Catchment case studies

The Catchment Team are working with farmers and other key stakeholders in the Worthing and Brighton areas to address high levels of nitrate at our drinking water sources.

By partnering with the Arun to Adur Farmers Group in Worthing and the Chalk Management Partnership (now The Aquifer Partnership) in Brighton, we have been able to:

• raise awareness of how drinking water sources are affected by nitrate leaching from agriculture (often due to fertiliser usage)
• fund soil health monitoring and specialist advice to promote more efficient fertiliser usage
• develop and incentivise a range of measures that can be implemented on farms to reduce how much nitrate from fertilisers leaches into groundwater, such as:
  • establishing a ‘cover crop’ over winter to take up excess nitrate in the soil and reduce soil erosion
  • fallow (rest) periods between crops
  • putting high priority areas into grassland rather than cropping
  • 'precision farming' – using satellite imagery and soil data to only apply fertiliser where it is needed.

This catchment-based approach, addressing the causes of high nitrate levels, aims to reduce our reliance on costly, engineered nitrate removal solutions and ensure our drinking water sources are sustainable in the long term. By promoting sustainable farming practices, we can also achieve benefits for the farming community and the natural environment.

We have successfully run two pesticide amnesty projects with local farmers in Sussex (Brighton and Worthing) and in Kent (Medway). The Kent project was co-funded by Kent County Council and North Kent Marshes Internal Drainage Board.

Around 100 farmers participated in these projects and 4,200 litres of potentially harmful chemicals were removed from our catchments.

We wanted to help farmers get rid of stores of unwanted and out-of-date chemicals such as pesticides. Without intervention these chemicals can potentially leak into the soil and end up in surface waters and ground waters, and cause damage to the environment. Once these chemicals get into our drinking water supplies we have to use enhanced treatment processes to remove them to meet the drinking water quality standards.

The amnesty really helped us to engage with farmers and landowners, and start conversations with them about the vital role they play in ensuring the health of habitats and safeguarding our water supplies. 

This work will benefit woodlands, grasslands and wetland areas across the Scotney estate, a Site of Special Scientific Interest, for many years to come.

Working in partnership with the National Trust was a natural fit with the scheme aligning perfectly with the Trust’s goal of actively contributing to the improvement of the water environment for the benefit of everyone.

“As a conservation charity, it’s our responsibility to look after the Scotney Castle estate for nature. This project sits hand in hand with the work we do here, with particular benefits in terms of landscape scale wildlife corridors and habitat improvements.

Thanks to the work of our partners, we hope to see a real boost in the health of the river in the years to come. National Trust will survey for dragonflies, newt and butterflies while Southern Water continues to survey aquatic invertebrates.” - Mark Musgrave, Area Ranger, Scotney Castle

The river enhancement project is a key element of our Bewl Water Mitigation Scheme to reduce the impact of releases from nearby Bewl Water reservoir, by creating a more natural flow that’s closer to how nature intended.

Southern Water's supply area covers Kent, Sussex, Hampshire and the Isle of Wight in the South East, supplying over one million homes and businesses.

70% of the water we supply comes from groundwater abstraction, and 80% of that groundwater is supplied from the chalk.

The groundwater in the chalk provides important base flow to chalk rivers and streams, resulting in clear and clean water, which supports a rich and diverse ecosystem. The Rivers Test and Itchen in west Hampshire are among the world’s finest examples of chalk stream.

Southern Water for many years has sought to balance the need to supply water to our customers, at the same time, ensuring there is enough water left to support the environment.

However, the pressures of more extreme weather events and a growing population all put strain on these important calk rivers. Consequently we are working with the Environment Agency, landowners and key stakeholders through our Water Industry National Environment Programme (WINEP) to meet the objectives of the Water Framework Directive, and carrying out investigations to inform the amount of water for the environment, and if our abstractions are having an impact.

To protect the important chalk habitat if it is found that our chalk abstraction is having an impact, as part of the mitigation our abstraction licence would be updated, reducing the abstraction, and making more groundwater base flow available for the environment.

It must be said that often just making more water available for the environment does not necessarily fully address the issues to our chalk rivers and stream, which might have become heavily modified through the passage of time, for example from milling, fishing, urban development, with straightening, concrete lining, milling, weirs to name a few.

Consequently to ensure the objective of protecting the important chalk habitat, Southern Water also carries out river and wetlands enhancement often as part of a mitigation package, which helps to provide ecological resilience to the river, with the creation and enhancement of natural habitat, the removal of barriers to fish passage and improving the hydromorphological function.

River enhancement schemes

Examples of our recent river enhancement schemes include:

Isle of Wight – Lukely Brook

The Lukely Brook is located on the Isle of Wight and is designated a ‘Heavily Modified Water Body’ (HMWB) under the Water Framework Directive (WFD).

While the upper part of its catchment is rural, the HMWB status relates to its lower, more urbanised reaches, due to the historical use of these sections support industry (e.g. mills) and to provide potable supply – the brook currently flows through a series of mill ponds, leats and fords as a result.

In AMP5, the Lukely Brook was the subject of a National Environment Programme (NEP) WFD investigation.

The investigation concluded:

• The Lukely Brook is heavily modified and that appropriate mitigation measures were not in place.
• The ‘poor’ status in fish populations was primarily due to the morphology and barriers and fish passage.

In AMP6, Southern Water worked in partnership with the Environment Agency, landowners and the Newport Rivers Group to implement river enhancements at four separate locations, designed to help mitigate the issues identified in AMP5, with improving fish passage of the Lukely Brook.

At two site locations Larinier fish and Eel passes were installed:

At one location a series of 'pre barrage' weirs were installed with central notches to allow fish passage:

At the last location, three rock weirs with central notches were installed to allow fish passage:

Kent – Little Stour

The Environment Agency, during the Alleviation of Low Flows scheme (ALF), identified the Little Stour in Kent (including its tributaries the Nailbourne and Wingham River) as one of forty priority rivers in England and Wales giving cause for concern, due to low flows caused by groundwater abstractions for public water supply.

Low flows in the Little Stour are also impacted by historic channel modification. Milling and channel realignment resulted in the river being moved from the valley bottom, disconnecting the river from the groundwater upon which it relies.

In AMP6 and AMP7, Southern Water and its project partners, Affinity Water, South East Water, the Environment Agency and landowners, have been designing and delivering a scheme to enhance the ecology of the Little Stour by:

• improving fish passage around Littlebourne Mill
• improving resilience of fish stocks within the river
• providing additional habitat enhancements.

- Chris Woolhouse, Catchment Hydrogeology Strategy Manager

People living in south Hampshire have always relied on the Rivers Test and Itchen for their water. So reductions to the amount of water that the Environment Agency allows us to take from these two rivers poses a significant challenge to us.

These reductions aim to secure the health of these rivers while reducing the amount of water we can take from them during drought. The changes mean a shortfall of about 80% of the amount needed to supply our customers in south Hampshire.

We have until 2027 to meet the new conditions and plan to invest more than £800 million to make up the shortfall, while ensuring water resources continue to be resilient and environmentally sustainable. Our wide-ranging plans include desalination, new pipelines from neighbouring water companies, reducing leakage and improving water efficiency.

- Nigel Hepworth, Water Resources Policy Manager

Many of our raw drinking water sources in Sussex are situated in the region’s famous chalk downland.

Across the Brighton and Worthing Chalk Block, the level of nitrate within the aquifer can be high, and we have  traditionally relied on water treatment processes in order to adhere to the strict drinking standards for customer supply.

Our new, more sustainable approach to protecting the current and future drinking water sources is based on the idea that prevention is better than cure. We’re using catchment management to identify how land use, pollution hazards and
groundwater pathways could impact on water quality. Then we’re working to understand what we need to do to protect groundwater quality at source, so that costly and energy-intensive treatment can be minimised, or even avoided, further down the line.

Across the Brighton and Worthing Chalk Block, we’ve funded long-term land management incentives to implement best practice measures that reduce nitrate leaching into the groundwater. Alongside this, farmers can use our capital grants scheme to apply for funds towards infrastructure that will also help to reduce pollution.

In the Worthing Chalk Block, we are working with a cluster of farmers who have come together to form the Arun and Adur Farmer Group. Together, we’re exploring more sustainable ways of using nitrate in these rural settings. For example, we
have worked with farmers to carry out soil testing to identify exactly what their crops need – and how much – so fertilisers can be used more efficiently without impacting yields. This gives the farmer value for money while protecting our water
sources and the environment.

Across the Brighton Chalk Block, we are part of The Aquifier Partnership (TAP), alongside Brighton and Hove City Council, the South Downs National Park Authority and the Environment Agency. Through this collaboration, we are undertaking research, engagement and awareness campaigns for both urban and rural pollution sources.

This long-term strategy will help to provide a resilient water supply for future generations while reducing the number of nitrate treatment works needed. The approaches implemented to protect water quality also provide benefits for soil health, carbon, as well as the wildlife and biodiversity of
the iconic Chalk Block.

- Claire Neale, Catchment Management Strategy Manager

Southern Water’s Catchment team has been working with a local farm to help improve its pesticide handling facilities and reduce the risk of chemicals reaching our groundwater sources.

Located on the outskirts of our Steyning groundwater catchment, Paythorn Farm is a mixed arable and livestock farm with land on the South Downs and the Low Weald.  As a ‘conventional’ (non-organic) farm, it uses pesticides to control weeds, pests and diseases in its crops, when recommended by its agronomist.

Some studies suggest that up to 40% of pesticides reaching our watercourses come from filling and handling practices in farm yards, rather than spraying in the field. At Paythorn Farm the existing process was to fill its pesticide sprayer on an outdoor area of yard, a common practice on farms. The Farm Manager was aware this posed a risk to water quality as drips and spills weren’t being contained and approached Southern Water in 2019 to ask about potential funding.

Southern Water was able to offer a grant of £10,000 through our Farm Capital Grant Scheme to help the farm build a new bunded filling area linked to a biofilter – a biological on-farm treatment system that can greatly reduce pesticide concentrations in water.  Any drips or spills can now be contained and treated on site, which reduces the risk of any of these chemicals reaching our abstractions.