Environmental groups team up to call for stricter water nitrate limit

Monday, 5 July 2021

Environmental activists blame runoff from dairy farms for nitrate pollution in New Zealand’s waterways. (File photo)

Four major Kiwi environmental organisations have teamed up to push for the Government to set a strict nitrate pollution limit of less than 1 milligram per litre in New Zealand’s waterways.

In last year’s new freshwater standards, the Government set a national bottom line for nitrate-nitrogen of 2.4 mg/L, meaning councils could not let the nitrate level in rivers rise above that.

It did not set a bottom line for dissolved inorganic nitrogen but the Ministry for the Environment (MfE) committed in May to reconsidering the possibility of a 1 mg/L bottom line in the next year.

In a joint statement, Forest & Bird, Greenpeace, the Environmental Defence Society and Choose Clean Water said the major cause of nitrate pollution was the big increase in dairy cows and synthetic nitrogen fertiliser use since 1990.

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Farmers used fertilisers to add nutrients to the soil, which were ingested by cows and excreted, eventually trickling into waterways.

Forest & Bird freshwater advocate Annabeth Cohen said all New Zealanders wanted to see their local rivers flourishing with life, “full of native fish and insects, and surrounded by bush and birdsong”.

“We urge the Government to accept the scientific consensus that ecosystem health is not possible if nitrate pollution in waterways exceeds 1 milligram per litre.

“This is a conservative standard of freshwater quality, despite what the agri-industry would have New Zealand believe.”

Marnie Prickett, of Choose Clean Water, said the groups were united in backing the science, which was clear and robust.

“It is not a big ask to set a nitrate limit under one. Many regional councils already manage nitrate pollution to more stringent levels.”

Horizons Regional Council managed nitrates to 0.44 mg/L, while Hawke’s Bay Regional Council set its limit at 0.8 mg/L.

Selwyn residents with private wells on their properties recently had the chance to get their nitrate levels tested.

“The Government will fail to meet its own freshwater standards without a nitrogen pollution limit of under one.”

Greenpeace Aotearoa senior campaigner Steve Abel said a precautionary approach was needed, given emerging research showing links between nitrate contamination and human health effects, including bowel cancer and premature births.

The current 11.3 mg/L drinking water limit was more than 10 times higher than 0.87 mg/L – the level linked to increased bowel cancer risk in a major Danish study published in 2018.

New research released this year found the chances of a premature birth increased by 47 per cent when nitrates in drinking water were just 5 mg/L.

“We are part of nature, so it makes sense that human and ecosystem health are aligned on acceptable nitrate levels in water. A nitrate limit under 1 mg/L responds to what the science tells us about water that is safer for rivers and people.”

Environmental Defence Society chief executive Gary Taylor said it was important to understand a nitrate concentration of less than 1 mg/L did not mean pristine water.

But it was the bottom line needed to prevent algae and cyanobacteria growth, which killed off freshwater fish and invertebrates, he said.

An MfE spokesperson said that while the Government considered a bottom line for inorganic nitrogen in water, its Essential Freshwater package included other measures to improve river and lake health.

Those included an immediate fertiliser application cap of 190 kilograms of nitrogen, per hectare, per year.

Councils were also required to develop regional policy statements and plans that met the National Policy Statement for Freshwater Management.

Most New Zealand rivers already had nitrate pollution readings under 1 milligram, the environmental groups said, although some were much higher.

In May, the New Zealand Federation of Freshwater Anglers tested nitrate levels at seven points in Canterbury’s Selwyn River and found 9.83 mg/L of water at one site, Chamberlains Ford.