The sustainable water supply project discussed in this article is the first in Danish history to use protection zones to safeguard groundwater from the effects of agricultural production. As experience with groundwater protection zones was very limited 10 years ago, the project involved comprehensive and systematic monitoring to determine the effects of the protection zones on groundwater quality.
The establishment of protection zones around waterworks is a simple and inexpensive way to safeguard the drinking water resource. As more than 99% of Denmark's drinking water supply derives from the nation's naturally pure groundwater, protection of the groundwater resource from agricultural and industrial contamination is accorded high priority Agricultural use of nitrate fertilizers can considerably deteriorate the quality of the groundwater. In Aarhus County alone, more than 100 out of 600 waterworks have been closed due to nitrate contamination.