Wollondilly Council fears the Macarthur region's iconic koala population could go extinct if the state government doesn't step in soon.
The council has made a submission to the NSW Legislative Council's 'Inquiry into Koala Populations and Habitat in NSW'.
Council staff have called on the government to prepare a strategy to specifically manage koala populations in south-west Sydney, including Wollondilly.
Infrastructure and environment acting director Alex Stengl said the council's submission implored the government to take adequate action now to avoid an "extinction crisis" in the near future.
"It is council's view that the NSW Department of Planning, Industry and Environment has been undertaking land use planning which adversely impacts the survival of koalas within the Wollondilly local government area," she said.
"We are strongly concerned that the largest chlamydia disease free koala population in NSW is not currently protected by an Integrated Regional Conservation Plan."
Ms Stengl said the council welcomed the inquiry but believed there was inadequate consideration of development pressure on the local koala population in growth areas.
The submission highlighted council's long-term concern that the revision of the Koala Habitat Protection Planning Policy remains incomplete, particularly in relation to the lack of an up-to-date list of koala tree species and an adequate definition of 'core habitat' for koalas.
The council also pointed out the strategy did not provide an appropriate approach to stabilising and increasing koala numbers as recommended by the NSW chief scientist and engineers.
Koalas are an iconic part of Wollondilly's natural history.
The first recorded European sighting of a koala occurred near Bargo in 1798.
Increasing numbers of koalas have been recorded at a range of locations within the Wollondilly region in recent years.
The current estimated koala population in the shire is between 350 and 400 animals.
Council has been advocating for the protection of koala habitat corridors in the Wilton and Appin growth areas over the past two years.
Wollondilly Council's submission to the inquiry is one of nearly 300 that were received.
A final report is due on June 15, 2020.