riordan said she was interested in having the water tested because she had been reading about the link between nitrate levels and cancer.

The water taken from a tap at her house recorded a nitrate level of 7.4mg/litre, which she said worried her.

“I think it’s very related to the high incidence of cancer in this area,” Mrs Riordan said.

“The only solution I see is to collect water off our roof for drinking water but we grow all our vegetables in our garden and water the garden with the bore.”

The water resident Caroline Lennon submitted for testing recorded 8.1mg/litre.

“I didn’t think that was very good at all,” Mrs Lennon said.

She also was considering collecting rainwater to drink.

Farmer Robina-Lee Johnston, who lives at the Gore end of the Hokonui Hills, took a sample of tap water which is sourced from a spring about 1.5km from the house.

That sample recorded .78mg/litre.

Nitrogen fertiliser was used sparingly on the farm, which could explain the low level of nitrates Mrs Johnston said.

“I am quite rapt.”

Nugget Point resident Bronwyn Bain’s sample, taken from the rain water tank which supplies her house, recorded .5mg/litre.

Mrs Bain said that was a “fantastic” result, as she expected seagull faeces which landed on the roof might have pushed the nitrate reading up.

Altogether 51 people had their water tested at the event and apart from the two readings under 1mg/l, the rest ranged from 6.3mg/litre to 8.88mg/litre.

Greenpeace Aotearoa senior campaigner Steve Abel said he was “very concerned” about how high nitrate levels were in the town’s water samples.

“In fact 100% of them were over the 5mg/l which is the risk for pre-term birth and all of them are well over the cancer risk limit of 0.87mg/litre,” he said.

A Danish study had shown there was a link between bowel cancer and nitrate levels above .87mg/litre.

It was not easy to remove nitrate once it was in water and the best option was to stop it getting there.

“That means taking some hard choices around phasing out synthetic nitrogen fertiliser and lowering stocking rates.”