How to 'Check Clean Dry' when you move
Follow these steps when you move between lakes and rivers.
Check – for what is visible
Remove any plant matter, mud or visible clams from your gear and leave it at the river or lake bank, or put it in the rubbish.
Drain all river or lake water from your boat and gear.
Clean – for what is not visible
Blast your gear and craft with tap water onto grass, not into a stormwater system or drain.
For absorbent materials, use one of these treatments and refer to manufacturer’s instructions if needed:
- Soak in hot tap water (50°C to 55°C) for at least 5 minutes, or
- Soak in 5% bleach solution (5-litre mix = 250ml bleach in 4.75 litres water) for an hour, or
- Freeze till solid (overnight), or
- Soak in salt solution at 100ppt (parts per thousand) (5-litre mix = 500g salt in 5 litres warm water) for 4 hours.
Dry – to be sure
- Gear: allow gear to dry to touch, inside and out, then leave it to dry for at least 48 hours (2 days) before using again.
- Watercraft: dry areas inside the watercraft where water has pooled, for example with an old towel, and then leave the craft to dry for at least 48 hours (2 days). The hull of a watercraft will dry when towed.
These 'Check Clean Dry' steps will also help stop the spread of other freshwater pest species.
Find more detailed 'Check Clean Dry' instructions, including videos
'Check Clean Dry' for the South Island
The current invasive species risks in the South Island differ from the North Island, so a different set of 'Check Clean Dry' requirements applies.
Information about the invasive clams
Non-native invasive clams were found in a stretch of the Waikato River in 2023 and in a man-made lagoon near Taupō in 2024. For details about what we're doing, the rules in force, and how you can help prevent them spreading visit the invasive clams web page.
Exotic invasive clams (Corbicula)
Video: How to ‘Check Clean Dry’ your boat and gear – North Island (2.36)
Transcript – show/hide
[Footage of champion rower Mahé Drysdale, spraying a boat with water from a hose next to a lake.]
[Mahé talks to the camera, and we see images of his past success and video of his family paddling.]
"Kia ora. Like many New Zealanders, as a family, we really enjoy being active in our lakes and rivers."
[A car is seen towing a boat up the slipway, followed by footage of a boat on a river or lake.]
"But we all need to be careful not to take a nasty hitchhiker with us if we move to another lake or river.
"Because weeds and pests like didymo, hornwort, and the invasive clam can choke our fresh waters.
[Images of didymo, hornwort, and freshwater clams are shown.]
[Mahé is seen standing by a boat.]
"The rules have changed, so let's make sure you're up-to-date. Here are the three steps of Check, Clean, Dry."
[Mahé is shown, checking under and around a boat.]
"Check, for what's visible."
[Mahé removes weed from the boat.]
"Check your boat and gear and take off any weed or other matter that you may see."
[Mahé throws weed on the bank and puts weed into a bin.]
"Leave it on the bank or put it in the rubbish bin. Never wash it down a drain."
[Footage of a life jacket with weed on it, footage of an anchor with weed.]
"Remember to check your life jackets, your anchor, and any rope that's been in the water."
[Mahé checks under the bow of the boat and on the trailer]
"Get down and look under your boat and trailer too."
[Mahé drains water from the boat and pulls out a bung on the boat]
"Drain all water and remember to pull out all bungs from around your craft.
[Mahé faces the camera and then walks beside the boat and faces the camera again]
"Clean, for what's not visible. This is for all the things that are too small to see. Like fish eggs, tiny clams, or algae. Just because you can't see them doesn't mean they're not there.
[Footage of Mahé spraying the side of a boat with a hose.]
"How to clean. First, give all your craft and gear a good blast. Use tap water and don't let it run into a stormwater drain. Wash out places where things can get stuck."
[Footage of Mahé soaking a life jacket.]
"Next, use a treatment to clean gear made of absorbent materials like life jackets. You have three main treatment options."
[Details of the hot water treatment are visible on the left of the screen.]
"The most effective is very hot water."
[Detail of the bleach treatment are shown on the left of the screen]
"Or you could soak it in water with household bleach."
[Details of the freeze option are shown on the left of the screen]
"Or the third option is to freeze the item until solid, which is usually overnight."
[Picture of a boat and the word "Dry" is shown on the right of the screen.]
"Dry, to be sure."
[Footage of Mahé leaning on a boat at a river or lake.]
"And finally, any moisture helps these weeds and pests survive. So it's important you let everything dry."
[The camera zooms in to show different parts of a boat.]
"Firstly, make sure your craft and gear is completely dry to touch, inside and out. If you tow your boat for 20 kilometres on a hot day, the hull will dry."
[Footage of Mahé walking towards a boat.]
"But you may need to dry out pooled areas inside the craft with an old towel."
[Footage of a hand using a towel to dry the inside of a boat.]
"And then, leave everything to dry for at least another two full days before you use it again."
[Footage of Mahé walking towards and around a boat.]
"So those are the basics for boats. And the principle is the same for any craft or gear that you may use. That's how we protect our lakes and rivers from these freshwater invaders for generations to come.
[Mahé looks at the camera.]
"So, are you in?"
[Footage of a boat pulling up the slip way and hill with a 'Check Clean Dry' propeller protector.]
[The words 'Check Clean Dry' are shown on screen.]
[End of transcript]
