9. Good-Quality Groundwater

9. Good-Quality Groundwater. Photo: Jeppe Wikström/Johnér Bildbyrå."Groundwater must provide a safe and sustainable supply of drinking water and contribute to viable habitats for flora and fauna in lakes and watercourses."

Groundwater is important as drinking water for humans, and also affects the habitats of plants and animals in surface waters. Emissions of environmentally hazardous substances can contaminate this water resource – pesticides are one example, particularly in agricultural areas of southern Sweden. Sodium chloride (common salt) from roads salted in winter has also found its way into groundwater. As well as affecting the quality of the water, this causes corrosion of water mains.

Water moves in a continuous cycle. It evaporates as water vapour from lakes and seas, and falls to the earth’s surface as rain and snow. Some of it seeps down through soil and rock to form groundwater, which in turn, after a certain residence time in the ground – determined by local conditions – discharges into lakes, watercourses and seas.

What are the challenges?

In general, demand for and hence the pressures on groundwater are increasing. This is partly because people are moving permanently to coastal areas and what used to be second homes. To prevent groundwater contamination, water protection areas need to be established.

Eskers and similar formations in the landscape are important sources of drinking water. These natural gravel deposits are also of significance for our energy supply, the natural and cultural landscape, and recreation. At the same time, there is pressure to extract gravel from them, for concrete and other uses. By creating more protection areas, the authorities can safeguard deposits of this kind against exploitation.

We need to know more about how groundwater affects surface waters. Contaminants such as mercury and nutrients may be transferred from groundwater to lakes and watercourses, but as yet we have a poor general understanding of the processes involved.