Jewel-coloured geothermal lakes near Taupo, which have dropped dramatically in the past six months, will not regenerate.
Most of the alum lakes, a cluster of brilliant blue, green and red lakes surrounded by the Wairakei geothermal field, have dropped at least 2m in the past four months and6m since 1997, according to measurements taken by the Institute of Geothermal and Nuclear Sciences.
Scientists believe the falling water level may be a delayed reaction to drops in underground pressure 30 or 40 years ago.
The lakes are unlikely to refill, says geophysicist Chris Bromley. They are visibly shallower and greener, falling victim to algae that has clouded the water.
The effect of a recent geothermal eruption makes the area even less visually appealing.
The blast last week killed pine trees surrounding the lakes and sprayed mud over a large area.
Meanwhile, Ngati Tuwharetoa and the Department of Conservation are still hoping to preserve what is a rapidly disappearing resource.
A spokesman for the tribe said they were "very concerned" by the water loss and found it hard to believe that Contact Energy's nearby bore field, where steam is extracted for energy, did not play a role.
But the two lakes closest to the bore field have been least affected by the water loss.
The northernmost alum lake has not dropped since scientists last measured it in November, and the nearby red lake, known as the "Claret Cup," has lost only half a metre in that time.
Mr Bromley said Contact's activities in the bore field had not changed significantly in the past five years and it was unlikely they had any impact on the lakes.
In the 1970s and 80s, the institute measured a 30m drop in the Wairakei geothermal field's water table.
When scientists first saw declines in the alum lakes two years ago they thought it was related, said Mr Bromley. But the historic water loss did not explain the speed with which water was seeping away today.
