Fight against weed paying off: Linz

Land Information New Zealand has spent millions clearing lagarosiphon from Lake Wānaka. PHOTO:...
Land Information New Zealand has spent millions clearing lagarosiphon from Lake Wānaka. PHOTO: SUPPLIED
More than $14 million has been spent by the Crown in the past 10 years clearing lagarosiphon from Lake Wānaka.

Toitu Te Whenua Land Information New Zealand (Linz) said in a release last month that 20 years of dedicated effort and community support is finally paying off in the fight to clear Lake Wānaka of the invasive weed.

Lagarosiphon is one of New Zealand’s worst submerged weeds and was first recorded in Lake Wānaka in the 1970s. It can form tall, dense surface-reaching weed beds that can interfere with recreational activities and smother native plants.

This autumn, the management committee’s control programme was on track to remove weed beds remaining in the western part of the lake, which stretches along more than 13km of shoreline. This would allow the containment line to be moved further south to include the Paddock and Parkins Bays area, a long-awaited milestone.

Lagarosiphon was introduced to New Zealand as an aquarium plant, but it has spread rapidly throughout the country’s waterways.

In answer to questions, Linz said it was updating the lagarosiphon management plan for the lake to outline the process to date and refresh goals for the next 10 years.

Linz said over the past 10 years it had spent more than $14 million removing the weed and monitoring progress in Lake Wānaka.

The government agency said despite all that money spent there was a chance it could come back.

Linz biosecurity manager Tracey Burton said there was every chance it could reinfest cleared areas.

"The community is our best defence against this", she said.

"When moving between water bodies it is incredibly important people stop to check, clean and dry their gear. Users who do this play a major role in reducing the spread of lagarosiphon."

Clearing the lake of the weed was the ultimate goal of agencies of the Lake Wānaka Lagarosiphon Management Committee led by Linz.

— Staff reporter