Kaipara's mayor is urging action on climate change because rising seas will inundate some of the most productive land north of Auckland.
The Kaipara District Council this week signed up to the local government leaders' declaration on climate change.
Kaipara mayor Jason Smith said the council had to sign the declaration because climate change would hit the district hard.
It has more than 1000 kilometres of coastline and more than 25,000 hectares of land within a metre of the current high-tide mark.
"That land is some of the most valuable, versatile soils north of Auckland.
"It is where all of New Zealand's kumara industry is, for example ... all the kumara that everyone in New Zealand eats, comes from there.
"But the important thing is, the predictions that we ... are having to prepare for predicted sea-level rises of 1.5 metres or 1.2 metres or 1.7 metres or 1.9 metres.
"There are different projections out there. The key is, all of those are above the levels of a large proportion of our land.
"What are we going to do in this space?"
With the climate change declaration, he said the district was "putting our hand up and sending a signal to the rest of the councils in New Zealand".
"We have some of the lowest lying communities in New Zealand, and we're only a very small council, just north of Auckland and the climate change story is very real for us."
He said while there was no estimate of what those assets at risk of sea level rise were worth one of the district's towns, Ruawai, was already below sea level at high tide.
Dargaville and Ruawei were already protected by sea walls, the latter was built 100 years ago.
Dr Smith said the declaration showed residents that the council was prepared to lead the way on tricky issues associated with a changing climate.
The council only signed up to the declaration now because commissioners were in charge when the declaration was created.