Only 2% of New Zealand’s large lakes are in good health, bleak report finds

In tourism adverts and on movie screens, Aotearoa has sold its pristine landscapes, churning alpine waterfalls and bright jade-braided rivers to the world, under the tagline “100% pure New Zealand”.

A new report, however, reveals the dire state of many of the country’s fresh waterways: contaminated by thousands of sewage overflows, flooded with nutrient pollution, blooming with toxic algae, risking public health and rendered unswimmable to the communities that have lived by them for years.

The ministry of environment report found just 2% of large lakes were in “good or very good” health. More than half – 55% – of the country’s total river length showed “moderate or severe impairment” from organic pollution or nutrient enrichment – typically caused by effluent and runoff from farming, and 45% of rivers were unswimmable, due to campylobacter infection risk.

The report “unflinchingly identifies the appalling state of lowland freshwaters of Aotearoa,” Mike Joy, a senior freshwater and governance researcher at Victoria University of Wellington, said. Prof Jenny Webster-Brown, president of the Freshwater Sciences Society, called it “dismal”. The report “should be able to galvanise the stewards of our environment into action,” she said. “We know what needs to be done to reverse these trends.”

Sewage overflows emptied into freshwater systems at a rate of more than 11 a day. Wastewater service providers reported more than 4,200 overflows due to wet weather events, or blockages and failures during dry weather between July 2020 and June 2021. “People’s health is put at risk by pollution from sources such as wastewater overflows and livestock runoff,” the report concluded.

Dr Tim Chambers, a senior public health research fellow at the University of Otago, said the results were “sobering”.

Behind many of the results lies New Zealand’s rapid intensification of dairy farming, to feed its export markets. The dairy industry now forms a significant chunk of New Zealand’s economy, accounting for about 3% of GDP and 20% of total exports in 2020 – around $17bn of export revenue each year. “Aotearoa has experienced one of the highest rates of agricultural land intensification over recent decades internationally,” Chambers said, with dairy cow numbers almost doubling nationally from 3.4m in 1990 to 6.3m in 2019 – with some South Island regions “seeing 10-fold and 16-fold increases during this same period”.

The enormous expansion of dairying land has required extensive irrigation and fertiliser use, particularly in the dry, windy plains of the South Island. Over the same decade, irrigated land has doubled, with about 75% of this increase attributable to dairy intensification. That combination: irrigation pulled from the rivers and nitrogen or phosphate-based fertilisers washing back downstream has had a substantial impact on rivers, wetlands and lakes.

While there have been significant efforts under way by farmers to reduce runoff, the overall growth of farms has been offsetting many of those gains. The report concluded that while efforts to “reduce fertiliser use and keep stock out of waterways helped to reduce the amount of phosphorus and sediment reaching our rivers … because the number of farms grew, it’s estimated the total amount of nitrogen reaching rivers increased.”

New Zealand’s Labour government has made a number of commitments to return the country’s rivers to health since it was elected in 2017 – but those efforts appear to bearing limited fruit, with more waterways in decline than improving. Between 2001 and 2020, 56% of rivers were getting worse, and 25% were improving, the report found. For lakes, the report looked at the decade to 2020 - when 45% got worse and 36% improved.

Most New Zealand communities are based around waterways, where they are a source of food, recreation and beauty – and their degradation is altering the way New Zealanders live, as bodies of water become poisoned and inaccessible. Those effects are particularly pronounced for Māori, who maintain intimate relationships to waterways, regarding them as ancestral connections.

The degradation of waterways was also heavily affecting bird and fish populations that depend on freshwater for food and habitats. About two-thirds of freshwater native bird and fish species were either threatened with extinction or at risk of becoming threatened, the report found.

Natasha Lewis, deputy secretary for joint evidence, data and insights at the ministry for the environment, which produced the report, said the impact of damage to waterways was already significant: “When they’re degraded, it affects ecosystems, communities, people’s lives, and things that are important to New Zealanders from all walks of life,” she said.