The Check, Clean, Dry Campaign

New Zealand is an island nation that lies deep in the South Pacific. It consists of two main islands – the North Island and the South Island – separated by a 29km wide waterway, the Cook Strait.

The responsibility for protecting the nation’s unique biosecurity system rests with the Ministry of Agriculture and Forestry and its biosecurity group -  MAF Biosecurity New Zealand (MAFBNZ). 

MAFBNZ’s role includes facilitating international trade, protecting the health of New Zealanders and ensuring the welfare of New Zealand’s environment, flora and fauna, marine life and Maori resources.

MAFBNZ was established in late 2004 and about the same time, the invasive aquatic weed didymo was first detected in fresh waterways in the South Island, posing one of the first major challenges for the new organisation.

MAFBNZ needed to act decisively to stop didymo spreading throughout New Zealand, especially to the North Island, but was limited in its options. It found there were no scientific means to eradicate didymo and traditional pest control methods were not appropriate, so the focus turned to changing the behaviour of waterway users to limit the spread as scientific evidence indicates human behaviour is the cause of didymo spreading (rather than animal movements or climatic conditions).

The Check, Clean, Dry campaign was the Ministry’s response.

Created in 2005, the campaign simply asks waterway users to Check, Clean and Dry equipment and clothing when moving between waterways. The catch cry continues to be used up and down the country in communications by MAFBNZ and its many community based partners.

With limited research available about audience attitudes and behaviours, Check, Clean, Dry started essentially as a public information campaign. A growing pool of research over the past three years has enabled MAFBNZ to segment and target audiences through a wide range of social marketing techniques, and to develop into a true social marketing programme that is showing impressive results.

It has become a campaign that is led by communities, using local solutions to meet local needs and respond to local issues. It is reaching out to the most relevant audiences, through their own networks, and in ways that hit their individual triggers.

Total MAF expenditure on social marketing activities in the first three years of the didymo response was approximately $4.55 million (NZD).

To gauge the value of this spend, MAFBNZ carried out an economic impact assessment (March 2006) that found a 2-year delay to the arrival of didymo to the North Island would represent a cost saving to New Zealand of between $34.5m and $167.9m over the longer period 2004/05 to 2013/14. The same assessment estimated that the cost saving to New Zealand delaying the spread of didymo to the North Island to June 2008 had been $2.15 for every $1 spent on social marketing;  If the North Island remains free of didymo to June 2010, the estimated ratio will be $7.61 for every $1 spent on social marketing.

The problem

Sparkling and pristine waterways are an iconic part of New Zealand’s national identity.

They are the glistening images of postcards and tourist brochures; they are important habitats for valued wildlife; they are popular playgrounds for New Zealanders and visitors alike. World class water-based recreation and sport – swimming, fishing, boating, canoeing and kayaking are a way of life and essential to the thriving tourism economy.

Freshwater pests, like didymo, have the potential to put all that at risk.

The invasive microscopic algae didymosphenia geminata (didymo, or colloquially ‘rock snot’) was first detected in New Zealand in November 2004. It was found in the lower Waiau-Mararoa catchment at the very south of New Zealand’s South Island.

It will most likely never be known exactly how didymo first entered the river system, but it is believed it may have been unintentionally brought into New Zealand on recreational or industrial equipment from an affected area overseas.

Didymo can form massive blooms on the bottom of streams, rivers and lakes. It attaches itself to the stream bed by stalks, and forms a thick brown layer that smothers rocks, submerged plants and other materials.
Although not a significant health risk for humans, didymo can turn sparkling waterways into ugly, murky soups, and can impact on organisms that require the habitat to eat, breed and shelter

Adding to the problem – thanks to perfect climactic conditions – didymo has started to thrive in New Zealand. 
Phase one: information gathering

New Zealand had no international precedents to follow in the management or eradication of didymo – it needed to shape its own solutions.

This meant that very little scientific information about didymo was available to MAFBNZ – and there was a void on best practice evidence or advice. MAFBNZ didn’t know how didymo spread let alone how it could be controlled.

In response to the lack of information, the didymo science programme was established in November 2004; the aim was to research and validate information regarding identifying and detecting didymo, how it spread and how it could be contained, and the potential impacts of options for control and eradication.

Perhaps the most devastating discovery was that there was no safe or certain way to eradicate didymo.

So the focus had to shift from elimination to trying to slow the spread and minimise environmental and recreational impacts.

Containing didymo wasn’t going to be an easy job either; MAFBNZ discovered that didymo could be spread through a single drop of water, which can contain up to 1000 didymo cells.

Completely banning access to the contaminated areas wasn’t feasible so MAFBNZ looked to assess instead how equipment or clothing that came into contact with fresh water could be decontaminated.

In February 2005, New Zealand’s National Institute of Water and Atmospheric Research (NIWA) released a report that outlined its research into methods for decontamination. The report showed decontamination could be done by waterway users – and relatively easily – using standard household products such as nappy cleaner, antiseptics and detergent.

Identifying the behaviour required

The evidence pointed to one real solution: to change the behaviours of waterways users.

The spread of didymo could be slowed if waterways users decontaminate clothing and equipment between waterways.

Waterways users needed to CHECK equipment and remove any obvious debris, thoroughly CLEAN all equipment that had been in contact with the water with the most practical treatment (detergent, bleach, hot water), DRY it thoroughly, then wait for at least 48 hours.

With a clear behaviour change objective in its sights, MAFBNZ was able to successfully seek government funding for a three year social marketing programme to get waterway users to Check, Clean, Dry.

The strategic approach

MAFBNZ accepted that it was impossible to stop didymo spreading within the South Island so its primary objective changed to slowing the spread of didymo throughout New Zealand and keeping New Zealand’s North Island free of didymo for as long as possible.

To recognise the diverse audiences for Check, Clean, Dry, and to be consistent with social marketing best practice, MAFBNZ designed a multi-layered approach.

It began communicating using a broad brush approach for all potential audiences, largely through news media. And at the same time, The Nielsen Company  was commissioned to undertake focus group research in both the North and South Islands with high-risk water-using groups. It was found that although waterway users knew about didymo their understanding and acceptance of didymo and the actions they needed to take to stop didymo from spreading were widely disparate.

The Nielsen Company  also looked at what would motivate the target audiences to Check, Clean, Dry.  Ultimately, all waterway users were motivated by the personal consequences – the impacts on their sports and leisure activities and the regions in which they live. MAFBNZ needed to make the threat of didymo real to these users and show them what worse case scenarios could look like. It was also important for target audiences to see that the Government and MAFBNZ were taking an active role in the campaign so that waterway users didn’t feel the burden was too great and the cause futile.   

Armed with that knowledge, MAFBNZ designed a social marketing programme that primarily took a community-based approach to target high-risk water-user groups through the people and organisations they regularly come into contact with, the publications they read, at the waterways they use and events they attend. The priority group included kayakers, fly-fishers, jet-boaters and pleasure boaters.

The secondary target group was other waterways users, including the general public and visitors to New Zealand. The strategy was to reach this audience through mainstream media, traveller publications, locations and events.

The programme also had a focus on delivering ‘products’ that helped the target audiences to Check, Clean and Dry – such as cleaning stations at events, spray bottles and small packs of detergent.


MAFBNZ has implemented a range of tactics so that audiences would hear repeatedly, and from many different sources, what they needed to do and why. 

The core approach was to use the research that was being accumulated to tailor different communications for different audiences and to build  community based partnerships with organisations that were best placed to reach those audiences.

MAFBNZ partnered with numerous local and regional councils, environmental agencies, community and sporting groups, in the North and South Island, including kayak clubs, fishing clubs and rowing clubs. 

Engagement with frequent users of waterways through organisations in their own communities has meant the message has been delivered via channels they trust and at times and places where Check, Clean, Dry is relevant to them. MAFBNZ established many strong partnerships with these community based partners and provided them with tools as well as guidance to implement their own successful Check, Clean, Dry initiatives.

Sports and recreation groups have held demonstrations for club members on methods of cleaning down equipment. Others have bought equipment such as spray bottles and detergent, giving all members access to the cleaning products without them having to bring their own. Others have set up cleaning stations for water users to use after events.  

These groups have helped to make it taboo for members to not Check, Clean, Dry their gear.  Members took lead from each other rather than from instructions direct from MAFBNZ.  

MAFBNZ and partners have also attended events such as rowing meets, jet boat marathons and boat shows. These events have put a ‘public face’ to the campaign and provided opportunities to discuss didymo directly with the waterway users.

MAFBNZ has focussed on providing an effective range of information and resources to build awareness of Check, Clean, Dry. Partners were involved in creating these resources as well as providing channels to distribute them. Resources included signage at water access points, information at ferry terminals, a school package, information to distribute at events, fact sheets, posters, bumper stickers, jelly beans, sunscreen, key rings, portable sprayers and water bottles. Some advertising was also done, in support of community-based engagements.


As a government department investing taxpayer money, MAFBNZ needed to assess the effectiveness of the social marketing campaign using surveys of high-risk waterway users and an extensive science and technological programme.

To measure behaviour change and attitudes towards Check, Clean, Dry The Nielsen Company  conducted an annual survey throughout the response. The sample consisted of high risk waterway users who were contacted through their networks, including members of the Fish and Game network, The New Zealand Jet Boat River Racing Association and 4WD, kayak and boating clubs across New Zealand.

The survey asked a range of questions including whether respondents were aware of the Check, Clean, Dry campaign, what communications they had seen, and whether they had decontaminated their equipment between fresh waterways.

It also tested the direct links between the campaign and the behaviour change, by probing how much more likely people were to Check, Clean and Dry if they had seen the campaign (i.e. the causal links between outputs and outcomes). 
 Another method of measuring the campaign’s success was tracking how far and wide didymo had spread within New Zealand waterways. Through an extensive science and technological programme a lot was learned about the impacts, control options and distribution of didymo.


The Nielsen research (July 2009) concluded that the Check, Clean, Dry campaign has been successful in changing attitudes and behaviours of New Zealand’s fresh waterway users.

The research shows the risk of didymo is understood. Of those surveyed 89% of high-risk users agreed that didymo is a serious threat for New Zealand.

And people are Checking, Cleaning, Drying. The research showed that in 2009 100% of high-risk users in the South Island and 99% of high-risk users in the North Island were able to identify an action they take to help stop the spread of didymo. Of those, 71% always Check, Clean and Dry and 21% sometimes Check, Clean and Dry. Other behaviours people have adopted have included using different equipment (e.g. waders and fishing rods) between different waterways.

The 2009 research also shows a correlation between the social marketing programme’s outputs and the desired behaviour: 98% of people who always Check, Clean and Dry – and 95% of people who always / sometimes Check, Clean and Dry – have seen promotional items or received information from the campaign.

The measurement relies on self-reported behaviour change. But even so, there has been a significant improvement in people at least reporting that they do Check, Clean and Dry – with 30% of respondents in 2009 reporting that they are more vigilant than they were a year ago and only 4% saying they are less vigilant.

The proportions of high risk freshwater users who state that they think about how they can personally stop the spread of didymo, who state they have taken actions to do so, and who state that they always make an effort to Check Clean Dry have all shown improvement year on year over the last 3 years:
•    In 2009, 58% state they considered a lot how they could personally stop the spread of didymo compared to 41% in 200
•    In 2009, 84% state they've taken actions to do so compared to 76% in 200
•    In 2009 72% state they always make an effort to be totally compliant (i.e. CCD) compared to 64% in 2007.

Although it is impossible to confirm whether the spread of didymo has slowed due to the implementation of the Check, Clean, Dry campaign, it is significant to note that didymo has not yet been detected in the North Island.


The ability to illustrate the success of the campaign resulted in Check, Clean, Dry becoming the first major response the New Zealand Government has transitioned from an incursion response into a long-term management programme that includes an active ongoing role for MAFBNZ.

The long-term management programme will continue to reinforce to New Zealand’s fresh waterway users that it is important to continue to Check, Clean, Dry to protect our waterways not only from didymo but other aquatic weeds as well. New Zealanders will be reminded of what it is that New Zealand stands to lose if they do not take actions now to protect their treasured fresh waterways – a significant part of the New Zealand way of life.

Site Courtesy of
McKenzie-Mohr & Associates

Expertise in Community-Based Social Marketing