Freshwater weeds
Freshwater weeds threaten New Zealand's lakes, rivers, streams and wetlands and the plants and animals that live in them. We must prevent their arrival and establishment in our waterways, as eradication can often be expensive to undertake and impossible to achieve.
Reed sweet grass
How do freshwater weeds affect you?
- Unattractive aesthetic impact - infestations can ruin the aesthetic appeal of lakes, rivers and wetlands.
- Diminished recreational opportunities - swimming, boating, fishing and other recreational activities can be restricted.
- Loss of native biodiversity - introduced freshwater weeds can compete with native plants and animals, modifying their habitat and reducing food sources.
Freshwater weeds can also have adverse economic impacts:
- Clog hydro-electric dams.
- Restrict irrigation.
- Clog drains, which can cause flooding and erosion.
- Reduce suitable habitat for native fish, such as eel and whitebait.
Are you transporting freshwater weeds?
Didymo
People often accidentally spread freshwater weeds. Weed fragments can get caught on boats, trailers, water skis and fishing equipment, allowing them to be transported from one waterway to another.
In damp conditions freshwater weeds can survive out of water for long periods. Therefore they can be spread even if you do not use your equipment regularly.
It is important to remember that a small weed fragment can be enough to start a new infestation in a waterway.
Clean, Check, Dry to help prevent the
spread of didymo and other freshwater
pests
Leave it where you found it!
It only takes a few minutes to help prevent the spread of freshwater weeds.
Leave all fragments of waterweed where you found them or dispose of them in the rubbish.
How you can help
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Drainage and machinery contractors - ensure any weed is removed from machinery before moving to other water-bodies and waterways.
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Fishermen and eelers - remove all fragments of weed from nets, fishing equipment and waders before you leave the area. Salt bath and/or bleach fishing nets.
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Boat operators - check boats, motors, trailers and anchor lockers for tag-along weeds immediately on removal of equipment from the water.
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Aquarium owners - don't dispose of aquarium contents into or near a waterway.
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Duck shooters - check dogs, boots and boats for weed before you leave the area.
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Landowners - don't allow drainage equipment, eel nets or boats into water bodies on your property unless they are free of weeds.
What to do if you see an unusual freshwater plant
Note the location and take a sample if possible. Inform your local DOC office or your Regional Council Pest Plants Officer as soon as possible.
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