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