People using the Rotorua lakes are being asked to check their boats and gear are clean with trout fishing season getting underway.
Lake Tikitapu, Rotorua Photo: Public Domain
The biosecurity manager for Te Arawa Lakes Trust, William Anaru, said with 14 lakes it was easy for people to hop between them.
Biosecurity manager for Te Arawa Lakes Trust William Anaru (left). Photo: Supplied / Te Arawa Lakes Trust
But that could spread weeds and other pests that are in some lakes but not others.
"We're just trying to do whatever we can to stop the movement of those aquatic pests from lake to lake because they are a huge problem," Anaru said.
"Only a small piece of weed is enough to create a huge problem in our waters."
Anaru said the health of the lakes had been steadily improving after years of effort, but it wouldn't take much to undo the progress.
"Many people might remember down at the Rotorua lakefront it was almost like a landmass of weed when I was a kid, you could just about walk to Mokoia Island on this weed," Anaru said. "It smells real bad too.
"There's a lot more work getting rid of a pest than stopping it."
Anaru said the trust's 19 biosecurity officers - Hunga Tiaki, who are warranted under the Biosecurity Act - will be monitoring boat ramps this weekend and over summer.
But he was asking for help.
"Have a look around, check the anchor wells, check all the ropes, check your bung, empty any water that's come out of one lake and empty it before you leave, and things like that."