Wellington waterways with E coli are 'a public risk', says Forest & Bird

Monday, 15 October 2018

There's something in the water in Wellington - with some of the capital's streams having up to eight times the acceptable level of E coli.

Some Wellington streams have up to eight times the acceptable level of E coli.

E coli comes from the intestines of humans and animals, and it's likely coming from leaking sewage pipes.

Forest & Bird regional lower North Island manager Tom Kay said the results were disappointing.

'These are our local streams - the streams that run through out backyards and parks. They flow into our harbour that we swim in.'

Pollution in the Kaiwharawhara Stream in Wellington photographed in September.

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Ministry for the Environment guidelines for recreational water set a threshold of 260 colony-forming units (cfu) for E coli per 100ml, and any higher reading carries a risk of infection.

But according to the Greater Wellington Regional Council website, the Kaiwharawhara Stream in Ngaio Gorge had an E coli reading of 1300 cfu/100ml at last reading in June this year.

The Karori Stream in Makara had a last reading of 2300 cfu/100ml in May this year - eight times over the guideline.

The Porirua Stream at the Milk Depot read 900 cfu/100ml in May, and the Waiwhetu read 800 cfu/100ml.

Kay said people shouldn't have to drive half an hour to find a safe stream for kids to paddle in, or have to pay to visit a public pool because a local stream had sewage in it.

E coli counts in the Karori and Kaiwharawhara Stream proved they were 'definitely not safe', he said.

A Ministry for the Environment spokeswoman said urban waterways were some of the most polluted in the country.

'Urban stream pollution comes from stormwater runoff, sewage leaks and overflows.'

However, it was up to the regional councils to meet national direction for water quality, she said.

Wellington Water monitors 27 sites in Wellington monthly to identify problematic areas for stormwater issues. (File photo)

'[The ministry] is concerned at the state of urban streams generally, not only these specific examples.'

A Greater Wellington spokesman said the waterways close to central Wellington were highly vulnerable to contamination from the stormwater and wastewater systems.

The Kaiwharawhara Stream had an E. Coli reading of 1300 cfu/100mls at last reading in June this year. The measurement was taken at Ngaio Gorge. (File photo)

A 2014 Faecal Source Tracking investigation identified human faecal contamination as the major source.

Wellington had old and ageing infrastructure, and wastewater and stormwater pipes were leaking, he said.

'Swimming is not encouraged in these smaller urban waterways/urban streams.'

Wellington Water monitored 27 sites in Wellington monthly to identify problematic areas, he said.

'We don't excuse higher levels of E coli in urban streams, but we do minimise its potential health impacts by encouraging people to swim in safe waters.'