Win for Lake Wānaka in battle against aquatic weed

Toitū Te Whenua Land Information New Zealand (LINZ) has been leading the work to clear lagarosiphon from the lake, working closely with partner agencies and the community. 

Minister for Land Information Chris Penk announced sustained efforts over the last 20 years has seen lagarosiphon now largely cleared from Paddock Bay, Parkins Bay, Glendhu Bay, and Damper Bay. 

LINZ Biosecurity Manager Tracey Burton says the progress along this 40km of shoreline has enabled a shift of the containment line, which represents the divide between weed-free areas in the lake and areas infested with lagarosiphon. 

The containment line has now moved from the southern end of Bishops Bay to Damper Bay – the first shift since 2013. 

“We’re thrilled to have cleared more of the lake of this problematic weed. If left unchecked, lagarosiphon can form dense weed beds that smother native plants and restrict recreational access."

“This milestone is a promising sign that our vision to one day eradicate lagarosiphon from the lake may well be within reach.” 

Burton credits the use of hessian mats as a “game changer,” particularly in the larger shallow areas like Paddock Bay where lagarosiphon once thrived. 

The hessian mats smother the weed while allowing native plants to grow through and flourish. An inspection by the National Institute of Water and Atmospheric Research (NIWA), now part of Earth Sciences New Zealand, confirmed native plants are successfully re-establishing. 

Burton says community support has also played a vital role. 

“We couldn’t have achieved this without the help of lake users. We’re grateful to the lake users who continue to check, clean and dry their gear to prevent the spread of lagarosiphon.” 

The next goal is to progressively move the containment line further south toward Roys Bay, near the Wānaka township. 

“We look forward to building on this progress this season and the years to come,” says Burton. 

The control work is funded by LINZ, Queenstown Lakes District Council and Otago Regional Council, with support from the Lake Wānaka Aquatic Weed Management Committee. 

For more information on the announcement visit:

Beehive.govt.nz - Tide turns battle against Lake Wānaka weeds 

To find out more about LINZ biosecurity control work visit: 

Biosecurity and biodiversity