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An award winning project

The Big Biodiversity Challenge

Winner of the Community Engagement Award with Mace at the CIRIA Big Biodiversity Challenge Awards for the Rosendale Allotments Depave project

The Lord Mayor's 2015 Community Partners Award Winner

Supported London Wildlife Trust in winning the Lord Mayor’s Dragon Award for Community Partnership through hosting the nomination film at the Rosendale Allotments Depave project (a project created in partnership with Mace, Lambeth Council and the local community)

Lambeth Community Pride Awards

Runner up in the Innovation category at Lambeth Community Pride Awards for the Cressingham Rain Gardens in partnership with local residents

Winner of the Sustainable Water Industry Group (SWIG) Award for Open Spaces and Agriculture

Winner of the Sustainable Water Industry Group (SWIG) Award for Open Spaces and Agriculture and Highly commended for the SWIG Award for Communication (non-schools based)


The Lost Effra project - sustainable water management in London

Lost Effra, Sam MellishImage credit: Sam Mellish

What is the Lost Effra project?

Imagine if every household in London depaved their front garden, built a green roof on their shed or fitted a water butt to capture rainwater from their roof…

Lost Effra is a project led by London Wildlife Trust that empowers communities to create green landscape features to increase local resilience to the changing climate whilst also improving neighbourhoods for people and wildlife.

The project is based within the catchment of the culverted river Effra that runs through a highly urbanised and socially diverse area of South London, removing concrete and tarmac and creating new green spaces that manage rainwater more intelligently. The presence of the Effra, one of London’s lost rivers, in the sewers beneath the area increases its vulnerability to flooding in times of heavy rainfall.

Through working with local people on urban greening projects, we are making London more resilient to extreme weather whilst supporting London’s biodiversity and empowering people to create and maintain their own urban greenspaces.

Commissioned by Defra and the Carnegie Trust in 2013, the project is now made possible through support from Thames Water, the Greater London Authority and Lambeth Council, as well as the valuable input and assistance from a range of local stakeholders, community groups and private sector partners.

Our work so far

Throughout 2013 we conducted a detailed scoping phase, producing a strategy document on how to deliver sustainable water management on a community scale. The report, A New Way to Manage Water is available here.

Since 2014, we have been working with communities in Herne Hill and Brixton, creating new living landscape features such as green roofs, rain gardens and through taking up hard paving that help to make the area more resilient to environmental change.

The following projects have been completed by the Lost Effra project, in partnership with local people and other local stakeholders.

Cressingham Rain Gardens, SW2

We worked with residents from the Cressingham Gardens estate, volunteer landscape architect David McCollum and Lambeth Council to create a 30 metre green corridor including a series of three rain gardens.

The rain gardens each receive rainwater from a downpipe from the roof of a large residential building next to the gardens. Rainwater that fell on this uninspiring area of grass was previously sent running downhill into the Brixton flood risk area is now caught and held temporarily in the gardens before being taken up by plants and naturally soaking into the ground.

Rainwater is now used to water the gardens, nurturing the plants and supporting the insects and birds that they provide the gardens act as important urban habitats for.

The project has been made a huge success by the residents to look after and maintain the gardens – many thanks to all of those who have been involved.

Courtesy of Sam Mellish


Depaving at Rosendale Allotments, SE24

One of the largest allotment sites in south London, Rosendale Allotments is an 18 acre steeply sloping clay site with a significant impact on flood risk in its surrounding area, Herne Hill.

The concrete forecourt that previously acted as a bottleneck for rainwater runoff from the site was transformed through a collaboration between Mace and London Wildlife Trust, working with plot holders and the Rosendale Allotment Association to remove the concrete forecourt. The previously impermeable surface has been replace it with 100 square metres of new wildflower meadow and recycled plastic block paving that can hold 80 cubic metres of rainwater runoff – enough to fill 8,000 baths!

Now when it rains, rainwater that flows down to the forecourt is stored in a thick layer of recycled crushed stone beneath the block paving and the sudden heavy flows of water that cause flash flooding in times of heavy rain are reduced. In time, the water evaporates back into the air, or is slowly released into the sewers after the main flow of runoff in a storm has passed.

The project acts as a valuable local example of depaving; showing ways of working with nature to reduce flood risk and boost local wildlife. It was funded by Mace, Lambeth Council and J. Coffey.

Rosendale Allotments depaving project
















London Wildlife Trust’s ongoing partnership with Mace through practical conservation on our reserves and outreach projects such as this one have helped us to win the Lord Mayor’s Dragon Award for partnership with the community. Click below to see the video.




Green roof workshops at Sydenham Hill Wood, SE26

Another key part of Lost Effra is to give local people the skills and knowledge to take on their own projects to create new living areas in their neighbourhoods through accessible and engaging workshops.

Through one day green roof workshops, we lead a group of volunteers through the process of building a small scale green roof through from design to planting. At the end of the day, we have built and planted a green roof and people go home with the skills and knowledge to build a green roof on their garden shed, flat roof or bike shelter.

Sydenham Hill Wood green roof workshop


If you would like to find out about upcoming workshops please email Helen Spring, Lost Effra Project Coordinator at

Living with Rainwater 

Living with Rainwater is a community guide to creating urban greenspaces for environmental resilience.

The Lost Effra’s introductory guide to creating household scale rain gardens, building green roofs, depaving and fitting rainwater harvesting is available free online just by clicking on the image below. 

Find out more and get involved

If you are a local resident or community group that would like to find out more about starting a green roof, rain garden or depaving project in your part of the Effra catchment then we would love to hear from you.

Whether you have a simple idea for an area that you have always wanted to green up, a roof that’s crying out for a green topping or a flooding problem in your communal area then please get in touch. We can help plan, find funding and deliver projects with you.

Alternatively, if you would like to be kept up to date with events, workshops and meetings please get in touch and ask to be included on the Lost Effra mailing list.

Please contact Helen Spring, Lost Effra Project Coordinator on

Follow us on Twitter @LostEffra 

Cressingham Rain Gardens, SW2 Image Credit: Sam Mellish