Weir Removal – Acorn Bank, Cumbria, National Trust
Client: National Trust / Environment Agency Project Type: Weir Removal | Fish Passage | River Restoration Key Statistic: 45 m naturalised river reach | 800+ tonnes of stone
Project Overview
TM Lindsay Ltd delivered the sensitive removal and naturalisation of a failing weir on Crowdundle Beck at Acorn Bank in Cumbria.
The project involved removing the redundant structure and replacing it with a nature-based boulder cascade, improving river connectivity while maintaining the water supply required by the historic Acorn Bank Watermill.
Our Delivery
Following removal of the deteriorating weir, our team constructed a natural boulder cascade extending approximately 45 metres along the river reach.
More than 800 tonnes of locally sourced gravel, cobbles and boulders were used to create a carefully constructed sequence of cascades and pools.
The finished channel was designed to provide a more natural transition through the former weir location while improving upstream fish passage and creating varied aquatic habitat.
Working Within a Sensitive Setting
The project required the needs of river restoration, ecology and heritage to be carefully balanced.
Works were undertaken with ecological and archaeological supervision to protect the surrounding environment, designated habitats and any features of archaeological significance encountered during construction.
Key Works
Complete removal of the redundant weir
45 m natural boulder cascade
800+ tonnes of locally sourced gravel, cobbles and boulders
Cascade and pool construction
Improved upstream fish passage
Aquatic habitat creation
Protection of the historic watermill supply
Ecological supervision
Archaeological supervision
Project Outcome
The project replaced an ageing hard-engineered structure with a more natural river form, improving ecological connectivity while retaining an important part of Acorn Bank's historic water-management system.
The completed scheme demonstrates TM Lindsay Ltd's ability to deliver technically demanding in-river construction where environmental, engineering and heritage requirements must all be carefully managed.
Environmental & Heritage Oversight
Throughout the project, our team worked under the supervision of both a qualified ecologist and an archaeologist to:
Safeguard the surrounding river environment.
Ensure that any archaeological finds were properly recorded and preserved.
Avoid disturbance to protected species and designated habitats during construction.
Outcome & Benefits
Improved river connectivity and biodiversity.
Enhanced upstream habitat availability for key aquatic species.
Long-term protection of Acorn Bank’s historical watermill infrastructure.
Delivery of a sustainable and low-impact alternative to hard-engineered weirs
Funding & Partnerships
This project was funded through the UK Government’s Species Survival Fund, developed by Defra and its Arm’s-Length Bodies. It is being delivered by The National Lottery Heritage Fund, in partnership with Natural England and the Environment Agency.
