Mystery behind foul smell wafting through Tauranga revealed

A bad smell wafting through Tauranga prompted a flurry of complaints. Photo / File

The cause behind a mysterious foul smell that wafted through several Tauranga suburbs this week can finally be revealed.

A combination of humidity, lack of wind and the city's stormwater network is believed to have prompted a "highly unusual" number of complaints to Tauranga City Council and Bay of Plenty Regional Council on Tuesday.

Reports of the foul-smelling odour dominated city community social media pages with people from Ōtumoetai, Brookfield, Mount Maunganui and Pāpāmoa questioning what the smell was, with some asking the paper; suggesting a possible removal of mangroves being to blame.

Tauranga city environmental programme lead Radleigh Cairns said in a statement yesterday the council received six calls regarding odours on Tuesday, "which is highly unusual".

"There were no infrastructure issues that we could identify," he said.

"The main cause is likely to have been the lack of wind and high humidity on Tuesday, trapping odours and causing them to linger. We've had no further calls since."

The calls came from Pāpāmoa, Arataki, Maungatapu and Matapihi.

The regional council received five calls about the smell on Tuesday. Of these, three came from residents in Mount Maunganui and one from Pāpāmoa.

Regional council compliance manager, of urban, industry and response, Stephen Mellor said the complaints "all related to sulphur smell coming from the stormwater network".

The complaints were assessed as non-urgent, meaning that due to Covid-19 restrictions no one has been able to conduct site visits or carry out associated investigations to determine the exact source of the odour.

"We have instead passed on the information to Tauranga City Council who are responsible for maintaining the stormwater network and for ensuring that any discharges from it are compliant with consent requirements and Regional Natural Resources Plan rules."

Mellor said the weather conditions were near still that day, so if an odour was present it is likely that it would linger longer than in windy conditions.

A Tauranga man, who would not be named, said it appeared mangroves had recently been removed from the harbour, which might have been the reason for the odour.

Regional council principal adviser for land and water Jackson Efford said the council was not aware of any mature mangroves being recently removed.

"Some estuary care group volunteers may have undertaken very minor mangrove seedling removal works earlier in the year around Tauranga Harbour as part of their usual ongoing maintenance activities, but given the small scale of these works and the small size of seedlings, these are not expected to generate any odours at all or be associated in any way with recent odour complaints."

Efford said if significant areas of mature mangroves were removed, disturbance of anoxic sediments could generate an odour, "but this has not occurred anywhere recently that we are aware of".

The regional council is responsible for controlling mangrove removal activities through its Coastal Environment Plan.