Protection of groundwater against pollution

KEY POINTS

The directive includes:

• criteria for assessing the chemical status of groundwater;
• criteria for identifying significant and sustained upward trends in groundwater pollution levels, and for defining starting points for reversing these trends;
• preventing and limiting indirect discharges (after percolation through soil or subsoil) of pollutants into groundwater.

Groundwater chemical status

Groundwater is considered to have a good chemical status when:

• measured or predicted nitrate levels do not exceed 50 mg/l, while those of active pesticide ingredients, their metabolites and reaction products do not exceed 0.1 µg/l (a total of 0.5 µg/l for all pesticides measured);
• the levels of certain high-risk substances are below the threshold values set by EU countries; at the very least, this must include arsenic, cadmium, lead, mercury, ammonium, chloride, sulphate, nitrites, phosphorus (total)/ phosphates, trichloroethylene and tetrachloroethylene, as well as conductivity (the water’s electrical conductivity enables the concentrations of the various minerals dissolved in it to be measured);
• the concentration of any other pollutants conforms to the definition of good chemical status as set out in Annex V to the Water Framework Directive;
• if a value set as a quality standard or a threshold value is exceeded, an investigation confirms, among other things, that this does not pose a significant environmental risk.

The presence of pollutants in groundwater

• By 22 December 2008, EU countries had to set a threshold value for each pollutant identified in any of the bodies of groundwater within their territory considered to be at risk. As a minimum, they had to set threshold values for the list of pollutants indicated above. For each pollutant on the list, information (as defined in Annex III to this directive) must be provided on the groundwater bodies characterised as being at risk, as well as on how the threshold values were set. These threshold values must be included in the River Basin District Management Plans provided for under the Water Framework Directive. In 2010, the European Commission published a report based on the information provided by EU countries.
• EU countries must identify any significant and sustained upward trend in levels of pollutants found in bodies of groundwater. In order to do so, they must establish a monitoring programme in conformity with Annex IV to this directive.
• Taking account of Annex IV to the directive, EU countries must also define a starting point for reversing these upward trends. Trend reversals will focus on concentrations which pose a risk to associated aquatic ecosystems, dependent terrestrial ecosystems, human health or legitimate uses of the water environment.

Preventing and limiting discharges of pollutants

• The programme of measures drawn up for each river basin district under the Water Framework Directive must include preventing indirect discharges of all pollutants, in particular those hazardous substances mentioned in Points 1 to 6 of Annex VIII to the Water Framework Directive, as well as the substances mentioned in Points 7 to 9 of the Annex, when deemed to be hazardous. Furthermore, pollutants not listed as hazardous must also be limited if they pose a real or potential risk of pollution.
• Except in those cases where other EU legislation establishes more stringent requirements, preventive measures may exclude, among other things, the results of authorised direct discharges, pollutants present in such small quantities that they pose no risk, the results of accidents or natural disasters, or pollutants resulting from discharges which, for technical reasons, the competent authorities consider to be impossible to prevent or limit without resorting to measures that would increase the risk to human health or to the environment or to measures that would be disproportionately costly.