WG 2C workshop on Groundwater Status and Trends Brussels, 18 October 2004

1. WG 2C workshop on Groundwater Status and TrendsBrussels, 18 October 2004 General statements on status Threshold values Case of drinking water Monitoring Trends

2. General Statements on Status WG 2C workshop on Groundwater Status and Trends 18 October 2004

3. Main objectives of the common methodology for the evaluation of the chemical status • EU –wide comparability of the evaluation • Comparable evaluation of transboundary groundwater bodies (same status – same evaluation; 40% is transboundary in Hungary) • Well-based establishment of measures in RBMP • Less distortion in competition (in economy) HU Contribution

4. Groundwater bodies in Hungary (more than 40 % is transboundary) HU Contribution

5. Two main criteria for an unique methodology • Satisfying the quality status of the receptors directly influenced with the mass fluxes from the neighbouring groundwater body, as well as quality status of groundwater ecosystem • Account of the natural variability of the hydrogeological conditions between and within the aquifers • Note that the calculation of the contribution of groundwater fluxes in the overall receptors loads may be quite cumbersome – Need for homogeneous area delineation EWA Contribution

6. GQS is in general: • same as drinking water standard (less, if ecosystem requires stricter, e.g. Cu – this requires studies) • there are issued in legislation (EU or national) • prevention of indirect discharges meansin general: the concentration caused by pollution source (point, diffuse) in its surrounding does not exceed this value in any monitoring wells • if the concentration of the pollutant has been higher than GQS then the permissible concentration has to be defined in RBMP HU Contribution

7. SEQUEAU System 4 or 5 quality classes • Water uses (human consumption, industry, agricultural uses, animal watering, irrigation, energy (heat pumps)…) • The patrimonial status which measures the degree of deviation from the natural status due to anthroponic pressures • The ability to sustain the biology in the associated water courses (groundwater dependent ecosystems) BE-Wallonia Contribution

8. GW Italian classification: chemical status Class 1 Null or negligible anthropic impact with valuable hydro chemical characteristics Class 2 Reduced or sustainable anthropic impact over a long period and with good hydro chemical characteristics Class 3 Significant anthropic impact and with generally good hydro chemical characteristics, but with some signs of pollution Class 4 Relevant anthropic impact with poor hydro chemical characteristics Class 0 Null or negligible anthropic impact but with special natural hydro chemical facies in concentrations higher than the value of class 3 IT Contribution

9. GW Classification: GW chemical status (SCAS) IT Contribution

10. Decree on the GW quality (OJ RS, 11/02)Main features Limit values for 23 parameters ofchemical status – environmental standards for GW • Statistical treatment of monitoring data (same as proposed by WG 2.8) • Criteria for the determination of : GW chemical status , long term trends of pollution, endangered GW bodies SI Contribution

11. Considerations on Threshold Values WG 2C workshop on Groundwater Status and Trends 18 October 2004

12. Comment on “threshold values” (1) • Threshold values, evaluation of status & trends, design of monitoring are intimately entwined • Counterproductive to isolate them • Integrated approach necessary IAH /EG Contribution

13. Comment on “threshold values” (2) • Overriding objective EC Directives is: • mobilise member states to implement pollution and land-use control measures • Focus of monitoring on the effectiveness of existing and future management measures • Thus: focus on quality of contemporary recharge to groundwater bodies • not on the average quality of a groundwater body IAH /EG Contribution

14. Comment on “threshold values” (3) • Central idea: exceedance of threshold values triggers the need for management action • threshold value somewhere between background concentration and MAC • However, many thick aquifers have large response time lags (decades) • Defining thresholds in relation to average quality of groundwater body is a very blunt instrument for groundwater quality protection IAH /EG Contribution

15. Comment on “threshold values” (4) • Alternative: define TV’s in relation to the active recharge zone • exceedence of TV = trigger for management action. • Options: • threshold value > MAC when strong attenuation capacity (eg. denitrification) has been well proven • threshold value = MAC when no attenuation exists or where attenuation is too uncertain IAH /EG Contribution

16. Considerations for status & trends (1) • Trends to be determined in relatively recent replenishment to groundwater bodies • early warning network • effectiveness of measures can be assessed on a realistic management time scale of 5-10 years • Account of groundwater flow regime (age) and of potentially reactive “hydrochemical fronts” • Provide earliest possible indication of GW trends reflecting changes in overlying land-use practices IAH /EG Contribution

17. Considerations for status & trends (2) • Make groundwater monitoring stations representative for a given land-use category • instead of averaging of sites with widely-differing flow times and land-use influences • This enables estimation of the net contaminant flux from each land-use category • (land area of each category is known) • Appropriate weighted mean can be used to report the average quality of contemporary recharge to the whole groundwater body IAH /EG Contribution

18. Needs for an integrated approach • Need for taking into account the ‘response time lags’ of the aquifers, and to focus on the recharge zone of the groundwater bodies • early warning, demonstration of effectiveness of management measures) • TV’s can be related to contemporary recharge (much simpler to define them?) IAH /EG Contribution

19. Requirements(Some of them contradictory with each other) • Uniform methodology ↔ flexibility • Check the impact of pollution sources(80/68 /EEC) ↔ evaluate the status of the whole groundwater body (WFD) • We have EQS for Nitrate and Pesticide on EU level • We have to monitor as core parameters: Oxygen content, pH value, conductivity, Nitrate, Ammonium • We have to consider evaluating the chemical status: conductivity, concentration of everypollutantscould cause risk of failure, Nitrate, Pesticides, saline or other intrusions • Considering both pollution and natural background ( not to mix them) HU Contribution

20. TV = NBG +n x GQS TV = GQS if NBG = 0 TV = NBG + n x NBG > GQS TV = GQS if NBG + n x NBG < GQS Approaches Where: TV = threshold value for water body NBG = average of natural background GQS = groundwater quality standard n = factor, which is maximum 1 HU Contribution

21. Derivation of limit values using a tolerable daily intake approach • TDI = NOAEL or LOAEL/UF Noael: no-observed-adverse-effect level Loael: lowest-observed-adverse-effect level UF = uncertainty factor • GV = TDI x bw x P/C Bw= body weight P = fraction of the TDI allocated to drinking-water C = daily drinking-water consumption GV= guideline value FUTURE APPROACHES Ecotoxicological data-Background data IT Contribution

22. shallow gw with impacts of pollution 0 aquifers with confined gw 2 10 porozous layers of low and semi permeability 5 3 monitoring wells 20 20 35 50 Multilayered aquifer system of a groundwater body in the Great Hungarian Plain with different concentration of Arsenic (As) in µg/l HU Contribution

23. 50 95 5 10 35 0 0 Multilayered aquifer system of a groundwater body on the recharge area of the Great Hungarian Plain with Nitrate concentration (mg/l) of aquifers of different size HU Contribution

24. Natural background and the factor • NBG: have to be established on water body level during the preparation and supervision of the RBMP • NBG = GQS in the case of synthetic pollutants • „n” as factor is defined during the preparation and supervision of the RBMP In Hungary the Arsenic is one of the most critical substance of natural origin HU Contribution

25. Comment on “background concentration” • Some use it to imply the quality of in-situ groundwater not obviously impacted by any modern (20th century) anthropogenic activity; whilst others consider only the impact of synthetic chemicals in effect dating from the 1950s IAH /EG Contribution

26. Natural background levels • Both geochemical and statistical methods for the determination of NBG could be used, requiring expertise on geochemical behaviour of the substances for which threshold values are to be established • NBG often determined as fixed value that represents a hypothetical background concentration without taking into account the natural variability. A better solution would be to apply statistical methods taking into account the natural variability of chemical composition and determination of the probability distribution function EWA Contribution

27. Consequences • TV for synthetic substances can be defined in EU Directive or national legislation by 22.12.2005 (as WFD requires) • NBG, TV (not mentioned above), and „n” factor can be defined during preparation of RBMP • „n” factor can be suited to economic and social situation • The proposed system ensures both uniformity in legislation and flexibility by RBMP HU Contribution

28. THRESHOLD VALUES INORGANIC POLLUTANT IT Contribution

29. THRESHOLD VALUES ORGANIC POLLUTANT IT Contribution

30. Decree on the GW qualitySlovene standards Limit values SI Contribution

31. GW quality assessment according to Decree from 2002 on (1) • Determination of GW chemical status for the GWB (2002 – 2004 for aquifer) • Good chemical status: CLAM < LV for every parameter of chemical status CLAM: 95% confidence limit • Determination of long term trends for GWB SI Contribution

32. GW quality assessment according to Decree from 2002 on (2) Determination of endangered GWB: • one or more parameters CLAM > LV (for nitrates CLAM > 2*LV) or • upward trend for three or more parameters SI Contribution

33. Conclusions • Delineation of GWB is of crucial importance for GWB quality assessment • For chemical status determination monitoring network has to be representative for the whole GWB • Combined approach (chemical status + evaluation of GW pollution on individual sampling site or sector) enables more effective pollution controll SI Contribution

34. SEQUESO System Patrimonial status corresponding as closely as possible to the “natural” status (or in practice “reference” status) set as: • The usual analytical detection limits for organic compounds • An expert judgement for nitrates (10 mg/l) and some other parameters • Background concentrations not yet fixed – Consideration of soil policy in Belgium to determine these values • Thresholds similar to surface waters for biology, assuming a 100% feeding from groundwater – “biology” does not presently participate directly to the establishment of threshold values BE-Wallonia Contribution

35. SEQUESO System (2) • Use of DW standards applying after treatment but upstream of public networks • Consideration of soil remediation policies: reference values calculated as 95th upper percentile of the quality distribution of water abstractions unaffected by local plumes • Values presently under discussions by BE experts • Consideration of the results of the CIS WG 2.8 and the GwSTAT software • Examples of SEQUESO values: NH4 (0.5 mg/L) – As (10µg/L) – Cd (5 µg/L) – Cl (150 mg/L) – Pb (10 µg/L) – Hg (1 µg/L) – SO4 (250 mg/L) – tricholoréthylène and perchloréthylène (10 µ/L) BE-Wallonia Contribution

36. Applying the SEQESO system … a good monitoring network design is essential for proper aggregation to the GWBody level Example: Groundwater body RWM40 NO3 vulnerable zone Density : 14 sites / 500 km2 (according to high anthropic pressure) Representativity index (GwStat) = 85,3% Based on conceptual model : yes BE-Wallonia Contribution

37. RWM40 - Quality for the « Drinking water supply » use RWM40 Patrimonial status RWM40 - General Quality Index (orange means beyond the TV) BE-Wallonia Contribution

38. Conclusion: medium status ( the GWB needs a trend assessment for NO3) BE-Wallonia Contribution

39. TV methodology Intention to establish threshold values at national level, except when a groundwater body specific natural background values. Distinction is made between synthetic substances and parameters which can be found in water – so three groups are presently considered: • Synthetic substances (result of anthropogenic actions) – They should not be present in water (close to QL) • Nutrients and inorganic parameters (already based on requirements present in the Directive 75/440/EEC) • Heavy metals (need of monitoring to distinguish natural and anthropogenic origins – this is now being planned) PT Contribution

40. GIS view of aquifer and pumping stations Spatial Homogeneity Pumping Stations were selected to act as monitoring stations for the purpose of this analysis. The distribution of the monitoring stations was assessed to see whether it was spatially well distributed or homogeneous. The procedure followed was that developed by the WFD-GW Consortium. The representativity index, calculated using this software, resulted in a value of 63.6% - not surprising given that these sources are concentrated towards the centre of the island given its hydrological and geological characteristics. It must be noted that a representativity index of 80% was recommended by the Consortium. In order to ensure that the sites would be more representative, a better spread of sites would be needed. MT Contribution

41. Case of drinking water WG 2C workshop on Groundwater Status and Trends 18 October 2004

42. Drinking water and ‘good status’ • Water suppliers & waste water operators (services to 360 mln European citizens) • Goal: provide safe drinking water, which meets all standards, at lowest practicable costs, environmentally sustainable • EU-wide groundwater source for 2/3 of drinking water EUREAU Contribution

43. Drinking water and ‘good status’ (thresholds) • WFD: Safe drinking water requires groundwater protection • Incorporation of drinking water in thresholds is needed • Feasible without great consequences EUREAU Contribution

44. Drinking water requires groundwater protection • Article 7.1: MS shall “identify all bodies of water used for the abstraction of water intended for human consumption” • Article 7.2: MS shall “ensure that under the water treatment regime applied, the resulting water will meet the requirements of the Drinking Water Directive” • Article 7.3: MS shall “ensure protection in order to reduce the level of purification treatment required in the production of drinking water” EUREAU Contribution

45. Incorporation of drinking water in thresholds is needed • Article 7.3: “ensure protection to reduce level of treatment” • Basic treatment: EU-wide 90% of groundwater treatment plants BASIS FOR GOOD STATUS (THRESHOLDS) IS BASIC TREATMENT • Thresholds = dr. water standards + basic treatment • Drinking water standard: MAC-value, not average CONSISTENT WITH APPROACH FOR SURFACE WATER (STANDARDS FOR PRIORITY SUBSTANCES) EUREAU Contribution

46. Feasible without great consequences Limited to: • Groundwater bodies designated for drinking water abstraction • 48 parameters for which drinking water standards exist • Only when drinking water standards < ecological standards EUREAU Contribution

47. Conclusions on drinking water and groundwater thresholds • WFD => Incorporate ‘drinking water’ in thresholds • Thresholds = drinking water standards + basic treatment • Limited to: (a) groundwater bodies for drinking water abstraction, (b) substances under 98/83/EC, (c) drinking water < ecological standards • Elaboration of guidance in BRIDGE-project EUREAU Contribution

48. SEQUESO System Drinking water supply (DWS) recognised as the main use, 3 limits are defined with the following origins: • DWS1: guide level values of Directive 80/778/EEC or expert judgement based on statistical distribution of quality values • DWS2: parametric value of Directive 98/83/EC when relevant for raw water • DWS4: Guide or imperative value of Directive 75/440/EEC concerning the quality required for surface water intended for use as drinking water, or expert judgement on the maximum level of treatability of the raw water BE-Wallonia Contribution

49. An Analysis of Chloride Content in the Lower Coralline Limestone Aquifer (Malta) Groundwater in Malta and Gozo is an important source of drinking water and accounts for half of the public supply. It is mainly abstracted from the Oligocene limestone aquifers found at sea level that are highly sensitive to seawater intrusion. Location of Pumping Stations and galleries in the MSL Aquifer – Malta. The Lower Coralline Limestone aquifer is exploited in a number of ways. The Water Services Corporation operates seven pumping stations – horizontal galleries drilled at sea level with a total length of 40km. These together with some 100 boreholes, are used to exploit groundwater for drinking purposes. Pumping stations account for more than 50% of all groundwater abstracted for potable supply purposes. MT Contribution

50. Considerations on monitoring WG 2C workshop on Groundwater Status and Trends 18 October 2004