The Cann Weir project will undertake vital preparatory works for the removal of the weir to restore natural river processes and enable passage of Atlantic salmon on the River Plym in South Devon, UK.
The River Plym is located in South Devon, UK. It flows from Dartmoor National Park through the Plym Valley, passing through the city of Plymouth before reaching the Plym Estuary, which is designated as a Special Area of Conservation and Protected Marine Area. The river supports a wide range of wildlife and is recognised as an English Priority Salmon River. Plymbridge Woods, where the weir is located, forms part of the National Trust Plymbridge Woods Estate and provides public access along the river within a wooded valley on the edge of Plymouth.
| Project status | Live |
|---|---|
| Project type | Dam removal: pre-demolition |
| Country | United Kingdom |
| River | Plym |
| Focal species | Atlantic salmon |
| Organisation | National Trust |
| Website | coming soon. |
Cann Weir is located on the River Plym approximately 6 km from the estuary and is associated with the historic industrialisation and quarrying of the Plym Valley. The river supports Atlantic salmon, alongside other priority species including brown trout, European eel, brook lamprey and sea lamprey.
A previous study assessed the passability of Cann Weir and concluded that it acts as a complete barrier to upstream migration for all target species under all modelled flow conditions. While some individuals may pass during high flows, the weir significantly restricts access to high-quality spawning grounds further upstream in the River Plym and its tributary, the River Meavy.
There are no known downstream barriers, and funding from the Open Rivers Programme provides an important opportunity to work towards removal of the barrier, restoring natural processes and fish passage along this section of the river.
This phase of the project builds on feasibility and options appraisal work already undertaken at the site. It will deliver surveys, ground investigations and detailed design required to support consent applications for the proposed barrier removal. This will be carried out alongside stakeholder and public engagement to ensure the project’s objectives are clearly communicated and supported.
The primary aim of the barrier removal is to restore fish passage along the River Plym. In addition, it is expected to deliver wider benefits, including improved coarse sediment transport, enhanced geomorphological processes and increased resilience to extreme low and high flow events associated with climate change. The latest salmon stock assessment (CEFAS et al., 2025) classifies the River Plym population as ‘At Risk’. Restoring access to upstream spawning habitats will help strengthen population resilience.
The project will also complement ongoing restoration efforts in the catchment, including headwater restoration, and aligns with Atlantic salmon being identified as a priority species under the Devon Local Nature Recovery Strategy.
Funded by
