It said that the container terminal can grow on its current footprint for approximately twenty years, but this is sensitive to the growth assumption modelled.
The report said the multi-cargo wharves will become progressively more constrained over the next five to 10 years.
If the port company loses the use of Captain Cook Wharf - immediate action by way of reclamation or some other means of adding space would be required to manage present volumes of multi-cargo.
A council group has proposed extending Captain Cook Wharf and demolishing Marsden wharf to accommodate the growing number of cruise ships.
The report's author, Nick Allison, said the capacity of the multi-cargo wharves are coming under increasing pressure.
They are used to land cargos that aren't typically carried by containers, such as building materials, vegetables, wheat, vehicles and other goods used by households in Auckland and elsewhere in New Zealand. The ships are getting much larger and wharves were built to manage such vessels.
Mr Allison said the situation is further aggravated by the rapid increase in the number and increased size of cruise ships.
NZIER chief executive Laurie Kubiak said that many everyday goods coming through the multi-cargo wharves are important for the livelihood of Aucklanders in ways that are not always obvious.
For example, most of New Zealand's vehicle imports come through the Port of Auckland.
These imports create about 3500 jobs in vehicle wholesaling and distribution businesses, and these jobs are concentrated in South Auckland.
The report is the second stage of a review of Ports of Auckland's expansion plans.
The first stage of the review was an independent technical study by PricewaterhouseCoopers(PwC) of the freight needs of the Upper North Island ports.
The second stage was commissioned to look at Ports of Auckland's wider impacts on the city.
In August 2013, the council voted to make further reclamation of the Waitemata Harbour for port business a "non-complying" activity in the draft Unitary Plan, as a holding measure until it received the second stage of the review.
The rule put the brakes on the port company's plans to expand up to 179m into the harbour while the council, as 100 per cent owner of the port, decides how the port fits into the city landscape.
In August 2013, Mayor Len Brown said: "Before we make any decisions about whether the ports expands or otherwise, we need an informed discussion with Aucklanders, underpinned by a robust study that includes consideration of economic, social and environmental factors."
The issue follows a campaign by the Herald since January 2012 against further reclamation of the Waitemata Harbour by Ports of Auckland. This led the council to commission the two-stage review.
Ports of Auckland has been confident the study will vindicate its own expansionary plans, saying its own studies show the best way to cater for Auckland's growing freight demand was to expand the existing port.
The company has maintained "it is the cheapest, least environmentally damaging option and delivers the best economic result for Auckland and Auckland ratepayers".
Heart of the City business association, Auckland Institute of Architects, the architects' Urban Auckland wing and the Westhaven Marina Users Association have been among those opposed to the port company's expansion plans.
