Lake Wānaka weed clearance starts tomorrow

Around four rugby fields worth of hessian mats will be laid on the floor of Lake Wānaka to help eradicate lagarosiphon from the lake.    

The work is led by Toitū Te Whenua Land Information (LINZ) as part of its annual biosecurity control programme.

LINZ Biosecurity Manager Tracey Burton says starting tomorrow (February 27), divers will be in the lake over the next two months working hard to build on progress made over the past 20 years to clear lagarosiphon from the lake’s shoreline.

“The initial focus of divers will be monitoring the weed-free part of the lake and hand weeding any isolated plants.  

“They will then turn their attention to controlling the weed outside of the weed-free area, working their way away from the western side of the lake towards Roys Bay, near the township.  

“In this part of the lake, divers will install around 4.5 hectares of hessian mats to smother the weed.” 

Burton says it’s essential to control lagarosiphon as it can take over and choke waterways, smother native plants and impact how we use our lakes.  

She says the ultimate goal continues to be eradicating lagarosiphon from the lake.  

“We’ve made good progress over the last few years, and we’re excited to see what impact we can make this season. 

“We’re hopeful these efforts will enable us to clear the weed from more parts of the lake and enable us to move the containment line further towards the township as we push to progressively clear the lake.” 

The containment line represents the divide between weed-free areas in the lake and areas infested with lagarosiphon. It currently stretches from the southern point of the peninsula to the southern point of Bishops Bay.  

Burton says the goal this season is to move the containment line further south to include Paddock Bay, Parkins Bay and Glendhu Bay in the weed-free areas.  

“Little by little we’re pushing the containment line out and we’re hopeful we can do that again with these continued efforts.” 

She says the community have also contributed to the success of containing the weed through checking, cleaning and drying their gear to prevent it spreading.  

The control work will be carried out by LINZ biosecurity delivery partner Boffa Miskell Limited and is partly funded by Queenstown Lakes District Council.

Lake users are asked to please be aware of the dive flags and to avoid the area, if possible.   

To find out more about LINZ biosecurity control work, including current and upcoming lake weed control work, visit: Biosecurity and biodiversity