Eel Passes

Eel Passes – Fully tailored packages


  • Modular eel passes allowing installation around any structure
  • Proven design, developed with nationwide experts
  • Robust, long lasting construction
  • Customisation available if required
  • Survey, design liaison and installation all part of the service


Historically, water control structures such as weirs and pumping stations prevent a barrier to the natural migration of eels and elvers. Therefore, causing declining numbers over recent years. ACE have worked tirelessly with nationwide experts to develop a range of passage equipment to reduce the impact of the installation of our flow control equipment. In turn this naturally lead to ACE being employed nationwide to advise and supply eel pass equipment around existing and new structures.


Elvers have a natural instinct to seek out fresh water, having started life in the sea. When they encounter a barrier, they attempt to migrate upstream. For instance via wet grass, leaks in structures and other sources of fresh water. This has been hampered in recent years following improvements in seal designs on sluices, removal of vegetation and urbanisation. However, the installation of ACE eel passes can reduce this decline. By simulating wet grass and providing an attraction flow, elvers can find a safe route to continue their journey inland.


Instinctive design

ACE eel passes follow a fairly simple concept to use elver’s instincts to attract and promote safe passage:


  • Suitable climbing substrate, and a flow to keep it moist (usually HDPE channel, with brush substrate of a suitable pitch)
  • A point of no-return at the highest point (to ensure safe passage)- typically a splitter box
  • Swift, smooth descent to flush eels into the upstream watercourse, away from seaward flow


Although the concept is simple, the delivery can be complex due to obstructions, traffic routes and existing services. ACE use a modular, proven concept, which allows the systems to be unobtrusive and work with minimal disruption. We also regularly update and modify the eel passes to accommodate particular requirements to suit sites. Whether this includes provision to trap and monitor eels, provide public interaction facilities for education, or additional security to prevent vandalism. We can assist.

All-inclusive service

As part of the service, ACE will visit your site and carry out a full survey and appraisal of existing structures. Provide advice based on over 10 years of experience, drawing on best practice around the UK. Our design is then provided using 3d modelling software to clearly visualize the interface with the site. In addition, any safety or construction considerations that are required. All of which can assist with consent application.


Once designed, ACE use modern, robust materials to make a pass that will remain reliable for many years, and easy to install, maintain and monitor safely, but above all provide an effective and reliable passage route for numerous elvers.


Where required, ACE will provide site management, fully in line with CDM regulations, NICEIC installed electrical control panels, and all site equipment, in a full turnkey package.

Types to suit any application

To ensure reliability, ACE would usually recommend a powered pass, using a pump to provide debris free water, at a controlled rate to keep the pass moist and attract eels to it, making it effective during all conditions. We do understand however that some sites prevent this, due to remote access, or other factors which require alternative arrangements.


We offer:

  • Powered, pumped passes, ideally mains powered (however solar powered systems can be provided)
  • Gravity fed passes, using modular channel system as above (if power is impractical)
  • Gravity fed passes, using eel tile substrate (e.g. weir mounted)
  • Gravity fed, vertically mounted passes (sandwich construction)- where width of pass is restricted
  • Tilting Weir/Sluice mounted passes
  • Integrated passes (e.g. part of a fish pass)


In all cases, we are happy to accommodate special requirements, so please talk to us- to discuss your requirements, please contact us.



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