Calls to curb invasive species spread via untreated water transfer in England and Wales

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Development of cities and the demands of agriculture mean that huge volumes of untreated water from lakes, reservoirs and rivers are now routinely moved large distances, across countries, up to hundreds of miles, using pipelines, tunnels and water supply canals. Known as raw water transfers schemes, these projects are essential for human uses but risk moving not just water but also wildlife, spreading invasive and non-native species, such as zander fish and zebra mussels.

In a series of new papers, researchers from Newcastle University and the University of Stirling are now warning that invasive species can be moved between often unlinked waterbodies by the intentional transfer of water and call for action.

Publishing their findings in the journal Management of Biological Invasions, the experts highlight the need to add raw water transfers (RWTs) into coordinated surveillance and management plans to meet national and international targets on tackling invasive and non-native species, and recommend exploring options to improve RWT information access and stakeholder collaboration within the INNS management community.

They also call for increased awareness of the risks associated with RWTs and the spread of invasive and non-native species and say these actions will deliver additional benefits to support the conservation of freshwater biodiversity in a rapidly changing world.

How RWTs are managed varies between countries, but they are typically managed by private water companies, or local and central government. In England, the majority of RWTs are owned and managed by water companies. The Environment Agency (EA) also controls a number of RWTs.

The research team cites data showing 110 surface water transfers in England and Wales which can transfer between 45–150 million liters per day, around 43 of which cross one or more catchment boundary (39%).

Top biodiversity threat

Study lead author, Ava Waine, Ph.D. researcher at Newcastle University's School of Natural and Environmental Sciences, said, "Invasive species are one of the top threats to biodiversity and the economy globally. Raw water transfers move invasive species around between different environments, but researchers in the invasion ecology field are only now becoming mindful of the extent of their impact, and industry and regulators aren't yet fully aware of the invasion risk or how to manage it.

"Recently, England, followed a few years later by Scotland, became the first country in the world to require that raw water transfers be managed to prevent invasive species spread.

"I have been working with Northumbrian Water to address the issues. The results highlight that raw water transfers are a virtually unknown mode of species spread, and some changes to national and international biodiversity policy is required so that researchers around the globe become more aware of the issue, and we have a better chance of solving the problem."

Study co-author, Dr. Zarah Pattison, Senior Lecturer in Plant Sciences, University of Stirling, added, "This is a call to action. We need to take the risk of invasive and non-native species spread through raw water transfers seriously and invest in research to determine the severity of this risk for all taxonomic groups of species."

This research builds on a recently published study by the same team, in which the experts describe how RWTs are creating a pathway for the spread of freshwater invasive non-native species in countries worldwide. In the study, the team suggests modifying the corridor category in the Convention on Biological Diversity's pathway classification framework to include RWTs as a distinct sub-category.

The authors argue this reclassification would improve understanding of RWTs, help manage their risks, and guide policy development to better address the spread of invasive and non-native species.

More information: Ava Waine et al, Integrated management of the raw water transfer invasion pathway, Management of Biological Invasions (2024). DOI: 10.3391/mbi.2025.16.1.14

Provided by Newcastle University