Lagarosiphon is a pest plant present in some of Otago's waterways. It can choke waterways, and impact on recreational activities in lakes and rivers.


It was sold as an aquarium or ornamental pond plant and is thought to have been accidentally introduced to our waterways through disposal into drains and ponds.

Lagarosiphon spreads rapidly, displacing native plants and makes swimming and other water-based leisure activities less pleasant. It can grow up to 4 metres in length, choking and blocking our lakes and rivers.

It's found in lakes Wanaka, Dunstan and Roxburgh, and parts of the Clutha River and Kawarau River and is important to keep it out of Lake Wakatipu.

Management and control 

Together with other stakeholders, we are working to curb the spread of lagarosiphon and have removed many tonnes since it was first spotted in our waterways in the early 1970s. 

You can help stop it spreading further by making sure you leave the weed behind. 

Always check your:

  • fishing gear
  • propeller
  • anchor
  • trailer

View the Ten Year Lagarosiphon Management Plan for Lake Wanaka.

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