An application to increase the amount of nitrogen going into the Waipara River in North Canterbury was opposed by the local rūnanga, arguing further pollution would be culturally unacceptable.

When Hoana Burgman goes away, she says goodbye to the river. She does not say goodbye to her house, or her town, because they are objects and the river is not.

In the small North Canterbury community of Waipara, a rūnanga is taking a stand against the pollution of the river, which has been significant to Māori for centuries.

It has done so by opposing a resource consent application by a large irrigation scheme on grounds rarely cited in such matters: cultural offence.

If successful, it would be a blow for the long-planned scheme, seen by some as vital to the economic future of a dry farming district. It would also send a clear message that freshwater pollution is not just an environmental issue, but increasingly a cultural one, too.

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DAVID WALKER/STUFF The braided river flows out to sea near Amberley.

For some Canterbury Māori, the agricultural pressures on the environment have gone too far, which has pitted two world views against each other: One in which rivers have mauri (a life force), and one where rivers are resources that can support a community's economic livelihood.

The Māori proverb goes "Ko au te awa. Ko te awa ko au" (I am the river. The river is me). So what happens when the river becomes polluted?

For centuries, the mana whenua of Waipara, Te Ngāi Tūāhuriri, have traversed the rivers of North Canterbury. The Waipara River was part of the trail to the West Coast, and relics from that era - multiple Pā sites, middens, and rock art areas - still remain.

The river was once a meeting place for the many rūnanga that make up Ngāi Tahu, and until recently, was a place where mahinga kai was practiced.

But like many rivers, the Waipara has degraded. It is not yet among the region's worst, but it is over-allocated for irrigation, and Environment Canterbury (ECan) deem it a "red zone," meaning water quality outcomes are not being met.

For the rūnanga who serve as guardians, the decline of the region's rivers has come at a personal cost.

"The degradation of the rivers has happened in my lifetime and I am ashamed to pass them on to my children and mokopuna in the state they are in at present," Hoana Burgman, a Kaumātua (elder) of Te Ngāi Tūāhuriri, says.

"In my lifetime, this has happened. And it's something I'm very sad about... my grandfather would be disgusted. We feel we're letting down our tīpuna (ancestors)."

NGĀI TAHU Hoana Burgman, kaumātua of Te Ngāi Tūāhuriri, says the pollution of the Waipara River must stop.

The rūnunga has made its stand at a time of public concern about the environmental implications of agriculture.

The Hurunui Water Project (HWP) has applied to add around 150 tonnes of nitrogen to land surrounding the Waipara River, on behalf of the scheme's shareholders. It has asked for the consent to apply until 2050.

It already has permission to take and use the water, but needs approval for the extra nitrogen pollution that would come off the land as a result.

There was no public consultation for the application; the only parties deemed to be affected were Ngāi Tahu and Te Ngāi Tūāhuriri.

They both responded forcefully, arguing that any more pollution would be a violation of the river's cultural significance. For Māori, a river (awa) cannot be split into its individual parts, but is seen as something whole; a presence with mana and spiritual characteristics of its own, more like a living being, with immense cultural significance.

The degradation of the region's rivers has been particularly obvious in the last 20 years, Burgman says. When she has visitors, she no longer takes fish from the river, but buys them from the supermarket: Whenever she has a day off, she visits the rivers she has known for nearly 80 years, and has watched them change.

The rūnanga has tried for years to advocate for the rivers, Burgman says, but has been repeatedly discounted.

"Next to my own family, those rivers mean everything," she says.

"They say 'where's your technical knowledge, you're not hydrologists' - no, we aren't, but we have a whakapapa there. I have eight generations of my immediate whanau who have fished on those rivers, so I don't need technical advice, I can see it by looking, and fishing, and living on those rivers. I'm 78 and I can remember going to those rivers as long as I remember."

DAVID WALKER/STUFF The Waipara River, like many Canterbury rivers, is under pressure from surrounding agriculture.

The irrigation scheme has been 20 years in the making, and is increasingly seen by the district's farmers as vital for economic survival. Some are still reeling from a savage drought two years ago, which was followed by the large earthquake centred in the district.

The scheme has become polarising, however, amid a public backlash against freshwater pollution. The Hurunui District Council has proposed to buy shares, which has further exposed tensions and pitted some residents against each other and against the council itself.

For Chris Pile, HWP's chief executive, the scheme would not just benefit farmers, but bring the life-giving properties of water to a dry district, where communities were visibly waning.

"There is overwhelming evidence that access to reliable water creates jobs and improves the regional economy," he says.

"You only have to look at Ashburton, Timaru and Oamaru to see this evidence. In contrast, Hurunui townships are really struggling to sustain themselves."

In regards to the consent application, he said the resource consent process was "very robust" within a set of highly scrutinised and strict regional rules. Farmers on the scheme would be strictly regulated, and were required to submit farm environment plans, do on-farm planting and fence off waterways.

The scheme itself, he says, went beyond what was required by law, and was committed to responsible environmental management.

"Our commitment to environmentally sustainable practices goes further than just complying with legislation," he says.

"We have also taken advice from specialist advisors, water consultants and nutrient management experts to develop proposed consent conditions to ensure we have the tools to protect the environment."

HWP had already and would continue to discuss Te Ngāi Tūāhuriri's concerns with the rūnanga.

SUPPLIED Hurunui Water Project chief executive Chris Pile.

The decision will be made by independent commissioners, on behalf of ECan, the regional council.

ECan has recommended the consent be approved, as long as HWP uses an an approach described as an "adaptive management regime". Because there had been little previous monitoring of the river, there is uncertainty about the effects of the added irrigation; The adaptive regime would require more monitoring, and if there was evidence the river was degrading, farmers may be required to change their practices.

For Ngāi Tahu, which submitted against the consent alongside Te Ngāi Tūāhuriri, it meant the river could be allowed to worsen, which it says is inconsistent with regional and national rules requiring water quality be improved.

"It is disappointing that Environment Canterbury, as the steward of the region's freshwater resources, has interpreted and applied its planning documents in such a way that it has recommended that consent be granted," its submission says.

"It is required to uphold the integrity of those plans. The grant of consent in this instance would undermine their integrity."

It is a tightrope for Ngāi Tahu, which has many business interests in the rural sector, but has increasingly moved to oppose what it believes are environmentally damaging practices. It recently negotiated with the Lyttelton Port Company for tighter conditions on its dredging plan in Lyttelton Harbour, which the iwi believed would be environmentally unacceptable.

KIRK HARGREAVES/STUFF A dry sheep farm in Waipara during a drought in 2015.

In 2011, when the HWP scheme was approved in a larger form than currently planned, Ngāi Tahu's submission was neutral.

Ngāi Tahu is itself a shareholder in HWP, via Ngāi Tahu Farming, and the scheme's storage pond is proposed to go on Ngāi Tahu's land. HWP's board of directors once included a Ngāi Tahu appointee, which is no longer the case.

Ngāi Tahu declined to comment, citing the fact the resource consent process was ongoing.

But Hoana Bergman says she speaks for Te Ngāi Tūāhuriri, not Ngāi Tahu - they are mana whenua, and believe something needs to change.

"It's beyond belief what's happened in the last 50 years," she says. "It all comes down to economics, it's all about money. It's about people making money, and to hell with the river.

"When you have had generation after generation being able to fish and live on those rivers, it really does break your heart.

"They should always be passed on in a better state than we got them. That's what's so terrible for me and my brothers and sisters, that we can't do that - we'll be dead and gone and the rivers will be looking that way as well."

HOW POLLUTED IS THE WAIPARA RIVER?

The Waipara River is unusual among Canterbury rivers because it has high levels of phosphorus, owing to the area's geology.

The phosphorus, part of which is exacerbated by surrounding farms, causes the growth of periphyton, a nuisance green algae.

A concern about adding more nitrogen to the river is that it can produce cyanobacteria mats, which can be poisonous. Cyanobacteria is a growing problem in Canterbury, and leads to the closure of many swimming spots in the summer months.

ECan surface water scientist Dr Adrian Meredith said in his evidence that increasing the nitrogen load "is likely to further detrimentally change and effect the ecological health of the river," and by changing the phosphorus/nitrogen balance, could lead to the presence of cyanobacteria.

The river's health is largely dictated by its flow, he said, which can reduce to a trickle in the summer months. HWP argues that some of the surrounding groundwater takes could be given up once the scheme is running, which would reduce irrigation pressure on the river.