What are the problems?
Cannop Ponds are classed as reservoirs under the Reservoirs Act 1975. Together, both reservoirs hold over 100,000m3 (the equivalent of 40 Olympic-size swimming pools) of water above the surrounding ground level. This means there is a potential risk to life if the reservoirs were to fail, and so they are classified by the Environment Agency as “high risk”.
Water seepage through the Lower Cannop dam has been an on-going issue for many decades, creating holes, or voids, within the structure. We have been maintaining and repairing these voids since the 1970s.
Since the near-failure of Toddbrook Reservoir in Derbyshire in 2019, which led to the emergency evacuation of around 1,500 homes, reservoir safety regulations have become much more strict across the UK. The incident highlighted the importance of ensuring dams and spillways can safely withstand extreme weather events and that reservoirs can be managed effectively in an emergency.
In February 2021 a large void formed next to the spillway wall of Lower Cannop Dam, and so an inspection was carried out by an independent reservoir engineer. This found significant voids under the spillway which were filled with concrete. This “patch and repair” was never a long-term solution and does not fix the underlying problems.
We also found that the spillways at both Upper and Lower Cannop were not large enough to cope with the extreme rainfall expected with our changing climate. This leaves the dams in danger of ‘over-topping’, where excess water flows over the top of the dam. Over-topping is a common cause of dam failures worldwide because water quickly erode the outer face of earth dams, causing them to collapse.
Significant engineering work is required to overcome these issues, which is why we began to explore various options. The more we looked at what Cannop Ponds could be – for the community, for the climate, and for nature – the more the legal obligation to do something presented itself as an opportunity improve the site as a whole.
Project objectives
Our main objective has always been to make the reservoirs safe. It was for this reason that doing nothing was not an option.
We also had four additional objectives which have helped us to reach a conclusion on the best solution:
- Climate – The risk of flooding is increasing with our changing climate. This project will ensure Cannop Ponds are resilient to storms so that the valley is protected from flooding from dam failure.
- People – Cannop Ponds is a popular location both for local people and visitors. The project will benefit people in the long-term, allowing people of all ages and abilities to spend time outdoors.
- Nature – Cannop Ponds is a haven for wildlife, and our plans will help even more species thrive by creating new habitats and improving conditions in and around the water.
- Heritage – This project respects the heritage of Cannop Valley, and we will work to bring some of those stories from the past to life for our visitors of today and tomorrow. .
Narrowing down the options
In March 2023, we presented four options to the public for the future of Cannop Ponds. The results of this consultation were shared with the public in August 2023.
In October 2023, we received a flood modelling report detailing the results of a flood risk model. The results showed that the re-naturalisation of Cannop Brook could potentially increase future flood risk and so this option was immediately discounted.
The three options were assessed against the project's overall objectives, with careful consideration given to the survey results and public views and comments. All this information helped inform the Outline Business Case for the project. In January 2024, the Forestry England Executive Board approved our decision, and we shared our chosen option for Cannop Ponds with the public in February 2024.
Developing the design
2024 saw a lengthy process of procuring and onboarding a design and build supplier for the project - Balfour Beatty were appointed as our principal contractor, and they have worked with Mott MacDonald to develop an outline design based on Arup’s early concept design. Development of the outline design for the scheme began in November.
From mid-2025, we re-evaluated the outline design and the procurement route for the project. This led to the decision to update the project brief and refine several aspects of the design, particularly at Upper Pond to provide a better community space and opportunities for nature. Further alterations and updates were made to the outline design at the start of 2026, which included updating the hydraulic modelling of the site to refine the proposed design.
Throughout this period, detailed assessments and surveys were carried out across the site, as well as continued engagement with Forest of Dean District Council, the Environment Agency, Natural England, and other public bodies.
What happens next?
We will collate the feedback we receive from our 2026 public engagement events. Where appropriate, comments will be incorporated into the design and planning process.
We intend to submit the planning application in early 2027. Given the scale and complexity of the project, the application will be supported by a full Environmental Impact Assessment (EIA).
Detailed design work will take place which will see the proposals developed further and incorporate any changes required because of surveys, technical assessments and feedback from stakeholders. We will seek a range of regulatory approvals, including Habitat Regulations Assessment (HRA) consent, Water Framework Directive assessments and approval of the reservoir safety works by a Qualified Civil Engineer.
Assuming the planning application is approved, we will then develop the detailed construction drawings and confirm all of the final construction arrangements and costs with Balfour Beatty. We will also need to carry out all of the pre-construction planning conditions, including measures to protect wildlife during construction.
Construction is expected to begin in 2028 and will take around two years. We will continue to keep you informed about progress and any impacts associated with the works.
Have a question?
You can find frequently asked questions about our plans for Cannop Ponds on our main project page.
If your question hasn't been answered, you can email the project team at cannopponds@forestryengland.uk
