Work to prevent the spread of lakeweed from Lake Benmore, into nearby lakes that support our hydroelectric power generation, is due to get underway mid next week.
The control efforts to manage lagarosiphon at the popular Canterbury lake are part of Toitū Te Whenua Land Information New Zealand’s (LINZ) annual biosecurity programme.
Left uncontrolled, lagarosiphon can take over lakes, choke waterways, smother native aquatic plants, interfere with hydroelectric power generation and recreational activities like boating and fishing.

A helicopter undertaking herbicide control at Lake Benmore, where control of lagarosiphon is due to get underway next week. Image credit: Boffa Miskell
LINZ Biosecurity Manager Tracey Burton says divers will survey the lakebed and use a range of methods to control the weed, including hessian mats, hand weeding and herbicides.
“This work is essential to maintain the health of the lake and will also help prevent further spread of lagarosiphon to weed free areas within Lake Benmore and into Lakes Aviemore and Waitaki, which are both part of the Waitaki hydro scheme.
“Lake Waitaki is currently free of the weed and there is a limited amount in Lake Aviemore, and we want to keep it that way.
“It’s important these hydro lakes – which generate enough electricity each year for around 830,000 average New Zealand homes – are kept free from lagarosiphon as it can block intake screens and potentially affect power generation.”
Burton says lake users can also play a part in helping stop the spread of aquatic weeds by checking, cleaning and drying all gear.
“While parts of Lake Benmore are already affected by lagarosiphon, we also need to protect it from other freshwater pests, such as hornwort, New Zealand’s worst submerged weed, and other pests like the gold clam currently only in the North Island”.
The work is expected to take around a month and is expected to be completed by mid-March.
The control work is being carried out by LINZ biosecurity delivery partner Boffa Miskell Limited.
This work is funded by LINZ, Meridian Energy and Environment Canterbury.
To find out more about LINZ biosecurity control work, including current and upcoming lake weed control work, visit: Biosecurity and biodiversity
Media contact
Email: media@linz.govt.nz