The proposal to raise its wall would increase the dam’s capacity by fifty per cent, placing 65 kilometres of wilderness streams and rivers within the World Heritage site under direct threat from dam water inundation. Australian Government documents obtained through a freedom of information request have said of the dam proposal:

“The impact of increased flood water levels within the dam is likely to have extensive and significant impacts on listed threatened species and communities and world and national heritage values of the Greater Blue Mountains World Heritage Area.”