As at: May 2007

The Groundwater Map

The water at the bottom of it all

Groundwater is a major element of the natural balance. It is part of the hydrological cycle and performs important ecological functions. Groundwater resources close to the surface supply plants with water and form valuable wet biotopes. Groundwater discharges in springs and feeds streams and rivers. Thus the quality and quantity of the groundwater influence surface waters as well. More than 70% of our drinking water comes from groundwater, making it Germany’s most important drinking water resource. However, groundwater is also a habitat in its own right possessing great biological diversity. Living conditions are determined by two factors, oligotrophy and darkness, which make groundwater a unique ecosystem. Only few highly specialised groups of organisms colonise the upper groundwater layers. Life decreases with increasing depth. However, biological diversity is surprisingly great due to the large spectrum of species within the groups. Apart from metazoa living in the groundwater, microorganisms make up the largest share of the biomass. It is therefore of great importance for sustainable development and secure future water supplies to ensure full-coverage, use-oriented precautionary protection for groundwater.

Cleaning and retention capacities of the overlaying soil have been overestimated in the past. With the expansion of the measurement networks for monitoring groundwater quality, it became clear that there is substantial widespread pollution of groundwater, and that a large number of risks exist. Besides point sources or linear inputs like contaminated sites, old deposits, accidents involving substances dangerous to water or leaks in sewers, groundwater is above all polluted by or at risk from diffuse inputs due to industry, agriculture and transport.

These many and various risks are now being combated at European Union level as well. To supplement the Water Framework Directive, special additional regulations to protect groundwater were introduced in a "daughter directive", which entered into force on 16 January 2007. The aim of the new Groundwater Directive is to lay down specific measures for the prevention and containment of groundwater pollution. This includes criteria for the evaluation of good chemical status, for the determination of significant and sustained upward trends in the concentration of pollutants in the groundwater and for the determination of a starting point for trend reversal.

The draft Directive takes over the quality standards of the Water Framework Directive with regard to concentrations of nitrate (50 mg/l) and pesticides (0,1 µg/l). However, it does not lay down quality standards for other pollutants. Instead, Member States are obliged to define threshold values for those parameters/substances that constitute a risk to the groundwater body according to the categorisation carried out under the Water Framework Directive. A minimum set of parameters is prescribed by the draft Directive. The different values can be defined at national level, at river basin level or at the level of individual groundwater bodies.
The Member States transmit to the Commission a list of all pollutants for which they have defined threshold values. Significant and sustained upward trends of pollutant loads in the groundwater have to be determined and reversed with the help of programmes of measures. A value of a maximum of 75% of the quality standard or the threshold values, respectively, is recommended as a starting point for trend reversal in accordance with Article 17 of the Water Framework Directive. Moreover, Member States are to ensure that indirect inputs of pollutants are limited in such a way as to maintain the good chemical status of the groundwater body. The new Groundwater Directive is to be transposed into national legislation by January 2009.

Further Information:

• www.bmu.de/english/water_management