This page was written in July 2010.
People who live in north-west England are being affected by their first hosepipe ban in 14 years. A prolonged dry spell has led to unusually low water levels in rivers and reservoirs, but BGS data show that groundwater levels in the deeper aquifers in the region are currently in the normal range.
BGS holds over one million measurements of groundwater levels in the National Groundwater Level Archive. Some wells have been monitored for over 100 years, enabling us to look at very long term changes. Data from a 90 metre deep borehole at Skirwith (near Kirkby Lonsdale) shows that groundwater levels in some parts of the Permo-Triassic Sandstone that underlie the North West are around average for July, based on data collected since 1978.
Groundwater provides about 15 per cent of public water supply in north-west England and is particularly valuable during times of surface water shortages.
BGS has an active research project in north-west England. We are studying interactions between groundwater and surface water in the Eden Valley, looking particularly at how land use can affect water quality. Our monitoring indicates that groundwater levels in small upland sub-catchments (with less groundwater storage capacity) have fallen in response to the lack of rainfall. Our hydrogeologists regularly monitor water quality from wells, boreholes, springs, and streams.
The current drought provides a rare opportunity to study an extreme event and we will be undertaking additional sampling during the summer to observe what impacts the dry spell has had on water quality. We expect to see increased concentrations of contaminants such as nitrate due to reduced dilution.
Groundwater supplies are mainly replenished during autumn and winter, and are not so affected by periods of unusually low summer rainfall as surface waters.
Major aquifers (rocks with large groundwater stores) such as the Permo-Triassic Sandstones of north-west England are buffered against periods of low rainfall because of their ability to store vast volumes of water.
Groundwater contributes about 30 per cent of public water supply over England and Wales, and over 80 per cent in south-east England. Groundwater is also of great importance to private users, such as farmers, who abstract from their own wells and boreholes.