A MAN remains in the Royal Adelaide Hospital after he crashed a home made billy cart while trespassing on the spillway of the South Para Reservoir near Williamstown.

Just after 5pm, three men aged between 32 and 44 years-old, illegally trespassed into the South Para Reservoir taking in turns riding a homemade billy cart down on the steep embankment of the spillway, when it crashed at high speed seriously injuring a 44 year-old who was driving.

Police and emergency services responded and a 44-year-old man who had serious abrasions and head injuries was flown from the base of the spillway to the Royal Adelaide Hospital.

His condition is not life threatening.

Williamstown Police seized the billy cart which will be destroyed while all three men will also receive an ‘on the spot’ fine for more than $300 for trespassing.