Check Clean Dry for the South Island

Stop pests invading our lakes and rivers. Check, clean, dry.

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

For absorbent materials, use one of these treatments and refer to manufacturer’s guide if needed:

Soak in 10% dishwashing solution (1 part dishwashing liquid to 9 parts water) for 10 minutes, or
Soak in or spray with 2% bleach solution (200ml bleach diluted in 10 litres of water) and leave for 1 minute, or
Freeze till solid (overnight).

Find more detailed 'Check Clean Dry' instructions, including videos

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.

Check the North Island 'Check Clean Dry' requirements

Due to the clam incursion in Waikato, there are new 'Check Clean Dry' requirements for the North Island, which are different from the South Island.

'Check Clean Dry' for the North Island

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 – South Island (2.26)

Transcript – show/hide

[The 'Check, Clean, Dry' logo is seen with a spray bottle]

[Ashton Reiser, New Zealand elite sprint kayaker is at a lake and talking to the camera.]

Ashton: Kia ora. Like a lot of New Zealanders, I really enjoy being active in our rivers and lakes.

[Video of Ashton kayaking on the lake. There is hornwort on his paddle.]

Ashton: But we all need to be careful not to take nasty hitchhikers with us if we move to another lake or river. Because invasive weeds and pests like didymo and hornwort can choke our fresh waters.

[Ashton walks around a boat, talking to the camera and showing pieces of weed on the anchor, boat and trailer.]

Ashton: And that's why we need to check, clean, dry. There are a few things to know. Firstly, if you move between waterways, there's a risk of spread. Secondly, some parts of your gear are more risky than others. Like places on your trailer where weed can snag.

And remember to check your anchor and any places where water can pool and keep unwanted organisms alive.

Let's go through the 3 steps of check, clean, dry.

[The 'Check, Clean, Dry' logo appears with a spray bottle. The word "Check" is highlighted.]

[Ashton is seen looking over the boat and all its gear, including the anchor and chain, propeller, and tow hook-up, and picking any plant material he finds. He leaves them on the bank and puts some in a rubbish bin.]

Ashton: Check your gear and take off any bits of weed you can see.

Leave it on the bank or put it in a rubbish bin. Never wash weeds down the drain.

[The 'Check, Clean, Dry' logo appears with a spray bottle. The word "Clean" is highlighted.]

[Ashton is sitting on the grass with a plastic bin of water and a bottle of dish detergent. He is using a measuring cup to put detergent into the water.]

[Message on the screen: For things you can’t see, use 10% dishwashing liquid with water.]

Ashton: Clean any gear that's been in contact with lake or river water using a cleaning mix. That will kill algae like didymo or lake snow. Most people use a mix of 10% dishwashing liquid with water. But you could use 2% bleach or hot water.

[A lifejacket is shown being submerged in the bucket of sudsy water. Then a hand switches on a water tap.]

Ashton: Using water alone doesn't kill these weeds and pests. In fact, it keeps them alive longer. Leave for 10 minutes before rinsing with tap water.

[Ashton sprays cleaning mix all around the boat, like the engine turbine, anchor rope and carpet areas.]

Ashton: Be strategic. Spray the areas that could remain damp or wet.

Include gear that's made of absorbent materials like the anchor rope or carpeted areas.

When you tow your boat, the outside of the house should dry. So you don't need to clean that.

[The 'Check, Clean, Dry' logo appears with a spray bottle. The word "Dry" is highlighted.]

[Ashton walks around the boat. On screen is an image of didymo on a fishing rod. Different parts of the boat are shown dry]

Ashton: It's best if your boat and gear are completely dry before you go into another river or lake. Didymo for example, can survive for a month on damp gear. Drying completely is an acceptable alternative to cleaning with detergent.

That's it for powerboats. And these principles apply to all water activities. This is how we protect our rivers and lakes from freshwater invaders for generations to come. So, are you in?

[The truck drives aways towing the boat.]

[Message on the screen: Helps protect your lakes and rivers]

[The Check, Clean, Dry logo appears, and an acknowledgement to Ashton Reiser and NIWA. The logos for Biosecurity New Zealand and Ko Tātou/This Is Us appear at the bottom of the screen.]