The remains of a body have been found in Handois Reservoir, St Lawrence, close to where Adrian Lynch went missing.
Jersey Police say his family have been informed, but formal identification is 'likely to take some time'.
A call was received at 10:40 am from a worker at the reservoir, who reported finding the remains of a body partly submerged in the water.
Adrian was last seen on CCTV at the Thistlegrove site, near Bon Air Stables in St Lawrence in December 2015.
That's around 100 metres away from the reservoir, using a possible route via La Rue de la Scelleterie and Le Hucquet.
Police and Crime Scene Investigation are currently at the scene and the public are being asked to stay away from the area.
The reservoir is in the 'high priority' search area, shown in a map issued by police in May.
20-year-old Adrian disappeared after attending a work Christmas party, in the early hours of Saturday 5th December 2015.
Police wound up the investigation in February after investigating all enquiries.
The father of Adrian Lynch has said his family can finally move forward, after the inquest into his death was closed.
The service began at 2:30pm this afternoon at the Methodist Centre in town.
Family and friends will gather in St Helier today, for a memorial service for Adrian Lynch.