But a group pushing for the gorge, which closed to the public in 2004, to be protected in a new national park says homes will be too close to the Ginninderra Creek corridors to safeguard wildlife, including the vulnerable pink-tailed worm lizard. Ginninderra Falls Association president Chris Watson said: "They are too close to the falls. In NSW they [developers] are going for broke, only 100 metres from the falls. "

The Riverview Group is proposing 11,500 homes in a continuous community straddling the border and bounded by the Murrumbidgee River and Ginninderra Creek The proponents propose a conservation trust, drawing on multimillion-dollar contributions from the ACT Government and NSW land sales, to manage the river corridor.

Similar to the ACT's Mulligans Flat and Jerrabomberra Wetlands Trust, the new trust would oversee conservation, bushfire management, maintain lookouts and paths, and capitalise on tourist opportunities.

Mr Watson says he is ambivalent about the governance model, and would prefer the ACT Parks and Conservation Service's professional staff to oversee the corridor. But the Conservation Council ACT welcomes the trust model and Riverview Group's early identification of areas of ecological significance.

Riverview Group director David Maxwell said the corridor boundary to protect wildlife was decided on after extensive surveys and studies, which drew on field surveys by University of Canberra environmental experts Will Osborne and David Wong.

"As a consequence, the conservation corridor around the Murrumbidgee River and Ginninderra Creek narrows and widens from the waterways from 100 metres to 1.5 kilometres, depending on the scientifically established ecological values of the area," Mr Maxwell said.

"That habitat edge in NSW, including the land near the falls and gorge areas, was subsequently checked and refined on the ground by field inspection by the consultant team in consultation with officers from the NSW Office of Environment and Heritage in September, 2013."

Mr Maxwell said the Ginninderra Falls Association wanted a much bigger conservation area within a national park. "We don't believe it needs to be that large. But a conservation trust allows it to work, it gets [the land] open, and at this stage you are going to start with 600 hectares. It is not a bad start."

Mr Maxwell said his and Mr Watson's interests were aligned, and the only way to manage the gorge and surrounding land was re-zoning. "Nothing will change without the re-zoning," he said.

The project has passed its first planning hurdle, with NSW Planning and Environment allowing Yass Valley Council to submit a rezoning proposal for the NSW portion of the land. Public notifications in the ACT needed for changing the Territory Plan and National Capital Plan will begin in May and June.

The project covers rural heritage sites, including West Belconnen Farmhouse, an odour buffer around 200,000 battery hens, previously unrecorded Aboriginal archeological sites, a quarry, and a buffer around the West Belconnen tip, where 150,000 tonnes of contaminated material from Mr Fluffy homes is being dumped.

Commuter roads into West Belconnen will be upgraded if the project is approved. Much of the discussion in coming years will centre on the best option for delivering services from the ACT into the NSW portion of the "Parkwood" subdivision. Stages one to three in the ACT will be developed from 2016 to 2021, and land will not be released in NSW until 2033.

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