Based on the first review under Article 10 of Directive 2006/118/EC, not enough information is available to set new groundwater quality standards in Annex I to that Directive for any pollutants, but technical adaptations in accordance with Article 8 of that Directive are necessary in its Annex II.

Common principles for the determination of background levels need to be applied in order to improve the comparability of threshold values.

There is considerable potential for nitrogen and phosphorus in groundwater to present a eutrophication risk to associated surface waters and to directly dependent terrestrial ecosystems. Besides nitrates, already included in Annex I to Directive 2006/118/EC, and ammonium, included in Annex II to that Directive, nitrites, as a contributor to total nitrogen, and total phosphorus, either as such or as phosphates, should also be considered by Member States when establishing threshold values.

The need to obtain and respond to new information on other substances posing a potential risk should be acknowledged. Therefore, a watch list for pollutants of groundwater should be established under the Common Implementation Strategy for Directive 2000/60/EC of the European Parliament and of the Council2 to increase the availability of monitoring data on substances posing a risk or potential risk to bodies of groundwater, and thereby facilitate the identification of substances, including emerging pollutants, for which groundwater quality standards or threshold values should be set.

The information provided by Member States on the pollutants and indicators for which threshold values have been established, in particular as regards the methodologies related to groundwater chemical status assessment, proved insufficient in the first river basin management plans to enable proper understanding and comparison of the results. The relevant requirements regarding the information to be provided should be clarified and complemented in order to ensure the transparency of that assessment. The information provided would also facilitate comparison of the chemical status assessment results across the Member States and contribute to a potential future harmonisation of methodologies for establishing groundwater threshold values.

Directive 2006/118/EC should therefore be amended accordingly.

The measures provided for in this Directive are in accordance with the opinion of the Committee under Article 9 of Directive 2006/118/EC,