Flooding at a property in Tarena St, Mamaku, where testing around drains has shown exceptionally high levels of E. coli.
A Mamaku resident is calling on Rotorua Lakes Council to find solutions to the flooding she believes brings “E. coli floating past our back door”.
The illness-causing bacteria was found at levels up to 18,000 times higher than considered safe for recreation in recent tests at Fiona Montgomerie’s Tarena St property.
The council said the area’s stormwater system is routinely inspected and maintained, but has limitations. A councillor said there are no quick fixes.
Montgomerie told a Rotorua Rural Community Board meeting this month that her property had suffered from flooding issues for more than a decade.
She said she believed the water that flowed in from surrounding higher properties potentially transported the contaminated material.
Her property slopes down from the street and is on a residential block in the rural village.
E. coli, or Escherichia coli, is a bacteria found in the guts of warm-blooded mammals and birds. Some strains can cause serious illness, including gastric issues and kidney complications. It can be life-threatening in vulnerable people.
E. coli levels are measured in colony forming units (CFU) per 100ml.
There are no guidelines for safe levels of E. coli in stormwater, but 540 CFU per 100ml and above is unsafe for freshwater swimming, according to Land Air Water Aotearoa. Any amount of E. coli in drinking water is considered unsafe.
Testing on February 13 by the Bay of Plenty Regional Council measured E. coli levels of 9.9 million CFU per 100ml in Montgomerie’s middle lawn drain and 890,000 CFU per 100ml in ponding in her driveway.
The back garden drain reading was 220 CFU per 100ml.
Montgomerie said testers told her they had never seen a reading so high at a residential property.
“I’m nervous about it,” she said.
“We’re just out here living in Third-World conditions and paying our rates just to have E. coli floating past our back door.”
Montgomerie said the flooding on her lawn was sometimes up to the top of her gumboots.
She said she had regular infections, including in a wound after surgery, and she was wary of growing plants or produce in the garden.
She said she had been telling the Rotorua Lakes Council about the flooding issue since she bought the property 12 years ago, but there had been little to no action.
She said a potential septic tank issue and animals on the property were initially suggested as possible contributors of the E. coli.
But Montgomerie said her septic tank was regularly maintained and had been emptied twice in the past 11 years. She did not believe her dozen or so chickens and one goat could be responsible for such a high reading.
She said the Rotorua council had checked her drains for blockages with a camera in February but she was told they found nothing.
In her opinion, a substandard stormwater system in Mamaku, combined with potential septic tank issues at nearby properties, was the culprit.
“It’s wrong,” she said.
“I keep saying, ‘Can we make a plan?’ Tell me what I need to do. But they don’t come back with anything.
“It’s disgusting and needs to be addressed.”
Rotorua Lakes Council infrastructure and assets manager Stavros Michael said Mamaku’s stormwater system was routinely inspected and maintained.
“It is important to note that its design capacity has limitations to address any weather events,” Michael said.
“Before the recent heavy rainfall events, the system was inspected to ensure there were no blockages or known issues.”
He said the council knew of some surface flooding in parts of the village during the most recent heavy rainstorm, but was “not aware” of any residential flooding.
He said any changes to the stormwater system in Mamaku would need to be considered as part of Long-Term Plan deliberations because of the level of investment required.
“We encourage residents to make a submission during the Long‑term Plan consultation process, which is currently scheduled for April next year,” he said.
Bay of Plenty Regional Council’s regulatory compliance manager, Stephen Mellor, confirmed testing at the site found “elevated” E. coli levels and that Toi Te Ora Public Health had been notified.
He said reticulated sewerage is not currently provided in Mamaku and is instead managed through on‑site effluent systems.
He said the regional and district councils were working on the matter, but as “inquiries are still underway”, it would be inappropriate to comment further.
Rotorua Lakes Council rural ward councillor Karen Barker said she would be happy to work with Montgomerie to find a solution and that she understood her concerns.
But she said it was not likely to be a quick fix.
“There’s a combination of factors,” she said, highlighting the area’s inconsistent elevation, lack of stormwater channels on some roads, and property works that have knock-on impacts.
She also said some of the “best stormwater reticulation systems” could not cope with the levels of rain increasingly seen across the district.
“There are no simple answers. It likely requires a community-wide approach rather than individual fixes.”
She said she would be checking in with the council staff responsible for any follow-up work to ensure the situation was still being investigated.
Mathew Nash is a Local Democracy Reporting journalist based at the Rotorua Daily Post. He has previously written for SunLive, been a regular contributor to RNZ and was a football reporter in the UK for eight years.
– LDR is local body journalism co-funded by RNZ and NZ On Air.