One man is dead and a man and a woman are suffering hypothermia after more than five hours in the water after their boat capsized on Warragamba Dam, west of Sydney. The boat was being used by Sydney Water to conduct a routine water sampling operation, a Sydney Water spokesman said.
The agency is waiting for police to confirm exactly how many of its officers are involved.
Other agencies working on the dam sometimes take part in the sampling runs, the spokesman said.
The area is closed to the public.
The trio had been in the water since the boat capsized about 10.30am today, a spokesman for the NRMA CareFlight helicopter said.
A man had died, and a man and a woman would be airlifted from the banks of the dam to a nearby park for transport to Nepean Hospital by road ambulance.
A New South Wales Ambulance spokesman also said one man had died and that the trio had been in the water for a long time.
The trio was located by the NRMA CareFlight helicopter about 4pm after they were called to search the dam.