Permission to run the landfill, which is next to a polluted stream and estuary full of rubbish, expired 18 months ago.
However, a new dump site at Smooth Hill, granted permission by the Environment Court in May 2023, is not yet ready.
Independent commissioner Rob van Voorthuysen, who led the hearing for the Otago Regional Council (ORC), granted resource consents to operate at Green Island for another 35 years.
Dunedin City Council chief executive Sandy Graham had told him it was unlikely Smooth Hill would be ready to accept waste until 2029 "at the earliest".
The Green Island landfill has taken rubbish since 1954 and, in the hearing, there was acceptance by Mr van Voorthuysen the tip’s contents, and any negative impact from it, would not go away soon.
"It would be fanciful to suggest that the Green Island landfill should be removed upon its closure or that the generation of leachate from it should somehow be required to cease," Mr van Voorthuysen said.
He took the view that refusing consents would not result in a better environmental outcome as there was "no ability to turn off the discharges; leachate will continue to be generated in waste, and stormwater will continue to run off the surface of the landfill."
He argued rubbish disposal was necessary and continuation of the Green Island landfill was appropriate "until the modern Smooth Hill Landfill is commissioned".
The hearing heard that during the tip’s remaining operational life, stormwater potentially contaminated with waste material would be directed to the tip’s leachate system for treatment. When the tip closes it will be capped and runoff directed to sediment ponds prior to discharge to the stream.
The tip sits next to both Kaikarae/Kaikorai Stream and estuary. Both suffer from pollution and rubbish and there are impacts on wildlife.
There are various factors including the stream’s journey, before it reaches the estuary, through the industrialised and inhabited Kaikorai Valley and Green Island suburbs.
GHD technical director of human health risk Dr Kylie Dodd noted to the hearing that elevated concentrations of nitrate, zinc and PFAS were found both upstream and downstream of the landfill.
Fish & Game environmental officer Nigel Paragreen said the area had the potential to be a restored haven for birds, fish and macroinvertebrates, creating a significant amenity for fishing and visiting.
He said a report should be undertaken that addressed the contamination issues at a whole-catchment scale.
Mr van Voorthuysen said such a report would not be made a condition of the consents as it was not the DCC’s responsibility to do such reports.
However, he agreed a catchment-wide study, led by the Otago Regional Council or others, would be an "effective way to understand the condition of the broader catchment".
Mr van Voorthuysen said the 35-year term sought was "appropriate for a regionally significant infrastructure project".
Speaking to the Otago Daily Times, Mr Paragreen said he understood there was a regional council commitment to restoring the estuary "and we need to ensure the landfill doesn’t stop that being achieved. We will be watching as the years go by and expect genuine improvements".
"It is a hell of a job but people want to be around the stream and the estuary. It has been heavily polluted for quite a long time but the potential for change is huge."
Ōtākou rūnaka upoko Edward Ellison said it had been a "long saga and we have been engaged all the way through. We are looking for that day when the landfill is moved to an appropriate site ... bearing in mind that doesn’t fix the problem of the Kaikarae, which is a long-term issue."
