Threshold Values rationalisation current state of work Water Framework Directive Common Implementation Strategy – Working Group Groundwater Johannes Grath Rob Ward Manuel Sapiano WG GW Vienna, 8 9 October 2018

Starting point: Objective 1 Terms of Reference A more in-depth assessment of pollutants causing the greatest risks and contributing to poor status of GWBs considering results of 2nd RBMP e.g. nitrate, naturally occurring inorganic substances (e.g. arsenic) and selected synthetic organic substances) Main emphasis on general quality assessment (GQA) test: To determine whether there are comparable TVs for the GQA test for the selected pollutants (as mentioned above) WG GW Nottingham, 17-18 October 2017

Focus of current work Assumption in TOR: „TVs for GQA test show less variability than TVs for a wider range of tests and for selected pollutants“ Selected pollutants: primarily those, which cause frequently failure to achieve good chemical status Reference: Draft EEA report „European waters – assessment of status and pressures 2018“ Analyses of TVs in the current report: variability rather low Based on the assessment of available data, it seems that assumption in TOR holds true Hence, compliance regime was not analysed in detail Analysis of compliance regime remains a point to consider

Work after Berne meeting: Discussion in Berne Proposal to add a reference indicating that the WG GW is aware that there is more information on TVs at EEA available.  It turned out that the TVs at EEA are not available for particular status tests. Hence, the information cannot by used for the current activity, which is assessing TVs for the General Quality Assessment (GQA) Test Comments by group of volunteers Amendment of the draft, submission to the group of volunteers again and elaboration of final draft version Upload on CIRCABC on 18. September 2018 

RBMP2 results

Example Matrix for showing numeric TVs and aggregation period

Conclusions and recommendations I Analysis limited to those pollutants which very frequently cause failure to achieve good groundwater chemical status. TVs for these most significant pollutants do not exhibit particularly high variability; It seems that the assumption holds true that the TVs for the GQA test – at least for the synthetic organic pollutants subject to this inventory and for previously analysed inorganic substances – show less variability than TVs for a wider range of tests and substances (as reported by Amec Foster & Wheeler (2015); The compliance regime used to calculate GWB status from monitoring results remains a point to consider

Conclusions and recommendations II Differentiation between reporting and analyses of TVs and presentation of TVs at the European scale: In order to address the issue at the appropriate level of detail and to allow for discussions at the expert level. Any adjustments to the reported data and the structure necessary need to be as small as possible, to be discussed in DIS).

Conclusions and recommendations III Presention of TVs at the European scale in a simplified way – reduced to GQA test and most relevant pollutants. Guidance should be developed to complement and reinforce relevant provisions on TVs and their reporting. Particular outliers could be analysed and commented separately. Effects of the consideration of NBL on TVs and subsequently on the assessment of groundwater chemical status and its comparison across the EU could be described and illustrated. Further discussions to support the mutual understanding of different approaches in Member States to improve comparability of TVs, and to improve and simplify reporting should be performed under the CIS.

Group of volunteers Activity lead Manuel Sapiano, Rob Ward, Johannes Grath Activity members Elisabetta Preziosi, Klaus Hinsby, Jaqueline Claessens, Inga Retike