A Greens and Labor-dominated NSW parliamentary committee has found koala populations have been shrinking throughout the state, due to the effects of land clearing for agriculture, mining and development.

It concluded the official government estimate of 36,000 koalas within the state was "outdated and unreliable", given dramatic declines in key local populations since 2012.

At least 5000 koalas are also estimated to have perished during the 2019-20 bushfires.

Some parts of the state, such as Port Macquarie, lost up to 90 per cent of their koala populations in the fires.

"Given the scale of loss to koala populations across New South Wales as a result of the 2019- 20 bushfires and without urgent government intervention to protect habitat and address all other threats, the koala will become extinct in NSW before 2050," their report said.

The committee called for a halt to salvage logging operations in light of the fires.

"In light of the above evidence and the ongoing recovery efforts in burnt forests, the committee acknowledges that the forests are essential habitats for not just koalas, but other threatened species, and need to be monitored for recovery before any further decisions about salvage logging are made," their report said.

"The committee thus recommends that the government consider the impacts of logging in all public native (non-plantation) forests in the context of enabling koala habitat to be first identified and then protected by a combination of transferring land to national parks ... where appropriate."

It also urged the government to rule out opening up old growth forests in the state forest reserve for logging.

The inquiry was set up more than a year ago after series concerns about the future of the koala.

Even before the fires, the species had seen a 26 per cent decline in numbers.

The committee heard from James Fitzgerald, a wildlife carer based near Canberra, who lost both his home and all of his animal enclosures in the January fires. The koalas he had rescued from earlier fires were also lost.

Mr Fitzgerald said many koalas he was now finding were extremely thin and had to euthanised.

"Their luck is running out because there is just no food across vast areas," Mr Fitzgerald told the inquiry.

The species was also vulnerable to the increasing impacts of climate change.

The recent drought also meant koalas were no longer able to get adequate hydration from eucalyptus leaves, and were descending from trees to drink from garden hoses and water bowls.

Chair of the committee, Greens MP Cate Faehrmann, warned future generations may not see a koala in the wild again if the report was ignored.

"Following the disastrous 2019-20 bushfire season, it is undoubtable that the game has changed dramatically for koalas. The evidence could not be more stark. The only way our children's grandchildren will see a koala in the wild in NSW will be if the government acts upon the committee's recommendations," Ms Faehrmann said.

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