1. 3.7.2007 | Slide 1 Chemical Status Assessment 9:00 – 11:00 3 July 2007

2. 3.7.2007 | Slide 2 Chemical Status Assessment Outline Status of document / 4 comments received so far Important open issues/questions: Schedule for the assessments Aggregation period (annual / X-annual) Harmonisation need with the requirements of the Nitrate and Pesticide Directives. Discussion Approach for assessing the extent of exceedance (4.3.1) Conclusions (agreed results and further action until the Lisbon-meeting)

3. 3.7.2007 | Slide 3 Chemical Status Assessment Comments Introduction Clearly describe the environmental objectives in the introduction – similar to 2.2 TV-paper - Laszlo, Manuel Compliance testing Testing of GWB not at risk is not feasible as no TVs are available - Manuel Kind of aggregation When is double aggregation needed ? – Laszlo Consider false positives due to LOQ replacement - Manuel

4. 3.7.2007 | Slide 4 Chemical Status Assessment Comments Extent of exceedance (4.3.1) Agrees approach – Laszlo 50% too much, better 40% or even 30% - Laszlo Procedure not applicable for groups of GWBs. In case of exceedance: splitting of group and assessment whether an assessment of exceedance is relevant / applicable – Magnus Replace area weighting by volume weighting - Leo Formulate text in guidance style and not in rule style - Leo

5. 3.7.2007 | Slide 5 Chemical Status Assessment Comments Saltwater intrusion (4.3.2) 1 upward trend is too stringent (step 3) – Laszlo Impact on 1 point of abstraction is too stringent (step 4) – Laszlo DWPA (4.3.5) Not acceptable at all. If DWPA is GWB, 4.3.1 can not be applied. Problem with baseline level – Laszlo No assessment whether baseline level is exceeded. Only following 2 tests: 7.2 and 7.3 - Manuel 7.2 - water after treatment does not exceed DWS 7.3 - no deterioration (no upward trend)

6. 3.7.2007 | Slide 6 Chemical Status Assessment Comments Annex (8) - Leo explain 'volume ratio' (8.1.1) comments to confidence (8.1.2): increase confidence by clustering for 2-5 sites: use t-test clearify upper confidence limit network check not needed General comments Clearly quote text coming from Directives and guidelines – Laszlo not 'poor status', but 'not at good status‘ - Manuel 'background level' not 'natural background level‘ - Manuel appreciates the use of flow charts - Magnus

7. 3.7.2007 | Slide 7 Important issues – need for discussion

8. 3.7.2007 | Slide 8 Chemical Status Assessment Schedule

9. 3.7.2007 | Slide 9 Chemical Status Assessment Aggregation Aggregation period (annual / X-annual) bi,- 6-annual ????  Annual aggregation (Annex III 2 c; Annex III 3 GWD) Aggregation on body level (double aggregation)  Annex III 2 b GWD refers to Annex V 2.4.5 WFD which requires body aggregation

10. 3.7.2007 | Slide 10 Chemical Status Assessment Approach for assessing extent Extent of exceedance (4.3.1) Replace area weighting by volume weighting – Leo  Weighting according to conceptual model principles which was the basis for the network design Procedure not applicable for groups of GWBs. In case of exceedance: splitting of group and assessment whether an assessment of exceedance is relevant / applicable – Magnus 50% too much, better 40% or even 30% - Laszlo Approach for assessing the extent

11. 3.7.2007 | Slide 11 Chemical status assessment 2 approaches for assessing the extent What is the (weighted) extent of exceedances of GW-QS or TVs in a GWB ? Is the upper confidence limit of the (weighted) aggregated GWB mean exceeding a GW-QS or TV ? Good chemical status for this test Not good chemical status for this test. ≤ 20% No Yes > 50% > 20% and ≤ 50% Extent of exceedance <= 20 % + Confidence of the Extent < 50 %

12. 3.7.2007 | Slide 12 Chemical status assessment Comparison of approaches 2 different Methods: Extent of exceedance > 20 & <= 50 + Confidence limit (CL) of the body arithmetic mean < QS/TV CL95 = 95 % probability that the mean value is below this CL CL is decreasing with increasing number of sites and decreasing variability of concentrations Extent of exceedance < 20 + Confidence of the Extent < 50 % (Upper Limit) Only little discrepancies between the 2 proposed methods (43 of 316 cases). Upper limit of Extent is stricter <= 5 sites Between 20 and 27 % exceedance Examples

13. 3.7.2007 | Slide 13 Chemical status assessment Example 1 GWB: NL002 Parameter: nitrate (TV=50 mg/l) Year: 1998 Extent above TV: 20 % (12/59 sites) Arithmetic Mean (AM): 31 mg/l Confidence Limit of AM: 47 mg/l Upper Limit Extent: 31 %

14. 3.7.2007 | Slide 14 Chemical status assessment Example 2 GWB: DK300 Parameter: nickel (TV=20 µg/l) Year: 1996 Extent above TV: 33 % (3/9 sites) Arithmetic Mean (AM): 14 µg/l Confidence Limit of AM: 31 µg/l Upper Limit Extent: 68 %

15. 3.7.2007 | Slide 15 Chemical status assessment Example 3 GWB: PTM2 Parameter: chloride (TV=200 mg/l) Year: 1998 Extent above TV: 0 % (0/3 sites) Arithmetic Mean (AM): 111 mg/l Confidence Limit of AM: 162 mg/l Upper Limit Extent: 63 %

16. 3.7.2007 | Slide 16 Chemical status assessment Example 4 GWB: DE001 Parameter: nitrate (TV=50mg/l) Year: 1990 Extent above TV: 26 % (29/111 sites) Arithmetic Mean (AM): 40 mg/l Confidence Limit of AM: 51 mg/l Upper Limit Extent: 34 %

17. 3.7.2007 | Slide 17 Chemical Status Assessment Intrusion Saltwater intrusion (4.3.2) 1 upward trend is too stringent (step 3) – Laszlo Impact on 1 point of abstraction is too stringent (step 4) – Laszlo 

18. 3.7.2007 | Slide 18 Chemical Status Assessment DWPA DWPA (4.3.5) Not acceptable at all. If DWPA is GWB, 4.3.1 can not be applied. Problem with baseline level – Laszlo No assessment whether baseline level is exceeded. Only following 2 tests: 7.2 and 7.3 - Manuel 7.2 - water after treatment does not exceed DWS 7.3 - no deterioration (no upward trend) 

19. 3.7.2007 | Slide 19 Chemical Status Assessment Nitrate / Pesticide Directive Harmonisation need with the requirements of the Nitrate and Pesticide Directives  NO3-Directive: vulnerable zone = Annex IV protected area. Measures (action programme) needed under the NO3-D independent of GWB status but now with time target (2015)

20. 3.7.2007 | Slide 20 Chemical Status Assessment Conclusions/results for Lisbon Conclusions