Anti-1080 campaigners dispute a West Coast Public Health report, which suggested that 1080 poisoned baits found in the water supply of the town of Ross in June had been deliberately planted.
West Coast medical officer of health Dr Cheryl Brunton said analysis of the baits revealed they contained high levels of the 1080 toxin and had retained their shape, suggesting they had only been in the water a few hours.
In addition, flight records from the Animal Health Board showed the helicopter operator remained 300m away from the water supply, on the other side of a ridge.
"Statements and interviews of witnesses are being collected, though it appears this may have been an incident of deliberate contamination, rather than a breach of permit conditions," Dr Brunton said in the report.
However, Farmers Against Ten Eighty spokeswoman Mary Molloy cast doubt on Dr Brunton's statement, and stuck by what she said the people of Ross, 31km south west of Hokitika, had seen.
"I just don't know if Dr Brunton is qualified to make that statement.
"There are people in Ross who saw the helicopter fly up the valley containing the water supply and saw it swing right round. What has been recorded on the helicopter GPS is obviously quite different from what was sighted by locals."
Even if the helicopter had been 300m away, that was still close enough to drop baits in the water supply, depending on the height it was flying at the time. Pellets could also be released in between operations if they had been caught on the helicopter tracks.
"It is accepted that pellets can spread up to 500m - the greater the height, the greater the spread. There are all sorts of factors that come into it," Mrs Molloy said.
"We just hate the poison. I don't know anyone who would put it where it could harm other people. I would be very disappointed and very surprised if they had. And if (the pellets) were not all recovered they could be in the Ross water supply now, which would be terrible."
NZPA