"It has always been a safe spot to swim but I think jetskis are becoming more popular and people are becoming less aware of the boating rules they need to follow to ensure the safety of people swimming in the area."
Whanganui District Council senior parks officer Wendy Bainbridge said the council had no jurisdiction over the rules on the water but encouraged users of Lake Wiritoa to adhere to Maritime New Zealand guidelines.
Under Maritime NZ's "rules on the water" boats and jetskis must not exceed a speed of five knots (a fast walking speed) if it's within 200m of the shore, within 200m of a boat displaying a diver's flag, within 50m of any other boat, within 50m of a person swimming or on a power boat if any person has any part of their body outside the rails or edge of the deck.
Maritime NZ states on its website that to operate any water craft capable of exceeding 10 knots, drivers must be over 15 years old.
"Even though no licence is required to operate a pleasure boat in New Zealand, ignorance of any maritime rules or regional bylaws is not accepted as an excuse. Failure to comply can lead to instant fines or prosecution," the website states.
Dr Robinson said she felt it was a safety issue that was being ignored and needed addressing.
"Jetskiers out there were being incredibly thoughtless and unaware of the power of their boats and the dangers they could cause."
She said she approached the jetskiers who were causing havoc and had people come up to her afterwards saying "good job".
"I think a lot of people picnicking on the shore with kids swimming in the lake were getting a bit fed up."
Dr Robinson said there needed to be updated signage in visible areas and someone needed to take responsibility for regulating the drivers who weren't following the rules.
Ms Bainbridge said they had signage reminding people about the regulations at the Wanganui Water Ski clubhouse and toilets in the passive area.
"We are happy with the signage at present and have not received any other complaints about jetskis or boat users at Lake Wiritoa in the last year," Ms Bainbridge said.
A Maritime NZ spokeswoman said members of the public could report dangerous driving on the water and an accident that may occur to the Maritime NZ online incident reporting system.
The spokeswoman said it was an offence for the skipper on the boat involved not to report an accident within 48 hours to Maritime NZ.
To visit the online incident reporting page follow: https://www.maritimenz.govt.nz/report-online/
