Thousands of fish will benefit from improved access to vital habitats following the installation of a new fish pass in Mildenhall and at Newby Bridge Weir.
A new £1.2 million fish pass on the River Lark in Mildenhall improves migration for trout, eels, and coarse fish.
Separately, work is underway to replace an outdated eel pass at Newby Bridge Weir to encourage better migration for the critically endangered European eel.
River Lark
The natural limestone fish passage at Turf Lock on the River Lark has replaced 2 weirs that were preventing wild brown trout, eels and coarse fish from migrating upstream.
Photo: Bob Jones / River Lark near Mildenhall. Creative Commons
Built as a rock ramp-style fish pass using natural materials, boulders were carefully placed to disrupt the flow. The new design allows fish to swim between boulders, as they move upstream, which provide shelter and creates better conditions for migration across varying water levels and flows.
Lou Mayer, environment programme manager for the Environment Agency in Suffolk, said:
It’s fantastic to see work completed on this important project and witness fish swimming up into Mildenhall for the first time in centuries. Chalk streams are a valuable natural resource that the Environment Agency and its partners are working hard to restore and protect.
Over time, there has been a gradual decline in both biodiversity and the overall health of the River Lark’s ecosystem. This project and other planned initiatives will help this river continue to recover and become more resilient to future challenges of climate change.
River Leven
Activity is underway to replace an eel pass in Cumbria as part of work by the Environment Agency to improve river ecosystems and support the safe migration of the European eel.
The European eel has suffered a dramatic decline in recent decades due to habitat loss, overfishing and barriers such as weirs that disrupt its long migration routes.
Action is now being taken to improve eel passage in the River Leven by replacing the existing fish pass at Newby Bridge. It is outdated and no longer meets modern standards for safety, remote monitoring, or effective water management.
The project will introduce a hybrid eel pass system, designed to enhance eel migration and biodiversity while minimising any environmental impact.
At the heart of the improvements is an intelligent float switch-controlled pump. This system activates during low water flows to assist eel movement, ensuring their continued migration even in challenging conditions.
When water levels rise, the float switch automatically deactivates the pump which will allow migrating eels to use the natural river flow. This is especially important to help promote effective movement to their local habitats .
This adaptive pumping approach not only supports the local eel population but also reduces energy consumption, contributing to a more sustainable water management solution.
Improvements for maintenance, reliability and resilience
Once completed, the pass will also feature pebble resin strips, a specialised material that aids eel movement while limiting the build-up of debris.
During periods of high flow, the design allows for natural self-cleaning, reducing the need for manual maintenance and helping to maintain higher water quality standards by minimising blockages and stagnation.
To further improve efficiency, the system has been designed for easy visual inspection from the riverbank and will include remote monitoring capabilities, strengthening overall maintenance, reliability, and long-term resilience.
Francis Frimpong, Environment Agency project manager, said: This new eel pass is another step forward in improving river connectivity and enhancing biodiversity. By enabling eels to navigate past man-made barriers, we’re helping to restore their natural migratory routes and strengthen their numbers for the future.