Check, Clean, Dry
Hornwort is a highly invasive freshwater pest plant. Photo credit: Bay Of Plenty Regional Council
Preventing the spread of freshwater aquatic pests
Here in Southland we’re lucky to have plenty of lakes and rivers to enjoy for recreational purposes and it’s important we look after them. You can spread freshwater pests, like didymo and lagarosiphon, through your activities in and around waterways. If you’ve been in a lake, river, stream or wetland and plan to move to another within 48 hours, you must clean all your gear that has been wet using the ‘Clean, Check, Dry’ method.
While didymo impacts parts of Southland, it hasn’t spread everywhere so it’s important to Clean, Check, Dry to keep it this way.
There are many aquatic pests and weeds that could threaten Southland’s freshwater systems. To learn more about those head to the Southland Pest Hub.
The 'Check, Clean, Dry' method
To prevent the spread of invasive freshwater pests (like didymo), whenever you move between waterways you must check, clean, and dry all your gear that comes into contact with water. If you don't want to treat your gear, make sure you only use it in one waterway.
Check
Remove any plant matter from your gear and leave it at the site (the river or lake bank), or put it in the rubbish. Don't wash plant material down any drain.
Clean
Use 10% dishwashing detergent mixed with water and leave the item wet for 10 minutes.
The rule of thumb for 10% detergent mix is:
- for a 250ml (small) spray bottle, put in 1 and half tablespoons
- for a 500ml (large) spray bottle, put in 3 tablespoons
- for a 10-litre bucket, put in 1 litre of detergent.
There are a few other cleaning options that might work better for you.
Option | Amount | Treatment time |
Dishwashing detergent or nappy cleaner | 10% mix | Soak or spray all surfaces and leave wet for at least 10 minutes |
Bleach | 2% mix (200mls diluted to litres in water) | Soak or spray all surfaces for at least 1 minute |
Hot water | Above 60°C Above 45°C | Soak for at least 1 minute Soak for at least 20 minutes |
Freezing | Until solid |
Cleaning large volumes of gear
If you have large amounts of gear (for example if you have a fishing or diving business), you can find other suitable options in Appendix 3 of Check, Clean, Dry: Information for sporting event organisers.
'Check, Clean, Dry' for sporting event organisers [PDF, 2.6 MB]
Make sure you:
- follow the manufacturer's safety instructions for any cleaning products
- choose a method that won't damage your gear
- check the cleaning mix has penetrated right through the item before you soak it for the recommended time
- check our cleaning instructions for specific items – some have different cleaning requirements.
Dry
Ensure your gear is completely dry to touch, inside and out, then leave dry for at least another 48 hours before you use it (didymo can survive for months on moist gear).
Treatment by drying
Drying can be used as stand-alone treatment for non-absorbent items if you take great care to:
- make sure gear is completely dry to touch, inside and out
- leave dry for at least another 48 hours (after drying), before entering a different waterway.
Southland Pest Hub
More more information on freshwater pests in Southland and how to identify them check out the Southland Pest Hub.
Legal requirement to clean gear
The South Island is a Controlled Area for the invasive freshwater algae didymo (also known as rock snot), which was first detected there in 2004. This makes it a legal requirement to clean all gear used in the water before going from one South Island waterway to another. So far, no didymo has been found in the North Island.
Under the Biosecurity Act (1993) there is a requirement not to spread invasive freshwater weeds and pests anywhere in New Zealand.
