Four of New Zealand’s leading environmental organisations are urging the Government to defend native species and human health by setting a nitrate pollution limit under one milligram per litre for waterways.

A nitrate limit, which will define the maximum amount of nitrate pollution allowed in rivers, was left out of last year’s freshwater standards, in-line with industry demands. The limit is now being reassessed by the Ministry for the Environment and Minister Parker.

The major causes of nitrate pollution are a huge increase in dairy cows and synthetic nitrogen fertiliser use since 1990.

Marnie Prickett of Choose Clean Water says, “Forest & Bird, Greenpeace, the Environmental Defence Society, and Choose Clean Water are united in backing the science, which is clear and robust. The absolute maximum nitrate pollution that should be allowed is less than one milligram per litre.”

Forest & Bird Freshwater Advocate Annabeth Cohen says, “We all want to be able to look out over our local rivers and see them 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 isn’t possible if nitrate pollution in waterways exceeds 1 mg/L.

“This is a conservative standard of freshwater quality, despite what the agri-industry would have New Zealand believe. We need to stay under one, just to ensure the river can support life,” says Ms Cohen.

Marnie Prickett of Choose Clean Water says, “It’s 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 is managing to 0.44 mg/L, while Hawkes Bay Regional Council set their limit at 0.8 mg/L.

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

Greenpeace Aotearoa senior campaigner Steve Abel says, “With emerging research showing links between nitrate contamination and health effects including bowel cancer and premature births, a precautionary approach to human health also depends on nitrate contamination in water being under one.”

The current health limit of nitrate in drinking water of 11.3 mg/L is over 10 times higher than 0.87 mg/L, the nitrate level linked to increased bowel cancer risk in a major Danish study published in 2018.

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

The Environmental Defence Society Chief Executive, Gary Taylor says, “It’s important the Government and New Zealand understand that a nitrate concentration of less than 1 mg/L does not mean pristine. It is the environmental bottom line required to prevent periphyton growth which kills off fish and invertebrates in freshwater systems.

“The Ministry for the Environment itself recommended last year that nitrates not be allowed to exceed 1 mg/L, as did the majority of the Science and Technical Advisory Group advising on the Fresh Water Standards.”

Most New Zealand rivers already have a nitrate pollution reading of under one. The four environmental organisations say the Government needs to ensure the health of these rivers is protected, while bringing back the health of heavily polluted rivers.

“The science is clear — it’s crucial the Government listens to the experts and brings in a nitrogen limit of under one to keep Aotearoa healthy for generations to come,” they say.

Note: The nitrate pollution limit of 1 mg/L is measured as dissolved inorganic nitrogen (DIN). This was the advice of the Government's Science and Technical Advisory group in the development of the recent freshwater reforms.

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