Work will continue across several of Otago’s lakes as part of a spring effort to clean up and protect the region’s waterways.
Divers will be monitoring and hand-weeding over the coming weeks, they will focus on Frankton Marina as part of a wider programme.
The control efforts are part of Toitū Te Whenua Land Information New Zealand’s (Linz) annual Otago Lakes biosecurity programme.
Linz Biosecurity Manager Tracey Burton said controlling lagarosiphon was vital to prevent its spread and protect Otago’s lakes.
"We’re proud to have helped keep Lake Wakatipu largely free of lagarosiphon, and we’re committed to keeping it that way.
"If lagarosiphon were to establish in Lake Wakatipu it would be extremely difficult to remove and could have significant environmental, economic and recreational impacts."
She said one of the biggest risks of spreading the weed into the lake was boats travelling from the Kawarau River.
"We ask boat users to do their bit by turning off their engines at the checkpoint just below the Kawarau Falls Bridge. This simple action helps dislodge any weed fragments and prevent them from entering the lake."
Lagarosiphon can quickly dominate freshwater ecosystems, choking waterways, smothering native aquatic plants and impacting recreational use.
The work at Lake Wakatipu is expected to take a couple of weeks.
Next, divers will begin at Lake Wānaka in mid-October, to check eradication zones, hand-remove any newly established weeds, repair hessian matting and carry out control in high-use areas.
Control works will also take place at Lake Dunstan from mid-November and Kawarau River in late November.
Further control efforts will take place across the lakes between February and May 2026.
Linz is working in partnership with community groups, and organisations including Contact Energy, Otago Regional Council and Queenstown Lakes District Council, who provide additional funding support for this vital work.
Ms Burton said lake users also played a crucial role in protecting our lakes by following the "Check, Clean, Dry" steps — especially when moving between waterways.
The "Check, Clean, Dry" campaign is led by the Ministry for Primary Industries in partnership locally with Otago Regional Council.
These efforts in Otago are part of Linz wider aquatic weed control programme, which also involves work at key lakes in South Canterbury and Waikato.
