Nearly 4,000 tonnes of invasive aquatic weed were removed from Britain’s canals and waterways during 2025 by a single contractor, highlighting the growing impact of climate change on one of the UK’s oldest and most important infrastructure networks and underlining the need for urgent action.
The scale of the problem has been highlighted by marine and waterways engineering specialist The Rothen Group, which warns that unmanaged vegetation poses serious risks not only to the appearance of waterways, but also to flood prevention, navigation safety, biodiversity and community wellbeing.
ALL PHOTOS: THE ROTHEN GROUP
Clear water is essential for reducing flood risk. Without regular vegetation management, large mats of invasive species such as floating pennywort can block weirs, culverts and drainage systems, increasing the likelihood of flooding. These dense growths can also make waterways unsafe for boaters, with weed capable of completely blocking canals or becoming entangled around propellers, rudders and paddles.
Commissioned by the Canal & River Trust, The Rothen Group worked with partners to eradicate more than 3,800 tonnes of weed across the UK in 2025. This included the removal of almost 1,700 tonnes from major waterways such as the Grand Union Canal in Uxbridge, Brentford Lock in London, and the River Lea in Waltham Abbey.
The work was carried out using specialist weed-cutting boats equipped with tugs and hoppers, alongside crane hoppers for tackling larger floating mats, allowing weed to be safely removed and placed on the bank.
The Rothen Group has warned that the threat posed by non-native aquatic vegetation is increasing. Invasive species out-compete native plants for light, water, nutrients and habitat, while also reducing oxygen levels in the water, which harms fish and other wildlife. Without intervention, this imbalance can severely damage canal ecosystems.
Warmer summers and longer growing seasons are accelerating weed growth year on year, making regular management increasingly important. Effective weed removal improves water quality, supports local communities, protects biodiversity, and helps ensure canals remain both attractive recreational spaces and functional transport routes.
However, maintaining these benefits depends on continued investment. The report reinforces calls for greater Government funding to support the upkeep of the national waterways network, echoing long-standing appeals from organisations including the Inland Waterways Association and Fund Britain’s Waterways.
Without sustained funding and coordinated action, the ecological, social and economic value of Britain’s canal network could be put at risk. With proper investment, however, the waterways can continue to serve as vital corridors for wildlife, climate resilience and community wellbeing.
