Fish Pass to Allow for Trout Migration

If you walk along the river Lark in the centre of Mildenhall, you may well come across this strange-looking structure: the fish pass. Part of a project between BFER and the Environment Agency, this is the end result of years of work and is now very nearly complete.

The river Lark is one of only around 200 chalk streams in the world – a globally rare habitat found mostly in southern England. These rivers are naturally fed by underground aquifers with water that is clean, cool, and mineral-rich and support a unique variety of wildlife.
Historic structures like mills and locks have had a lasting impact on the river Lark, disrupting the river’s natural flow, hindering habitat-forming processes, and blocking the movement of migratory fish, preventing them from reaching their spawning grounds or escaping poor water conditions. This has led to a gradual decline in biodiversity and the health of the river’s ecosystem.

Turf Lock, located in Mildenhall, has long acted as a barrier to fish passage, so the Turf Lock fish pass was built to address some of these problems and is part of a wider effort to restore the health of the river Lark. Throughout the BFER scheme, work has been carried out to remove in-river structures and install fish passes along the river to support the free movement of native species such as wild brown trout, eels, and other river wildlife. By improving habitat quality and removing obstacles to fish migration, this work helps wildlife thrive and builds resilience for the future.

Now the temporary dam, to allow the work to be carried out at Turf Lock, has been removed and normal river flows have resumed. The final in-channel works, following testing of the fish pass, are underway to ensure the pass allows the passage of smaller fish, as well as the larger trout.

Residents are reassured that removal of the Turf Lock weirs will not increase flood risk and the work fully complies with the Water Framework Directive and contributes to improving the health and biodiversity of the river Lark. The Environment Agency would like to thank local residents and visitors for their patience and understanding throughout what has been a complex and challenging project and to apologise for any inconvenience caused during these works.

To mark the project’s completion, an informative celebration event is planned for the end of June, which will allow locals to come and discuss the works, and the wider plans for the river Lark. More information about this event can be found here: Turf Lock Celebration.

We will also be installing interpretation panels at the fish pass site which will provide the history for the in-river structures removed, and explain how the fish pass works, as well as the benefits it will have for the river.

For the safety of the public and to protect local wildlife, the public is kindly reminded to observe the fish pass from the riverbank only. While it offers a fascinating view of river restoration, this structure is not safe for paddling, swimming, or water sports.