Excluding Northport as a possible site for taking over some of Ports of Auckland's work doesn't make sense, especially when the Firth of Thames and Muriwai are considered better options, Northland's economic development boss says.

The Ports Future Study, set up by Auckland mayor Len Brown, had been looking at a long-list of 12 possible port locations that could work from a purely technical perspective. Northport and the Kaipara Harbour were both earmarked as options for taking over some of Auckland's future port freight.

But the Port Future Study's Consensus Working Group has whittled the list down to three: Manukau Harbour area; Firth of Thames area (within the Auckland region) and Muriwai area.

The decision has left Northland Inc CEO David Wilson dumbfounded, saying it made no sense to look at areas like Muriwai and Firth of Thames when there as a perfectly good, deep-water port that's under utilised at Marsden Point.

Advertisement

"We thought it was a sensible option to look at Marsden Point. This makes no sense and Northland Inc is very interested to know what criteria was used to reach this decision," Mr Wilson said.

"Why build new infrastructure when there is the under-utilised deep water port at Northport?"

He said Northport has already been mooted as an alternative to Auckland for vehicle imports while other options simply don't stack up.

"There is little doubt as a deep-water port Northport has both potential and capability to handle a lot of the Auckland's freight and presents the best and most viable option to the Port Future Study group," Mr Wilson said.

Study Group chairman Rick Boven said the study's consultants have projected Auckland's long-term future freight and cruise needs and assessed what could be required in 50 years to accommodate it.

"Auckland is on a steep growth trajectory. With an expected population of at least 2.6 million and potentially quadrupling of freight trade in the next 50 years. Auckland will need a strategy to ensure freight can flow for continued trade and prosperity", Dr Boven said.

He said once further analysis had been done there will be a clearer picture of how each option stacks up on costs and wider economic effects.

"Some options are likely to be cost prohibitive", Dr Boven said.

NZ First leader and Northland MP Winston Peters, who is campaigning for Northport to take over much of Northland's freight, said the shortlist options defies logic.

"The logical, and one would have thought, most obvious answer is Northport, the closest port to most of the country's international markets," Mr Peters said.

"But the Consensus Working Group making recommendations to the Auckland Council has turned a blind eye to even suggesting it might be a contender."

New Zealand First's member's bill, the Waitemata Harbour Protection Bill, is awaiting introduction to Parliament. It would stop expansion of the Ports of Auckland at its existing site.