Clay’s Lake Habitat Creation


Over many years, the Crawley and Horley area suffered from repeated flooding events from the upper reaches of the River Mole. In 2000, 109 homes were flooded – following this event, the Environment Agency developed a mitigation scheme, including the enlargement of an existing dam at Clay’s Lake.

This was a very substantial project, involving several years of construction, at a total cost of £5.4M, which commenced in late 2014. The project would increase reservoir capacity from 10,000m3 to 400,000m3. Clearly, a project on this scale involved significant earthworks. Ecosulis was appointed to undertake a range of habitat creation schemes across these newly exposed areas. We also restored 1.2ha of degraded heathland adjacent to the works which had been used for commercial forestry.

The site encompasses a wide variety of habitats, from pond to wildflower meadow (right), heathland and bog to native woodland and reedbed. Ecosulis is responsible for the maintenance of each of these areas from 2016 to 2024.

Our habitat creation work completed in 2020, and we are now exclusively involved in site maintenance. This comprises upkeep of deer fencing, habitat management, ecological monitoring and site access maintenance.

Project brief

Ecosulis wasn’t just involved in restoring nature, but also had a hand in the landscaping work and subsequent site maintenance.

We’re always happy to roll up our sleeves and solve problems that arise on site – here are some of the projects that we’ve worked on over our 8 years here:

– Created over 1.2ha of wildflower meadow
– Planted over 10,000 trees and shrub with guards
– Installed 600m2 coir pallet-based reedbed
– Removed over 2000m of GCN fencing
– Supplied and installed 50m of access material
– Installed 100m of deer fencing
– Created 200m of French drain
– Maintenance of all habitats




manage Biodiversity

Our initial intervention, sensitively designed to factor in the local context, led to a dramatic boost in biodiversity across plant and animal species. The site is now a haven for wildlife.

Protect Habitats

With such a varied topology, this site allowed us to create a rich mosaic of habitats, which maximised biodiversity. We were also able to restore the degraded heathland and bog with careful management and planting.

empower-us-to-act People

We worked closely with the Environment Agency and the two landowners who own each side of the site, to ensure that all decisions were effectively and transparently communicated. The habitat, stabilising the hillside and soaking up runoff, should further reduce flood risk, acting as a natural sponge.

How we added value

Sensitive Habitat Restoration

With the site lying adjacent to an existing woodland, and partially overlapping a relict heathland, a context-sensitive planting scheme was essential.

Our expertise in rewilding enabled us to select native trees, shrubs, climbing plants and wildflowers which would thrive, boosting biodiversity. Indeed, even trained ecologists could now mistake certain planted areas for naturally-regenerated growth.

In just one recent visit, our team found Nightjar (Amber list bird species), Grass Snake, Slow Worm, many Wood Ant nests, 100s of bees, butterflies, dragonflies and newly-emerged frogs scattering across the wildflower meadow. This animal diversity reflects the diversity of plant species which have been introduced to the site.

Restored woodland habitat
Marsh Thistle growing in the bog
Active Rewilding

Our approach to this project may be described as ‘active rewilding’ – this is distinct from ‘passive rewilding’ which is ‘leaving land to recover by itself’. 

Active rewilding, in contrast, focuses on a big initial intervention, to correct the course of natural processes and guide them towards a more balanced end state. E.g. we didn’t leave a few weeds to take over the whole site – rather, we intervened, seeding wildflowers and Yellow Rattle to reduce the vigour of grasses. At the end of this initial period, human inputs were significantly reduced but biodiversity continued to climb as the ecosystem started to heal itself.

By selecting the right species of plant, putting them in the right place and making targeted interventions like cutting bracken or putting in deer fencing, we set the ecosystem on the right trajectory. This delivers results quickly, as demonstrated at Clay’s Lake.

Want to learn more about rewilding and nature recovery?

Read more insights or explore our previous work.