Shifting Auckland's port to Manukau Harbour could be the "straw that breaks the camel's back" in the severely degraded waterbody, say concerned iwi and environmentalists.
They add such a move would also fly in the face of the Crown's Treaty of Waitangi obligations, and a 1985 Waitangi Tribunal ruling that said there should be no more reclamations of the harbour, where Māori first arrived over 1000 years ago.
On Tuesday the Government released its latest report into the question of where the country's largest port should go.
Like those before it, the report noted the current location on Auckland's CBD waterfront had limited "social licence" in how much more it could expand.
It had about 30 years' capacity and there was a 10-15 year window for making a final decision on relocation.
It followed another report released in December, that recommended moving the port to Northport, just south of Whangārei.
This report, produced by Sapere, took a longer-term view at freight capacity, and concluded Manukau as the preferred option when looking at a minimum 60 year period.
It also found it the most cost-effective, given its proximity to freight hubs in South Auckland, and to produce the least carbon emissions.
Critics however pointed out the relative shallowness of the harbour and prevailing westerly swells pushing sand in - meaning it would need to be continuously dredged - along with the notoriously rough bar entrance.
But, as noted in a supporting document, such a move would also likely run into major challenges from iwi, with many outstanding Treaty grievances, along with major environmental issues which would make gaining resource consents challenging.
The health of the Manukau Harbour was the subject of one of the first claims ever lodged in the Waitangi Tribunal (Wai 8), led by the late Ngāti Te Ata and Waiohua leader Dame Ngāneko Minhinnick.
Dame Ngāneko, who died in 2017 aged 77, went to the tribunal in 1982 over pollution by the Māngere sewage treatment plant, the NZ Steel mill at Glenbrook and other developments.
The Manukau Report in 1985 paved the way towards the Resource Management Act 1991, which makes statutory allowance for Māori environmental concerns.
It also called for any future land reclamation in the harbour to be prohibited.
In consultation for Sapere report, iwi and hapū in the Manukau Harbour area expressed "significant concern" about the environmental and cultural impacts of dredging and land reclamation required to construct a port.
In particular, Ngāti te Ata said the re-establishment of a commercial port in the Manukau could be the "straw that breaks the camel's back", given the ailing health of the waterbody, which is a breeding ground for many marine mammals and home to a range of rare bird species.
"Ngāti te Ata were very conscious about how their recently deceased rangatira Nganeko Minhinnick might have reacted to the proposition of dredging and reclamation within her beloved harbour," the report said.
Roimata Minhinnick, one of Dame Ngāneko's sons and Ngāti te Ata CEO, said he had not been consulted personally over the latest report.
There were "major concerns", but it was too early to say if they supported or opposed the proposal.
"How would mum feel? She was about the principal, and our role in protection/kaitiaki, and that has not changed.
"Our identity goes hand in hand with the harbour, and we have concerns based on that relationship.
"But we want to employ our people, like everyone, and are keen to explore what kaitiaki could look like. The key is that we are at the table."
There were three sites on the Manukau Harbour that were examined for a future port: central Manukau Harbour, Hikihiki and Puhinui.
All three options entailed constructing a 250ha reclaimed island in the middle of the harbour.
One option needed a 9km causeway to connect it to the mainland, and all would require major dredging works and plan changes.
Each option site had "significant marine and terrestrial ecology, areas of outstanding natural character and areas of significant value to mana whenua".
"Thus, obtaining the necessary resource consents to establish and operate a new port anywhere in Manukau Harbour will present considerable challenges," the report said.
Tainui Group Holdings (TGH) advised they did not favour the Manukau and that also reflected the wishes of their owners, Waikato-Tainui.
A spokesman for the iwi told the Herald they had not yet considered the final report, but any impact on their customary rights and interests would require formal engagement with them.
Former president of the Manukau Harbour Protection Society John McCaffery said he could not see "any chance" of a court approving a port being consented in the harbour.
"Wai 8 made it really clear the reclamation and discharges were a violation of the Treaty, and any further interference would be a breach," said McCaffery, a former senior lecturer at the University of Auckland and who submitted in support of the Manukau claim in the 1984 hearing.
The western harbours were never settled during the Treaty settlement process, and many outstanding grievances remained and were currently being negotiated, McCaffery said.
"Since Pākehā arrived it has been one continuous abuse after another. It's been the industrial discharges, the sewage plant, the rubbish dump, and now when people decide they don't want the port on Auckland's front door, they want to dump it here."
The Manukau Harbour Protection Society, of which McCaffery remained a member, was "completely opposed" to the idea.
"It would be akin to placing a new town in the middle of a national park," McCaffery said.
"The whole place is a special ecological area, breeding ground for a whole range of fisheries and birds, it is a very special place."
However, while iwi and hapū held "significant concerns", they also said a port could bring the spotlight onto the harbour for environmental and cultural restoration.
Iwi also recognised the work and business opportunities, ranging from constructing and operating the port, to service industries and even tourism.
Meanwhile Ngāti Whātua Ōrākei, which owns a vast area of land near the current port site, said it was "concerned to ensure there is no delay in moving the Auckland Port operations from the city".
Whatever decision was made, the report authors warned iwi needed to be closely involved in the decision-making process, one "befitting the Treaty partnership – including the sharing of detailed information and analysis, and resourcing to facilitate informed decision-making".
Transport Minister Phil Twyford said moving the Port of Auckland was one of the most important infrastructure decisions New Zealand faced.
"While the Sapere report presented five options for the relocation of the Port of Auckland, detailed analysis on each option still has to be carried out.
"Our Government recognises each of the options affects multiple iwi and hapū interests. And we acknowledge there will not be a uniformed view amongst different iwi.
"No decision on the future location of the port will be made by a future Labour-led Government without substantial engagement with mana whenua."
The Manukau Claim
The health of the Manukau Harbour was the subject of one of the first claims ever lodged in the Waitangi Tribunal (Wai 8), led by the late Ngāti Te Ata and Waiohua rangatira Dame Ngāneko Minhinnick.
Dame Ngāneko, who died in 2017 aged 77, from Tahuna Marae at Waiuku went to the tribunal in 1982 over pollution by the Māngere sewage treatment plant, the NZ Steel mill at Glenbrook and other developments.
"We are frankly appalled by the events of the past and by the effect that they have had on the Manukau tribes," the authors noted in their 1985 report, stating grievances ran right back to the land confiscations of the 1860s.
"Underlying this claim is an enormous sense of grievance, injustice and outrage that continues to haunt the Manukau Māori and bedevil the prospect of harmony in greater Auckland."
It was the most wide-ranging claim the Tribunal had considered up to that time, and its findings set out a new basis for the Māori role as kaitiaki, or guardians, of their ancestral lands and waterways throughout the country.
"There is a myth that Māori values will unnecessarily impede progress," the tribunal said in its report.
"Māori values are no more inimical to progress than Western values. The Māori are not seeking to entrench the past but to build on it. Their society is not static. They are developers too.
"Their plea is not to stop progress but to make better progress and to progress together.
"It is not that they would opt out of development in New Zealand. It is rather they need to know they have a proper place in it."
The report, and Dame Ngāneko's subsequent submissions to the Government, laid the groundwork for what became the 1991 Resource Management Act.
She took her case to the world stage, inviting a United Nations rapporteur to Tahuna Marae and attending many UN forums on indigenous issues.
While some work has taken place to restore the health of the Manukau Harbour, which receives the city's treated sewage through the Māngere Wastewater Treatment Plant, research shows ongoing water quality issues.
A recent report showed ecology and water quality in the harbour had gone from a D in 2016 to E in 2018.