Lugarno residents have banded together to fight the demolition and redevelopment of the historic 'Glenlee' property.
Local author, Glenyss Barnham, formed the Save Glenlee Resident Action Group to raise awareness about the issue.
She said she was passionate about Lugarno's history and environment.
"When I read that this significant piece of Lugarno's historical, cultural landscape and 200 trees were proposed to be demolished or destroyed, I was outraged," Ms Barnham said.
"Trees including mature trees that are 70 to 80 years old, historic trees, trees that contribute significantly to the health of the area and trees that, along with their understory, provide habitat for many threatened species of wildlife.
"I knew I couldn't stop it myself, but I believe in people power."
The homestead and surrounding bushland, which is located on the banks of the Georges River, could soon be subdivided into 31 residential lots, pending approval from the Georges River Local Planning Panel.
The development application lodged on May 6 also includes demolition works, construction of new roads, drainage and tree removal.
Ms Barnham said she was delighted to see 70 people attended the groups first meeting on short notice.
She said residents were concerned about the felling of the trees, traffic congestion, aboriginal heritage, overdevelopment of the site and impacts on the Georges River.
"They expressed concern that it is the last remaining untouched historic site of its kind in our LGA (local government area), and it should be preserved for the community and future generations," she said.
"[We hope to] raise awareness of the impending development and how it will irrevocably change the face of the Lugarno peninsular and its natural environment if it is not stopped - and to help people connect and express their concerns within the community."
Fellow Lugarno resident Megan Argent launched a petition earlier this year calling on the NSW government to purchase the historic 'Glenlee' property.
Mrs Argent said Glenlee, also known as Lugarno Farm, is listed on the National Trust Register as a part of the Lugarno Early Settlers Local Heritage Precinct.
"It is an irreplaceable part of St George district history," Mrs Argent said.
"It has been beautifully preserved by the same family as a working farm since 1908 and contains culturally significant evidence of Aboriginal occupation.
"There is no other site left like it in our LGA and it is a snapshot in time of our agricultural past, preserved since the area was first settled."
Georges River Environmental Alliance secretary Dr Sharyn Cullis said the organisation also held concerns about the impact of stormwater on the Georges River if the 80 Boronia Parade development is to be approved.
"The design of the stormwater system for this gross over-development of Glenlee is deeply disturbing," she said.
"The proposed underground pipe and drain system will channel and dump the entire stormwater load of those established streets and this additional estate through one huge outlet pipe onto what is now a steep and pretty little creek-line that is approximately 50 metres from its confluence with Lime Kiln Bay, on the Georges River."
Georges River councillor Sam Elmir raised a question with notice about the proposed development at a recent council meeting.
The council officer's response to Cr Elmir's questions stated that the land could only be compulsorily acquired by the council "if an adopted strategic study showed that Peakhurst Ward had a shortage of open space".
However, it also noted, "the Peakhurst Ward has the highest amount of open space per dwelling in the local government area".
"The site is not currently available for sale," the report stated.
"A compulsory acquisition of the site would need to occur in accordance with the provisions of the Land Acquisition (Just Terms Compensation) Act 1991.
"Council would need to resolve to prepare a planning proposal (Draft LEP) for the site and rezone it to RE1 Public Recreation (open space) and list the site on the land acquisition map.
"It is expected that based on its current residential zoning and the statutory requirement to take into account the site's development potential, the estimated cost of acquisition could exceed $15 million.
"Council would need to engage a qualified valuer to obtain a valuation to confirm this estimate."
To sign the petition, visit: parliament.nsw.gov.au.
