In July the Independent Planning Commission approved an extension of the existing Brandy Hill rock quarry by some 55 hectares, much of what residents claim is core koala habitat.

Last Friday Greens MP Cate Faehrmann, chair of the Upper House Inquiry into Koala Populations and Habitat in NSW, met with members of the Brandy Hill and Seaham Action Group to discuss the impacts of this decision on the koala colony.

Ms Faehrmann said that while the NSW Premier had gone silent on the issue of loss of koala habitat, the challenge was now for federal environment minister Sussan Ley to step up.

"The minister has been given the opportunity to show true leadership and use her powers to prevent our koala population from hurtling closer to extinction," she said.

"Following the recent bushfires, Ms Ley determined to protect our threatened species so we are calling on her to act now and stop the destruction. We cannot wait another 2-3 years."

A spokesperson for Ms Ley said the minister had the power under the Environmental Protection Biodiversity Conservation Act to "accept the decision or not" on matters impacting on national environmental significance

"A decision is set to be made on September 8."

A spokesperson for quarry owner Hanson said that the Biodiversity Conservation Division assessment reported the project was unlikely to impact the spotted-tail quoll or swift parrot and that the removal of koala habitat could be offset through suitable biodiversity offset credits.

"As part of operations, areas of native vegetation will be retained within land owned by Hanson to the north east, north west and west of the development area, which contain habitat opportunities for koalas similar to that within the quarry site," the spokesperson said.

"Additionally, land close by to the property is the subject of two separate BioBanking Agreement, which [will] improve or maintain the condition of native vegetation to support the koala habitat."

Chantal Parslow Redman, a Brandy Hill resident and action group representative, said it would be a tragedy if the development was allowed to go ahead.

She said their final hope rested with environment minister.

"We've got less than 20 days left before the minister decides whether or not she will protect these koalas, at a time when they are hurtling towards extinction in NSW. We're running out of time to save these incredible creatures," she said.

"In just five days since starting the '30 Days to Save Port Stephens Koalas' campaign, we've received photos and video documenting about 30 separate sightings of koalas on and near the quarry site - including mothers and joeys. This destruction of core koala habitat is a threat to the breeding population in this area."

Ms Parslow Redman, a mother of three young children, said that she could not bear the thought of having her kids growing up in a state where there were no longer any koalas in the wild.

"Despite the IPC's suggestion that there are no breeding females in the area, I've seen females and their joeys right near the site. It's believed there are only a few hundred koalas remaining in Port Stephens, after a huge decline in numbers," she said.

"Port Stephens has one of the last remaining koalas populations on the east coast of Australia. More than 30,000 koalas died around the country during the recent bushfire emergency."

This group's page can be accessed at facebook.com/groups/savepskoalas.