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Friday, 26 April 2019 05:55 pm

Dead harbour: North Island’s biggest estuary ‘very sick indeed’

HarbourMAIN 1 top

AS a young boy, Taku Parai would often be sent to pick up his family’s tea. He’d cross the short distance from his home on the Takapuwahia Pa to the shores of Porirua Harbour and cast his net wide.

The waters teemed with kaimoana: cod, snapper, kahawai, flounder, mullet – around 30 species of fish in all – plus piles of mussels, cockles, bubus and pipis.

“It was our breadbasket. All our sustenance, all our livelihoods came from the harbour and Porirua Stream.”

Occasionally, Taku says, this abundance made him greedy. He remembers being told to bring back six flounders for breakfast and proudly returning home with ten.

“Dad gave me a pull on the ear and said ‘can’t you count?’

“Our philosophy was always to just take what we needed, and leave the rest.”

For Ngati Toa, the harbour’s generosity was not something to be taken for granted. Subsequent guardians were less considerate, however. The laissez-faire attitude of consecutive governments, local and national, condemned the estuary to decades of abuse.

As Porirua and the northern Wellington suburbs grew, it was physically modified, polluted and silted up. And, slowly but surely, the fish began to disappear.

From the earliest days of Porirua village, local Maori were fighting to protect their vital marine resources. In 1883 a Ngati Toa delegation begged the government to ensure burgeoning urban development would leave the harbour unspoilt.

But not long after, the Porirua Lunatic Asylum was built at Elsdon. The institution’s drains, already condemned as ‘scandalous’ in a 1904 report, were by the 1950s pumping 136,000 gallons of effluent a day into the Porirua Stream. At Takapuwahia, less than 3km away, Taku’s young cousins were dying from typhoid.

“While they were pumping that rubbish into the stream, we were gathering our food down here in the harbour. No consultation, no dialogue. Our people had no idea of the danger.”

Harbour MAIN 3 TakuTaku Parai (right) was born in 1955. Four years later work began on the new Porirua CBD, a massive development requiring the demolition of most of the old village and the dumping of more than 770,000 cubic metres of rock and soil at the head of the harbour.

The pipi and flounder beds used by generations of Taku Parai’s family were extinguished by the new Titahi Bay Rd, and the harbour’s fish stocks began a swift and steep decline.

The loss of this prized resource had a huge impact on Ngati Toa’s mana, he says. “It broke the hearts of our old people that other iwi would leave here and say ‘Ngati Toa has nothing’.

“There was there a lot of anger. If it’d been an earlier time we’d have gone to battle over it, without question.”

Today, Porirua Harbour is very sick indeed

The lower North Island’s largest marine estuary – comprising the Onepoto Arm, which runs north from the CBD out to the sea at Mana, and the east-flowing Pauatahanui Inlet – is being attacked on all sides.

From the surrounding agricultural smallholdings comes fertiliser run-off, DDT residue and livestock faecal contamination.

Heavy metals – copper from car brake pads, zinc from galvanised rubber tyres – wash off State Highway 1 and into its waters. And mud, tonnes of the stuff, is carried by stormwater and streams into the harbour.

Harbour MAIN 5

MAN'S INTRUSION: A digger comes to grief in Porirua Harbour (Stuff image).

As Keith Calder, the harbour strategy co-ordinator at Porirua City Council, says: “The reality is, without our intervention, anything we put on the ground around the Porirua Basin could only ever, end up in one place – the Porirua Harbour.

“Whether its litter, fertiliser, paint, carwash detergent or the chemicals leaching off our roofing iron, everything goes downhill.”

Of all the threats the harbour faces, sedimentation – the process by which eroded soil is washed through streams and stormwater pipes and out in the harbour basin – is by far the most serious.

For millennia, this process raised the base of the Porirua Harbour by an average of between 1mm and 1.5mm each year. But a study last year found that net average deposition rates are now 5.7mm/year in the Onepoto Arm and 9.1mm/year in Pauatahanui Inlet, five to ten times natural rates.

While every estuary’s lifespan is finite, the rocketing rate of accumulation is threatening to kill Porirua Harbour long before its time, the study said:

Allowing for uncertainties, at current deposition rates Pauatahanui Inlet will have ceased to exist over the next 145-195 years and the Onepoto Arm over the next 290-390 years.

Sedimentation poses immediate threats

Suspended in water, sedimentation clogs fish gills and reduces their visual foraging abilities. Lying on the harbour floor, it smothers algae food sources and destroys shellfish habitats.

In Pauatahanui Inlet, for example, cockle numbers have halved since 1976, a fact widely attributed to increased sedimentation run-off from the expanding Whitby suburbs.

Throughout the harbour, the problem is made worse by a weakening of the “tidal prism”, the amount of water pushed in and out by tides. Tide-blocking structures like the Paremata road and rail bridges are a contributory factor, but the main culprit is sedimentation itself.

“With the filling up of the sediment, you’re raising the bed of the harbour and reducing its capacity to take the tide in.” Keith Calder says. As the harbour loses its ability to “self-flush”, the real danger is that the sedimentation rates are going to be exponential, not lineal.

And here’s the kicker: those contaminants leaching from our roads, roofs and atmosphere are drawn like a magnet to the silt accumulating on the harbour’s floor. The mud pouring into the harbour is a veritable stew of heavy metals and poisonous chemicals.

As in most urban marine environments, locals are resigned to being unable to collect shellfish from the harbour. Perhaps a more powerful illustration of the harbour’s toxicity comes from those, like Aniuwaru ki Porirua waka ama club members, who regularly complain of infected sores and cuts after prolonged exposure to its waters.

Crusading marine environmentalist

It’s early Saturday morning and I’m clambering over a hill high above Porirua Harbour, as crusading marine environmentalist Jim Mikoz strides on ahead.

Harbour MAIN 4 JimA gap-toothed, 63-year-old in black aviator sunglasses, Mikoz (left) prides himself on being a thorn in the side of local government. He’s brought me up here for a primer on the shortcomings of council sediment control.

We stop at sediment traps, tiered ponds designed to catch the silt run-off from large-scale developments. None of them, Jim says, are regularly cleared.

“They’re dug out and then just left. They use aluminium sulphate [to drag silt particles to the bottom of the ponds], but what’s the point if they’re not going to maintain them? As soon as it rains these ponds overflow and all that silt and those chemicals go straight into the stormwater, and into the harbour.”

Jim points at Jessie, his black Labrador who is attempting to puddle in the muddy water. “Look at that. That pond was originally dug out to a depth of two or three metres and now it isn’t even deep enough for a dog to swim in.”

As we walk back to the four-wheel drive, Jim tells me about his long campaign against pollution in Wellington’s estuary systems.

As president of the Wellington Recreational Marine Fishers Association, he has made countless submissions to government in an attempt to highlight how freshwater degradation is destroying marine food sources and spawning grounds. He carries his camera with him, obsessively cataloguing blocked streams, eroding banks and neglected sediment traps.

It was his photos that convinced Ngati Toa that something had to be done, he says. “I’m their expert. Without me they wouldn’t have known [about the state of the waterways]. The council isn’t telling them anything and they’re getting pissed off about it.”

We drive south along the route of the Porirua Stream, stopping every few minutes so Jim can point out places where the streambank has fallen into the water. The wrong kind of riparian planting – or worse, no planting at all – has left the edges of the stream exposed to the elements and liable to collapse. The result: more erosion, and more silt in the harbour.

Mikoz says the only solution is to dredge, and quickly. Wait much longer and the Mana marina, located at the mouth of the harbour, will soon be landlocked.

I put Jim’s claims to harbour strategy co-ordinator Keith Calder. He pauses a long time and lets out a sigh. “Jim has some good points, but the problem is you have to spend so much time filtering out the crap.

“It’d be different if he was saying ‘some of these sediment structures are not working or not being maintained, or both’, but instead he says the councils are not doing their job, sediment controls are a joke. You know, he can take you to places it’s not working, but I can take you places it is.”

Calder says he understands people’s impatience to have the harbour dredged. “This delay isn’t about us being tight-arsed, it’s about us saying we understand the nature of the problems, we just don’t know how to solve them. At the moment, if we rush into it, I can’t guarantee it’s going to work.”

What’s needed, he says, is a long-term action plan that addresses all the threats currently facing the harbour. “We’re saying ‘things are bad, but it’s not about the past. What is the situation now, and what do we do about the future?'”

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PAUATAHANUI INLET: Picture by Porirua City Council's Keith Calder.

In 2006, the Porirua City Council allocated $2.6 million towards rescuing the harbour. Calder’s job was created, and research work began.

Understanding the reasons and impact of excess sedimentation is a priority. A detailed hydro-dynamic computer model of the base of the harbour has been commissioned, and will form the framework for any decisions on dredging.

The cost of the computer modelling will be shared between the Porirua, Wellington and Greater Wellington regional councils, with support from the NZ Transport Agency and the Transmission Gully Motorway team.

Both Greater Wellington Regional Council and Wellington City, under whose remit 70% of the Porirua Stream catchment falls, have pledged their support for the harbour regeneration project.

“The reality is we’re going to need money from other sources – other councils, central government – because the issues here are significant. And while lump sums (like Porirua’s $2.6 million) are great, what we really need is ongoing commitment,” Calder says.

He jabs a finger at a map marked with potential developments in the area. “Windfarm. Rural residential intensification. Urban development. Transmission Gully motorway. One hundred percent of Wellington’s green field development will happen in the Porirua Stream catchment. And in the next 25-30 years, fifty per cent of Wellington’s regional growth will happen here.

“We’ve already got a problem, what’s the chance that this will improve it? Zilch.”

While government support will be key, Calder is careful to characterise the project as “co-led” with Ngati Toa. “When I hear Taku Parai speak about what the iwi has lost, I feel embarrassed for what [local government] has done.

“We’re not asking them to contribute a cent towards this – it’s not even an issue. As far as we’re concerned, Ngati Toa didn’t create the problem and it didn’t even enter our thinking that they should pay.”

He says Jim Mikoz’s accusation of poor communication between the council and Ngati Toa is “totally wrong”. “Jim’s got the ear of a small number of people, but the fact is we are required to liaise with Ngati Toa through the runanga only.”

What’s being done

Harbour MAIN 2Ngati Toa spokesperson Jennie Smeaton says there is a “really good relationship” with the council. In February, the iwi held a harbour issues hui that will feed into what has been a long process of public consultation on the issue.

By June this year, a draft Porirua Harbour Catchment Strategy, setting out the problems and proposing a way forward, should be ready to go out for further discussion. The strategy will include a “healthy harbour” education programme aimed at everyone who lives in the Porirua Basin.

“We need to give people the top 10 hints for cleaning up the harbour. For example, people should be made aware they shouldn’t wash their car on an impermeable surface, but on a lawn. And how do we reach the Polynesian community? The obvious way is through the churches.

“After all, from a biblical point of view there’s actually a mandate to look after God’s creation.

“This needs us all to participate. If the harbour is worth saving, it’s worth recruiting as many people as possible. We’re going to be asking everyone, ‘what can you do to help?'”

A final action plan won’t be ready for implementation until midway through next year, but a lot is being done to help the harbour in the meantime.

Calder points to the Pauatahanui Inlet fencing and re-vegetation project, which has significantly reduced the amount of sediment and faecal contamination entering the harbour from rural streams.

And in 2008, Porirua Council introduced its own sediment control by-law to help stem the flow of silt from property developments. Since then, Greater Wellington Regional Council has announced a review of its earthworks controls.

But everyone I spoke to agreed the real problem is a lack of resources, not regulations. Guardians of Pauatahanui Inlet chair John Wells says he has “a lot of sympathy” for the regional council.

“They have the regulatory mechanisms in place [to stop the discharge of sediment into waterways] – in fact those resource consent conditions are pretty draconian.

“The problem is in monitoring them. Half the time, something happens and by the time the council inspector arrives the next day, it’s too late and the damage has been done.”

But no matter how well enforced, the Resource Management Act can only do so much. Without a total commitment from every stakeholder – government, commercial and private – the harbour’s future looks bleak.

It’s something former Methodist minister Keith Calder is passionate about. Talking about the problems facing Porirua Harbour, he takes on an almost evangelical tone.

“We’ve never paid the true cost of developing the Porirua basin – the harbour has. And it has to end. We’ve had our ‘drugs, sex and rock n roll’ for the last 150 years and now the party’s over.

“We have to live up to our responsibilities, not just to our own kids and the rest of the community, but to future generations.”

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is a graduate from Whitireia's National Diploma in Journalism (Multimedia) who now works at Metro magazine in Auckland. While on the diploma programme she won the North & South Feature Writing Award.
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  1. Great article, fair, well researched and covers all bases and viewpoints. I pulled on my waders last year (2009) and inspected Porirua Stream for whitebait but saw hardly any aquatic life. It was a dead and disgusting slum. Thankyou Catherine McGregor for pointing out the success of nearby Pauatahanui Inlet.
    Alan Knowles

  2. Excellent article. The money hungry council to date has paid mere lip service to the sad state of our harbour. The council only seems concerned with jamming more houses in and squandering rates on unnecessary monuments while our environment dies around us.
    Every time we experience rain the harbour turns brown with clayish mud for up to a week.

    We need action. The council should make riparian planting of streams compulsory and create silt traps on the many streams which have been foolishly piped to the sea in the past.

  3. excellent article mate

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