Benson weir replacement

Background

The Benson Weir replacement project is part of our ongoing work to refurbish major assets along the non-tidal Thames to improve our Navigation service.

The footpath over Benson Weir unfortunately needed to be closed in November 2022 due to increasing safety concerns resulting from the accelerated weakening of the overall structure. The weir structure has performed well over its operational life but has been affected in recent years by the impact of floating objects against the deteriorated steelwork.

Planning for the new weir

Our project team developed a business case during 2023 to secure the funding to progress the design and construction work. Technical designs for the new weir were completed in January 2024, and construction started in June 2024.

Creating the new weir

This significant project needed to be delivered over a 2-year period due to its scale and complexity. Periods of high flows during the construction work increased the complexity and duration of this project as our contractor used floating pontoons to position all of their cranes and equipment.

We prioritised the replacement of the weir gates to enable our operational staff to be able to continue managing the River Thames flows throughout the project. Our contractor then focused on the creation of a new structure that allows many fish and eel species to pass easily though the weir structure. This fish / eel pass will help to improve the overall biodiversity of the non-tidal Thames and is something that we aim to achieve with every major weir refurbishment.

We have also improved the weir guarding system that reduces the likelihood of objects hitting the new weir during periods of increased river flow.

Our contractor has substantially completed the weir replacement works, and the weir walkway re-opens at 9am on 1 April 2026. The improved walkway over the weir has an increased width of 1.5m, compared to the previous 0.9m. This will allow more Thames Path users to walk over the weir more freely and also allows for our operational staff to adjust the weir gates when needed without obstructing walkers.

Photos of the completed Weir

Contact us

Please email enquiries_thm@environment-agency.gov.uk(External link)(External link) if you have any queries regarding this project. 

You can also phone our National Customer Contact Centre on 03708 506 506 (Monday to Friday, 8am to 6pm)