Environment

Water abstraction (low flow rivers)

Over the last 20 years the environmental impact of abstracting groundwater for public water supply in our region has come under scrutiny.

Concerns have surrounded the catchments Chitterne Brook, River Wylye, Malmesbury Avon, Upper Bristol Avon River Piddle in Dorset.

It was thought that our abstraction was reducing the flow in these rivers causing them to run very low during dry summers.

Flow reduction can reduce the growth of plant life and cause pollution. However calling a halt to abstraction from groundwater would lead to a loss of public water supply, which means finding an alternative resource.

Background

We proposed a £105m replacement scheme in our 2000-2005 business plan which the water regulator Ofwat did not support on the grounds of cost.

Instead it asked the Environment Agency (EA) and English Nature (EN) to work with us to find a less expensive solution, which was formally adopted by the signing of a Statement of Intent in June 2002.

This aims to minimise the use of the groundwater sources affecting the rivers Chitterne, Wylye, Piddle and the Upper Bristol and Malmesbury Avons, 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.

We also helped to maintain adequate river flows by pumping water into a river to supplement flow, known as stream support.

Since 2002 we have operated these sources as per the Statement of Intent and monitored the effect on the flows and river ecology.

In 2006 the monitoring was reviewed and reported to the stakeholders. A revised Statement of Intent was agreed and trialled from 2007 to March 2010.

The trials are now complete and a final report was issued to the stakeholders (EA, DEFRA, Natural England and Wiltshire Fisheries Association) in June 2010.

Applications to vary the relevant abstraction licences for Chitterne, Alton Pancras and Cowbridge and to provide stream support will be made in 2010 in line with the trial outcomes agreed with the EA.