However, the spokesperson said that, given the risks of more severe flooding in the Hawkesbury Nepean Valley, the minister paused the approval of future residential rezonings in the north-west to allow for the completion of the business case and so “the minister has confidence new development can be safely evacuated”.

An Infrastructure NSW spokesperson said the agency expected the government would see its business case for the flood strategy “in the coming months”.

Asked whether the agency should speed up its modelling for evacuation routes, Mr Stokes replied, “I would certainly encourage them to get on with it, because, frankly, there’s a lot of, there’s a lot of jobs, and infrastructure that can’t progress until we have a final business case”.

Chas Keys, a former deputy director-general of the NSW State Emergency Service, welcomed the development halt, saying the government was creating an increasingly vulnerable population from the way planning had progressed in the Hawkesbury-Nepean Valley.

“There is a serious problem with population growth, which obviously happens at the end of big cities and, in this case, we’ve got it in the worst possible flood environment in the state,” he said.

Urban Development Institute of Australia CEO Steve Mann said the decision could cost thousands of jobs and cause house prices to rise: “Our concern is the government’s ability to expeditiously find a solution to this issue.”

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Property Council NSW executive director Jane Fitzgerald said the Castlereagh Connection, a proposed freeway between the M7 and Castlereagh, and running through a road corridor set aside 70 years ago, was a “key piece of infrastructure that should be progressed”.

In a May 2020 letter responding to Penrith City Council’s pleas for the route to be prioritised, an Infrastructure NSW official wrote, “while a significant flood event has high impact, given its low probability it is difficult to justify the economic benefit when compared with the high cost of building the Castlereagh Connection.”

“Transport for NSW has advised that the Castlereagh Connection is currently not prioritised and, therefore, no funds are available to undertake a business case,” the official said in the letter. Infrastructure Australia has included the road on its 2021 high priority list.

A January 2019 report published by Infrastructure NSW regarding flood risk management in the Hawkesbury-Nepean Valley said there was “insufficient road capacity to safely evacuate the at-risk population” within the limited flood forecast time.

A Transport for NSW spokesperson said work on planning for the connection was continuing but wouldn’t specify what that entailed.