Contract n° SSPI-2004-006538
BR B R ID I DG GE E
Ba B ac ck kg gr ro ou un nd d c cR Ri it te er ri ia a f fo or r t th he e I ID De en nt ti if fi ic ca at ti io on n o of f G Gr ro ou un nd dw wa at te er r t th hr rE Es sh ho ol ld ds s Research for Policy Support
D14: Report on National Methodologies for Groundwater Threshold Values (Main text – Synthesis)
Due date of deliverable: 31 August 2005 Actual submission date: 14 February 2006
The deliverable authors are responsible for the content
Start date of the project : 1 January 2005 Duration : 2 years
AUTHOR: Kim DAHLSTROM AFFILIATION: DEPA
ADDRESS: Strandgade 29; 1401 Copenhagen, DK TEL.: +45-32-66 03 88
EMAIL: kda@mst.dk FURTHER AUTHORS: Dietmar MÜLLER
Revision [2]
Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006) Dissimination level
PU Public
C ONTENTS
1 FOREWORD...3
2 PERSPECTIVES ON GROUNDWATER PROTECTION...4
2.1 PRESSURE ON GROUNDWATER RESOURCES...4
3 COMPARISON OF KEY ELEMENTS ...8
3.1 WATER SUPPLY SOURCES...8
3.2 WATER SUPPLY CATEGORIES...9
3.3 GROUNDWATER QUALITY CRITERIA...9
3.3.1 Terminology ...10
3.3.2 Methods used ...10
3.3.3 Usage of the criteria...11
3.4 VARIABILITY IN BACKGROUND CONCENTRATION AND IN GROUNDWATER QUALITY CRITERIA...11
3.5 METHODOLOGIES TO CONSIDER IN PROCESS TO DERIVE THRESHOLDS...13
4 CONCLUSIONS AND SUMMARY...14
4.1 CONCLUSIONS...14
4.1.1 Terminology ...15
4.1.2 Background concentration and Groundwater Quality Criteria - general use...15
4.1.3 Use of ecotoxicological data ...15
4.2 LINKAGES TO GROUNDWATER MONITORING...16
4.2.1 Aggregation of monitoring data...16
4.2.2 Considerations on monitoring design ...16
4.3 SUMMARY...16
1 Foreword
This report is the result of the work in work-package 3 “Criteria for environmental thresholds and methodology to define a good status”, activity 3-1 ”National methodologies of
groundwater protection”. The purpose of this report is to review and describe the national methodologies used for groundwater protection up to 2003, when the Ground Water Directive was presented for the Commission. Further, the aim is to describe current administrative practice and the general applicability of the criteria.
The results in the report give an overview of the initiatives by Member States on groundwater protection and of the considerations behind the establishment of national groundwater quality criteria and / or other environmental standards.
Information on national procedures on how to obtain environmental standards or
groundwater quality criteria, combined with knowledge on monitoring data for example, is expected to be crucial in the forthcoming process. This process aims to develop common threshold values or methodologies to develop threshold values defining good and poor status.
This review focuses on the most important initiatives and measures taken in order to prevent pollution and restore polluted groundwater resources.
Special attention is given to the following issues:
- Why is groundwater protected?
- Utilisation of groundwater
- Protection strategies for diffuse and point sources - Monitoring approaches
- Groundwater quality
Design of monitoring networks, collection of data and data processing is not the scope of this report.
The report is divide into two volumes; the main text and secondly an appendix containing the reports from the member States on “National Methods for Groundwater Protection”.
The following partners have contributed to the report:
AT Austria , Johannes Grath/ Andreas Scheidleder BE Belgium (Flanders) Jan Bonders
BG Bulgaria Rossita B. Gorova DE Germany Ruediger Wolter DK Denmark Kim Dahlstrøm
ES Spain Juan Grima
EST Estonia Andres Marandi FR France Ariane Blume LT Lithuania Kestutis Marandi NL Netherlands Hilde Passier PL Poland Stanislaw Witczak UK United Kingdom Alwyn Hart/ Jan Hookey
Kim Dahlstrøm Dietmar Müller January 2006
Leader of activity 3.1 Chair of Work-package 3
The substantial parts of the work under activity 3.1 were completed from January 2005 to September 2005.
2 Perspectives on groundwater protection
Discussing procedures and methodologies to provide figures defining good or poor status is always influenced by tradition and arguments based on the specific circumstances in specific Member States e.g. the prevailing use and treatment of groundwater.
Before the chapters representing the national methodologies for groundwater protection, there is a more general and broad perspective of the groundwater resource.
The objectives of sections 2 and 3 are firstly to give an outlook on the need for groundwater protection, which is the main purpose of the Water Framework Directive and the
Groundwater Directive, and secondly to compare some of the key elements presented by the Member States.
The data used are mainly from the partners’ national text contribution on National Methods for Groundwater Protection (NMGP). However, exceptions include data regarding the gross domestic product and data regarding land use, pesticide and fertiliser consumption. These data are in general retrieved from the European Environment Agency in order to have more comparable data e.g. with respect to the definition and year of collection.
The data in the NMGP are collected in various manners and scales in the States represented and therefore not directly comparable. Despite several checks of numbers, understanding of data and use of data, readers are urged to look into the specific NMGP for further clarification and details. Due to the differences in definitions and ways of collecting of data, readers should interpret our data and results with caution.
2.1 Pressure on groundwater resources
The pressure on the groundwater resource is not easy to determine with accuracy at national level due to lack of representative data and high local variability. In order to compare
differences and similarities regarding groundwater resources, estimates have to be based on readily available and more general data.
Hence, the following description should only be seen as an attempt to give broad indication of the challenges some Member States could face in the future.
2.1.1 Indication of the available resource
From a sustainable viewpoint, the available groundwater resource is related to the amount of water infiltrating to the aquifers and the amount abstracted. The amount of water infiltration to the aquifers can roughly be estimated by multiplying the land area by the net precipitation.
River discharge will influence the size of the groundwater resource, but data are scarce and in general not available or if they are available, they are not strictly related to size of the aquifer. Under field conditions the amount of water infiltration to the aquifers will typically be less than the net precipitation.
The amount of abstracted groundwater is in general related to the size of the population.
With this simplification the available resource (AR) can be estimated as:
AR= (net precipitation x area) / population
2.1.2 Indication of resource pressure
The Gross Domestic Product expresses the production of goods and services by a Member State. In general, higher industrial production will consume a greater amount of groundwater.
If the land area of a Member State is small, it will result in a higher pressure on the natural resources compared to a State with the same GDP but with a larger area. With this
simplification the resource pressure (RP) can be estimated as:
RP= GDP/area
It could, however, be argued that higher GDP creates prosperity that makes it possible to implement more strict groundwater protection.
The data for the Member States are listed in table 1. The following definitions are used according to the European Environmental Agency’s website:
• The Agricultural Area is the sum of Arable land, Permanent crops and Permanent pastures. Arable Land is the land under temporary crops, temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow (less than five years). Permanent Crops is the land cultivated with crops that occupy the land for long periods and need not be replanted after each harvest.
Permanent Pasture is the land used permanently (five years or more) for herbaceous forage crops, either cultivated or growing wild. Forests and Woodland include land under natural or planted stands of trees, whether productive or not (Source: FAO).
• Pesticide consumption data refer to the quantity of pesticides used in or sold to the agricultural sector expressed in tonnes of active ingredients. Data are presented for the following major groups: insecticides; mineral oils; herbicides; fungicides,
bactericides and seed treatments; plant growth regulators; rodenticides (Source:
FAO).
• Nitrogen fertiliser consumption data refer to metric tonnes of plant nutrients as nitrogen (N) (Source:FAO).
Table 1: Data on the Member States involved in this report.
Population [Mill.]
Area [1.000 km2]
Net precipitation
[mm/yr]
GDP (1) [bill. Euro]
Agricultural land (2) [1.000 km2]
Pesticide consumption
(2)
1000 t
Nitrogen fertiliser consumption (2)
[1.000 t]
AT 8.1 84 644 243.639 34 3.1 120
BE(3) 10.4 31 300 52.676 18 4.2 298
BG (4) 7.8 111 189 320.679 63 4.5 172
DE 82.5 357 327 2311.2 170 51.2 1792
DK 5.4 43 300 166.171 27 6.2 211
ES (5) 44 506 230 910.249 294 35.7 1111
EST 1.4 45 400 16.606 9 n. d. 20
FR 58.5 544 345 1667.0 296 99.6 2397
LT 3.4 65.3 125 32.19 35 1.3 102
NL 16 34 242 468.446 19 7.5 296
PL 38.6 312 175 399.324 184 8.3 862
UK (5)(6) 58.8 243.6 592 1634.96 170 61.8 1197
n. d. = no data
(1) Based on data from www.nationmaster.com GDP (2002) 1 US$= 1.07 Euro (2) EEA data service at http://dataservice.eea.eu.int/dataservice/
(3) Data from National Methods for Groundwater Protection, see volume 2 “Appendix”
(4) Net precipitation is estimated as equal to renewable resource from www.igrac.nl Data on pesticide consumption is from National Methods for Groundwater Protection (5) Net precipitation is estimated as equal to renewable resource from www.igrac.nl (6) Data on pesticide consumption is from 2000.
The indication of available resource and pressure on the resource is shown in figure 1.
Indication of available resource and pressure on the resource
0 2 4 6 8 10 12 14 16
Au stria
Be lgium
Bulgari a
Ge rmany
Denm ark
Sp ain
Estoni a
Franc e Lithuan
ia
Netherl
ands Poland
United K ingdom
Available resource indicator
1000m3/yr/pers Resource pressure indicator bill euro/1000 km2
Figure 1: Bar chart showing the estimate of the available resource and the pressure on the resource. Data for Belgium represent the Flemish situation.
Low available resource and high resource pressure indicate that a high level of groundwater protection is needed. Based on the assumptions mentioned above, this rough estimate (see figure 1) indicates that Estonia and Austria seem to have favourable conditions, while e.g.
the Netherlands, Germany, United Kingdom and Denmark might have a higher need for protection initiatives.
Pressure due to application of pesticides and fertiliser can be estimated based on some of the same principles:
PP (pesticide pressure) = pesticide amount / (net precipitation x farming area) PP estimates the pesticide load per volume of water.
FP (fertiliser pressure) can be estimated in the same manner.
In this context fertiliser is defined as commercial fertiliser not including manure etc. from livestock. Numbers express tonnes of nitrogen fertiliser.
FP = fertiliser amount/ net precipitation x agricultural land.
FP estimates the fertiliser load per volume of water.
The indication of pressure on the resource due to application of pesticides and fertiliser is illustrated in figure 2.
Figure 2: Bar chart showing the estimated pressure from pesticides and fertiliser. Note the different units. Data for Belgium represent the Flemish situation
.
It should be noted that pesticides and fertilisers are regulated in other directives than the Water Framework Directive (WFD). Diffuse sources are important to take into account when dealing with groundwater protection.
The presented data on fertiliser and pesticides should only be seen as trends and it is not possible to evaluate weather nitrate or pesticide pose the highest risk to the groundwater resource.
The pressures from pesticides and fertilisers seem to be of the same order of magnitude for all States. It should be noted that the “attenuation” factors have to be fairly high if commonly applied standards for pesticides in groundwater of around 0.5 µg/l are to be met.
According to the WFD every Member State has to file an article 5 report. This includes an analysis of the characteristics of river basin districts and a review of the impact of human activity on the status of surface waters and on groundwater, also indicating which (ground) water bodies are at risk of pollution by specific
contaminants. Comparison between the results in this report and the article 5 reports could be the first step to validate the trends in this report and to indicate if the main problems are related to nitrate or pesticides.
In d ic a tio n o f p re s s u re fro m p e s tic id e s a n d fe rtilis e r
0 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0
Austria Belgium Bulgaria Germany Denmark Spain Estonia France Lithuania Netherlands Poland United
Concentration
P e s t ic id e p re s s u re in d ic a t o r u g / l F e rt ilis e r p re s s u re in d ic a t o r g / m 3
3 Comparison of key elements
3.1 Water supply sources
A direct comparison between the different water supply sources listed by Member States has to be conducted with some caution due to the fact that data do not always reflect the same source. E.g. some States define spring water as groundwater, while others separate
groundwater and spring water. Artificial recharge e.g. by bank infiltration could also introduce some uncertainty because some see it as groundwater but others as surface water. All data have been retrieved from the Member States’ NMGP and additional details can be found here, see appendix.
Figure 3 summarises data on water supply sources from the Member States.
Water supply sources
0%
20%
40%
60%
80%
100%
Austria Belgium
Bulgaria Germany
Denm ark
Spain Estonia
Franc e Lithuania
Nether land
s
Poland U.K.
Other % Spring water % Surface water % Groundwater %
Figure 3: Bar chart showing the distribution of different sources of water supply. Data for Belgium represent the Flemish situation.
Remarks:
Belgium: Data provided by Flanders. See NMGP for further details.
Bulgaria: spring water is included in groundwater. See NMGP for further details.
France: spring water is included in groundwater
U.K.: England and Wales. See NMGP for further details.
Others: E.g. artificial recharge imported water.
From figure 3 it can be seen that all States use 30 % or more of groundwater as a source for water supply. The only exemption is France that only uses 20 % of groundwater. Lithuania, Denmark and Austria (when spring water is considered as emerging groundwater) rely entirely on groundwater, while in Germany, Poland, Estonia and Austria groundwater constitutes 50 % or more of the source for water supply.
France, the Netherlands, United Kingdom, Spain and Bulgaria rely to a higher degree on surface water. However, it should be noted that in many States the supply conditions show a large range of variation. The United Kingdom has very variable conditions regarding the use of groundwater as a source for water supply. Some regions use 70 % groundwater while others only use surface water. In some of the German federal states (Länder) about 100% of the drinking water stems from groundwater resources.
3.2 Water supply categories
There is some uncertainty in the division between consumption in some of the categories e.g. industry and agriculture, the percentage of drinking water in “domestic” and household consumption and some States include cooling water for power plants and fisheries while others exclude them.
The category “Other” includes e.g. remediation pumping and loss of water due to leaks.
No details on different consumption categories were found for The United Kingdom.
Water consumption divided into catagories
0%
20%
40%
60%
80%
100%
Austria Belgiu
m Bulgaria
Germa ny
De nm
ark Spain
Es tonia
France Lithuania
Net herla
nds Poland
U.K.
Other % Agriculture % Industry % Drinking water %
Figure 4: Bars showing the distribution of different consumption categories. Data for Belgium represent the Flemish situation.
Remarks:
Belgium: Data provided by Flanders. See NMGP for further details.
Bulgaria: See NMGP for further details.
Germany: Cooling water consumption is not included in "Industry". See NMGP for further details.
U.K.: England and Wales. Fish farms and power generation not included. See NMGP for further details.
Poland: the distribution covers consumption of groundwater.
Other: include e.g. remediation pumping, loss of water due to leaks.
The data indicate that for many States drinking water consumption constitutes less than 50
%. Only in Bulgaria, Denmark, France, Poland and United Kingdom does consumption of drinking water exceed 50%.
Spain, as the most southern country has, as expected, a much higher consumption in the Agriculture category, probably due to irrigation.
3.3 Groundwater Quality Criteria
Many Member States have defined quality criteria for groundwater for the routine work on groundwater protection. The terminology, the context of use and the philosophy behind the
retrieval of the criteria differ from State to State. The identification and use of background concentration also varies from State to State.
In order to obtain operational conditions and a uniform and consistent basis for assessing the sample e.g. by comparing with a specific criterion, it is necessary to define and specify the following:
- how groundwater samples are collected, - how samples are analysed,
- where a well and screen is placed,
- when and how data are processed e.g. if there are several data from the same sampling point or several sampling points form the same aquifer, and
- the action taken if the criterion is exceeded.
3.3.1 Terminology
At the moment there is no consensus on common terminology regarding ground water quality standards. The criteria are sometimes named groundwater quality criteria,
background value, groundwater standards, ecological value, insignificance threshold value, or patrimonial status, and some States have not specified groundwater quality standards.
In general the term ‘natural background level’ is not used or defined. Some State have concentration values define background level or background concentration. The term threshold or threshold values is in general not defined or used. The only exemption is the States that entered EU recently and where legislation and groundwater protection seems to be influenced by the ideas in the WFD. The terminology related to the WFD often refers to Natural Background Level (NBL) and Thresholds / Threshold values (TV).
In order to make clear separation between the terminology before 2003 and the terminology related to the WFD, background concentration (BGC) and Groundwater Quality Criterion (GQC) expressed, as a concentration will be used here. Therefore, it should be kept in mind that the term NBL is different to BCL and that the GQC is the broad term covering a wide range of national terms for different environmental quality standards for groundwater.
3.3.2 Methods used
Some Member States have used a precautionary approach and defined the CQC as 60 % of the drinking water standard where data are assessed over 2 years based on the mean value.
Others define the background concentration or the groundwater quality criteria as the 90 % percentile of national monitoring data and use the criteria to define if the aquifer is impacted by contamination. Some Member States have decided to develop additional clean-up values based on the WHO guidelines on Tolerable Daily Intake.
Another approach is the insignificance threshold value, which takes into account that minor changes can occur due to anthropogenic activities in limited areas. The value defines the concentration where no relevant ecotoxic effects can occur. The values exceed regional background concentration. The value ensures that groundwater can be used as drinking water everywhere and that groundwater is intact as a habitat. The derivation requires human toxicological and eco-toxicological data.
Groundwater quality criteria can also be derived on the basis of the principle that the
groundwater quality has to be able to meet the drinking water standard after simple treatment (sand filtration and aeration) at the waterworks.
The assessment of groundwater quality can also be done by evaluation, if a list of
parameters fulfils a certain value. The suggested parameters are EC (electrical conductivity), pH, COD, chloride, nitrate, ammonium and hazardous substances in combination with the requirement that 90 % of the sample points have to meet a specified value. Others have chosen the same procedure, but suggested a slightly different list of parameters as indicators for pollution: EC, pH, O2, ammonium, chloride and sulphate. These methodologies seem to be influenced by the thinking in the WFD.
Some prefer a site-by-site evaluation where the groundwater is assessed in relation to different uses e.g. drinking water, industry, irrigation or energy production. A consequence of this methodology is that there is no single generic value defining the groundwater quality.
Finally, some Member States derive threshold values on the basis of considering the typical background level, the origin of a substance (natural or/and anthropogenic), and the possible impact on the recipient (e.g. risk level for ecosystems) and/or human receptor (e.g. aesthetic effect (taste, odour and colour) and health effect (toxic, carcinogenic or mutagenic)). This methodology seems to be influenced by the thinking in the WFD.
The various GQC are set for groundwater in general and not related to geological setting or aquifer typology.
3.3.3 Usage of the criteria
Some States have specified the use of the GQC very clearly e.g. to assess the quality of the water concerning physical, chemical and biological parameters.
Others define the background concentration or the groundwater quality criteria as the
“normal” level found in non-contaminated areas and use this value to define if an aquifer is contaminated and / or to set the clean-up level.
The insignificance threshold value defines the line between a minor chemical change in the groundwater and a harmful contamination, but it is only applicable for contamination from point sources and not on the scale of an aquifer.
Some have chosen to establish a relationship between intervention value (seriously contaminated), target values (the goal for groundwater quality and sustainable water
management), negligible risk level and background level (derived e.g. as the 90 % percentile of data from the national monitoring programme).
Finally, some of the States that recently entered the EU use the GQC or threshold value to define good quality
3.4 Variability in Background Concentration and in Groundwater Quality Criteria
In appendix 1 the different terminology for background concentrations and the Groundwater Quality Criteria are listed for a limited number of parameters; chloride, sulphate, arsenic, cadmium, nickel, benzene, trichloroethylene and naphthalene. The parameters have been chosen to represent naturally occurring compounds and metals as well as frequently observed organic contaminants in groundwater. Cadmium is included in appendix 1 but excluded in the text below because the values show extreme variability compared to the other parameters.
In order to describe the variation, some of the most common statistical parameters are calculated and shown in figures 5 and 6. The mean values are used where there is a range of values or where there are different classes of values in the table in appendix 1.
When assessing the data, it is important to remember that the data set is incomplete
because not all States have defined the background concentrations and/or the groundwater quality criteria or/and they have slightly different definitions.
Groundwater Background Concentration
0 10 20 30 40 50 60
Conc. ug/l
Min value Max value Mean Median
Standard deviation 90 % percentile
Chloride in mg/l
Nickel
Sulphate Arsenic BenzeneTrichloroeth Naphthal.
Figure 5: Showing the statistical parameters for background concentration level in groundwater. Note the unit for chloride is mg/l, while the other units are µg/l.
Groundwater Qality Criteria
0 50 100 150 200 250 300
Conc. ug/l
Min value Max value Mean Median
Standard deviation 90 % percentile
Chloride in mg/l
Sulphate in mg/l
Arsenic Nickel Benzene Trichloroeth. Naphthalene
Figure 6: Showing the statistical parameters for the groundwater quality criteria. Note that the unit for chloride and sulphate is mg/l, while other units are µg/l.
As expected, the lowest values are found in what is considered to express background concentrations compared with the groundwater quality criteria. Even though the
concentration range does not separate the background concentration and the groundwater quality criteria, many of the other parameters show a clear distinction e.g. the value for the median, the mean and the 90% percentile. This distinction is clear, despite of different methodology and motivation for deriving the BGC and GQC, as well as a wide range of geological settings, meteorological conditions, and water supply demand and consumption categories in the States represented.
If regional or local data are available and taken into consideration in the assessment of a groundwater body, it is believed that the variation will be further decreased.
3.5 Methodologies to consider in process to derive thresholds
The review and evaluation of the National Methods for Groundwater Protection (NMGP) provided by the partners clearly shows that no single methodology or derived BGC or GQC satisfies the different definitions listed in the Water Framework Directive. In the WFD the target is to determine the status of an aquifer or part of an aquifer defined as a groundwater body. It is rather common that GQC can trigger measures at a local scale or at a point source of pollution. Status assessment such as a groundwater quality assessment at larger scales (for geographical areas or aquifers) is rare. Nevertheless status assessment under the WFD might incorporate national experiences on quality assessment and common elements which may be in line with the environmental objectives defined by the WFD.
Background concentration (BGC)
Some Member States have defined the ‘background concentrations’ of naturally occurring compounds (e.g. metals and chloride) and anthropogenic contaminants representing non- contaminated areas. Some Member States have defined it e.g. with data from the national monitoring network. ‘Background concentrations’ could be defined at European and national level, if the Member States can provide sufficient data. Background concentrations could also be defined for different groundwater bodies if data are available. The approach of defining the ‘natural background concentration’ is a central subject for further dialogue and
development under the auspices of the Bridge-project.
Groundwater Quality Criteria (GQC)
A majority of the Member States has defined groundwater quality criteria that in different relations express the quality of groundwater as a single generic value of concentration. Wide ranges of terms are used. Many take into consideration the specific compounds’ toxicity, either directly or indirectly. In general, the criteria are derived in order to support decision- making e.g. in relation to clean up of point sources, risk assessment and/or in relation to priority setting. The generic criteria also seem to be set in order to secure that groundwater has the quality required to satisfy drinking water criteria after treatment at waterworks. This procedure would probably lead to some variability in the criteria among the Member States, depending on the technological level of the treatment used. Criteria could be developed at Member-State level and differentiated for different groundwater bodies.
It has to be noted that if drinking water standards or standards already adopted are based on sophisticated water treatment at the waterworks, this might cause high groundwater criteria which could not be protective for ecological receptors (associated surface water, dependent terrestrial ecosystems). This has to be evaluated for each substance or pollutant specifically.
Fraction of drinking water standard
Some Member States have chosen a certain fraction of the drinking water standard e.g. 60
% to define the divide between good and poor quality. This procedure would lead to uniform and comparable generic values. On the other hand, the values would be independent of different types of aquifers and water treatment at the waterworks. It is thought to be protective for some surface waters, but not all.
Receptor approach
One Member State suggests a “receptor approach”. In brief, the concentration defining good or poor status is site-specific and depending on the attenuation capacity, which acts to decrease any impact at the receptor. In general the longer the distance and travel time, the higher the permissible concentration due to sorption, dilution and degradation of the
substances under natural conditions in the aquifer. This procedure requires more and detailed site-specific data and probably monitoring as well. Assessments need in general to be revised if new receptors are identified or if new wells are established. Variation range of concentrations is expected to be huge due to the effect of degradation among the different Member States and among the different groundwater bodies if applied.
The procedures mentioned above could be used as inspiration in the further process on how to derive thresholds to define good and poor status. It should be kept in mind that it is crucial to relate the procedure to numbers of monitoring wells, data collection, data processing and decision making to ensure that the procedure is operational in all Member States.
4 Conclusions and summary
4.1 Conclusions
As mentioned in the foreword, this report is a review focusing on national groundwater protection methods before 2003 when the draft of the Ground Water Directive was issued. It also explains why no single philosophy, terminology and procedure on how to develop groundwater quality criteria prevails.
Many of the criteria seem to be related to management of point sources taking toxicological considerations into account directly or indirectly. In general these do not assess the potential impact on surface water that discharging groundwater could have, even if the groundwater criteria were satisfied. The thinking was probably that surface waters were more robust than groundwater hence that surface water was not at risk, if groundwater could meet the
groundwater quality criteria.
One kind of criteria that could be used to define good or poor status is the natural
background level (NBL) but this criterion requires that it is possible to distinguish elevated concentration levels e.g. of metals due to natural ore rich deposits from pollution introduced by anthropogenic activity. This is a challenging task demanding detailed and comprehensive surveys. One can argue that if NBL is not exceeded then surface waters will - in principle – be protected as well.
In general it can be summarised that none of the reported national approaches for deriving BGC and GQC seem to correspond to the objectives for threshold values to define good and poor status and the conceptual thinking in the WFD and the draft of the GWD. There are only rather few approaches that take ecological criteria into account and that can be considered as trying to establish environmental thresholds for groundwater quality.
As conceptual understanding of interactions of groundwater to aquatic and dependent terrestrial ecosystems is very complex and aquifer specific, these approaches usually keep to rather conservative and pragmatic approaches. Furthermore, these GQC generally only represent general environmental quality targets for data assessment but they are not applied to aggregated data nor strictly connected to obligatory actions and measures.
4.1.1 Terminology
As a prerequisite to build a common methodology on deriving threshold values, it is
necessary to enhance the common understanding and define commonly used terms clearly.
E.g. the question of whether to use the terms ‘natural background concentrations’ or
‘background concentrations’ may depend on data availability’ and pragmatism.
As for possible difficulties to identify ‘natural background concentrations’ with negligible anthropogenic impact, the pragmatic way forward could be to use ‘background
concentrations’ (e.g. ambient conditions across a substantial area representing natural conditions and minor anthropogenic impacts due to diffuse inputs).
The term ‘threshold value’ is part of the negotiations on the new Groundwater Directive. The introduction of further terms should be generally avoided.
4.1.2 Background concentration and Groundwater Quality Criteria - general use
Often, background concentrations and groundwater quality criteria are set on the basis of the drinking standards in order to assess groundwater quality at national level.
Some Member States refer to and have defined the background level of naturally occurring compounds and contaminants representing non contaminated areas. Although it seems to be a subject for further dialogue how to define the natural background level, some countries have been able to define a background concentration e.g. with data from the national monitoring network. If a background concentration is defined it will probably, in general, be considered as ‘protective’ for surface waters and dependent terrestrial ecosystems.
When discussing background concentrations as appropriate criteria within a methodology on thresholds, it is also common to make a distinction between natural and man-made
(synthetic or non-natural) substances. Referring to reported national background concentrations to derive threshold values it can be discussed to define background
concentrations for different natural parameter groups depending on the possible variance of natural concentrations (due to aquifer geology).
It has also to be recognised that drinking water standards are quite commonly used in particular where groundwater is ‘traditionally’ the main source for drinking water supply.
Using drinking water standards as starting point to identify general quality criteria, additional considerations on water treatment, as requested by the WFD, already took place in some countries and could also be involved within a methodology for threshold values.
4.1.3 Use of ecotoxicological data
Besides transferring Environmental Quality Standards from surface water as a starting point to set the environment for groundwater, the general use of ecotoxicological data (e.g.
threshold value = negligible risk level) from tests with surface-water organisms can be discussed. In particular concerning metals this criterion might be accommodated by adding
background values and ecotoxicological data (threshold value = background value + negligible risk level).
4.2 Linkages to groundwater monitoring
4.2.1 Aggregation of monitoring data
Some of the NMGP reports received refer to the summary report on groundwater quality monitoring network designs for groundwater bodies (BRIDGE: Deliverable 13, version 18.10.2005). Here it was pointed out that the majority of countries seem to have no tradition for or in-depth experience of assessing aggregated monitoring data of a substantial area to get an ‘overview’ on something like a ‘regional state’ of groundwater quality. Besides lacking experience, there are further limitations from low densities of monitoring networks, where reports show densities less than one monitoring well per 1.000 km², and the likely complexity of groundwater characteristics, age and travel times of groundwater.
Furthermore, it has to be recognised that principles on how to analyse monitoring data are a major discussion point within the negotiation of the draft Groundwater Directive and
therefore, at least until the final political agreements, not a subject of discussion within the BRIDGE-project.
4.2.2 Considerations on monitoring design
The general aim of monitoring is ‘to give a representative overview of the status and trend of a groundwater body’. The reported monitoring schemes underpin a need to think and discuss how monitoring networks will be established for different situations. Depending on the
groundwater body, the given pressures, the distribution of pressures and the connected receptors, concepts to design the monitoring will probably show a wide range covering monitoring wells with different purposes. Besides obvious considerations on hydrogeological conditions, the selection of monitoring wells can aim at:
- monitoring possible sources of impacts
- monitoring to cover the area of the groundwater body by a evenly distributed network, which might be considered as monitoring the pathway from pressures to receptors or monitoring the evolution of groundwater quality along its flowline, and
- monitoring the quality nearby receptors.
A common concept to derive thresholds has to reflect on the design of the monitoring networks, where and why monitoring wells have been selected, and the comparability of samples.
4.3 Summary
Member States have different groundwater resources available and different pressure on these resources. The challenges concerning nitrogen fertilisers and pesticides seem to be similar and the scale of the potential problems at least is in the same order of magnitude.
Water supply sources (spring water, surface water and groundwater) and the different consumption categories (agriculture, industry and drinking water) show a higher range of variation.
Concerning quality criteria there is no uniform definition for background concentration or other groundwater quality criteria. The different GQC, which have been applied at national
level so far, have not been targeted at describing good or poor status of an aquifer or part of an aquifer similar to a groundwater body. Note that the different criteria were usually
developed despite limited data. There seems to be a clear distinction between the
concentration level assessed as background concentration level and national ‘groundwater quality criteria’, but none of them intentionally protect surface waters.
Thresholds under the WFD can be derived based on or inspired by the thinking behind the background level or other national groundwater criteria, or perhaps by combining some of the procedures described. If based on the existing data, some pragmatism is required as well.
Obviously any agreement on criteria will have to be based on a clear definition of a common terminology. Furthermore, any criteria applied will need to take account of the prerequisites given by the hydrogeological characteristics of specific groundwater bodies and the
consequential monitoring implemented.
STATUS, CONFIDENTIALITY AND ACCESSIBILITY
Status Confidentiality Accessibility
S0 Approved/Released x PU public x Work-space x
S1 Reviewed PP Restricted to other programme participants
(including the Commission Services) Internet x S2 Pending for review RE
Restricted to a group specified by the consortium (including the Commission Services)
Paper x
S3 Draft for comments CO
Confidential, only for members of the consortium (including the Commission Services)
S4 Under preparation
Appendix 1: Background Concentration levels and Groundwater Quality Criteria.
Austria Belgium (Flanders)
Groundwater area Quality criteria Quality criteria related to clean up Threshold value Gw guideline value Gw max tolerable value Threshold surface water Background value Clean up value
µg/l µg/l µg/l µg/l µg/l µg/l
Chloride 60000 25000 n.d. 200000 n.d. n.d.
Sulphate 150000 25000 250000 250000 n.d. n.d.
Arsenic 30 n.d. 50 100 5 20
Cadmium 3 n.d. 5 5 1 5
Nickel 30 n.d. 50 50 10 40
Benzene 1 n.d. n.d. n.d. 0,5 10 Trichloroethylene 18 n.d. n.d. n.d. 0,5 70
Naphthalene n.d. n.d. n.d. n.d. 0,02 60
Bulgaria Germany Denmark
Ecological value and contaminant value Groundwater criteria Criteria for groundwater
Environmental threshold Threshold for pollution Background level Groundwater criteria
µg/l µg/l µg/l µg/l µg/l
Chloride 30 100 250000 n.d. n.d.
Sulphate 50 150 240000 n.d. n.d.
Arsenic 10 30 10 0,1 - 8 8 Cadmium 1 5 0,5 0,005 - 0,5 0,5 Nickel 20 100 14 0,1- 10 10
Benzene 0,2 30 1 0 1
Trichloroethylene n.d. n.d. 10 0 1
Naphthalene 0,1 50 n.d. 0 n.d.
France Patrimonial status
PS1 pristine Gw PS2 Anthropogenic contaminated PS3 Significant deterioration PS4 Important deterioration PS5 Very important deterioration µg/l µg/l µg/l µg/l µg/l
Chloride n.d. n.d. n.d. n.d. n.d.
Sulphate n.d. n.d. n.d. n.d. n.d.
Arsenic n.d. n.d. n.d. n.d. n.d.
Cadmium n.d. n.d. n.d. n.d. n.d.
Nickel n.d. n.d. n.d. n.d. n.d.
Benzene 0,5 2,5 5 25 n.d.
Trichloroethylene 0,1 0,5 1 5 n.d.
Naphthalene n.d. n.d. n.d. n.d. n.d.
The Netherlands Poland Groundwater criteria Groundwater thresholds Background concentration Target value
(< 10 m bgl)
Intervention value Natural background Threshold bad / good status
µg/l µg/l µg/l µg/l µg/l Chloride n.d. 100000 n.d. 5000 – 60000 250000
Sulphate n.d n.d. n.d. 0,05 100
Arsenic 7 10 60 0,1 - 0,5 5
Cadmium 0,06 0,4 6 2000 –60000 300000 Nickel 2,1 15 75 1,0 - 5,0 50
Benzene n.d. 0,2 30 n.d. n.d.
Trichloroethylene n.d. 24 500 n.d. n.d.
Naphthalene n.d. 0,01 70 n.d. n.d.
Comments on tables:
n.d. = no data listed in the text contribution from the Member State.
The Netherlands: Listed data for the target values represent values valid < 10 m BGL. Do see the National Methods for Groundwater Protection for further data.
The following Member States have not listed criteria in their report “National Methods for Groundwater Protection”: Spain, Estonia, Lithuania and United Kingdom (England and Wales).
Comments on Member State specificalities Austria:
The threshold value is used to assess groundwater areas.
Belgium (Flanders):
Two sets of criteria. The first set of quality criteria for groundwater and surface water giving a guideline value, a maximal tolerable level in groundwater and a threshold value for surface water for drinking water production. The derivations of the values are unclear. The second set of criteria is used in relation to clean up of contaminated sites. The background levels represent normal levels found in non-contaminated areas. The clean up level represents the concentration that is harmful to health (people) and / or environment.
Bulgaria:
For groundwater ecological and contamination values are defined on basis of background levels in groundwater in Bulgaria and foreign standards on groundwater.
Germany:
No legally binding criteria. The threshold values listed define ‘insignificance threshold values’ is used to assess groundwater contamination at a local scale.
Denmark:
The background level is thought to represent the groundwater concentration in non-contaminated areas and is derived on basis of data from the national monitoring network. The groundwater criteria are set in order to define the quality to groundwater to ensure that the drinking water standard can be satisfied after simple treatment (aeration and sand filtration).
Estonia:
In 2004 a new Water Act was adopted defining good and bad status. This is earlier than the time period focused on in this report.
France:
The SEQ-eaux souterraines principle defines no single groundwater criterion but assesses groundwater in relation to the intended usage e.g. drinking water, industry, irrigation and energy, patrimonial status and biological potentialities. The patrimonial statuses (PS1 to PS5) refer to the natural status of groundwater and define the degree of deviation from the natural status. Biological potentialities refer to where groundwater is assessed in relation to associated surface waters.
The Netherlands:
Generic standards for groundwater comprehend a target value, background concentration and an intervention value. Background values are defined as 90 percentile of the concentration measured in the national groundwater-monitoring network. The target value is the goal for quality and if reached sustainable management is achieved. The target value for non-metals is based on risks for ecosystems. For metals in shallow groundwater < 10 m the target value is based on a semi-natural background level. For metals in deeper groundwater > 10 m, the target value is based on added risk method: ecosystem-risk levels are added to natural background levels. The intervention value is based on stringent human and eco-toxicological effects of pollutants.
Poland:
Groundwater is divided into 5 classes. The thresholds separating the different classes are derived by assessing the typical background level, origin of constituent’s (natural or anthropogenic) and the effect of the constituents.
Spain & Lithuania:
No criteria are listed in the text contribution.
United Kingdom (England and Wales):
At present there are no groundwater quality standards. Environmental quality standards for surface water (fresh and marine waters) are available.
