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Invasive species control

Our waterway network is home to many invasive species, which cause a variety of problems. From interfering with navigation and water control to reducing water quality and habitat availability, invasive species can have a huge impact on our canals and rivers.

Floating pennywork covering most of canal with boat moored at side

Non-native invasive species are considered the second greatest threat to native wildlife and they cost the UK economy up to £1.7 billion a year. Every year we spend around £700,000 treating invasive weeds. However, these direct control costs are likely to represent a small proportion of the wider impact of invasive species

As non-native invasive species are often introduced to the waterway network by well-meaning members of the public, we have been working with Defra and the Non-Native Species Secretariat to raise awareness of the problems they cause. One main objective we have is increasing the awareness of Check, Clean, Dry. This is an awareness campaign developed by UK Government, devolved Governments, Water Companies, Wildlife Conservation organisations, and angling and boating organisations. The aim is to raise public awareness about invasive species and how we can all help to limit their spread across the countryside

If you're concerned that an invasive species has not been dealt with on our waterways please get in touch with your local office and we'll consider it. Some invasive species can be managed by volunteers, like Himalayan balsam and Ragwort. Check our volunteering pages for details of how to get involved and make a difference to our waterways.

The main offenders

Close up of Japanese knotweed growing out of water

Japanese knotweed We're fighting a brutal battle against Japanese knotweed. One of the most invasive weeds in Britain, Japanese Knotweed's dense growth crowds out native vegetation, erodes riverbanks and causes structural damage.

We spray it once a year to try and keep it under control. However, it's impossible to eradicate it completely as it can grow from the smallest fragment of root.

Floating pennywort under a bridge

Floating pennywort Floating pennywort is a major problem for us as it can grow and spread rapidly, causing operational and safety concerns. The plant can grow from the smallest fragment if it is broken up. A single infestation in one location can cost us up to £25,000 a year to treat and without proper management can block our waterways.

Read how a team of volunteers helped to tackle floating pennywort on the River Soar.

Giant hogweed (copyright GBNNSS

Giant hogweed Giant hogweed is a concern for us because it is harmful to people if they touch the plant. We aim to act as soon as possible when we become aware of this plant growing on our waterways. We spray the plant and know where it tends to occur year on year, but if the plants flower it can produce up to 10,000 seeds, so it is key we know where new plants are early so we can deal with it early.

Himalayan Balasam (copyright GBNNSS)

Himalayan balsam
Himalayan balsam is now widespread along our network. It outcompetes native plants and when it dies back in winter results in erosion of banksides. The most effective control method is manual hand pulling, however this is a time-consuming activity and is often reliant on volunteer time. Visit our volunteering pages for details of how to get involved during early summer and make a difference to our waterways

Reporting potential invasive species

While we try and monitor and control invasive non-native species where we have the resources, there is always the threat of new species being brought onto our waterways. One of the most common ways plants become invasive is through escaping from gardens.

Our partners are always seeking more information on where plants are starting to endanger our waterway habitats. Early identification that a plant species has the potential to be invasive is key.

If an ornamental plant is growing so strongly that it needs to be controlled to prevent it overgrowing other plants, it has the potential to be invasive in the wild. This can be reported via the Plant Alert website.

Last Edited: 25 March 2022

photo of a location on the canals
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