Diver inspecting hessian matting in Lake Wanaka. Photo credit: NIWA
We manage many lakebeds on behalf of the Crown, including Lake Karāpiro in the Waikato, the Waitaki Lakes in Canterbury, and Lakes Wānaka, Whakatipu and Dunstan in Otago. LINZ also funds aquatic weed control in the Rotorua Te Arawa Lakes.
Invasive submerged weeds pose a significant threat to our lakes. The worst three established aquatic weeds are Lagarosiphon major, Egeria densa and Ceratophyllum demersum.
Lagarosiphon is established in most North Island lakes and occurs in scattered dense populations in parts of the South Island. LINZ carries out control work in the Waitaki Lakes in Canterbury as well as Lakes Wānaka and Dunstan and the Kawarau River in Otago.
Egeria is widespread in the North Island and in Marlborough but occurs only in a small number of locations elsewhere in the South Island.
Hornwort is widespread and well established across the North Island, while the entire South Island operates an exclusion programme to prevent its establishment.
These invasive weeds can form dense surface-reaching weed beds that smother native plants, restrict recreational activities such as swimming, boating and fishing, and interfere with hydro-electric generation.
To guide and coordinate control efforts, our work is directed by individual lakeweed management plans. These plans outline our strategy for each of the lakes we manage and detail the control methods used.
Lakeweed management plans
News stories about our work
- Endurance and innovation: Fighting lagarosiphon in Lake Wānaka | Boffa Miskell
- Benthic barriers: the missing tool for aquatic weed eradication | Boffa Miskell
What you can do to help our lakes
Get to know your enemy – Freshwater pest species | Earth Sciences New Zealand | NIWA
Help stop the spread: Check, Clean, Dry
If you’re moving boats or gear between waterways, please remember to Check, Clean and Dry your gear to prevent the spread of aquatic pests.
- Check: Remove any plant material from your gear and leave it at the site (the river or lake bank) or put it in the rubbish.
- Clean: Thoroughly clean all gear (as per the MPI guidelines) before moving between waterways.
- Dry: Ensure your gear is completely dry to touch, inside and out, then leave it dry for at least another 48 hours before you use it.
Find out more on the Ministry for Primary Industries website.