Consent has been granted to dredge Whangārei Harbour clearing the way for fully laden super-sized fuel tankers to visit the Marsden Point oil refinery.
The "Suezmax" tankers already visit the refinery regularly but could only do so 90 per cent full because of the channel depth.
Refining NZ sought the consent on the basis a deeper, straighter channel to allow greater oil shipments would mean ultimately, fewer tanker visits would be needed - with less impact or danger to the environment.
This week, a panel of three independent commissioners granted a raft of resource consents to deepen and realign theh Whangārei Harbour entrance and approaches.
Chair Sharon McGarry, Dr Rob Lieffering and Sheena Tepania heard the company's applications on behalf of the Northland Regional Council over seven days during late February and March this year.
In a 140-page decision, the commissioners granted the company 13 consents, most valid for a 35-year period. Those relating to navigational aids were given 25-year consents.
The application was publicly notified on September 13 last year, attracting 50 submissions, one of which from the Ngatiwai Trust Board was subsequently withdrawn.
Of the remaining 49 submissions, 18 were in support, 29 opposed and two neutral.
Supporters felt the project would have a range of positive economic and environmental effects for Whangārei and Northland, including improved environmental performance through fewer tankers visiting the harbour.
In contrast, opponents' concerns were wide ranging and included a lengthy list of cultural concerns and fears the risks of oil spills or accidents would increase with the use of larger Suezmax tankers.
They expressed concern actual effects might differ from Refining NZ computer models and questioned the effects of the project on local commercial and recreational fisheries.
Some said there had been inadequate consultation on those associated areas.
Of major concern also was the stability of nearby Mair Bank. Submitters were concerned about the proximity of proposed dredging and spoil disposal sites to Mair Bank, the Motukaroro Marine Reserve or other sensitive ecosystems.
The commissioners concluded the project was "unlikely to have any significant adverse effects on the environment and is generally consistent with the relevant statutory planning documents and provisions".
They said particular regard had been paid to potential cumulative effects of the project and the importance of maintaining the long-term stability of Mair Bank.
"In taking into account the existing environment, we conclude that the applicant's final proffered conditions, as changed by us in this decision, adequately avoid, mitigate or remedy the actual and potential effects of the project to a level that they are not significant and are, in our view, acceptable," the commissioners' report stated.
The decision is subject to appeal for 15 working days. The full decision and details of all the conditions is available online at nrc.govt.nz/consentdecisions