It was drawn from about 70 days of work by archaeologists, with the Indigenous community given merely 28 days to respond, she said.
A full survey would reveal perhaps thousands of Indigenous sites and signs of traditional owners’ connection to country, such as scar trees, whose bark has been removed for canoes and other uses, she said.
“The law protects statues in the middle of Sydney, but they allow people to blow up sites that are 40,000 years old or drown them,” said Ms Brown, whose family members were the last Indigenous people forced to leave the area when Lake Burragorang filled behind the dam wall six decades ago.
The protection of Indigenous heritage has gained international attention following the blasting in May of the Juukan Gorge in the Pilbara by mining giant Rio Tinto.
Rio responded to the uproar over the legal destruction of the site to mine iron ore by announcing on Friday that three senior executives, including chief executive Jean-Sebastien Jacques, would leave the company within six months.
The Berejiklian government is likely to face increased scrutiny over its scant survey of Indigenous sites within the likely impact zone if the dam project proceeds.
A leaked document obtained by the Herald shows the environment, energy and science unit of the Planning Department found many flaws in the draft environmental impact assessment of expected impacts.
One issue of concern was that the scientific assessment of Aboriginal heritage had been conducted by just one person who spent only one day in the field reviewing the archaeologists’ work.
“It cannot be assumed that any one practitioner will have the full range of skills required to investigate and assess cultural significance and harm,” the document said.
The department also rejected the findings that “short-term inundation will not impact on Aboriginal objects and values”, adding that the draft survey had also ignored advice in 2018 that an anthropological study and specialist rock art study should be done.
Sharyn Halls, an elder with the Gundungurra Aboriginal Heritage Association, said the Rio blasting had put destruction of Indigenous culture “on the top of the list”.
She was able to find dozens of worked stones, including an axe head, at Burnt Flat near the Wollondilly River during a visit on Thursday.
The area, a mix of private land and national park, had not been surveyed as part of the draft EIS.
“Do they want to know?” she said. “If you don’t know, you don’t have to address the problem.”
Among the known sites are several rock shelters known to contain art that even now sit just above the water line.
Painted on sandstone, the work would probably be stripped away with any inundation, even if only temporarily, Ms Brown said.
Stuart Ayres, the Minister for Western Sydney in charge of the project, said, “Engagement with registered Aboriginal parties and Aboriginal communities that have a connection to the land has been under way since 2017.
“The NSW government looks forward to the environmental impact study public exhibition, which will allow for the proposal to be assessed on its merits and for all interested stakeholders to provide comment.”
Gaining access to traditional sites has become more onerous since the government began preparations for the wall raising, Ms Brown said.
“Sometimes it does feel like they don’t want us to be here,” she said.
Peter Hannam writes on environment issues for The Sydney Morning Herald and The Age.