A boat driver has been convicted of the dangerous use of a vessel over two ski biscuit incidents at Lake Karapiro in Waikato.
A rider being towed by Daniel Willis in January 2012 narrowly missed a protruding branch in an inlet where power-driven vessels are prohibited.
Soon after, a woman rider he was towing, well in excess of the 5km/h speed limit, hit a pillar under the Horahora bridge seriously injuring her left ankle.
At the Tauranga District Court, a judge fined Willis $1000 and ordered him to pay the injured rider reparation of $2350.
The 22-year-old was also fined $500 for failing to report the matter to Maritime New Zealand.
Waikato Regional Council navigation safety manager Nicole Botherway says his behaviour could have easily have resulted in a fatality.
"We encourage people to have fun on the water - but putting people at this kind of risk is unacceptable."
Ms Botherway says a many vessel incidents are under-reported, but the council needs to know about them.