Four people spoke against the modification, which if approved would allow Unity Mining to process gold using cyanide at Majors Creek, in the headwaters of the Eurobodalla’s water supply.

One speaker claimed Unity provided incorrect information in its modification application. 

Eurobodalla resident Dr Emmett O’Loughlin, a former chief research scientist with the CSIRO, said Unity Mining’s data, in an environmental assessment to support its application to modify the mine, under-estimated rainfall and overestimated evaporation. 

Consequently, the tailings dam would have a higher probability of discharges of contaminated liquids into nearby creeks and ultimately the Deua River, the major water supply for 100,000 downstream users. 

Unity Mining has claimed the rainfall data, used to calculate monthly inputs into the tailings dam, was from the Braidwood weather station. 

Dr O’Loughlin claims these were “incorrect and significantly different” from rainfall statistics published by the Bureau of Meteorology

“The bias is further increased by ignoring the quality controlled rainfall data from the Majors Creek weather station, which shows that rainfall at the mine site is 30 per cent higher than Braidwood rainfall,” Dr O’Loughlin said.

He said Majors Creek data should have been used, instead of Braidwood’s.

Unity Mining chief executive officer Andrew McIllwain also spoke and said he would take notice of Dr O’Loughlin’s claims. 

“We used three or four years of rainfall data from a weather station that we have on site (at the mine),” he said. 

“I respect that the weather patterns vary significantly between Braidwood and Moruya.

“Our access to data is far greater and I do not think that we have taken a minimalist approach by any means.” 

Richard Roberts, of Broulee, said the cyanide processing plant “must never” be approved. 

“The toxicity it will harbour must never be allowed to hang over this community,” he said. 

“The existing fresh water supply must be secured and maintained, not just for today’s community, but for future generations. 

“The impacts of a disaster on the landowners along the river have been totally ignored.”

Deua River resident Peter Cormick said the Deua catchment and the water it supplied should never be subject to even the slightest risk of contamination. 

“Risks might be calculated to be acceptable, but in the event of their realisation, those calculations count for nothing,” he said, 

“The central issue is the location of the mine. 

“Sitting high above the water catchment for many tens of thousands, it is no place for a tailings storage facility that carries with it even the slightest of risks of contamination.”