Forestry England is moving forwards with plans to tackle the safety concerns around the ageing Cannop dams
At the end of 2022, Forestry England received the independent inspection report for Upper Cannop Ponds. This report classifies Upper Cannop as a ‘category B’ reservoir, which is defined as one where a breach or failure could result in a loss of life and could result in extensive damage downstream. Both Upper and Lower Cannop reservoirs are defined as ‘high risk’ by the Environment Agency.
In the summer of 2022, Forestry England announced that the future of Cannop Ponds was uncertain.
With the information available at the time, Forestry England set out to explain to the community the problems facing the two dams, and what options were being explored for the future of Cannop Ponds. No decision has been made about the future of the dams.
With lots of questions and concerns circulating in the autumn, Forestry England is today releasing a clear and concise document ‘Cannop Ponds: The Next Chapter’ which sets out the background and range of options for Cannop Ponds. We are also committing to sharing information with the public over the coming weeks, leading to a public engagement session where people will be able to have their say.
Since the summer, a great deal of additional survey work has been undertaken to better understand the current position.
These include technical surveys to find out more about the construction and condition of the two dams and spillways, and surveys to verify the depth of the two reservoirs, and shape of the valley floor below the water.
Wildlife surveys have been undertaken to more fully record what plants, fish, animals and insects use Cannop Ponds currently.
We have also commissioned preliminary ecological and heritage impact assessments.
This survey work is on-going as we further our knowledge of the site, so that decisions on the future are well informed.
Kevin Stannard, Deputy Surveyor of the Forest of Dean, said:
“Last summer the pubic expressed just how passionately they care for Cannop Ponds. This came as no surprise, and I encourage people to engage with the facts and share their ideas and concerns for the future.
Our aim has always been to be as open and transparent as we can, which is why we broke the news when we did, while still gathering all the information we need.
This new document sets out where we are now, the problems we face and what our priorities are for ensuring that the best solution is found. We are committed to ensuring it’s a solution that helps the Forest, its people and wildlife, thrive into the future and remain as resilient as possible against our changing climate and the biodiversity crisis.”
High risk reservoirs
Cannop Ponds are classified as two separate ‘high risk’ reservoirs by the Environment Agency. Whilst historically the two reservoirs were treated as a single entity, in cascade, the two are now separately registered. This is because individually, both hold over 25,000m3 of water, which is the current legal threshold for registration under the Reservoirs Act (1975).
Between the two reservoirs, over 100,000m3 of water is stored.
Both Upper and Lower Cannop are unable to safely contain a one in a 150-year flood event due to inadequately-sized spillways. Both spillways are structurally deficient and there are on-going concerns regarding leakage and ‘voiding’ linked to their age and historic construction methods that leave them vulnerable to failure.
The failure of one or both dams could lead to loss of life, and would result in significant damage in the villages of Parkend and Whitecroft, and could cause property flooding in Lydney. Doing nothing is not an option.
Keep up to date with the project www.forestryengland.uk/article/the-future-cannop-ponds