background levelmeans the concentration of a substance or the value of an indicator in a body of groundwater corresponding to no, or only very minor, anthropogenic alterations to undisturbed conditions;
baseline levelmeans the average value measured at least during the reference years 2007 and 2008 on the basis of monitoring programmes implemented under Article 8 of Directive 2000/60/EC or, in the case of substances identified after these reference years, during the first period for which a representative period of monitoring data is available;
groundwater quality standardmeans an environmental quality standard expressed as the concentration of a particular pollutant, group of pollutants or indicator of pollution in groundwater, which should not be exceeded in order to protect human health and the environment;
indicator of pollutionmeans a parameter which can be monitored to give a value that is representative of the level or concentration of a pollutant or a group of pollutants and thus of the risk posed by them.
input of pollutants into groundwatermeans the direct or indirect introduction of pollutants into groundwater as a result of human activity;
significant and sustained upward trendmeans any statistically and environmentally significant increase of concentration of a pollutant, group of pollutants, or indicator of pollution in groundwater for which trend reversal is identified as being necessary in accordance with Article 5;
threshold valuemeans a groundwater quality standard established at Union level and listed in Annex II part D or established by Member States in accordance with Article 3(1)(b);