A revived East-West Link (EWL) could mean trouble for a rare wildlife haven and set a "terrible precedent" for Auckland, an environment group fears.
The EWL was a $1.85b priority roading project of the previous government, connecting SH20 at Onehunga and SH1 at Mt Wellington with a four-lane highway.
In November, when it was still in the design phase, Prime Minister Jacinda Ardern met with Auckland Mayor Phil Goff and announced the road would not go ahead in its current form.
However, an independent board of inquiry last week issued its final decision confirming the designations and granting the resource consents for the project, two months after the Environmental Protection Authority released its draft decision on the project.
Sally Gepp, a solicitor for Forest and Bird, said the decision to grant consent for the road went against policies to protect the environment in the Auckland Unitary Plan (AUP).
"The ink is barely dry on these policies, which Forest and Bird fought long and hard for, and already they are being overridden by a road," Gepp said.
"This is a terrible precedent for Auckland. Even though the Government has said the road is not going ahead in its current form, this decision means plans could be revived by future governments."
Forest and Bird made a submission against the road extension as it proposed to cross Anns Creek, a rare ecosystem of lava shrubland habitats and wetlands containing threatened plants and identified as a significant ecological area in the AUP.
The group argued the road would also take away feeding areas for migrating birds and other endangered and rare birds including the wrybilled plover.
Submissions against the road also came from Ngati Whatua Orakei, Te Kawerau a Maki and Makaurau Marae along with other community groups, on the grounds of its adverse environmental and cultural effects.
Forest and Bird was considering the decision and whether to lodge an appeal.
A NZ Transport Agency spokesperson said the decision was "an important part in the ongoing statutory process", but added the consents were "enabling" and not obligatory.
Separately, NZTA was working with the Government as it developed a new policy statement on land transport, part of which included a review of the EWL to identify options to provide a lower cost, better value solution.
NZTA had been working with Auckland Transport, Auckland Council, mana whenua and the community around transport issues in that area of Auckland since 2013, and was committed to getting a solution that met needs "now and in the future", the spokesperson said.