Why Auckland’s beaches are unswimmable every time it rains, and what’s being done to turn it around

Ngarimu Blair has never swum in the waters of Ōkahu Bay, the ancestral waters of his hapū Ngāti Whātua Ōrākei.

Not out of a lack of want but an intergenerational fear of getting violently ill.

Blair grew up with stories like that of his great grandfather who returned home from World War I to find his debt repaid with a pipe pumping raw sewage and hospital waste into their treasured place of recreation and kaimoana.

He heard stories from his grandfather, who lost cousins to typhoid and dysentery, believed to have been caused by swimming in the polluted waters.

The pipe was blocked off by the time Blair was born, but still to this day, every time it rains and the pipes flood, diluted sewage flows into Ōkahu Bay.

“I have never swum there, and likewise a lot of people in their 40s have not never either, because they grew up on the same stories,” Blair tells the Herald.

But it’s also the toxic effects on the kāpata kai, or marine food cupboard, that has had a huge impact on the coastal hapū identity.

“It’s had a terrible impact on the health of our people. But obviously it also impacted the shellfish, which was quite an embarrassing thing as a tribe not being able to put kaimoana on the table when guests arrived from across the country.

“It’s been an indignity on our people.”

ŌKahu Bay is far from alone when it comes to water pollution, evidenced this week when over 50 beaches across the region were deemed unsafe to swim in due to estimated high Ecoli levels.

As they always do, the revelations caused widespread outrage – National’s environment spokesperson Scott Simpson even weighed in calling for a formal investigation.

Auckland mayor Phil Goff told the Herald Simpson’s comments were “silly”.

“We have known the issues for decades, so the idea of a formal investigation is completely superfluous.”

The causes that make so many of our beaches unswimmable following rainfall – and some even in dry weather – are complex, but are not unique to the city in New Zealand, or the world for that matter.

When Auckland was developing in the early 1900s the first sewer networks – laid under early suburbs like Herne Bay through Parnell – combined waste and stormwater into the same pipes, carrying it – untreated – to various outfall locations.

About four per cent of the city currently does not have separated waste and stormwater pipes.

This means when it rains too much the pipes are designed to overflow through various manholes, and run into waterways to be carried to sea.

As the city modernised, new suburbs and developments separated the waste and stormwater – wastewater being taken to the treatment plant at Māngere and ultimately discharged into the Manukau Harbour, and stormwater carried out to sea.

But for myriad reasons, these systems have their own problems.

Ageing wastewater pipes can crack, causing leakages and enabling them to be inundated with stormwater in heavy rain, causing more overflows.

Blockages, mainly caused by people flushing wet wipes, are also a common reason for overflows.

There are about 220 overflow points in the city network, each discharging diluted sewage between two and 52 times a year, according to Watercare.

The brunt is felt disproportionately across the city, with hotspots like Meola Creek – running from Mt Albert to the Waitematā – taking among the highest levels of and most polluted water. Where it runs into the sea at Cox’s Bay is a permanent no-swim sign.

Over the past few decades, slow progress has been made to address these water-quality issues.

A Herald investigation in 2017 found many of these overflow points were discharging sewage every time rained, and international tourists were alarmed to discover they couldn’t safely swim in “100 per cent pure” Aotearoa.

Soon Mayor Phil Goff brought in a water-quality targeted rate, which would raise $450m over a decade and brought forward the major water-quality programmes, including the Western Isthmus programme – jointly funded with Watercare – by 20 years.

The $700m programme, expected to be finished by 2028, will see some properties in the inner-western suburbs have their wastewater separated from the combined network.

But perhaps the biggest impact on Auckland’s water quality will come from Watercare’s $1.2 billion Central Interceptor, a sort of “sewage highway” to which smaller pipes will connect and travel from Grey Lynn to the Māngere treatment plant.

Early last year, the first part of the 4.5m-wide, 14.7km-long tunnel was dug 110m below ground, using a massive German-designed tunnel-boring machine.

When completed at the end of 2025, the CI will reduce overflows on the western beaches in central Auckland and waterways by more than 80 per cent, the spill spots reducing to just 10 and predicted to overflow fewer than six times a year.

Waterways like Meola Creek, which for over a century has regularly flowed with Auckland’s waste, will finally get a chance to heal.

“These problems are well over a century in the making,” Goff said.

“What we are doing with the Central Interceptor and the Western Isthmus programme, and later Eastern Isthmus and Manukau, are the biggest water quality investments seen in this country.”

Watercare acting chief operations officer Anin Nama said alongside these major projects, staff were inspecting and fixing cracked pipes and checking properties for illegal wastewater connections.

“There is a lot going on, and these are big jobs involving a lot of people, and a lot of money.

“But the important thing is that it can’t just be Watercare or [council] Healthy Waters – everyone needs to play their part.:

Another pioneering game-changer for the city has been the Safeswim monitoring programme and website.

Auckland Council general manager healthy waters Craig McIlroy said previously water monitoring was done once a week, on a Wednesday, with a helicopter taking samples.

If the weather was bad, it didn’t fly, meaning there was no water-quality guidance for that week.

But even if a sample was taken, if it then rained on the Friday the rating would still class the beach as safe.

Using historical data along with the latest weather forecasts and tidal information Safeswim provides forecast models on the swimmability of 84 locations, updating by the hour.

It’ll either class a spot as green – safe for swimming, or red, meaning there is a heightened chance of getting ill.

Most spots will be clear 24 hours after rainfall, or two tidal circles.

Currently, whenever there is heavy rain, dozens of city beaches will see little red flags.

McIlroy said the aim of all the work underway was to make each spot across the region swimmable at least 95 per cent of the time.

“To see somewhere like Cox’s Bay, which probably has the worst water quality in Auckland, swimmable 95 per cent of the time by 2028 will be a massive win.”

Goff said this programme meant Auckland was “the most transparent city in the world” when it came to water quality.

“We are not hiding the fact water quality is bad, but wanted to give people as much information as possible.”

Nama said it was this increasing intolerance for poor water quality that was driving much of their work, rather than actual decreasing water quality.

“We have always planned for growth. Whenever a development goes in, we assess the impact on the network.

“But now there is more visibility on the quality of water, more transparency and awareness, rather than it getting worse.”

Concerns had been raised that while the CI would take wastewater from the Waitematā, it would increase the amount flowing through the treatment centre and into the Manukau Harbour.

Nama said this was not the case, as works were already underway to upgrade the Rosedale water treatment plant and for the equivalent wastewater of 100,000 households to be diverted there from Māngere.

Although swimmability was a widely-held value, both Watercare and the council were working with mana whenua to develop water monitoring models that incorporate mātauranga Māori, including concepts such as mauri, the life-supporting ability of water; with western science.

Part of this was behind work at Ōkahu Bay to clear the waters, in partnership with Ngāti Whātua Ōrākei.

Over the past few decades this has seen the original sewer pipe removed and work to separate the storm and wastewater on track to almost completely eliminate overflows by the end of this year.

Ultimately the aim is for people to be able to safely swim, and for the kaimoana to return.

“When that happens it will be a momentous occasion,” Blair said.

It’s a slow process, Blair hoping one day he will feel comfortable enough for that first swim.

“It’ll be a great day when people are swimming there freely, and I’ll join too, as long as it is guaranteed safe.”

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