The efforts to control the invasive weed will continue until mid-December.
The work is part of Toitū Te Whenua Land Information New Zealand’s (Linz) annual Otago Lakes biosecurity programme.
Linz biosecurity manager Tracey Burton said weeding was essential for lake health and lake users’ enjoyment this summer.
“Left uncontrolled, lagarosiphon can take over lakes, choke waterways, smother native aquatic plants and impact how we use our lakes . . . Ultimately we’re hoping to clear lagarosiphon from [Lake Wanaka].’’
In Lake Wānaka, the divers would be checking eradication zones north of Roy’s Peninsula and fixing wear and tear on hessian mats in Parkins and Paddock bays.
Ms Burton said eradication zones were where invasive weeds had been completely cleared.
Divers would focus on removing the odd weed that had come back.
“Divers will control the tall, dense weed around high-use areas, including boat ramps and swimming areas, to prevent it spreading further.”
Over the coming weeks, work would also begin in the Upper Kawarau River.
More control efforts across the lakes take place between February and May 2025.
The work has been funded by Contact Energy, the Otago Regional Council and Queenstown Lakes District Council.
Linz works with several groups, including the Lake Wānaka Lagarosiphon Management Committee and Lake Dunstan Aquatic Weed Management Group, mana whenua and the community to help stop the spread of lagarosiphon.
Lake users could also help prevent lagarosiphon spreading between waterways by checking, cleaning and drying their gear to ensure fragments of lagarosiphon are not caught up in it.
The ‘‘Check, Clean, Dry’’ campaign is led by the Ministry for Primary Industries in partnership with the ORC. — APL
