Traditional owners say they have not been given enough time to assess the cultural heritage impact of a plan to raise the wall of Warragamba dam and flood world heritage-listed areas of the Blue Mountains, as two local mayors demand that a state government representative faces community concerns at a public meeting this Friday.

Indigenous custodians say document looking at impact of flooding parts of Blue Mountains is hard to follow

Kazan Brown opposes the plan to raise the Warragamba dam level and flood world heritage-listed areas. Photograph: Jessica Hromas/The Guardian

The New South Wales government wants to raise the dam wall by at least 14 metres to reduce flood risks to western Sydney suburbs downstream. But green groups, Aboriginal traditional owners and Unesco are against the proposal, with the world heritage committee announcing last month that it was “likely to have an impact on the outstanding universal value” of the area.

A Gundungurra woman, Kazan Brown, said traditional owners had been given just 40 days to respond to the 2,000-page report, which was not enough time.

Brown said because the draft report was confidential, she risked a hefty fine if she shared any of it with others, which was also preventing her from seeking professional advice on how to understand and respond to its contents.

“I’ve been to uni, I’ve got a couple of degrees, and I’m struggling to understand this report,” Brown said. “It’s full of stuff that shouldn’t be in there – like gradient, soil samples and so on – that aren’t relevant to Aboriginal culture.

“We’d like to have it peer-reviewed by a cultural heritage officer, an archaeologist and an anthropologist, and we need another month to write a decent response.

“The whole process was not done properly. They only surveyed a quarter of the area – just over 26%. In that one area they found more than 300 sites.”

A spokesman for WaterNSW says the report could not be shared because it contains culturally sensitive information, including locations and details of sites. “This information belongs to the traditional owners,” the spokesman said.

But he said they had been given 42 days to review and comment on the report, which was longer than necessary. “Given the length and detail in the report, a longer period than the mandatory 28 days was allowed for this process,” he said.