Is it birds - or human sewage?

The sign that greets would-be swimmers at the Kerikeri Basin. Photo / supplied

The Northland Regional Council's sign at the pier by Kerikeri's Stone Store says 'Swimming not advised,' but Vision Kerikeri is questioning that, and the explanation given by the council, that source tracking results have shown the faecal contamination at the Stone Store emanates from birds.

Vision Kerikeri's Inge Bremer said according to the council's website, it was safe to swim at the Rainbow Falls (where the water was sampled on December 12), but no samples were taken at the Stone Store because the long-term average showed it to be unsafe.

"On December 18 we counted a total of only 50 geese and ducks at the Mission House, and doubted that NRC's blaming them for the pollution with E. coli in such a rather voluminous river was justified," Bremer said.

So Vision Kerikeri took water samples at the golf club bridge, the Stone Store bridge and the Stone Store pier, right beside the sign saying that swimming was not advisable due to bacterial contamination. The results, from Far North Lab, in Tāipa, indicated that all three sites were suitable for swimming, with E. coli counts of 270 (pier), 112 (golf course bridge), and 88 (Stone Store bridge). The permissible count was currently 540, which was raised from 260 about three years ago).

"Since the E. coli count is low enough for the river to be swimmable with the water fowl being present, they cannot really be the cause of the higher E. coli levels at other times. There must be some other cause," Bremer said.

"A resident next to the wastewater collection basin and pumping station at Tuatahi Place told us that the concrete waste water tank between her house and the river sometimes stinks to high heaven. Transfield Services empties the tank from time to time - maybe not often enough? Or could it be that floodwater causes the tank to overflow sometimes?"

Vision Kerikeri had repeatedly approached the Northland Regional and Far North District Councils over recent years, to clarify the reason for sometimes substantially higher pollution levels at the Stone Store compared to Rainbow Falls (for example on January 23, 2017, the day after substantial rainfall, the NRC recorded an E. coli level of 3076 at Rainbow Falls and 9804 at the Stone Store), without ever getting a response other than pointing to the other council.

Without no cattle farms along the 5km of river banks, VKK suspect non-functioning septic tanks "or the like" for the contamination.

"The NRC CEO further states that their sampling at selected river locations 'are generally not designed to investigate potential contamination sources; for this we run other more targeted programmes.' Without apparent success at the Kerikeri River.

"We expect the NRC and FNDC to finally investigate the real cause/s of pollution, and take steps to stop it, as well as to recommence regular water testing at the Stone Store Basin to enable swimming when the water is sufficiently clean," she added.

"So much could be gained from a very big Kororipo Basin swimming pool surrounded by the newly restored Te Ahurea (the old Rewa's Village), the Stone Store, the Plough and Feather and the Honey

House Cafe, biffing up domestic tourism and improving local leisure time."