To keep our waterways clean and free of pest species, we work closely with Ministry for Primary IndustriesFish and GameDOC and Horizons Regional Council.

Freshwater pest species

Originally, the "Check, Clean Dry" method was created to prevent the spread of didymo, or "rock snot" from waterway to waterway. Didymo is not currently present in waterways in the Wellington region, but can spread via a single drop of water, so it is crucial that we keep our waterways free of it.

Using the Check, Clean, Dry method can also help to control the spread of other known pest species such as hornwort, parrot's feather and koi carp. Freshwater pest species are damaging to our freshwater ecosystems because they:

  • Block waterways
  • Reduce native plant and fish populations
  • Prevent recreational activities
  • Are extremely difficult, sometimes impossible, to eradicate once established.

Koi carp pose the highest ecological risk of all pest fish in New Zealand, and they are here in our region.

Aquatic pest plants like parrot's feather are spread between waterways by human activity and lead to sediment build up that can cause flooding.

These pests can only be spread from waterway to waterway by human activity. Once they are established, they can be impossible to remove, so it is our responsibility to make sure we prevent this from happening. If you don't want to clean your gear between every waterway, every time, you will need to limit your activity to one waterway.

The Check, Clean, Dry method

The Check, Clean Dry method is the most effective way of preventing freshwater pests from spreading between waterways and is recommended across New Zealand by the Ministry for Primary Industries (MPI). The method includes:

  • Checking and removing plant matter from your gear and disposing of it either by leaving it at the site, or in the rubbish. Do not wash plant material down any drain.
  • Cleaning any gear that has come into contact with the water. There is more than one way of cleaning your gear - choose the method that suits your gear best. More time should be allowed for more absorbent materials:
    • Soak or spray all surfaces with a 10% solution of dishwashing detergent (1L diluted to 10 litres in water) for at least 10 minutes
    • Soak or spray all surfaces with a 2% (200mls diluted to 10 litres in water) solution of bleach for at least 1 minute
    • Soak gear in water above 60°C for at least 1 minute
    • Soak gear in water above 45°C for at least 20 minutes
    • Freeze until solid.
  • Drying your gear for 48 hours (after it has become dry to touch) before using it in another waterway.

Most items can be cleaned using the standard method above, but some have specific requirements. Check out these additional details on cleaning specific items.

Using the Check, Clean, Dry method for sporting events

There is a guide on the MPI website for event organisers, and groups who deal with cleaning large amounts of gear. This is to help ensure that you, and the participants in your event, don't inadvertently spread freshwater pest species.

Check out the guidelines for sporting event organisers.

Greater Wellington can provide Check, Clean, Dry advocates to events at no cost. If you are organising an event in the Wellington region and would like our advocates to attend, please email us at

Freshwater pests and water quality

The only reason that a freshwater pest species will appear in a new waterway is if it has been brought there by human activity. However, factors like high nutrient levels can affect the growth rate of pests once they are introduced.

The quality of a waterway cannot cause these species to appear on their own, but it will be significantly affected by their presence.

Learn how to spot our freshwater pests and weeds in this quick guide.

Find out more about our freshwater pests and weeds.


If you have questions about the Check, Clean, Dry method, email 

To order Check, Clean, Dry brochures and guides, email

Updated December 19, 2022 at 3:35 PM

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