The United Nations World Heritage Committee has condemned plans to raise the Warragamba Dam wall.
The United Nations Environment Scientific and Cultural Organisation (UNESCO) committee has asserted "that any new dam proposals are incompatible with the Greater Blue Mountains World Heritage Area's world heritage status".
The committee decided, at its annual meeting in Azerbaijan today (July 4), that raising the dam wall and intermittently flooding large areas of the Greater Blue Mountains World Heritage Area would "likely impact on its outstanding universal value".
Former NSW Environment Minister Bob Debus, speaking at today's session of the World Heritage Committee meeting, challenged the NSW government to take its environmental responsibilities seriously.
"On the evidence available so far, the NSW government has treated the protection of outstanding universal value in a world heritage area as little more than an irritating afterthought," he told the committee.
"The World Heritage Committee has now moved the issue to centre stage.
"The NSW government's statements so far presume that the population living on the floodplain will be greatly increased.
"It has so far demonstrated very little interest in a rigorous assessment of alternative strategies for flood mitigation, urban planning and water supply, even though strategies clearly exist."
The committee has also placed a caveat on the dam approval, requiring the federal government to submit the environmental impact statement for review before any final approvals are made.
Give A Dam campaigner Harry Burkitt praised UNESCO's decision.
"When a country nominates an area for World Heritage status it undertakes to conserve its 'outstanding universal value' for future generations," he said.
"It is therefore of critical importance that the committee has required a rigorous assessment of environmental effects both above and below the dam wall with the purpose of avoiding any impact on the outstanding universal values of the Greater Blue Mountains World Heritage Area."
This news follows last month's announcement that an inquiry will be launched to examine the many question marks surrounding the proposal to raise the Warragamba Dam wall.
A NSW Upper House select committee has been established to investigate the proposal.
The committee will examine development interests on the western Sydney floodplain as well as the environmental impact that a raised dam wall would have on the Greater Blue Mountains World Heritage Area.
The committee will also work alongside UNESCO to assess the adequacy of the Environmental Impact Assessment process to date.