Designing and delivering the UK’s largest fish pass
Project facts
- ClientThe Environment Agency
- LocationColwick Country Park, Nottinghamshire, UK
- DateNovember 2018 – May 2024
- ChallengeCritical flood defences stopped fish from migrating upstream to spawn
- SolutionDesigning the UK’s largest fish pass to give species a safe route around sluices
The challenge: critical flood defences blocked migratory paths
The Environment Agency’s Holme Sluices have been controlling water levels in the River Trent for over 70 years. These structures are integral to managing the area’s flood risk, but they also create a barrier to migrating fish.
The Environment Agency wanted to find a way to restore a healthy watercourse and help fish to circumnavigate this critical flood defence and commissioned Royal HaskoningDHV to help.
The solution: an innovative fish pass to benefit wildlife and visitors
Our engineering experts designed a fish pass that would cause minimal disruption to the existing function of the Holme Sluices.
The fish pass comprises a 200m long, 6.5m wide and up to 6m deep bypass channel with 20 ascending pools connected by deep vertical slots, creating flow conditions suitable for a wide range of fish species to circumnavigate the sluices. We also included two new road bridges to provide access to the existing Holme Sluices compound.
As well as these practical measures, we included features that would appeal to and engage visitors, including a viewing platform, information points to inform the public about the scheme, and bespoke installations, sculptures, and artwork.
In addition to this design work, we were able to create a robust business case to secure funding, engineering consultancy, technical support, and site supervision during the two-year construction phase.
Royal HaskoningDHV should be proud of what they have achieved in bringing this incredibly complex fish pass project to a reality. The unique constraints of the location have led to a fully bespoke design, whilst also achieving the optimal conditions for fish passage at the largest barrier in the Midlands
The result: migration restored, natural habitat now accessible
The fish pass unlocks over 60km of habitat and delivers the right flow conditions for a wide range of species to continue their migration upstream. This particularly benefits Atlantic Salmon and endangered species like the European Eel, as it provides access to suitable environments for them to reproduce.
Beyond its local benefits, the fish pass is the largest in the UK – and has been featured in UK news as a great example of how flood defences and wildlife can exist in harmony.
