Green algal bloom in a small freshwater lake in New Zealand (Photo: Massey University
Green algal bloom in a small freshwater lake in New Zealand (Photo: Massey University

OPINIONScienceMay 29, 2020

Even China’s waterways are better protected than New Zealand’s

Green algal bloom in a small freshwater lake in New Zealand (Photo: Massey University
Green algal bloom in a small freshwater lake in New Zealand (Photo: Massey University

Te Mana o te Wai is being heralded as a game-changer for waterways. But for one freshwater scientist, it’s a bitter disappointment.

Two weeks into alert level two, it seems we have already forgotten all those resolutions about the pandemic being an environmental “wake-up call” to do things differently. Despite being issued by a government elected on a promise to halt and reverse the decline in freshwater quality, the highly anticipated “Action for Healthy Waterways” package – also known as Te Mana o te Wai – appears to ignore the science on protecting our waterway health. While there is considerable rhetoric in the $700m package about how and why we need clean water, there are no limits for the critical pollutants our waterways can endure and still protect ecological and human health.

The critical issue with the declining health of New Zealand waterways is increasing levels of nitrate-nitrogen. The main contributor to high nitrates in our waterways is urine from dairy cows, many of them fed on imported palm kernel extract because of a lack of grass to support all the cows being farmed. No amount of fencing is going to prevent or slow that nitrogen getting into our waterways as it moves through the soil beneath riparian fences and vegetation. While I welcome the new limit on fertiliser inputs – that should save farmers plenty of money on unnecessary topdressing, at least – when it comes to reducing the amount of nitrate in our waterways, it’s like putting a sticking plaster on an amputated arm. What we need is far fewer cows.

I was a member of the 19-person Science and Technical Advisory Group (STAG) convened by the Ministry for the Environment to compile the massive amount of science showing nitrate bottom-line levels – currently set at 6.9 mg/l – are too high to protect ecosystem health. Many countries around the world, including China, have more sensible levels of around 1 mg/l to limit the impact of high nutrients on freshwater life.

While the majority of the STAG concurred that there was overwhelming science to support an upper limit of 1 mg/l of nitrogen, five of the members did not. Thus the government opted not to establish a nitrogen limit to protect ecosystem health, despite the large weight of evidence in support of a bottom line of 1 mg/l and the underlying precautionary principle that is supposed to apply under the RMA. There are numerous lines of evidence that high nutrients promote the growth of an increasing number of pathogenic zoonoses in our waterways (like STEC E. coli which can be lethal) and high nutrients have even been linked with high rates of colorectal cancer at concentrations around 0.8 mg/l of nitrate.

My main concern is that the ecological health of New Zealand’s waterways will continue to degrade without a nitrate limit. I understand that the government needs to balance multiple goals but I would have thought that stronger environmental protection for our waterways than in Europe and Asia would be necessary to protect our “100% pure” market advantage. Will those markets really be satisfied that a few farmers are fencing their streams? And if tourism is to make a comeback, will those visitors not want to swim in our rivers and lakes without getting sick?

Even the millions of dollars earmarked in the budget for pest and weed control to benefit biodiversity seems short sighted. All the science I am aware of clearly identifies climate change as the biggest threat facing our threatened species. Can we not remember back to February and the fires in Australia, where climate-induced firestorms destroyed vast swaths of native habitat and the associated biodiversity? What point is there in removing pests and weeds to allow our biodiversity to thrive, if the disease, drought, fire, flood and storms from climate change are going to destroy their habitats? It’s hard to have a thriving biodiversity if it has nowhere to live.

Mere weeks ago, the government was wisely using the best science to avoid a more severe and deadly Covid-19 crisis than those in the USA, UK and Brazil. Scientists like me hoped for the same kind of evidence-based thinking on the nitrates that are poisoning our waterways. But now it seems the reflection and strategic thinking of lockdown has evaporated like so many New Year’s resolutions, all in the service of short term economic growth.

Keep going!