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Biosecurity in Open Water Swimming - #spreadthewordnottheweed


Invasive non-native species of wildlife can hitchhike on bodies, body hair, equipment, footwear, clothing and boats. You may inadvertently spread the aliens even if you just go for a paddle! Every time you leave any water such as a river, tarn or lake you need to perform three simple steps. 


Check your equipment and clothing for living organisms. Pay particular attention to damp or hard to inspect areas.

Clean and wash all equipment, footwear and clothes thoroughly. If you do come across any organisms, leave them at the water body where you found them or on a hard surface to die out.

Dry all equipment and clothing. Some species can live for many days in damp conditions.

Check Clean Dry


If you’re planning a swim/run/swim adventure consider the order in which you travel. Go from the cleanest lakes, rivers and tarns first. For example: DO NOT swim in Derwent Water, then Blackmoss Pot, then Buttermere, followed by Crummock. Even if you wear new swim gear species such as the highly invasive New Zealand Pygmy Weed may secrete itself about your person, swim footwear, kayak, paddle board, towfloat etc etc.

ALWAYS travel from the cleanest body of water, so in this example it is essential to start in Buttermere, then go to Crummock, then Blackmoss Pot and end up in the dirtiest, which sadly is Derwent Water, where the New Zealand Pygmy Weed has rapidly spread so that it is now considered a real threat to our last few remaining pristine bodies of water. At times Derwent Water is unswimmable. We want to save the last three lakes from the same fate.

Please help by ensuring you take nothing with you between bodies of water, no hitchhikers hiding in your body hair or clothes!


Wild Swim Bag

Rinse all swimwear and equipment with fresh water and dispose of rinsing water onto the ground NOT down the drain or plughole. Once in the drainage system it will work its way into any body of water it wishes. Spread over flowerbeds or the ground it has less chance of entering our water system.

Swimsuits, once rinsed, can be washed in the washing machine or just hung to dry.

If you are camping rinse all gear in the body of water in which you swam, leaving organisms where they belong. Dry thoroughly before entering another body of water, or use clean, dry swimwear. Use bottled water to rinse your body, particularly in areas hard to spot hitchhikers!

Wild Swim Bag

Frog Graham and other similar organised or self organised challenges present a threat to these lakes too - please consider approaching your challenge so that you are swimming in the cleaner lakes first. Stop, think and reflect. Your challenge may cause our pristine lakes to die unless we all take the essential precautions.

Paddle boarders, kayakers, triathletes, swimmers, day trippers, tourists - everyone who enjoys the pristine beauty of these waters - be aware, be vigilant, be considerate, be clean. It takes but a few minutes to follow the rinsing and drying advice.

This biosecurity advice is relevant in other parts of the country, not just the Lake District. It is good practice to clean, rinse and dry clothing and equipment when going from one body of water to another wherever you are to avoid carrying non native species about with you. But, in particularly sensitive regions such as the Lake District, it is critical. And if you are with others always talk to them about what you are doing and why - the more people know about it the better.


For more info contact: Natural England, National Trust and West Cumbria Rivers Trust.

By Sara Barnes

Watch the Sky News report of 12 July 2020 on the importance of bio security featuring Sara 

Sara is a freelance writer who loves swimming in wild and not so wild water.

Instagram: @bumblebarnes


  • I wonder who’s telling the ducks and geese to cleanse their feet and feathers?

    Tony Stewardson
  • Just watched the news about cross country swimming ie swimming and walking from lake to lake across wild areas. While this may be exciting it’s a biosecurity nightmare and if this becomes popular in our wild areas it will directly take invasive species from water to water. Other Hobbies like boating and fishing are generally aware of this risk. In the case of larger boats they can be cleaned but don’t tend to go to remote areas. With kayaks its more of a problem that needs addressing but possibly they stick to larger bodies of water. With fishing generally there is less contact surfaces and tackle can be cleaned between outings or species have time to die off. With cross country try swimming, moving from lake to lake and tarn to tarn, there is much greater risk of spread and it would be harder to mitigate properly. We are relying on education to address this but it’s probably not possible before many waters are “polluted” and questionable whether its intrinsically possible for cross country swimming to be bio secure at all. I fear before anyone catches on to this it will be too late as wild swimming is becoming very popular and this creates its own impetus and commercial demand for rights and continuation of a hobby.

    Matt Wright
  • Seems like some good arguments in favour of skinny dipping


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