Three people were arrested on Saturday as tempers flared at a protest against a controversial poison drop near Nelson.
Protesters and neighbouring farmers were furious as helicopters took to the air to drop the poison, aimed at eradicating predators from the Brook-Waimarama sanctuary.
It's the first of three planned drops using brodifacoum poison, which is highly dangerous to both humans and animals. The drop is aimed at killing rodents inside a giant pest-fence at the 700-hectare sanctuary.
The drop was years in the planning - but only went ahead after an 11th-hour bid to stop it failed.
On Thursday, the Court of Appeal ruled against the Brook Valley Community Group's legal challenge to stop the operations.
But activists refused to let this stop them.
Operation media liaison Angela Ricker says eight people had been trespassed from the helicopter loading site on Friday, and a hole had been drilled in the helicopter's refill tank.
Sanctuary trust general manager Hudson Dodd says three rulings in court now have all decisively found for lawfulness of the operation, and the poison drop will help the environment.
"We are in our rights to go forward for something that will be of great benefit to the community because the concept is to clear pest mammals from the site to allow native species to regenerate," he says.
"We are going to restore this little slice of New Zealand to as close as we can to what New Zealand used to be before it was overrun by predators.
"Once the bait has broken down we will open the sanctuary."
The protesters were determined, and more protesters were found again on Saturday. Police were called, and three were arrested.
Farmer Tamika Simpson lives next to the drop zone, and says she was one of the protesters.
"I'm extremely worried - I don't believe the fence will contain the poison, the fence is not secure, this is not a safe operation," she says.
"I'm desperate to stop this unsafe operation. I have just asked some of the sanctuary people how my brother and I will sign MPI declarations that our stock are brodifacoum-free when we send our lambs for sale at Christmas as we've done for 90 years."
Ms Simpson says she wasn't given time to move her stock, and says she wasn't given enough notice.
Brook Valley Community Group lawyer Sue Grey says the poison drop is unwanted and illegal.
"This is an appalling day for justice and for the environment in NZ. We have a complete flagrant breach of the law by public authorities," she says.
"I find it incredibly sad and if the public don't get the outcomes through the justice system and through authorities the public have to take law into their own hands."