The Harbourmaster is describing rule breaking on the Clive River this summer as appalling.
Martin Moore said he was made aware of six incidents on the river last week, where people were misbehaving and flouting the rules.
"The behaviour in this early part of summer has been appalling.
"Last week, on the Wednesday evening there was three boats out their misbehaving, on Thursday there was a boat out misbehaving, and on Friday as well, and I went down to the river on Saturday morning to meet with a stand-up paddleboarder who had some issues with a jet ski.
"That's six incidents on the Clive River last week."
Power craft are not allowed to move faster than five knots on the Clive River after 5pm on Monday and Wednesdays, and after 8pm on other days of the week.
At other times, power craft are not allowed to travel faster than five knots when they are within 50m of another water user, a rule which extends to all waterways in New Zealand.
Moore said he would close off the boat ramp if the behaviour continued.
"It's highly likely we'll look at putting a gate on the ramp."
He said most of the rule breaking was happening at high tide.
"There's not a great deal of water in the Clive River, and so guys are flouting the time frame to work in with the tides."
Jim Edwards, who along with his wife Marie, runs educational waka tours on Clive River, says the river is getting busier and it is only a matter of time before someone gets hurt.
He said power craft are meant to stay in the lower part of the river below the bridge, unless they are a support boat, and recently he had to talk to a jet ski owner for breaking that rule.
"The waka ama had a double hull waka ama strapped together with a whole lot of children on board, and I was concerned because the jet ski was coming through the bridge and boating around them."
He said current signs use too much boating jargon, and needed to be written in plain English so the general public can understand them.
"People don't know what it means."
As well as obeying the rules on the Clive River, Moore wanted to remind people to be safe on the water throughout summer.
He said boaties needed to have two forms of waterproof communication on board at all times, for example a VHF radio and a cellphone in a plastic bag.
"If you can't be heard you can't be rescued."
He said he would be out on the water doing regular, random compliance checks throughout the summer.