Durham Constabulary along with fire and ambulance crews were called to an incident on the riverbank in Durham City near to Knightsgate Bridge at 8.25am today.
Early indications are that a 69-year-old suffered a medical condition and fell down the bank and into the water.
An eye witness has told Police Hour that the elderly man fell from his bike after suffering what she believes was a heart attack.
Having fallen down the hill he fell into the water and was given CPR within seconds of entering the water.
Members of the public and three medical students assisted at the scene until paramedics arrived.
He was taken to hospital in a serious condition but sadly pronounced dead a short time later.