Past conservation projects

Removing a barrier to fish passage on the Tillingbourne

Working in partnership with the Environment Agency (EA) and Fishtek, the project group successfully removed a concrete weir in Spring 2025, which was acting as a barrier to the passage of a range of fish species on the river.

Project outcomes

The barrier removal has resulted in a more natural and varied flow of water through the channel, expanding passage for fish including European Eel and Brown Trout. Additional gravel and rock should facilitate successful spawning and migration upriver.

The team also reprofiled and re-naturalised the river with gravel and a ‘pool and riffle’ sequence to further improve overall biodiversity and support a plethora of freshwater invertebrate species.

Monitoring ecological progress

Before the weir was removed, the Nature-based Solutions team carried out a River Condition Assessment and SWT’s Ecology Services consultancy conducted an Ecological Habitat Baseline Assessment.

In three to five years’ time a post-intervention survey will highlight the impact of changes from a modified channel to a re-naturalised one and assess the regeneration of marginal aquatic plants and vegetation. Likewise, a follow-up assessment of the surrounding habitat will highlight positive change via a Habitat Condition Score. Local fisheries, who were key stakeholders in the project, will be also be tracking changes in fish populations and dynamics.

Building a case for valley mire restoration

This project investigated the feasibility of restoring the valley mire habitat along the Wishmoor Bottom on Barossa, a lowland heathland nature reserve near Camberley, Surrey using Natural Flood Management (NFM) interventions. The project ran from February 2022 to March 2024. The aim of the project was to produce three key outputs to help consider NFM restoration interventions: a Digital Terrain Model (DTM) and Digital Elevation Model (DEM) delivered via drone LiDAR and an aerial photography survey; Soil Investigation Surveys; and a Hydrological Monitoring Programme. 

The project involved working with a number of different partners to undertake surveys to help demonstrate and consider the potential impact of NFM interventions. These included soil core sampling, LiDAR, a plant survey by the Surrey Botanical Society, a breeding bird survey and a River Condition Assessment.  

Following on from the successful completion of the feasibility study, it is hoped that valley mire restoration will be considered in the coming years. The results of the project have been shared with numerous partners and other organisations including other Wildlife Trusts. The project has also been used as a case study for a national Wildlife Trust research project into NFM.  

This project was delivered thanks to funding from Surrey County Council, the Banister Charitable Trust and the A J H Ashby Will Trust.  

Restoring habitats for aquatic wildlife

Cranleigh Waters has a long history of dredging which has left an over-wide and over-deep channel unable to support natural instream processes. In 2023, Surrey Wildlife Trust commissioned Cain Bio-Engineering to carry out river restoration work on a 500m stretch of Cranleigh Waters, upstream of Elm Bridge. This work forms part of a wider project known as the Cranleigh Waters Community Rivers Project, which began in 2018.

The project aimed to restore the natural fluvial geomorphological processes of this stretch of watercourse in order to maintain good-quality instream habitats. The introduction of NFM measures through these works also aimed to reduce flood risk within the catchment. 

The project involved: 

• Reprofiling the banks
• Creating low flow channels
• Installing woody material into the low flow riverbank to protect against erosion
• Narrowing parts of the channel along a 500m stretch of the watercourse. 

This stretch of the channel was re-profiled, reducing the width and enhancing the gravels to allow the river to function in a more natural way. In November 2023, water quality testing kits were purchased thanks to a grant from a local council. These kits were given to the Cranleigh Civic Society, and this has enabled volunteers to carry out tests for a range of factors including phosphates, nitrates and temperature. The data collected will be used to monitor general river health and gain a greater understanding of the effects of pollution events in Cranleigh.

This project was delivered thanks to funding from Thames Water, the Environment Agency, A2Dominion and Surrey County Council’s Flood Team.

Promoting green finance

Through this project, Surrey Wildlife Trust supported six pilot sites across Surrey to create landowner-led Natural Capital Investment Plans (LNCIPs) and develop a business case for landowners to deliver nature-friendly interventions thanks to funding from NEIRF (Natural Environment Investment Readiness Fund), Defra and the Environment Agency. 

The sites selected represented key locations within Surrey’s Biodiversity Opportunity Areas (BOAs). This process helped to explore sustainable delivery models for landowners, providing an opportunity to achieve nature’s recovery through the Local Nature Recovery Strategy (LNRS).  

The main focus was on Biodiversity Net Gain (BNG) through privately-owned ‘habitat banks’, however other options were also explored. The interventions proposed in the LNCIPs aimed to address a variety of issues depending on the needs of the landowner. These included climate change and flood resilience, reduced soil erosion, improved connectivity and condition of habitats, and improved public access/engagement. The LNCIPs provide an assessment of the potential NBS income streams based on the landowners’ objectives.

Following the success of this project, Surrey Wildlife Trust successfully applied for NEIRF funding in round 3 to continue the work exploring Green Finance. You can read about these projects here: NEIRF 3 [link to NEIRF 3 webpage].

Better management for grasslands and woodlands

This project focused on delivering site improvements to Surrey Wildlife Trust’s site, Wallis Wood as part of a Network Rail funded 'no net loss' project.

Improvements focused on grassland management and uplift, which encompassed compartmental seasonal grazing using a local grazier and an annual haycut to boost flora populations. Grazing infrastructure was installed comprising stock fencing and a fixed water supply to troughs. To boost biodiversity further these were lines with hedges, which connected to the outer edges of the woodland and provided additional habitat on site. 

Traditional woodland management, such as coppicing was undertaken with a wide range of work undertaken by the Surrey Wildlife Trust Volunteers, the Surrey Dormouse Group (SDG) and the Surrey Hedgelaying Society. Previously the site has supported Dormice, so a major review of the Dormouse boxes on site was undertaken by the SDG, and boxes re-sited, replaced and remapped. Annual checking is now underway by a licensed ecologist alongside a continued coppicing regime.

This project was an exemplar for collaborative working with SWT, local businesses, species specialist groups and volunteers working together to achieve better outcomes for nature. 

Creating better habitats for native fish 

Surrey Wildlife Trust, in partnership with St George’s College and the Environment Agency delivered a suite of improvements across 500m of the Chertsey Bourne in February and March 2018. The works were designed to: 

• Create fish spawning, foraging and refuge habitat.
• Improve channel morphology to maintain gravels and kick start natural processes within the channel.
• Create fish refuge and spawning areas in a backwater channel.
• Filter out pollutants from the St George’s College surface water drainage system.

The work involved felling a sycamore tree into the channel to promote deposition and create more structure within the channel, as well as enhancing an existing bar through gravel deposition on the riverbed. The deposited gravel also resulted in an increase to fish spawning habitat. 

A berm was installed on the inside of a bend which lacked any existing features to alter the flow dynamics. The berm will help to promote erosional and depositional processes downstream and create a more natural sinuosity to the channel. The berm was backfilled with brash and secured with hazel binders, and within weeks, the berm silted up. 

The backwater channel was dredged to reconnect it to the main Chertsey Bourne, and this resulted in a backwater fish refuge and nursery areas. As part of this work, the following enhancements were made:

• Silt was dredged from the backwater channel to provide deeper water habitat.
• The mouth of the channel was opened up to allow the free passage of fish in and out.
• Marginal shelves were created to provide shallow water habitat and opportunities for marginal vegetation to take hold.
• A reed bed was installed at the surface water outlet end of the channel to help filter pollutants from the St Georges college site.
• Trees were removed from around the channel to allow light onto the reed bed and marginal shelves.

Restoring a river to good health

Surrey Wildlife Trust, in partnership with South East Rivers Trust (SERT), have delivered restoration to a 1km stretch of the Addlestone Bourne in 2023 and 2024. This stretch of the Bourne exhibited riffle and pool habitat with the potential to provide good spawning habitat. However, over time the bed gravels had become compacted, reducing the opportunities for spawning. Additionally, the high banks and heavy tree cover made it difficult for marginal and aquatic vegetation to establish. There was very little cover or refuge for fish, leaving them vulnerable to predation and high flows. 

The works included: 

• Raising the bed height through introducing gravel to create improved fish spawning habitat.
• The removal of silt to increase the riverfly population.
• The installation of a berm to encourage point bar formation.
• V deflectors to create an exciting pool and riffle sequence.
• A new backwater along the ditch line.

The works carried out have resulted in increased flow dynamics as well as the introduction of ripple sequences. Woody material has been introduced into the river to provide increased fish cover, as well as introducing different flows to the river. 

The canopy over the river has been reduced to increase the light able to reach the water and allow the bankside vegetation and in channel vegetation to grow.

As part of the work, invasive species present on the site were removed to ensure they do not spread further. 

Protecting and extending hedgerow habitats

The Hedgerow Heritage project was delivered between 2020 and 2024 and was focused on hedgerows within the North Downs. The project aimed to create and restore hedgerows whilst also promoting them and the vital role they play in landscape recovery to the general public.

The project resulted in 12.82km of hedgerow being created or restored which included both hedge planting and hedgelaying, as well as 65.4km of hedgerow being managed and protected within a management plan. 

Volunteers were a key part of the project due to their role in planting and laying hedgerows, as well as surveying hedgerows to determine their health. 223 volunteers engaged with hedgerow survey training and 164 people received skills training. 35 staff and volunteers were also able to undertake a LANTRA hedgelaying qualification as part of the project.  

Two hedgelaying competitions were held for beginners to get involved in hedgelaying in 2023 and 2024 with a total of 45 competitors over both competitions. Both competitions were judged by Paul Matthews, the winner of the South of England Championship Cup for hedgelaying in 2024 and a local business owner (Hedges & Hurdles). These competitions provided the opportunity for volunteers to get involved and develop their practical skills. Over 100 people came along to spectate and had the opportunity to find out more about hedgerows and hedgelaying. 

In October 2023 over 1,000 people attended Surrey’s first Hedgerow Festival held as part of the project. The festival provided a wonderful opportunity for the public to understand the important role hedgerows have played for hundreds of years. The event was also the chance to celebrate the rich cultural and natural history of these ‘natural heroes’ with local musicians, sustainable food and small businesses all present as part of the event. 

The project also involved engaging with schools. Nearly 7,000 students were engaged through school assemblies and planting hedges on school grounds, providing these students with the opportunity to understand more about these biodiverse habitats. BioBlitzes were also run as part of the project to engage with families and inspire them.

In 2022 and 2023 Dorking Museum hosted an exhibition all about hedgerows and hedgelaying in the North Downs. Heritage tools were put on display as part of an exploration of the history of hedgerows. 

This project was funded by the Heritage Lottery Fund and was a real success, with people across Surrey getting the opportunity to learn more about hedgerows and understand the vital role they play in connecting our landscape.