Bournemouth Water has supported pioneering research led by the University of Exeter into innovative eel pass designs aimed at helping restore populations of the critically endangered European eel.

The university carried out tests as part of a collaboration with Bournemouth Water, Fishtek Consulting (part of the RSK group), the University of Exeter’s Department of Earth and Environmental Sciences and the Environment Agency which compared eel passage rates across existing plastic-based eel passes with a new design using natural gravel.

The new design was trialled at Bournemouth Water’s Knapp Mill Water Treatment Works by University of Exeter final-year environmental science student Ellie Strudwick for her dissertation project after spending a placement year working at Fishtek.

Ellie said:

“The European eel is a catadromous species – they grow and develop in freshwater for up to 20 years before they migrate across the Atlantic to the Sargasso Sea to breed.

“Juvenile eels (elvers) are small and vulnerable when they begin their upstream migration into freshwater, as they are immediately faced with river obstructions, such as weirs, dams and hydropower stations.

“These artificial barriers prevent elvers from migrating upstream to resource-rich habitat and have been a major cause of European eel population decline.”

Bournemouth Water contributed to the research by providing access to its Knapp Mill Water Treatment Works. This location has an existing eel pass but with a high abundance of juvenile eels and was the ideal place to carry out this type of research. The company also provided on the ground support to Ellie during her time there.

Pennon CEO, Susan Davy said:

“This is a brilliant example of what can happen when science, passion and collaboration come together.

"We’re proud to have played a small part in supporting Ellie and the team with this research – helping to protect one of the UK’s most endangered species.

"Projects like this show that with the right partnerships, we can find smart, nature-led solutions that make a real difference – not just for today, but for future generations too.”

The innovative eel pass designs developed through the research offer scalable, nature-based solutions that can be retrofitted to a wide range of structures.

Bournemouth Water is reviewing the results to inform future work at other sites where eel migration is impacted, supporting efforts to meet regulatory goals and environmental commitments under the Water Industry National Environment Programme (WINEP).

Adam Fryer, Fishtek’s Technical Director said:

"We are very grateful to Bournemouth Water for supporting our work by providing a candidate site for the research at its Knapp Mill Treatment Works, where there is a barrier to eel migration and a high abundance of juvenile eel.

“This study has given us a huge amount of information that can inform our eel pass design.

“In fact, we have already begun to apply this to existing sites and have installed two gravel type eel passes at a small weir on the Vicar Water and a weir upstream of the well-known Rufford ford on the Rainworth Water, both in Nottinghamshire.

“It also provides a framework to show how a collaborative approach among industry, academia, a water utility and the regulator can advance the field of fish passage research and optimise outcomes when designing and installing environmental mitigation.”

The European eel is classified as Critically Endangered by the IUCN, with numbers having declined by over 90% since the 1970s. Improving access to upstream habitats is one of the most effective ways to help the species recover.

Bournemouth Water is committed to protecting and enhancing the natural environment as part of its Green Recovery and Net Zero strategies, supporting biodiversity, and ensuring a sustainable water future for generations to come.