The Hawke's Bay Regional Council is rejecting claims the bacteria which brought Havelock North to a standstill came from the Tukituki River.
Council interim chief executive Liz Lambert said although it had been claimed the E.coli in the town's water supply, which caused a gastro virus affecting 4000 people, had come from the Tukituki River, this was not the case.
Hydrogeologist Gil Zemansky told Radio New Zealand yesterday contaminated water from the river could have gotten into the aquifer, following dry winter weather conditions.
I understand people's frustration but speculation is particularly unhelpful.
However HBRC's Resource Management Group manager Iain Maxwell said it was unlikely E. coli in the Tukituki River caused the contamination.
"As soon as we learned of the gastro bug outbreak, we conducted additional sampling on the lower Tukituki River and nearby bores held by private landowners. The river samples came back at typical levels for water quality," he said.
"Importantly, there was no E. coli in the bore samples between Tukituki River and Brookvale Rd."
Ms Lambert reiterated Mr Maxwell's comments, adding speculation was not needed at this stage of the investigation.
"We obviously want to help work out what the source of the contamination is, but there's a huge amount of speculation, it's particularly unhelpful at this time and it doesn't speed up the process," she said.
"I understand people's frustration but speculation is particularly unhelpful."
The river was tested early on, Ms Lambert said, and showed a "very low level" of E.coli.
Since the outbreak, private bores in the vicinity of the Havelock North water supply had also been tested, with council now "slowly working our way out".
As campylobacter did not live long, and could only travel a short distance, anything within 500 metres of the affected Brookvale bores had been of more significance than those further away.
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The regional council was working closely with Hastings District Council, the District Health Board and wider government agencies.
In light of these claims, Greenpeace has called for the Ruataniwha Dam to be scrapped.
Agriculture spokeswoman Genevieve Toop said the dam would compound the pollution problem by driving intensive dairy farming into the Tukituki catchment.
"If ever there was a time to pull the plug on this scheme, it's now," she said. "Greenpeace has been saying for some time that the Ruataniwha Dam will put local water sources at risk, because it will enable more dairy cows on the Ruataniwha Plains.
"What's happened in the last week-and-a-half is a massive wake-up call.