President of the National Parks Association of NSW's Far South Coast branch David Gallan said Tuesday's sighting reinforces the need to protect the Murrah Flora Reserves, and for reserves to be "absorbed" into Biamanga National Park.

Long-time threatened species researcher Chris Allen said scats from the animal will likely be genetically sequenced in order to uncover how the animal fits into the local population of around 50 animals.

"Genetic testing can take some time, but it gives us more information, and sometimes very important information," he said.

"It shows us its relationship to other animals, and also tells us whether they are suffering from chlamydia or koala retrovirus"

Mr Allen said studies by the University of Sydney have shown koalas south of the Murrah River have an up to 80 per cent chance of being chlamydia free.

Recent images captured by motion cameras in the Murrah reserve show several of the animals using installed water stations.

After the summer bushfire devastation, a mother and her joey spent 12 days alone in a stringybark tree on a private property near the Murrah Flora Reserve, and this week Mr Allen said post-bushfire surveys have indicated the South coast population is at a similar size despite the natural disaster.

"Every sighting is important at this time," he said.

He said given the close proximity of the animal to the road, the animals also face a serious threat of being killed by oncoming vehicles, particularly at night.

"If ever people see a koala it is important to let national parks know as soon as possible to allow surveyors to get out there as quickly as they can to record the sighting and check the health of the animal," he said.