Turf Lock Fish Pass - River Lark, Mildenhall

We are thrilled to share the successful delivery of a fish pass installation on the River Lark—one of the UK’s rare chalk streams— in Mildenhall, Suffolk.

Designed by Fishtek for the Environment Agency, the pass is built within the existing river channel using rip rap rock and strategically placed boulders, allowing vital upstream fish migration past two historic control structures.

Delivered by Breheny Civil Engineering under the AOMR Framework, following ECI and ground investigation via the old FOF Framework, for the Environment Agency.

Key site logistics included:

• Damming the river with a Robert Nicolas Portadam upstream and a Breheny Civil Engineering-designed dam downstream.
• Over-pumping via four electrically driven submersible pumps, supplied by GAP Plant, powered by remote low-noise diesel generators to minimise impact on nearby residential areas.

We encountered several challenges which we overcome, including:

• Navigating complex permits and environmental constraints.
• Managing unpredictable in-channel flows.
• Operating within a restricted site with limited access for plant and machinery.

We are proud to be part of a project that improves river health and biodiversity while balancing technical, environmental, and community sensitivities.

You can view the construction process here https://youtu.be/cAWepquaw98