A koala colony in northern NSW will decline regardless of the effects of a proposed highway upgrade, the Roads and Maritime Services says.
RMS on Tuesday released its Ballina Koala Plan and Population Viability Analysis (PVA), which assessed the likely impact an upgrade to the Pacific Highway from Broadwater to Coolgardie would have on about 200 local koalas.
The report found the Ballina koala population will decline over 50 years with or without the proposed highway upgrade because of disease, predators and koala deaths on roads other than the Pacific Highway.
The highway upgrade could reduce the projected koala population by 0-9.7 per cent, which could be compensated for by koala-proof fencing and establishing new habitat, the report found.
Pacific Highway general manager Bob Higgins said the Ballina Koala Plan and PVA had been endorsed by the Koala Expert Advisory Committee, which is chaired by NSW chief scientist and engineer Professor Mary O'Kane.
"The upgrade would be fully fenced to prevent animals from entering the road corridor and koala grids would be installed on interchange ramps to stop animal strikes from occurring," Mr Higgins said in a statement.
"About 26 wildlife crossings would also be installed as part of the upgrade, substantially increasing safe crossing points and about 130 hectares of koala feed trees will be planted to provide additional habitat," he said.
Groups opposing the upgrade plan say another highway route should be considered.
"The plan's purpose is to enable RMS to realise its decade-long investment in a route that's in the wrong place," Friends of the Koala president Lorraine Vass said in a statement on Tuesday.
"You only have to look at the scale of destruction, fragmentation and loss that's already occurred at Halfway Creek and in other upgraded sections to know that Ballina's koalas are doomed."
The plan has been submitted to federal Environment Minister Greg Hunt for approval, but Friends of the Koala, Save Ballina's Koalas campaigners and the International Fund for Animal Welfare say they need time to review the 309-page document.
"We understand that Minister Hunt and his department will welcome what we have to say," Ms Vass told AAP on Wednesday.
"Only a matter of days ago he was declared to be the world's best minister and we want to see the proof of that."
