The Department of Conservation (DoC) is taking an "extraordinary step" to ensure the public remains confident in its 1080 aerial drops.
The step will see DoC have its investigation of the Mapara aerial 1080 drop independently reviewed by the Waikato District Council after eight cattle died following the drop on September 6.
They say the cattle breached a fence line on the Mapara Wildlife Reserve, about 35 kilometres from the Waikato town, and entered into the pest control area.
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However anti-1080 activists claim the cattle were killed after the aerial drop of the poison went outside the drop's buffer zone.
Toxicology results show two of the eight cattle found dead had ingested 1080, DoC confirmed to Newshub.
"It is important to undertake this rigorous review to ensure the public can have confidence in the professional discipline the department brings to its operations," Acting Director General Mervyn English says.
The helicopter's GPS flight lines show there was no over-flight of the adjacent farm area, and there was a 50-metre buffer within the operational area in place.
During a pre-flight of the operational boundary a fortnight before the drop, DoC staff noted stock in the operational area and advised the farmer to remove the stock. The farmers later confirmed the stock had been removed, DoC says.
Cattle did not have access to 1080 bait on the farmers' paddocks, DoC claims.
Mr English says conducting operational reviews is standard practice after every pest control operation.