Low flow rivers
Many of the our region’s rivers are designated as Sites of Special Scientific Interest and as candidate Special Areas of Conservation under the EC Habitats Directive for their chalk river and other species.
Over the last 20 years reservations have been expressed about the environmental impact of groundwater abstractions and in the Wessex Water region these have concerned abstraction from the catchments of the River Wylye, Malmesbury Avon, Upper Bristol Avon, and River Piddle, in Dorset.
It was thought that abstraction for public water supply was reducing the flow in these rivers, causing them to run very low during dry summers. Such flow reduction can also affect the growth of water crowfoot, or ranunculus, and alter siltation and pollution levels.
These aspects affect the fishery, the appearance of the river and, where the site is designated as being of special scientific interest, or as a candidate Special Area of Conservation, the biodiversity interest.
Calling a halt to abstraction from the groundwater would lead to a loss of public water supply and mean finding an alternative resource elsewhere.
Wessex Water proposed a £105m replacement scheme in its 2000 - 2005 business plan, AMP3, which the water regulator Ofwat did not support on the grounds of cost.
Instead it asked that the Environment Agency (EA), English Nature (EN) and Wessex Water, who have worked together to solve the problem of low flows for a number of years, work to find a less expensive solution.
Following a period of further collaborative work a phased interim solution has been agreed for implementation from 2002 to 2006 and a number of lower priority sites were also investigated.
This solution was formally adopted by the signing of a Statement of Intent in June 2002 by Wessex Water, English Nature, the EA and Ofwat. The underlying detailed operation, associated monitoring and assessment is defined in an Operating Agreement, Section 20 of the Water Resources Act 1991) between Wessex Water and the EA.
The Statement of Intent measures involve minimising the use of the sources affecting the rivers Chitterne,Wylye; Cowbridge, Malmesbury Avon; and Alton Pancras, River Piddle, by:
- maximising the use of the supply from Bristol Water
- seeking additional water from Wimbleball reservoir
- pursuing further leakage control and implementing local stream support arrangements.
These three sites will be abstraction sources of last resort and in wet years they might not be used. However, under dry conditions when there is increased public demand for water they might need to be used up to typical current abstraction rates.
In addition, stream support will be used as a balancing measure to maintain adequate river flows. In 2006 the monitoring will be reviewed and finally reported. The details of the statement of intent and the reports are reported in the AMP3 section.
For the period 2005-2010, AMP4, the EA has identified a number of further sites, wetlands and rivers, which may be adversely affected by public water supply abstraction, which is shown below. Wessex Water will be investigating these sites to determine whether or not there is an adverse effect and whether local alterations can be applied to minimise that effect, see Investigations.
Information from these investigations will be used by the EA in determining its review of consents under the Habitats Regulations 1994 and for the Hampshire Avon, this review is programmed for March 2008.
During the next business plan period, AMP4, we will also be investigating alternative water resource options that can replace any licensed volumes that may be lost as a result of the investigations, the review of consents and the Statement of Intent studies.
This project, known as the Low flow Solutions project will look at the feasibility, cost and environmental impact of a number of potential resources in order to allow a preferred option to be selected in time for a substantive start by 2010, see Low Flow Solutions.
A technical steering group, comprising the EA, English Nature and Wessex Water, will jointly agree monitoring standards and the interpretation of the results of our investigation of rivers and wetland areas. Any new sources are likely to require permissions, including new abstraction licences, planning consents and land drainage consents, and these will also be subject public consultation. We will therefore undertake a public participation process to understand the opinions of stakeholders. These opinions, with the ecological and engineering studies, will contribute to the review of consents by the Environment Agency and thus influence the choice of any alternative sources of water.
If you need information that is not featured on these pages, please email: low.flows@wessexwater.co.uk or contact the low flows project manager on 01225 526000.