Working to keep Cannop Ponds safe for future generations
Cannop Ponds are two reservoirs within the Forest of Dean. The reservoirs were created in the 1820s through the construction of two dams across Cannop Brook. Both dams have had a long history of repairs to stop leaks and fill holes to prevent failure. The dams don’t meet modern requirements and so we are legally required to address the problems to ensure future safety.
The more we looked at what we would have to do to fix the issues, the more we saw opportunities to improve the whole site for the future. We are working on a project to reduce the risk of future flood events and create lasting benefits for local people, visitors and wildlife.
A different approach is being taken at Upper and Lower Cannop, to reflect the opportunities that each Pond presents. The two will work together to bring benefits to the wider forest environment. Lower Cannop will continue to be a large area of open water. The dam will be strengthened, and the spillway will be replaced with a completely new structure. A more natural approach will be taken at Upper Cannop, which will be improved to become a haven for wildlife.
Join us at a public engagement event
Attend one of our informal sessions on Thursday 24 and Wednesday 30 September to see the latest plans and illustrations, meet members of the project team, speak to the experts and find out more about our proposed scheme.
If you're unable to join us in person, you'll still be able to take part online through our virtual event space, which will be open from Thursday 24 September to Wednesday 22 October.
Image Gallery
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Managing the risk of future flooding
At Upper Cannop, we will reduce the risk of future flooding by lowering water levels, replacing the existing spillway with a new outlet channel, and improving the stability of the dam and northern causeway. The scheme will also include ongoing silt management and erosion protection, helping the Pond function more effectively during periods of heavy rainfall while ensuring the new infrastructure fits naturally within the surrounding landscape.
At Lower Cannop, we will improve the Pond’s ability to safely manage high water flows by constructing a larger spillway, lowering and extending the weir, and installing a permanent system to reduce water levels when maintenance is needed. Work will also be carried out to reduce seepage/leaking through the dam, to support the long-term safety and resilience of the site.
Enhancing conditions for wildlife
At Upper Cannop, we will create a more natural and wildlife-rich water’s edge with open water, marshes, reedbeds and wet woodland. New floating islands, meadows and grassland areas will provide valuable habitat for birds, pollinators and other wildlife. We will also make more space for nature by providing visitors with a dedicated all-access route, avoiding sensitive areas.
At Lower Cannop, we will enhance habitats around the Pond by improving the margins of the open water and installing bird and bat boxes. New eel passes at both Ponds will help species such as eels and lampreys move more freely along Cannop Brook, supporting healthier and better-connected freshwater ecosystems.
Improving the visitor experience
At Upper Cannop, we will create a more accessible and enjoyable visitor experience by improving access around the dam. Plans include a wider footbridge across the spillway, creating a new all-access trail and boardwalk in the area below the dam, providing a new wildlife viewing platform along the dam and more seating with a terraced picnic area. The Colliers Trail will also be rerouted away from the road to improve safety for walkers and cyclists.
At Lower Cannop, we will make it easier for people of all abilities to enjoy the site. Plans include a wider footbridge across the spillway and improved paths around the bridge and spillway. We will also be renewing existing and providing new accessible fishing platforms and associated access paths to allow fishing to continue for a wider audience. New interpretation of historic features such as the tramway, Bixslade Wharf and the stone works will help visitors discover the area's rich industrial heritage.
Have a question?
We will keep this page up to date with information as the project progresses, or you can follow us on Facebook for more news.
Below is a list of frequently asked questions about the Cannop Ponds project. If your question hasn't been answered, you can email the project team at cannopponds@forestryengland.uk
This is not a project that Forestry England has chosen to undertake; it is work that must be completed to comply with the Reservoirs Act 1975.
As large bodies of water held back by earth dams, Cannop Ponds fall under the remit of the Reservoirs Act 1975. Both reservoirs have serious problems with the earth embankments that hold back the water, as well as with the spillways that help manage water levels.
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.
Upper and Lower Cannop Ponds are classified by the Environment Agency as "high-risk" reservoirs. This classification does not mean the dams are unsafe, but it does recognise that there could be a risk to life if either dam were to fail. Together, the two reservoirs hold more than 100,000 cubic metres of water, so it is vital that they continue to meet the required safety standards.
Regular safety inspections have identified a number of Measures in the Interests of Safety (MIOS) at Cannop Ponds. These include works to address seepage through the dams, improve the reservoirs' ability to cope with large flood events, replace the existing spillways with larger structures capable of safely passing extreme flows, and to install permanent drawdown facilities so the reservoirs can be safely lowered for future inspection, maintenance and repairs.
Without these improvements, the reservoirs would not meet current legal and safety requirements. Carrying out the work now will help ensure Cannop Ponds remain safe, resilient and compliant for many years to come.
Since autumn 2022 we have carried out site investigations and survey work. Working with engineering consultancy Arup at that time, we produced four potential options that met the project's overall objectives, informed by data, surveys and modelling relating to the environment and the distribution and movement of water.
The more we looked at what we would have to do to secure Cannop Ponds, the more we saw opportunities to improve the whole site for the future.[FD1]
In March 2023, we presented those four options to the public at two public consultation events. Members of the public were invited to complete a survey to tell us which option they preferred, as well as share their views and concerns with us. The results of this survey were shared with the public in August 2023.
In October 2023, we received a flood modelling report detailing the results of a flood risk modelling exercise which had been carried out. One of the options we were considering was the re-naturalisation of Cannop Brook, but the results showed that this option could potentially increase future flood risk. Having already committed to deliver a project that would not cause any worsening of future flood risk, this option was discounted, leaving three remaining options to consider.
Those three options were assessed against the project's overall objectives, with careful consideration given to the survey results, public views and comments. Together, this evidence helped our decision on which option to take forward.
All this information helped 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.
The changes we are making at Cannop Ponds will help make the Ponds more resilient to stormwater flows and protect the valley from flooding by reducing the risk of dam failure. By increasing the amount of stormwater the reservoirs can hold, we can reduce the risk of flooding downstream during heavy rainfall.
With climate change making extreme storms more likely, it is essential to upgrade these structures. Currently, the dams are vulnerable during major storms. Their spillways, which act like overflow drains, are too small to handle the large volumes of water that could be produced during extreme events. When a spillway is too small, water can flow over the top of the dam, a situation known as ‘over-topping’, which is a common cause of dam failures worldwide.
The new larger spillway structure at Lower Cannop will be capable of passing future floods safely. Reducing the water level in Lower Cannop and increasing the height of the dam will also increase stormwater storage capacity and reduce flood risk. The existing spillway at Upper Cannop will also be replaced with a new outlet channel capable of safely passing future floods. The stability of the Upper Cannop dam will be improved by lowering and flattening the top and making the sides less steep, as well as improving the existing causeway at the northern end of Upper Cannop so it remains stable during major flood events.
In the long-term, the changes at Upper Cannop will hugely benefit wildlife and complement the retention of the large body of water at Lower Cannop. Our work will safeguard the protected species that currently call the Ponds home throughout the entire design and construction process.
At Upper Cannop, we will maintain areas of open water for native fish and other aquatic life. In addition, we are creating a more diverse and dynamic landscape with new marshes and reedbeds. These new habitats will provide significant benefits for a wide range of wildlife, including wetland birds, dragonflies, and otters.
This project is dedicated to enhancing the area's value for wildlife and is legally committed to achieving "biodiversity net gain," which means leaving the local environment in a measurably better condition than it was before.
The construction phase will cause some temporary disruption. To ensure the highest level of protection for the area's wildlife during this period, the project will be strictly guided by two important assessments:
- An Environmental Impact Assessment (EIA): This is a comprehensive evaluation of the project's potential environmental effects, ensuring that steps are taken to avoid or minimize them.
- A Habitat Regulations Assessment (HRA): This assessment specifically focuses on ensuring that the project will not negatively impact protected habitats and species.
We are collaborating closely with environmental experts and regulatory agencies to lessen the impact of construction. Our shared goal is to see the new and improved habitats flourish as quickly as possible once the work is complete.
Upper and Lower Cannop Ponds were built around 200 years ago to provide water to Parkend Ironworks.
The dams and spillways have changed over the years, so the heritage value is less about the structures themselves and more about the landscape heritage of the water bodies in the valley.
Keeping the Lower Cannop dam allows for interpretation of the Bixslade Tramway Crossing and its historic importance, taking stone from the quarries high up on the valley sides down to the ‘railway’ in the valley bottom. The current stone works is part of that same landscape heritage and will be largely unaffected by the project.
A lot of the earth embankment at Upper Cannop will be retained, again retaining the link to the past. However, the spillway will be replaced, and other alterations will need to be made.
We will continue to work with our delivery partners Balfour Beatty and Mott MacDonald to develop the engineering proposals. After the public engagement events we will further develop the plans and use the updates to prepare a planning application.
We intend to submit the planning application in early 2027. Assuming the planning application is approved, we will 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 the construction phase.
We hope to start construction in early 2028 and we expect this will take around two years to complete.
The project has been delayed due to the need for detailed technical assessments and ongoing stakeholder consultation. These steps are essential to ensure the planning application is robust and reflects the complexity of the site.
It has taken longer than expected to undertake the surveys and complete the design work necessary to develop the project proposals to the next stage. This has included appointing our construction delivery partner, Balfour Beatty.
Our priority is quality over speed. We’re taking the time to get this right - balancing safety, sustainability, and public feedback – to deliver a solution that protects and enhances this special place.
The proposal has been further developed in much more detail than the draft plans which were shared with the public in 2024.
The scheme has been fully designed, taking on board all of the additional survey information that we have since received, including topographic and bathymetry data.
The flood model has been further developed which has allowed us to calculate how big the new spillways need to be, and options for the drawdown facilities have been explored. It is important that we deliver a system which is easy to maintain and is as unobtrusive as possible. We have taken time to consider how the new spillways will look, blending into the natural environment as much as possible. We want Cannop Ponds to remain as a beautiful place to visit.
Options for improving the biodiversity have also been further developed - this includes consideration to species which are present but also some which are missing. For example, we only recorded six species of dragonfly and the new scheme should appeal to many more.
Yes! In the long-term, Cannop Ponds will continue to be an important place for local people and visitors.
Forestry England have no intention to stop or limit the public from visiting the site once the project has been completed. We will continue to welcome people of all ages, abilities and backgrounds to enjoy the wellbeing benefits of nature and the outdoors. A key part of our plans will be to improve the visitor experience across the site.
We will keep everyone safe by closing the site to visitors during the construction phase. The car park will be closed as it will be used as the main construction depot and site offices. The Colliers Trail will be permanently diverted to a new route so that it can remain open. The Public Right of Way across each of the dams will also be temporarily closed during construction.
The car park and picnic area will be reinstated once construction is completed.
Members of Yorkley Angling Club will continue to be able to fish at Lower Cannop when construction work is completed.
The fishing rights at Cannop Ponds have been let to the Yorkley Angling Club for many decades. This arrangement will continue on Lower Cannop, with new fishing platforms installed by the project, along with improved access paths.
The Colliers Trail will be permanently diverted to allow the trail to be used throughout the construction phase. This new route will also improve visitor safety, as cyclists will no longer need to share the driveway with cars, instead following a new route through the forest. People will still be able to cycle to and from Cannop Ponds via the Colliers Trail – as with Mallards Pike.
The hydroplant at Lower Cannop will be removed and will not be replaced.
The existing hydroplant isn’t very efficient due to the way the reservoirs work. Hydroplants need more reliable conditions with constant high flows. The flows at Lower Cannop are unreliable and we won’t be able to change this as part of the scheme.
From a historical perspective, getting an adequate and reliable flow of water for the waterwheel at Parkend Ironworks was troublesome from the start, and the hydroplant has suffered from the same issue.
The design of this major engineering scheme is still at an early stage, and the project cost will change as the detailed design and planning requirements are finalised. At this stage, based on input from our construction delivery partner, we anticipate the cost being in the region of £25m.
The project is being funded by Forestry England and is our organisation’s largest financial investment to date, to secure the future of this important asset for the Forest of Dean.
Forestry England is an executive agency, sponsored by the Forestry Commission. Forestry England manages more land and trees than any other organisation in England. We provide hundreds of car parks, maintain thousands of miles of trails, and plant millions of trees.
With less than 20% of our core funding coming from the government, we raise the remaining funds ourselves. Money raised is reinvested into the woodlands that Forestry England cares for.
Yes. For us to complete all the work needed at both Ponds, the water levels will need to be reduced.
Water levels in both Upper and Lower Cannop Ponds will need to be lowered, likely using pumps and siphons, although this detail will be developed during the next phase of the project. Lowering the water levels is essential so that we can remove the silt that has built up over time, remove and rebuild the spillways and inlets and repair and strengthen the dams.
In our current plans, we anticipate a full drawdown of the Upper Pond to facilitate construction. This is to ensure the silt in the basin can be dried out appropriately, as it will be used for landscaping purposes and the creation of the wetland habitat. We are currently looking at ways to continue the flow from Cannop Brook downstream.
Lower Pond does not need to be fully drained but may need some reduction in water level to create safe and dry working areas, mainly around the replacement of the lower spillway.
The visual impact of the construction works will be significant, with exposed Pond beds and reduced water levels.
We will provide more information on this operation when we move closer to that stage of construction.
Prior to desilting, fish in Upper Cannop will be removed, weighed, carried and stored in Lower Cannop. Fish welfare will be closely monitored and maintained until they are returned. At the appropriate time, an equivalent weight of native fish species will be netted in Lower Cannop and returned to Upper Cannop.
As Lower Pond does not need to be fully drained, we do not expect there to be any impact on the fish assemblage.
No, there is no link between the Cannop Ponds project and the Forest of Dean District Council's Biosphere application.
The crocodile will be kept and relocated. The final location is still to be confirmed.
