"Dangerously high" levels of bacteria indicating the presence of faeces have been found at two sites in Auckland's inner suburbs following water quality tests conducted by the New Zealand Herald Focus team.
A sample from Cox's Creek near Cox's Bay revealed E. coli levels of 590 cfu/100ml - about four times the 126 cfu limit for recreation.
A second sample taken at the head of Cox's Creek near Kelmarna Ave found E. coli at 190,000 cfu/100ml - more than 1500 times the upper safe limit and a serious threat to human health.
Leading wastewater biologist Gemma Tolich Allen said the result showed "dangerously high" levels of E. coli, a bacteria that indicates the presence of animal or human faecal matter in water.
She said Auckland's sewerage system is heading to Second World status, because the council and Watercare are continuing to allow untreated sewage into city harbours.
The tests - the samples were taken last Thursday and analysed by Watercare's Laboratory Services division - follow a Herald investigation into Auckland's sewage shame.
It has found one million cubic metres of wastewater and raw sewage is pouring into the harbour each year from 41 points around the inner city suburbs.
Swimming has also been banned at 10 Auckland beaches this summer because of worsening pollution from human and animal wastes.
Tolich Allen says the Herald Focus readings are "extraordinarily high" and indicative of a "grim situation".
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"It indicates significant pollution and means nobody should be swimming at that beach. It shouldn't be used for recreational contact.
"You wouldn't want your dog drinking from there, you certainly wouldn't want children to be playing anywhere near there."
Tolich Allen says Auckland's growing population, intensification and the council and Watercare's failure to act means the situation is getting worse.
"I'd say we are heading down to Second World status. I don't think you can claim First World status when you're discharging untreated sewerage into your coastal environment. Sadly people are only aware of the problem during summer, but it's happening all year round, every year."
Mayor Phil Goff has said water bills may have to rise to clean up the dirty harbour and instructed Watercare and council's Healthy Waters division to look at options and costings to speed up work.
"I think Aucklanders accept the fundamental principle that we have to invest in clean and safe beaches," Goff said.
Work is due to begin in the current council term on a $1 billion "Central Interceptor" pipe that cuts overflows into natural waterways by 80 per cent.
The remaining 20 per cent will be reduced only after the spending of a further $300 million on upgrading sewers feeding into the new pipe and $325m on a planned Waterfront Interceptor to tackle waste from St Mary's Bay and other shoreline suburbs.
Watercare chief executive Raveen Jaduram said in an email to councillor Mike Lee last year the council was allowing developments to occur knowing there was no adequate stormwater system and this would result in more frequent harbour spills.
As much as practical, Jaduram said, stormwater needed to be separated from the wastewater system. He stood by the comments yesterday.
Council Healthy Waters general manager Craig McIlroy said the wholesale separation of 16,000 homes on the old combined sewer-wastewater system did not make economic or social sense.
He said future growth would not have a significant impact on water quality issues.
"The adverse effect of more housing will be offset by short-term improvements such as requiring onsite detention of stormwater in combined areas before the new interceptors are built," McIlroy said.
Jaduram said the use of detention tanks in new developments to slow down the stormwater flow when it rains "is not a sustainable solution".
"What is required is proper investment in stormwater," he said in his email.
Council has provided figures to the Herald showing stormwater spending for growth, renewals, flood alleviation and environmental protection has steadily increased since the Super City was formed in 2010.
In the first full financial year, stormwater spending was $59m, well short of the $105m spent by the seven former territorial councils before the global financial crisis.
Since then, Auckland Council has increased stormwater spending to $110m and budgeted $150m this financial year.
McIlroy said Healthy Waters is also moving towards many points made in a 2014 report which recommended the council should move from a 1950s approach to stormwater towards a "water sensitive city" where stormwater delivers environmental benefits.
Water Quality Tests
• Sample taken from Cox's Creek near Cox's Bay revealed E. coli levels of 590 cfu/100ml
• Sample taken at the head of Cox's Creek just behind Kelmarna Ave found E. coli at 190,000 cfu/100ml - a level more than 1500 times the upper safe limit and a serious threat to human health
• The limit for recreation should be below 126 per 100ml
• Samples were collected last Thursday and tested by Watercare