An independent board of inquiry has given its go-ahead to the controversial so-called Holiday Highway, running from Puhoi to Warkworth north of Auckland.
In its draft report, released today, the board granted the 15 resource consents sought by the NZ Transport Agency, subject to the imposition of conditions. The highway is one of the Government's roads of national significance.
The board held a series of public meetings about the $760 million, 18.5km northern motorway extension.
In its decision, the board said it acknowledged there would be adverse effects but considered they could be "avoided, remedied and mitigated, both during construction and operation, through the design and the identification of specific mitigation measures which are to be included in the conditions for the designations and consent applications".
The Department of Conversation (DOC) opposed aspects of the proposal, raising a number of environmental concerns, including construction sediment entering the Puhoi estuary and Mahurangi Harbour, causing damage to marine life.
The controversial road has split the region with more than 180 submission received. About two-thirds supported the project while a quarter opposed it.
Supporters of the highway say it will cut travel time, reduce crashes and boost Northland's economy.
But opponents fear it could contaminate water supplies, destroy local habitats, and the money could be better spent on other projects.
Generation Zero were among a number of organisations who submitted against the proposals.
Auckland policy director Luke Christensen said it was concerned there was no economic analysis provided, nor a cost benefit ratio to back claims it would be of economic benefit to Northland.
"There was a number of unsubstantiated claims about how it would help Northland's economy," he said.
"It was up to them to prove it. What we found was that there would be minimal or negligible economic benefit."
Storm damage to Northland this month highlighted the region's resilience issues and Generation Zero would prefer to see money invested on the region's local roads, Christensen said.
"Only $100m is spent on Northlands roads per year. All the roads that have been causing trouble over the past couple of weeks- this $750m would fund a lot of local upgrades."
The Board of Inquiry's draft report made mention of a 'do nothing' option proposed by some submitters but it said the benefits of the motorway over the current SH1 route was "compelling in terms of road safety, travel times and more efficient fuel consumption."
A spokesman for The Campaign for Better Transport said the group was "obviously very disappointed" with today's decision, saying the toll road came at "a high environmental cost with very low economic proven benefits for Auckland or Warkworth".
Convenor Cameron Pitches said: "We're talking people who've been forced to sell half of their farm, forced to sell their houses, the loss of Kauri forests, the risk that the Puhoi or Mahurangi catchment would suffer from sedimentation.
"Our concern is that NZTA have not provided an economic evaluation for this project and the NZTA have not considered any alternatives apart from a four lane motorway that has to be tolled. The cost of this project is the thick end of $1 billion, we've seen that in Northland the roads are in a terrible state and its obvious for Northland's economy that's where it would be better spent."
The organisation proposed upgrading existing roads and putting a bypass around Warkworth, claiming it would be $500m cheaper.
NZTA acting Highway Manager Steve Mutton said that, subject to the board's final decision in September, construction of the motorway could start between 2016 and 2019.
It is estimated to take five years to build.
"While it's important to remember that the final decision is yet to be made, we are encouraged by the draft decision, which has followed an extremely rigorous fact-finding process.
"Whangarei to Auckland is one of New Zealand's key transport routes, and investigations on how to continue improving and securing this corridor are ongoing, including for the Wellsford to Warkworth section."
Mutton said the agency would study the details of the draft decision and provide comments back to the Environmental Protection Authority (EPA) within the 20-working day comment period.
"The draft decision is great news and an exciting and important step towards improving transport connections between Auckland and Northland and the rest of the upper North Island," he said.
The first stage of the project involves construction of a four-lane, 18.5km-long motorway from the Johnstone's Hill tunnels on State Highway 1 to a roundabout just north of the Warkworth town centre.
Ramps to and from Auckland are planned near the community of Puhoi.
The new motorway is one of seven Roads of National Significance identified by the Government as key to unlocking New Zealand's potential for economic growth.
The Green Party said the draft decision to grant resource consent to the proposed motorway didn't stop it being a waste of money.
"The Puhoi motorway is an unnecessary waste of taxpayer money that does nothing to improve Northland's roads or reduce the cost of transporting people and goods," Green Party transport spokesperson Julie Anne Genter said.
"The project is actually in the Auckland Region and will only encourage more long distance commuting by car, worsening congestion.
"There are far more pressing priorities that will improve road safety and make a real difference to Northland - like urgent maintenance and safety upgrades to SH1 north of Puhoi, improvements to Northland's regional roads, and the Marsden Point rail link."