A public meeting in Wellsford today will decide whether to place a rāhui on the Dome Valley dump site.
And the mayor of neighbouring Kaipara Jason Smith is urging locals to turn out in force.
The Chinese-owned company Waste Management has applied for resource consent for a landfill on its 1000-hectare site beside the Hoteo River, just south of Wellsford.
Auckland Council waste management said the region's existing landfills were nearly full and the new one was essential.
Kaipara mayor Jason Smith however said the prospect of 350 rubbish trucks a day on the dangerous Dome Valley highway was horrendous - and so was the threat to the environment.
He said the Hoteo River and the Kaipara harbour were already under threat from siltation.
"One of the concerns is there's an unacceptable risk of poisoning the Kaipara Harbour, not just in the short term but in the long term.
"The scale of the proposal is like nothing we have ever seen before."
The meeting starts at 1pm today at the Wellsford Community Hall.