• 374 new purposefully designed ‘leaky dams’ are being installed across Epping Forest – making it the largest natural flood-management project of its kind in the southeast.
• The scheme will reduce flood risk for over 500 homes by slowing peak flows during heavy rainfall and bring a range of ecological benefits to the Forest.
• City Corporation invests £150,000 of its Climate Action funding into the project. 

One of the southeast’s largest natural flood-management projects is underway in Epping Forest – the largest open space managed by the City of London Corporation as a registered charity. 

Over the next year, 374 purposefully designed ‘leaky dams’ will be installed in ditches and streams across “the Green Lungs of London” using natural materials such as logs and branches to slow water flow during periods of heavy rain. 

The vast majority of materials used will come directly from Epping Forest itself. 

Timber generated through routine habitat management and the City Corporation’s ongoing habitat restoration programme — including carefully planned thinning and pollarding to restore wood-pasture habitats and maintain tree health — will be reused to construct the leaky dams, reducing waste and working with the Forest’s natural processes. 

Once complete, the project is forecast to hold approximately 10,000 cubic metres of additional water within the Forest – the equivalent of four Olympic-sized swimming pools. 

The locations for each dam have been carefully selected using detailed hydrological modelling, which predicts how rainfall moves through the Forest and identifies the points where slowing water will have the greatest impact downstream. 

As well as helping to protect hundreds of homes, this retention and slow release of water will deliver a range of benefits for the Forest and its wildlife by: 

• Supporting tree health by retaining soil moisture and improving the Forest’s resilience to drought during dry weather
• Creating wetter habitats, allowing plants, fungi and wildlife to continue to thrive
• Improving water quality and soil stability by reducing erosion caused by fast-flowing water and trapping sediment before it moves downstream 

The project is backed by £200,000 of Local Levy from the from the Thames Regional Flood and Coastal Committee’s Natural Flood Management programme, administered through the Environment Agency, and supported by a further £150,000 from the City Corporation’s own Climate Action Strategy funds – delivering climate-resilience benefits for local communities from Essex to London. 

Working closely with the Thames Regional Flood and Coastal Committee, the multi-agency project pools together the expertise and experience from a range of partners, including: Essex County Council; the London Boroughs of Waltham Forest, and Redbridge; Epping Forest District Council; Natural England and local volunteers. 

Chair of the City of London Corporation’s Epping Forest and Commons Committee, Caroline Haines, said: 

“This is a landmark project for Epping Forest and the wider region. By working with nature, we can better protect local communities for whom the Forest is practically their back garden. 

“Not only will this initiative help safeguard homes and improve the landscape’s resilience to more extreme weather, it will also create conditions where wildlife can thrive, enhance the Forest’s ability to store carbon, and improve air quality. 

“A project of this scale requires many hands, and I am incredibly grateful to the partners, staff and volunteers already involved. With dozens of volunteer ‘beavers’ signed up and our new corporate volunteering opportunities now open, we’re inviting even more people to play a part in protecting this extraordinary landscape.” 

Head of Conservation for the Epping Forest charity, Tanith Cook, added: 

“There’s much more science behind these leaky dams than people might realise — what started with a simple review of the Forest’s streams and ditches led to an extensive hydrological modelling exercise, using computer programs to show how water moves through the Forest. We’ll be monitoring soil moisture and water levels inside trees and using satellite imagery to analyse the tree canopy’s health over time. 

“Some of the smaller dams can look like fallen branches or blockages, but they’re carefully designed and doing an important job. They are intentionally subtle, so please don’t tamper with them — they’re quietly protecting homes and helping the Forest thrive.” 

Cllr Mark Platt, Cabinet Member for Highways, Infrastructure and Sustainable Transport at Essex County Council, with responsibility for flood management said: 

“Essex County Council is pleased to see the installation of leaky dams in Epping Forest - an effective, nature-based solution that helps reduce flood risk while delivering real benefits for both local communities and wildlife 

“By slowing the flow of water, these dams create healthier river habitats, support biodiversity, and enhance the forest environment. This project also offers a valuable opportunity for volunteers to get involved and make a meaningful contribution to wildlife conservation. 

“I look forward to seeing this project develop, and it is a strong example of how Essex County Council can work with local partners to protect and enhance our unique natural environment.” 

Standing at around 8,000 acres, Epping Forest is one of the last remaining examples of ancient wood-pasture in southern England. It is both a Site of Special Scientific Interest and a Special Area of Conservation due to its national and international importance. 

ENDS 

Notes to editors 

The City of London Corporation is the governing body of the Square Mile, dedicated to supporting a diverse and sustainable London within a globally successful UK – www.cityoflondon.gov.uk. 

The City Corporation owns and manages a network of 11,000 acres of open spaces which remove carbon dioxide, contain important habitats and wildlife and improve air quality. 

The Epping Forest Leaky Dams project is due to be completed by Spring 2027. 

This project is one of several Carbon Removals and Land Management initiatives to help protect the existing carbon stored by our open spaces and to increase their carbon capturing (sequestration) capacity. 

Using open spaces to remove carbon – www.cityoflondon.gov.uk/services/environmental-health/climate-action/climate-action-projects/using-open-spaces-to-remove-carbon. 

More information about the City Corporation’s wider Climate Action Strategy – www.cityoflondon.gov.uk/services/environmental-health/climate-action/climate-action-strategy. 

For information on volunteering and corporate volunteering opportunities, visit www.cityoflondon.gov.uk/things-to-do/green-spaces/epping-forest/volunteer-at-epping-forest or email efvolunteering@cityoflondon.gov.uk. 

For leaky dam volunteering days, visit - www.eventbrite.co.uk/cc/leaky-dam-building-4798037 

List of project partners and volunteers 

• Thames Regional Flood and Coastal Committee are the main funder for the project through their Natural Flood Management (NFM) programme.
• Essex County Council are the lead local flood authority (LLFA) and lead applicant for the NFM grant; oversees governance, procurement, and delivery.
• London Borough of Waltham Forest are the partner LLFA and supported with the design, supporting volunteers and community engagement.
• London Borough of Redbridge and Epping Forest District Council were also local authority partners and provided planning input and environmental oversight.
• Teams across the City of London Corporation’s Environment Division were responsible for the delivery and technical leadership, including project management, ecological planning, and GIS mapping.
• Natural England provided SSSI consent and reviewed and approved the City Corporation’s Habitat Regulations Assessment screening.
• Epping Forest volunteering organisations, including Epping Forest Conservation Volunteers and Epping Forest Heritage Trust, assisted City Corporation teams with dam construction and maintenance.
• Edenvale Young were contracted as hydrological consultants, using expert modelling to ensure the design delivered the best outcome for both nature and flood defence.