A group of nine community associations and urban design groups are urging Aucklanders to oppose a planned 90 metre extension to Queens Wharf.
Auckland Council has lodged a 35-year resource consent to build the wharf into Waitematā Harbour, which it described as temporary.
But Michael Goldwater, from the lobby group Stop Stealing Our Harbour, said 35 years was not temporary.
"[It is] an egregious environmental blemish onto the people's wharf. It's unnecessary because there are other options available and the business case for it is completely exaggerated."
Public submissions for the extension's resource consent application close next Monday.