Work to tackle an invasive aquatic weed is underway in Lake Dunstan and Lake Wānaka before an influx of visitors this summer.

The efforts to manage lagarosiphon are part of an annual Otago lakes biosecurity programme led by Toitū Te Whenua Land Information New Zealand (LINZ).

Over the coming days divers will be removing the weed by hand in the upper Kawarau River to help prevent downstream infestations into Lake Dunstan and protect Lake Wakatipu, LINZ said in a statement to media.

Control measures were recently undertaken in Lake Wānaka, where biodegradable hessian matting is also being used to manage the weed.

Control works in Lake Dunstan and Lake Wānaka are set to continue in early 2023.

LINZ biosecurity and biodiversity manager Tracey Burton said this work will help reduce the impact of the weed on native plants, lake users, and prevent it spreading.

She said all lake users have a role to play in helping protect our lakes from lagarosiphon.

“This weed spreads very easily – just a tiny fragment caught on a boat motor or a waterski can transfer it from one lake or river to another.

“If you are heading out on the water, please check, clean, and dry all your gear– especially if you’re moving between waterways.”

The Check, Clean, Dry campaign is led by the Ministry for Primary Industries in partnership locally with Otago Regional Council. It is aimed at engaging visitors and communities to help prevent the spread of aquatic pest species.

Find out more about LINZ’s biosecurity control work, including current and upcoming lake weed control work here.