Emergency services were called to the Murray River near Perricoota Road, Moama, following reports a man had been seriously injured while skiing on the water at 10am on Sunday.
Victoria Ambulance paramedics found the man who had died at the scene.
He is yet to be identified.
NSW Police will investigate the circumstances surrounding the incident and are expected to speak to the media on Sunday afternoon.
The Southern 80 water ski race is held from February 9 to 11 and takes place on the Murray River from Torrumbarry to Echuca, where there are more than 120 bends in the river.
On Sunday it posted on social media that the race had been cancelled "due to an incident".
Earlier, ambulance officers were called to the same event to treat a man in his 40s with leg injuries. He was taken to Echuca Hospital in a stable condition.
The race attracts entries from all over Australia, plus international competitors from New Zealand, Great Britain and the US, according to the event's website.
In 2017, NSW driver David Morabito, 50, was pulled unconscious from the river and died after the ski boat he was driving flipped during the high-speed race.
In 2010, a 41-year-old Melbourne man died after he and another skiier crashed during the event.
In 2006, a 38-year-old man from NSW was being towed tandem at high speed behind a boat while practising for the event on February 11 when he fell and suffered fatal head injuries.
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