The rezoning process was “unreasonable and hasty” and failed to properly consider both an important koala corridor, and the transport and infrastructure needs of the area, Wollondilly Shire Council said.

The rezoning decision paved the way for the Walker Corporation to build 3600 new homes in an area just south of Picton Rd, with government forecasts of a population of almost 10,000. 

Promising “new homes for all life stages”, the Department of Planning and Environment rezoned the area under Sydney Region Growth Areas rules, to include low- and medium-density housing.

But Wollondilly Council will now appeal against this decision in the Land and Environment Court.

The council says advice was ignored from the Office of Environment and Heritage, warning that land within the primary koala corridor there should not be rezoned.

It also says the rezoning should not have been approved until infrastructure and transport planning had been completed, subject to community consultation.

Wollondilly Mayor Judith Hannan said she had tried to negotiate with Premier Gladys Berejiklian and Planning Minister Anthony Roberts.

“Council has tried to engage with the Premier and the Minister for Planning to restore a proper planning process and ensure these matters were fully addressed,” Cr Hannan said.

“This has proved futile and as a result, council has no alternative but to seek for the matter to be placed before the courts.

“Council has been put in the position where we have no choice but to appeal what we see as an unreasonable and hasty decision.”

Together with the state government’s Wilton New Town plan, the area would soon have more than 15,000 new homes.