Lost Effra SuDS projects

This page provides an overview of four SuDS projects across the Lost Effra catchment that help reduce surface water flood risk and improve water quality. They have also helped bring communities together.


Where & why were the SuDS projects built?

This SuDS scheme was part of the larger and longer-term Lost Effra programme. This has been run by London Wildlife Trust, in partnership with Lambeth Council and Thames Water, since 2013.

The scheme is based within the catchment of the fully culverted River Effra. The river is at risk of flooding in times of heavy rainfall. You can use this map to see where all the different Lost Effra projects are.

The scheme aims to show what local people can do on a household scale to make their area more resilient to flooding and climate change. This is mainly by creating community owned demonstration gardens and green roofs in visible public spaces. Local people are involved throughout.

Project description

Lowden Road traffic island rain gardens

In heavy rain, surface water collected near the traffic island at the Lowden Road / Milkwood Road junction due to a lack of gully pots. This neglected traffic island was covered in impermeable concrete paving slabs. It has now become an attractive and functional pedestrian space with 48m2 of new gardens. These have been carefully planted for wildlife value in partnership with the local community.

The rain gardens take in surface water from the pedestrian paths, and from the surrounding roads through kerb inlets. The traffic island also features an interpretation board introducing the concept of SuDS and small household-scale interventions. Local schools have created a mosaic inspired by the wildlife that would have been found in the River Effra.

Oborne Close depaving and community gardens

This low-rise housing estate features a popular pedestrian route downhill to Herne Hill station. Surface water from this hill contributed to repeated local surface water flooding. Along this route, 110m² of concrete paving slabs have been peeled back and replaced with four new, wildlife-rich community gardens. The gardens soak up rainwater and stop it from running down the hill towards the central Herne Hill flood risk zone.

Three rain garden planters have also been installed around the estate in locations suggested by residents. These will soak up rainwater from the rooftops of three houses.

As part of the project, free water butts were offered to all households on the estate. Four have been installed onto downpipes near the community gardens, to help water the gardens during dry summer weather.

The largest garden includes an interpretation board explaining the concept of depaving and its importance for climate change resilience. This is particularly important in the context of paving over private gardens.

As with all Lost Effra schemes, the gardens were designed and created with residents of Oborne Close and the local area.

Brockwell Park Green Roof

A green roof was created at Brockwell Park Community Greenhouses by 15 volunteers during a one-day group-build session. The aim was to give volunteers the skills they needed to build their own small scale green roofs at home and in local spaces.

They were supervised by London Wildlife Trust and local green roof installers Green Engineers, who provided:

  • an introduction to green roofs and their benefits for urban rainwater management, wildlife, and other ecosystem services
  • information about all materials used, where they can be sourced and costs
  • information about the plants chosen for the green roof, including their suitability for the conditions and value to local wildlife
  • DIY information for volunteers to take home with them and help them in building their own small-scale green roofs
  • email advice for those constructing green roofs

Another workshop showed a new group of volunteers how to plant the new biodiverse green roof and add deadwood features for invertebrates. A pre-existing but low-quality green roof was also upgraded by adding more substrate and new planting. This was to encourage biodiversity and increase rainwater attenuation.

Depaving at Calidore Close

A drought-tolerant wildlife garden was also created with residents from Calidore Close, SW2. The impermeable roadside entrance to this social housing estate contributed to localised flooding. This made it difficult for less mobile residents to access the building.

The new 25m² garden has been designed to need very little water in summer. This is because there are no opportunities for collecting rainwater for irrigation on the estate. The Tenants and Residents Association helped encourage local interest in the project. Chalk artwork marking out the area before depaving also helped raise local awareness of the project. The Project Officer worked closely with residents on the project design.


All four projects are maintained either by residents or by the relevant community group.  Care was taken not to take on projects where the community was not fully prepared to maintain the SuDS measures.


Environmental improvements

These four projects have converted 269m² of impermeable surfaces into free-draining gardens and biodiverse green roofs. They have all been designed to provide high value habitat for urban wildlife, specifically urban pollinators. Planting schemes have been shaped by the community and designed for local people to take care of. The projects have also installed 1,080 litres of rainwater harvesting capacity. This will provide a sustainable source of water for the gardens in periods of dry weather.

Community engagement and education

In total, the projects have directly engaged more than 500 local people through:

  • consultations;
  • community planting opportunities;
  • celebration events to mark the completion of projects; and
  • engagement projects with schools.

Local people have been involved throughout and given the chance to take part in the projects at all stages. This has helped the community ownership that is vital to secure ongoing maintenance of the SuDS measures.

Inviting people to join practical activities, like green roof builds and planting days can engage the public and raise awareness of the need for climate change resilience. Most people who attended project workshops and took part in practical activities reported higher awareness of flood resilience. They were also more motivated to act locally to reduce flood risk.

Eye-catching and accessible interpretation boards also continue the projects’ impact beyond construction.

Community cohesion

Being part of the project has helped increase residents’ sense of community cohesion. Planning meetings and planting days gave neighbours, who’d not met, a purpose. Residents often swapped numbers and email addresses to keep in contact. Residents described ‘feeling rooted in the community’.

At Oborne Close, residents pointed out one vegetated area that was shaded and poorly lit at night and had been the scene of muggings and other anti-social behaviour. This was turned into a rain garden with open vegetation, reducing the shading and helping make the area feel safer.

The Oborne Close project has now been used as a springboard to encourage other improvements around the estate. Residents have lobbied for other essential works to be completed. This includes fixing broken paving slabs, repairing dangerous missing paving on steps, and installing community noticeboards. The project has also led to continued discussions between residents and Lambeth Housing about establishing a Tenants and Residents Association.

Main challenges and lessons learned

Sub-surface infrastructure

The junction of Lowden Road and Milkwood Road previously supported a tram line and stop. As a result, there was considerable hardstanding underneath the traffic island’s paving. Removing this hardstanding across the whole traffic island would have made the project very expensive. This meant that the new pedestrian path across the island could not be made of permeable surfacing.


There are no outdoor water sources for watering the Lowden Road traffic island rain gardens. This is a problem that has been encountered on several Lost Effra projects in public spaces. Dry summers mean residents use jugs and watering cans to fill water pipes by the newly planted trees and plants whilst they become established.

Council contractors

At Oborne Close, the rain gardens inspired residents to plant extra areas across the estate. The plants were in the form of small plugs that had not yet fully established. As a result, much of the new planting was destroyed by council contractors clearing ivy from the wall. This will be replaced with more mature and obvious plants.

Browse pictures from the Lost Effra projects

Photos credit: Helen Spring, London Wildlife Trust

Lost Effra facts and figures

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