Fish passage |
When engineering meets ecology
As flood and water infrastructure must increasingly deliver biodiversity net gains alongside flood and supply resilience, engineers are finding new ways to design for wildlife without compromising the assets people depend on. Giles Squirrell, Growth Director at Ancora Group, looks at recent projects that show what that balance looks like in design and delivery
Embankments, weirs, sluices and pumping station intakes can therefore become barriers or hazards if eels are not considered from the start. This issue was exactly why the Eels Regulations 2009 were introduced, ensuring those managing or altering waterways were not endangering this protected species. Not to mention the potentially large fines that failing to adhere to the regulations brings, their introduction and the novel engineering solutions they demand introduce many challenges, ranging from design to material use through to delivery. Several recent projects show how to address these challenges, preserving the balance between ecology and essential infrastructure.
A pathway for eels at Skeffling Pumping Station
Construction of the new fish pass at Buckfast Abbey, where temporary water management measures allowed work to proceed within the fast-flowing River Dart
Complete Installation of two S1800 Hydrolox Screens and decking system - Courtesy of South West Water Fishtek Ltd Northbridge
FLOOD DEFENCES AND WATER infrastructure do not have to conflict with conservation. Protecting communities and water supplies can, and increasingly must, sit alongside protecting the ecosystems around them. Environmental regulations have helped drive this shift. Regulators now expect infrastructure to deliver biodiversity net gain, while engineers are asked to design for people and wildlife within the same schemes, and often the same physical structures. Few species illustrate that balance more clearly than
the European eel. Its population has fallen by more than 90% in recent decades, and its life cycle depends on movement between marine and freshwater habitats.
On the north bank of the Humber Estuary, embankment realignment and new intertidal habitat works created a specific challenge: helping migratory eels cross the earth embankment beside Skeffling Pumping Station without weakening its tidal flood defence role. An eel passage was proposed, but it needed the right
material: durable, environmentally sensitive and able to provide surface texture and moisture eels need to climb. Working with the Environment Agency, Hesselberg
Erosion Protection identified Open Stone Asphalt (OSA) as the best fit. Its engineered asphalt system provides a naturally rough finish that retains water, replicating the wet, textured conditions eels need to climb. Asphalt protection also benefits from up to 75% less embodied carbon than a concrete alternative. The team first built a test section to check the material
and profile before full installation. The trial confirmed that the OSA surface delivered the required roughness and moisture retention, allowing the complete eel passage to be installed in summer 2025 alongside the wider embankment works.
A modern fish pass at ancient
Buckfast Abbey Within the grounds of Buckfast Abbey, on the River Dart, an old weir had begun to collapse and total failure was imminent. Its pool and traverse fish pass were also dilapidated and no longer functional, and it was the last remaining weir on the Dart without a modern fish pass. The primary challenge at this site was water control.
The fast-flowing river and permeable existing dam structure demanded an elaborate water management system, without which construction at the site would have been near impossible.
34 | September 2026 |
www.waterpowermagazine.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45
