Parnell sinkhole: Authorities warn to stop all fishing in Waitematā Harbour as raw sewage pollutes water

People are being warned to stop fishing in the Waitematā Harbour for nearly a month after raw sewage stops pouring into the water, or risk getting violently ill.

Watercare says the temporary bypass solution that took effect last Tuesday appears to have stopped the sewage overflow as of Friday, after a massive sinkhole opened up in Parnell and resulted in the collapse of a wastewater pipe.

Small overflows during wet weather, however, will be more frequent until the Ōrākei Main Sewer is repaired, a Watercare spokesperson told the Herald.

Deputy director-general of New Zealand Food Safety at the Ministry for Primary Industries, Vincent Arbuckle, warned people not gather fish or eat any seafood from contaminated areas for at least 28 days once the sewage has stopped flowing into the harbour.

If eaten, contaminated seafood can cause gastroenteritis, which can cause nausea, vomiting and diarrhoea, Arbuckle said.

A sign advised no swimming at Judges Bay after a sewage pipe rupture at Saint Georges Bay Rd. Photo / Michael Craig

The public is also advised to check the Swimsafe website before heading out for any recreational activities in the harbour, said David Sinclair, the Te Whatu Ora National Public Health Northern Region medical officer of health.

A temporary bypass to resolve the leak went into operation last Tuesday after a 20-day rush, with Watercare saying these measures would substantially reduce the amount of overflow into the harbour.

These bypass pumps do have a far greater risk of blockage, with Watercare urging people to be mindful of what they flush.

The effects of the 13-metre-deep sinkhole and collapsed wastewater pipe resulted in a rāhui (ban) that covers the entire inner Waitematā Harbour and has been in place since September 28 with swimming and water quality warnings.

New Zealand Food Safety said it is monitoring the situation alongside the Auckland Council.

Watercare last week began a “targeted daily harbour sampling regime” after advice from marine environmental experts and mana whenua.

“We are also placing bags of oysters at locations from Westhaven to Ōkahu Bay. Samples from these bags will be tested every fortnight for bacteria and heavy metals. This information will supplement our data from the water sampling programme,” Watercare chief operations officer Mark Bourne said.

“We’ve engaged the Sea Cleaners Trust to carry out routine inspections of the harbour and report back to us. So far, they haven’t seen any more debris in the harbour than they normally would.”

Watercare will now focus on clearing the blockage in the sewer and engaging an engineering consultant to review the cause of the sinkhole.

If you have consumed affected kai moana or are concerned, call Healthline on 0800 611 116 or contact your primary healthcare provider for advice.