Status box

Title: Technical Report on Groundwater Dependent Terrestrial Ecosystems

Version no.: 1.0 (draft for discussion in WG C) Date: 20 April 2011

Authors: J. Schutten, W. Verweij Leader: J. Grath

This report focuses on terrestrial ecosystems only, due to limited resources available. A similar report for groundwater dependent aquatic ecosystems would be needed and could be developed along the structure of the technical report on GWDTEs.

Circulation and received comments:

This document provides the first draft for circulation at WG C and discussion at WG C plenary meeting in Budapest 28 April 2011.

Timetable:

28 April 2011: WG C meeting in Budapest 20 May 2011: Comments and case studies by members of WG C Summer 2011: Written approval by members of WG C Autumn 2011: submission to SCG

Contacts: Johannes Grath ([email protected]), Johan Schutten ([email protected]) and Wilko Verweij ([email protected])

Page 1 AUTHORS OF THE TECHNICAL REPORT Johan Schutten Scottish Environment Protection Agency (United Kingdom) Wilko Verweij RIVM (Netherlands)

LEAD OF THE ACTIVITY Johannes Grath Umweltbundesamt (Austria)

FURTHER MEMBERS OF THE ACTIVITY

Jose Luis Martin-Bordes UNESCO-IHP Balazs Horvath EC, DG Environment Johannes Drielsma Euromines

LIST OF USED ABBREVIATIONS

CIS – Common Implementation Strategy EQS – Environmental Quality Standard GWDTE – Groundwater Dependent Terrestrial Ecosystems MS – Member State RBMP – River Basin Management Plan TV – Threshold Value WFD – Water Framework Directive (2000/60/EC) WG C – CIS Working Group on Groundwater

Page 2 TABLE OF CONTENTS

1 Introduction...... 4 1.1 Background...... 4 1.2 Key concepts...... 4 1.2.1 Significant diminution and Significant damage...... 4 1.2.2 Monitoring , investigation and pollutant transfer...... 4 1.2.3 Threshold and Trigger values...... 5 1.2.4 Characterisation and Status assessment...... 5 1.3 Scope of this Technical Report...... 5 2 Key concepts...... 6 2.1 Groundwater dependent terrestrial ecosystems (GWDTE)...... 6 2.2 Significant damage to GWDTEs...... 7 3 Characterisation & Risk Assessment...... 8 3.1 Initial characterisation...... 8 3.2 Further characterisation...... 9 3.3 Other aspects of characterisation...... 12 3.3.1 Relationship with exemptions...... 12 3.3.2 Importance of good characterisation...... 12 3.3.3 WHICH ecosystems to include or include first? Prioritisation is essential but how?...... 13 3.3.4 How to determine whether an ecosystem is groundwater dependent?...... 13 4 How to determine the water quantity and quality needs of GWDTE’s?...... 14 4.1 Quantity needs of GWDTE...... 14 4.2 GWDTE and groundwater chemistry...... 15 5 Monitoring and Investigation...... 16 5.1 Monitoring...... 16 5.2 Investigations...... 17 6 Derivation of trigger and threshold values...... 18 6.1 Threshold values...... 18 6.2 Trigger values...... 18 6.3 Naturally adapted ecosystems that are dependent upon concentrations of naturally occurring substances above default threshold values)...... 19 7 Status assessment...... 21 7.1 Classification or status assessment...... 21 7.2 Status assessment and magnitude of damage to GWDTE...... 22 7.3 Staus assessment and size of GW body versus GWDTE...... 22 8 Recommendations...... 25 9 Summary of Case Studies...... 25 10 References (to update)...... 25

Page 3 1 Introduction

1.1 Background The Water Framework Directive (WFD; 2000/60/EC) aims to establish a framework for the protection of inland surface waters, transitional waters, coastal waters and groundwater. For groundwater, five environmental objectives are formulated in Article 4. Overall goal is good groundwater status, which is built up of good groundwater quantitative status and good groundwater chemical status. Definitions of these two terms are given in the WFD (Annex V). One of the elements in these definitions are relationships of groundwater with associated surface waters and dependent terrestrial ecosystems. At the plenary meeting of CIS Working Group C ‘Groundwater’ (WG C) in May 2010 in Madrid, several Member States reported about the difficulties of implementing the requirements regarding groundwater and associated surface waters and dependent terrestrial ecosystems. WG C agreed to arrange a half-day workshop back-to-back to the next meeting in October 2010 in Bruges, where Member States were given a platform to exchange experiences with these particular WFD provisions. The conclusion of this workshop was to draft a Technical Report addressing the key challenges, providing certain guidance and highlighting the still open issues.

1.2 Key concepts 1.2.1 Significant diminution and Significant damage One of the objectives for groundwater in Article 4 of the WFD is to achieve good groundwater status; this includes good quantitative and good chemical status. The definition of chemical status is set out in WFD Annex V 2.3.2., which states that that good groundwater chemical status is achieved when: “The chemical composition of the groundwater body is such that the concentrations of pollutants: – …. are not such as would result in failure to achieve the environmental objectives specified under Article 4 for associated surface waters nor any significant diminution of the ecological or chemical quality of such bodies nor in any significant damage to terrestrial ecosystems which depend directly on the groundwater body…..

The definition of good quantitative status is set out in WFD Annex V 2.1.2., which states that good groundwater quantitative status is achieved when: Accordingly, the level of groundwater is not subject to anthropogenic alterations such as would result in: – …. failure to achieve the environmental objectives specified under Article 4 for associated surface waters; – any significant diminution in the status of such waters; and – any significant damage to terrestrial ecosystems which depend directly on the groundwater body…..

These definitions give rise to a few questions. - what is significant diminution of groundwater dependent surface waters? - what is significant damage of groundwater dependent terrestrial ecosystems? 1.2.2 Monitoring , investigation and pollutant transfer Annex III of the GWD states that that for the purposes of investigating whether the conditions for good groundwater chemical status are met, Member States will, where relevant and

Page 4 necessary, and on the basis of relevant monitoring results and of a suitable conceptual model of the body of groundwater, assess: (b) the amounts and the concentrations of the pollutants being, or likely to be, transferred from the body of groundwater to the associated surface waters or directly dependent terrestrial ecosystems; (c) the likely impact of the amounts and concentrations of the pollutants transferred to the associated surface waters and directly dependent terrestrial ecosystems;

This gives rise to the following issues: - How to investigate the relationships between groundwater and associated surface waters - How to investigate the relationship between groundwater and groundwater dependent terrestrial ecosystems to ascertain the status (damaged or not) of the GWDTE and the impact of the groundwater body on his status. This monitoring is not part of WFD GW- body monitoring, but essential to determine the status of the GWDTE and the causal relationship to the GW body. 1.2.3 Threshold and Trigger values GWD Article 3 requires that “the threshold values applicable to good chemical status shall be based on the protection of the body of groundwater in accordance with Part A, points 1, 2 and 3 of Annex II, having particular regard to its impact on, and interrelationship with, associated surface waters and directly dependent terrestrial ecosystems and wetlands …”. GWD Annex I specifies that more stringent threshold values are needed if groundwater quality standards could result in failure to achieve the environmental objectives specified in Article 4 of Directive 2000/60/EC for associated bodies of surface water, or in any significant diminution of the ecological or chemical quality of such bodies, or in any significant damage to terrestrial ecosystems which depend directly on the body of groundwater. When establishing threshold values (GWD Annex II), Member States will consider the extent of interactions between groundwater and associated aquatic and dependent terrestrial ecosystems; This gives rise to the following issues: - How do we develop trigger values (e.g. EQS etc) for dependent ecosystems which will form the basis of threshold values for groundwater bodies. 1.2.4 Characterisation and Status assessment Depending on the results of the various characterization or risk assessments, several tests have to be performed to assess groundwater chemical status and groundwater quantitative status (according to CIS Guidance No. 18). The assessment of the protection of associated (connected) surface water bodies and the protection of GWDTE is considered by two test for each, the quantitative status assessment and the chemical status assessment.

Both chatacterisation and classification comprise elements which need further clarification and definition, which is tackled by this Technical Report.

1.3 Scope of this Technical Report This Technical Report is prepared by WG C under the Common Implementation Strategy of the WFD (CIS). Its purpose is to collate experience and suggest pragmatic technical solutions for the implementation of the provisions regarding the interaction of groundwater with dependent ecosystems as described under chapter 1.2. This report focuses on terrestrial ecosystems only, due to limited resources of the drafting team available. A similar report for groundwater dependent aquatic ecosystems

Page 5 would be needed and could be developed along the structure of the technical report on GWDTEs.

2 Key concepts

2.1 Groundwater dependent terrestrial ecosystems (GWDTE) In order for terrestrial ecosystems to be considered as part of the status assessment for groundwater bodies, they need to be ‘directly dependent’ on groundwater. This means that groundwater body should provide quantities, flow, level or quality needed to sustain the ecosystems which are the reasons for the significance of the GWDTE. This critical dependence upon groundwater can be during significant part or most of the year. For example, a fen in East Anglia (see situation type B) in the UK that is designated for its alkaline fen character under nature conservation i.e. Natural 2000, could be significantly damaged if a reduced groundwater input and shift in water source to rain, would change the character of the fen and as a consequence fail its nature conservation objectives.

In practice, it is not easy to determine which terrestrial ecosystems are directly dependent on groundwater and there will be a continuum of ecosystems between those that are dependent on groundwater bodies and those that are dependent on other water sources.

There are at least four types of situations where the groundwater is essential to a terrestrial ecosystem and where GWDTEs can form as shown in Figure 1:

A. A groundwater source directly irrigates the ecosystems and is visible as a spring or seepage. Examples of these include spring fed terrestrial ecosystems where high calcium content of the groundwater precipitates as tufa in the terrestrial ecosystems. In contrast, where springs feed a permanent lake or river system this would not be considered as a groundwater dependent terrestrial ecosystem, but a groundwater dependent aquatic ecosystem.

B. Groundwater collecting on impermeable strata, such as clay, in depressions in the landscape. These terrestrial ecosystems can be called fens, and their characteristic flora is directly influenced by the chemical composition of the groundwater it receives. This is in contrast to those terrestrial ecosystems where the ecology is substantially dependent on surface water (such as most swamps) or precipitation (such as raised bogs).

C. High groundwater tables maintain a seasonally waterlogged condition. Groundwater results in this instance from rainwater that has percolated through the dune sands and is present in so-called ‘wet slacks.’ The chemical composition of the water, resulting from its interaction with the dune sands, and the fluctuating nature of the water table are crucial in maintaining the ecological functioning of these terrestrial ecosystems.

D. A seasonally fluctuating groundwater table floods depressions intermittently. The resulting lakes, which are seasonal (ephemeral), have a characteristic flora which is directly related to their ecological or socio-economic significance. The terrestrial component, which is the main reason for its significance, needs to be crucially dependent upon the groundwater source to qualify as GWDTE.

Page 6 A. Ground Water discharges from B. Ground Water discharges from saturated soil or rock at one spot saturated soil or rock and collects on (spring) or discrete zone (seepage) an impermeable layer

GWDTE

Spring GWDTE GWDTE

Seepage River or lake River or lake

non or seasonally saturated soil or rock layers saturated soil or deeper rock layers non or seasonally saturated soil or rock layers Groundwater Dependent Terrestrial Ecosystem saturated soil or deeper rock layers impermeable layers

C. Ground Water discharges from saturated sand D. Ground Water discharges from saturated soil or rock and feeds ephemeral lakes or rivers

dune

sea

River or lake River or lake

non or seasonally saturated soil or rock layers saturated soil or deeper rock layers

Figure 1: Conceptual diagrams indicative of different types of groundwater-dependent terrestrial ecosystems

2.2 Significant damage to GWDTEs Significant damage to a groundwater dependent terrestrial ecosystem, caused by the quantity or quality of the groundwater it receives, or not receives, can cause a groundwater body to be classified at poor status.

CIS Guidance No. 12 explains that the expression ‘significant damage’ is based upon: a. the magnitude of the damage and b. the ecological or socio-economic significance of the terrestrial ecosystem.

The magnitude of the damage needs to be related to the capacity of the terrestrial ecosystem to continue to fulfil its ecological or socio-economic function. The significance of a GWDTE is also set out in CIS Guidance No. 12 ‘The role of wetlands in the Water Framework Directive’:

E.g. a tufa forming GWDTE that is crucial to a regional tourist driven economy could be considered to be of great socio economic significance. If pressures on groundwater caused reduced groundwater quality or quantity that leads to a reduction in tufa formation or presence of turfa resulting in a demising tourist attraction, this could be considered as significant damage. (e.g.Pamukkale, Turkey)

For those terrestrial ecosystems that belong to the Natura-2000-network, the conservation targets of the Natura-2000-area can be used. (The relation between WFD and Natura 2000 will be further discussed in a separate SGC paper.) This parallel approach would imply that if

Page 7 the conservation targets of the Natura-2000-area can not be reached due to groundwater quantitative or chemical situation, the groundwater body should be considered ‘at risk’ (during characterisation) or in poor status (during status assessment). For terrestrial ecosystems that are not part of the Natura-2000-network, a similar approach could be developed by the Member States, i.e. formulation of conservation targets, derivation of groundwater requirements (both quantitative and chemical status), then comparison of desired situation with actual situation. Then, if the targets are not met because of groundwater quantitative or chemical situation, the groundwater body should be considered ‘at risk’ or in poor status.

LOOK OUT! Defining significant damage includes both ecological and hydrogeological aspects and it is recommended that the work is carried out in multi-disciplinary teams. This will faciliatate exchange of knowledge and concepts between the diciplines and allows understanding of each others perspectives and ‘language’. Defining conservations targets outside Natura 2000 is not straightforward.

3 Characterisation & Risk Assessment

As discussed in Chapter 1, groundwater dependent ecosystems are part of status assessment for groundwater. Therefore, they are also relevant in the characterisation and risk assessment of groundwater bodies.

3.1 Initial characterisation The characterisation of groundwater bodies is a two-step-risk assessment procedure. First the initial characterisation has to be carried out. If the result of the initial characterisation is that a groundwater body is at risk, the further characterisation shall be carried out. The aim of the initial characterisation is that an assessment be made of the uses of groundwater and ‘the degree to which they are at risk of failing to meet the objectives for each groundwater body under Article 4.’ For groundwater, these objectives include interactions with ecosystems, as discussed in chapter 1. The initial characterisation (annex II of WFD) may employ any available data, including ‘hydrological, geological, pedological, land use, discharge, abstraction and other data’. One of the outcomes of the initial characterisation is that it should ‘identify those groundwater bodies for which there are directly dependent surface water ecosystems or terrestrial ecosystems.’ For example a spatial approach can be followed such as using proximity tests for quantitative and chemical pressures using spatial information to indicate pressures and possible linkages to GWDTE receptors. Screening can quickly be carried out using this method for both chemical and quantitative pressures on GWDTEs. Another approach is to use local expertise to identify GWDTEs and screen for pressures caused by the groundwater body. This approach is only practical where there are only a few GWDTEs or used in conjunction with a simple screening method to reduce the numbers of sites.

There are many different ways to determine if an ecosystem is dependent on groundwater. Monitoring results sometimes can be used for this purpose. Also output of hydrological models can be used, preferably in conjunction with a hydro-ecological conceptual model (see Guidance Document no.26). When no monitoring and modelling results are available, expert judgement may be used. For instance, ecologists can often tell by the plants they see in a

Page 8 terrestrial ecosystem, whether the ecosystem is groundwater dependent. Also, an orange- brown color in a small surface water, especially when combined with a blue layer of iron- oxidising bacteria, often indicates that fresh iron oxide precipitates, caused by anaerobic groundwater appearing on the surface. Such information is invaluable in determining which ecosystems are groundwater dependent. Disadvantage of this type of expert judgement is that it only tells whether the ecosystems are currently groundwater dependent. If an ecosystem was groundwater dependent in the past but is not any longer due to man-made groundwater table lowering, you may not be able to trace that in the field.

If an ecosystem is currently not groundwater dependent (due to man-made lowering of groundwater tables) but was in the natural situation, this should also be taken into account when identifying groundwater bodies with dependent ecosystems, because art. 4 of WFD requires that ‘Member States shall protect, enhance and restore all bodies of groundwater’ (italicization added by authors).

LOOK OUT! How far to go back in history do we need to go in deriving the need for restoring an ecosystem? What is the base year after which deterioration is to be tackled by the WFD?

At the end of the initial characterisation, it should be clear which groundwater bodies contain ecosystems that cause the groundwater body to be at risk of failing to meet the objectives for groundwater. For those groundwater bodies the further characterisation has to be carried out.

3.2 Further characterisation The further characterisation focuses on the impact of human activity. If a groundwater body is at risk due to effects on ecosystems, a) an inventory shall be made of all ecosystems with which the groundwater body is dynamically linked. This is different than the initial characterisation where it does not matter yet how many ecosystems are groundwater dependent. Inventory of all ecosystems The Water Framework Directive does not discriminate between groundwater dependent ecosystems. However, in practice, it may be necessary to prioritise ecosystems, e.g. when many ecosystems are connected to one groundwater body. CIS Guidance document 12 gives practical guidelines for prioritising terrestrial ecosystems (section 3.3, pages 21 till 25). Summarised the step-wise approach recommends to focus on Natura 2000 sites as well as on those ecosystems which can experience significant damage (either ecological or socio- economic). Although prioritisation may be necessary in the first planning cycle(s), ultimately all groundwater dependent ecosystems should be regarded.

LOOK OUT! For example, in the UK we prioritised by only dealing with GWDTE’s that were protected by natura conservation legislation (Natura 2000 and National protected sites)) in the first planning cycle. Other sites will be included in the next planning cycles.

Page 9 LOOK OUT! It may be useful to develop common categories of GWDTEs to help exchange of information and better comparison of methods between Member States. An example of simple categories of GWDTEs is given by SNIFFER (2009). Member States are encouraged to establish a common categorisation and co-operate on information and database sharing on the environmental requirements of wetland ecological features (such as plant communities). b) the exchange of water between the groundwater body and the ecosystems shall be estimated, i.e. the direction of flow and the rate of exchange. One needs to keep in mind that it is necessary to determine whether or not a GWDTE is significantly damaged due to the impact of groundwater, and thefore inclusion of anthropogenic pressures can focus the risk assessment. For example for further characterisation, a source-pathway-receptor (SPR) approach can be used to conceptualise groundwater flows and anthropogenic pressures (Figure 2).

source

pathway receptor

GWDTE

River or lake Abstraction

non or seasonally saturated soil or rock layers saturated soil or deeper rock layers The abstraction (source) will lower the groundwater table locally. This will result in a lower pressure in the saturated rock (hydro-geological pathway) and subsequently less discharge at the GWDTE (receptor)

Figure 2 Source-pathway-receptor linkages for a GWDTE

Source term For quantitative pressures, it is worth considering the amount of groundwater abstractions across the whole groundwater body, which may cause regional lowering of groundwater levels, in addition to those near the GWDTE. Local abstractions close to the GWDTE might have large impacts on the flow and discharge to the GWDTE and thus may be more damaging than abstractions some distance away in the groundwater body, even if they are of

Page 10 relatively small size. Equivalent recharge circles can be used to ascertain the spatial part of the pressure in relation to the location of the GWDTE

For chemical pressures, groundwater quality monitoring networks may provide sufficient data to estimate the average concentration of common pollutants that can adversely affect ecosystems, such as nitrates and phosphates. If such data are lacking, an estimate of chemical pressure may be obtained using chemical loading models. For example, where chemical pressures are from agriculture, agricultural information such as stocking densities, crop types and fertiliser loadings can be used.

Pathway Geological maps and data on superficial geology and hydraulic properties, such as hydraulic conductivity, may be used to understand the hydraulic connection between the groundwater body and the GWDTE. It should be noted however that very local differences in hydrological conductivity, such as at the bottom of a GWDTE where clay or silt layers might be present, can have major impacts on the overall hydraulic connectivity.

Receptor Generic sensitivities of ecological receptors (GWDTEs) are being developed on a country-by- country basis (Ref Hydro ecological guidelines EA, and Wheelers work). Comparison of this information between countries is recommended, which would require close cooperation between Member States. Existing eco-hydrological guidelines and databases on wetland ecology (such as vegetation communities) may be helpful to estimate the sensitivity of ecological receptors.

Generic threshold values (see 4) may also be used for risk screening/characterisation, where they are available. They should, however, be used with caution (see CIS Guidance 26, section 5.3.4). This will allow sites to be ruled in or out at the risk screening stage where there is a known risk, or where there is no risk. CIS Guidance 26 makes it clear that risk screening during initial characterisation ‘is a precautionary risk screening exercise, which is quite distinct from the need (to classify) assess whether there is actual damage to a groundwater body from human activity (i.e. poor status) and therefore whether remedial action (measures) should be taken.’

Page 11 Table 1 lists the sources of information that may be useful at each tier of risk assessment (Brooks et al., 2008).

3.3 Other aspects of characterisation Tier 1 Tier 2 Tier 3 Initial Further Evaluation and characterisation characterisation Classification Context Detail Site visit ? k o o

l Published maps Borehole archive ‘Get a feeling for the

o

t Databases Hydrometric archive site’

e

r Regional scale Local reports Picture morphology e h reports Local knowledge Identify hydrological W Modelling reports and ecological features Ecology reports Measurements On-site investigations ? r o f Topography Local geology Surface water inflows k o

o Geology Water level details Surface water outflows l

o Hydrogeology Flow records Flow rates t

t

a Soils Anecdotal evidence Water level controls h Land cover Habitat maps Head difference W Historical info Vegetation maps between water features ecological data. Electrical conductivity Near-surface geology Distribution of species / communities

3.3.1 Relationship with exemptions Annex II of the WFD also requires (2.4) that if Member States want to specify lower objectives for quantitative status of groundwater bodies, the impact on dependent ecosystems shall be considered. 3.3.2 Importance of good characterisation Guidance document 26 stresses the importance of a correct classification in terms of ‘at risk’ or ‘not at risk’. Eventually, in the last step of a tiered approach, a groundwater body should be classified as ‘at risk’ in case of doubt about its actual classification. An important reason for this suggested approach is that, if a groundwater body is declared as ‘not at risk’, monitoring obligations are different (see chapter 3) and requirements for status assessment are different. The GWD states that chemical status assessment only needs to be carried out for groundwater bodies identified as being at risk (Annex III 1 GWD). Groundwater bodies not at risk are automatically classified as being of good chemical status. Although this does not hold for quantitative status, it is important to be aware that a groundwater body erroneously classified as ‘not at risk’ automatically is classified as ‘good chemical status’ which may lead to not taking necessary measures.

Page 12 3.3.3 WHICH ecosystems to include or include first? Prioritisation is essential but how?

CIS 12 states that “‘There are potentially very large numbers of terrestrial ecosystems that are directly dependent on groundwater within the Community. Whilst many support features of value (ecological or socioeconomic), a screening tool will be essential to focus action on the most important sites and areas, so that Member States do not face an impossible administrative burden. Member States may use their own, nationally developed criteria for identifying those dependent terrestrial systems which they believe are of sufficient importance that damage to them, as a result of anthropogenic groundwater alterations, could legitimately be described as 'significant'.’

Member states can use lists of sites to determine their priority. Where there are only a few GWDTEs or where the pressures on the GWDTEs are well known it may be relatively easy to prioritise the sites.

However, where there are many potential sites, geo-spatial techniques (such as GIS) can be used to identify those sites with particular ecological or socio-economic significance. The priority on the list needs to be related to the importance of that function for the Member State. For example, a GWDTE that provides drinking water and is protected under EU nature conservation directives is likely to have a high priority.

The priority can also be related to anthropogenic groundwater pressures, such as abstraction or pollution, focussing on those sites with the greatest pressures first.

3.3.4 How to determine whether an ecosystem is groundwater dependent? In some cases, especially where the spring or seepage is clearly visible (figure 1, type A) it may be very clear that the GWDTE is directly dependent upon groundwater. In other cases, especially where the groundwater outflow is not so easily visible, it may be more difficult to determine the groundwater dependency of a GWDTE.

Member States might have sufficient information about the groundwater dependency of a GWDTE, and therefore may not need to assess this further. The first step is to determine the groundwater dependency of the features of significance, which will often be the ecological features (such as vegetation communities). Member States may have lists, drawn up by competent ecologists, which identify groundwater dependencies of a range of GWDTE types (i.e. Ref to UKTAG 5 A/B paper). Frequently there is uncertainty about the proportion of groundwater influence on a GWDTE compared to other sources. Therefore, a weight-of-evidence approach is recommended as a decision-making tool (CIS 26, section 2.5) to support the risk assessment.

A conceptual model (CIS Guidance No.26) which includes both GWDTE and groundwater body can help to understand the groundwater-dependency of the GWDTE. This will enable the different water sources to be considered, such as rainfall and surface water, alongside groundwater contributions. The model should be able to describe linkages and the hydrological pathway between the site and the groundwater body pressures, which will help inform the risk assessment or characterisation process. You may need to refine the conceptual model, possibly several

Page 13 times, as more data becomes available. Where available the model should include the eco- hydrological working of the site as well as the hydro(geo)logical mechanisms.

Approach for conceptual model development for specific habitats Conceptual models will help both ecologists and hydrogeologists to combine their data and assess the risk of significant damage to GWDTEs, the impact on the ecology of different water supply mechanisms, and the significance of changes in both water quantity and chemistry. Many examples of general hydrogeological conceptual models for GWDTEs exist (Lloyd et al. 1993; Winter, 1999; Dahl et al., 2006; Acreman and Miller, 2007). However, few of these conceptual models provide flow mechanisms which result in distinct or unique ecological types, and they often ignore the importance of the ‘top-layer’ of soil/superficial geology, which has crucial importance to the ecology, particularly plant communities (Wheeler, et al., 2009; Whiteman et al., 2009). To overcome these limitations, a Member State might choose to develop eco-hydrological conceptual models for specific habitats/plant communities such as Wheeler et al., 2009; Whiteman et al., 2010.

4 How to determine the water quantity and quality needs of GWDTE’s?

4.1 Quantity needs of GWDTE The amount of water that a GWDTE needs to fulfil its ecological or socio-economic functioning will vary throughout the year. There are however key ecological time periods during a year where groundwater is critical to the functioning of the GWDTE and these are the reason that a site has been determined to be a GWDTE. For example, groundwater discharge to a GWDTE wetland on a slope may be particularly important during the dry times of the year, such as during the summer months, where evapotranspiration is not replenished by rainwater.

The EU research project GENESIS might help to define those critical requirements

Water quantity variables can include:  discharge of groundwater to the site via springs and seepages - assessed by the relative volume of groundwater discharge to the GWDTE;  Maintenance of an upward hydraulic gradient from the groundwater body to the near surface deposits – assessed by the relative elevations of groundwater levels within the groundwater body and the GWDTE;  Maintenance of an upward flow of groundwater from the groundwater body to the near surface deposits – assessed by the relative volume of flow to the GWDTE;  Impacts on groundwater levels in the GWDTE as shown by changes in the depth to the water table;  Water saturation of the soil or soil moisture characteristics as a result of inputs from groundwater – assessed by consideration of typical soil hydraulic properties related to in water level and flow.

Expert ecologists in Member States may understand the water quantity needs of specific GWDTEs, but often there are no published numerical requirements, as these will often be related to the specific GWDTE. Where information is available, hydrogeological modelling

Page 14 can be used to identify and quantify groundwater sources to a GWDTE. This may be using a simple water balance right through to complex numerical groundwater modelling.

There is a growing evidence base of general water quantity requirements of GWDTEs , however an exchange of information across the EU Member States on the water quantity requirements of GWDTE categories would be highly appreciated.

Current knowledge includes (not exhaustive; WG-C please update and expand with your knowledge):  Niche (Dutch ref) and Niche (Vlaanderen)  Generic guidelines on the hydrological needs of specific ecology types (called eco- hydrological guidelines) (Barsoum et al., 2005; Mountford et al., 2005; Davy et al., 2006, 2010; Wheeler et al., 2004; Wheeler & Shaw, 2010; Whiteman et al., 2009; Whiteman et al., 2010);  technical reports or previous investigations of GWDTEs, for example in support of new abstractions

There will often be a need to derive GWDTE category specific water quantities, and these can be developed using an expert panel approach.

General water requirements of GWDTE categories need to be evaluated for application to a particular site or location. The local variability of shallow and deeper soil and rock layers and topography (land level) are crucial to understand GWDTE hydrological functioning, and will inform how the general GWDTE requirements can be applied to a particular site.

4.2 GWDTE and groundwater chemistry Characterisation should determine what groundwater chemical pressures may be acting on the GWDTE and information about pollutants present in the groundwater body should be obtained from the groundwater chemical monitoring network. For example, in an intensive agricultural setting, it is likely that the most important substances affecting GWDTEs are nitrate and phosphate. The substances which are identified as important should be considered as the basis of the risk assessment. Information such as the site being ‘significantly damaged’ and the groundwater body having elevated levels of the substances can be used.

When determining the impact of substances, the tolerance of different GWDTE categories can have a large range. For example, some GWDTE vegetation types only grow in certain locations due to the unique chemistry of the water supply in that area. Work has shown (references UK) that some vegetation types are also more or less tolerant of elevated substances, such as nutrients. Further work is needed to understand the effect of substances on different wetland categories.

In 4.1 we advocate an EU wide sharing of experience on water quanity needs of GWDTE’s. We also would advocate this approach to GWDTE water chemical needs and effects of substances.

The general effects of the concentration of substances of GWDTE categories, once established, will need to be evaluated for its application to a particular site or location. The local variability of shallow and deeper soil and rock layers and topography and the transformation of substances within the GWDTE will inform how the general GWDTE requirements can be applied to a particular site.

The general information on the effects of different substances on GWDTEs can be used to develop trigger values for GWDTE and thus inform groundwater body Thershold Values.

Page 15 5 Monitoring and Investigation

5.1 Monitoring

Annex V of the WFD (section 2.2.2) states that in each groundwater body the groundwater level shall be monitored, in particular groundwater bodies at risk and cross-boundary- groundwater bodies. Section 2.4.2 states that for surveillance monitoring, sufficient monitoring sites are needed for bodies at risk and for cross-boundary-groundwater bodies. However, Guidance Document 15 states that surveillance monitoring is needed in all groundwater bodies to validate risk assessment and enable trend assessments. Operational monitoring is only needed for groundwater bodies at risk. This again stresses the importance of a proper risk assessment, because a groundwater body erroneously designated as ‘not at risk’ might only be monitored at the beginning of a plan period within the surveillance monitoring, possibly hiding existing problems.

A lot of information is already available on monitoring, including monitoring of interactions between groundwater and ecosystems, e.g. Guidance Document 7 (monitoring), 15 (groundwater monitoring) and Technical Report on Groundwater Monitoring [REF] and in fact also the Guidance Document 26 on Risk Assessment and Conceptual Models. Not all information will be repeated here. Most relevant for this Technical Report are the clues that:  development of monitoring programs should go hand-in-hand with development of a conceptual model of the groundwater body (see Figure 6 from the Technical Report on Groundwater Monitoring);  that both monitoring of quantitative and chemical status should also focus on interaction of groundwater body with ecosystems. Therefore the monitoring networks of the WFD should take this into account. LOOK OUT! The WFD does not make specific provision for receptor-focused monitoring of GWDTEs but this will be needed to understand functioning of GWDTEs and to ensure the GWDTES do not deteriorate.

Page 16 5.2 Investigations

Investigations should provide the evidence base to understand whether a GWDTE is ‘significantly damaged’ and that this is caused by pressures on the groundwater body. This work needs to assess the magnitude of the damage, the hydrogeological linkage between the groundwater body and the GWDTE and the relative importance of groundwater for that particular wetland. This can be used to refine conceptual models and provide the evidence that is required to design and implement measures.

Monitoring should ensure that sites that were not previously classed as ‘significantly damaged’ do not become ‘significantly damaged’ as a result of groundwater body pressures - this would cause deterioration in status of the groundwater body. This could include a combination of ecological investigations to identify damage and hydrogeological investigations to determine that the damage is caused by groundwater body pressures

Page 17 6 Derivation of trigger and threshold values

6.1 Threshold values Article 3 of the GWD lays down criteria for assessing groundwater chemical status: “1. For the purposes of the assessment of the chemical status of a GWB [….] Member States shall use the following criteria: (a) groundwater quality standards as referred to in Annex I, (b) threshold values to be established by Member States in accordance with the procedure set out in Part A of Annex II […]”.

Where a groundwater quality standard is not sufficient to ensure that the environmental objectives set out in Article 4 of the WFD e.g. where concentrations in groundwater are causing or could cause significant damage to GWDTEs, then a more stringent concentration is required. These new values are ‘threshold values’ and should be set at an appropriate scale (national, river basin district or at groundwater body scale). These threshold values are then applied to the groundwater body (or relevant scale) during classification and if exceeded in the groundwater body, appropriate investigation is needed which forms part of the status assessment. The criteria required for the establishment of threshold values is set out in CIS 18: Guidance on groundwater status and trends assessment. One of the specific criteria is that TVs should ‘aim to protect associated aquatic ecosystems and groundwater dependent terrestrial ecosystems’.

The derivation of threshold values should be based on the receptors present in a groundwater body, i.e. human use and ecosystems. For surface waters present in a groundwater body, there are procedures available for deriving environmental quality standards (EQS; Technical Report; REF). Those EQS-values can be used to establish threshold values for the groundwater body. For terrestrial ecosystems, there is no similar technical report available. However, the procedures for deriving quality standards are very much the same. For the Dutch situation, the Waternood-instrument was developed (available at http://www.synbiosys.alterra.nl/waternood/ but only in Dutch). This instrument may be useful in countries with similar vegetation as in the Netherlands; for other countries, the same approach could be used to collect information about the requirements of ecosystems in terms of quantity of groundwater as well as chemical composition. The resulting information about requirements of ecosystems can be used to derive threshold values, if desired and possible in combination with the use of attenuation and dilution factors.

More information can be found in Guidance Document 18.

LOOK OUT! Co-operation is recommended between Member States to contrast and compare knowledge on the water quantity and effects of substances on different categories of GWDTE. This may be used by Member States to help develop threshold values

6.2 Trigger values Trigger values can be based upon generic sensitivities of GWDTE types (see 4). These values could be used during characterisation and exceedances would results in investigations to determine the magnitude of damage and causal linkage between damage and groundwater. .

Page 18 6.3 Naturally adapted ecosystems that are dependent upon concentrations of naturally occurring substances above default threshold values). Some ecosystems are adapted to higher concentrations of naturally occurring substances. This is not pollution according to the WFD.

For example in a region of the Netherlands, zinc naturally occurs in high concentrations. Local ecosystems are adapted to those conditions and therefore differ from ecosystems elsewhere. This should not be considered as pollution, because the origin is natural. If you would have a region with naturally low concencentrations of zinc in combination with high zinc emissions, the same type of ecosystem might develop. However, in such a case this should be considered as pollution and therefore measures may need to be considered.

When ecosystems of divergent sensitivity for a certain substance fall in one groundwater body, the threshold value should be based on the most sensitive receptor (see GD18 page 24). That ensures that in the first step of chemical status assessment, one can be sure that if all monitoring results are below the threshold value, all receptors are protected. The consequence can be that in parts of the groundwater body (where the naturally adapted ecosystems are), the threshold value is exceeded. This does not automatically (and in fact should not) lead to poor status. The suggested procedure in such a case is as follows:  derive the threshold value based on the most sensitive receptor (ecosystem, abstraction for human use).  compare monitoring results with threshold value.  if average of concentrations per monitoring point is lower than the threshold value, the GW-body is of good chemical status for this substance.  if average of concentrations per monitoring point is higher than the threshold value, start the ‘appropriate investigation’. Depending on the result of the appropriate investigation, assign either good or poor chemical status for this substance.

If a groundwater body contains ecosystems with high sensitivity for a substance as well as ecosystems with low sensitivity for the same substance, the ‘appropriate investigation’ might need to be carried out. If the exceedance is associated with the naturally adapted ecosystem, there is no reason to assign poor status.

Example: see Figure 3. In the north east part of the groundwater body there is an ecosystem naturally adapted to concentrations of 10 µg/l of a substance. In the south west part there is another ecosystem, much more sensitive. It tolerates the concentration of the pollutant up to 3 µg/l. The threshold value is established at 3 µg/l, to protect both ecosystems. One of the two monitoring points shows an average concentration of 8 µg/l, which is above the threshold value. This does not automatically lead to good chemical status. The ‘appropriate investigation’ demonstrates that in both corners of the groundwater body the measured concentration is lower than the value tolerated by the ecosystem in that part of the groundwater body. Supposing the high concentration in the north east part is of natural origin, this leads to good status for this substance. Note: this example of course is very simple. In practice, many factors may complicate this picture. It is just meant to illustrate the line of reasoning in case of a naturally adapted ecosystem.

Page 19 Groundwater body

Monitoring point; average [substance] = 8 µg/l Ecosystem naturally adapted to [substance] ≈ 10 µg/l Sensitive ecosystem; requires [substance] < 3 µg/l

Monitoring point; average [substance] = 2 µg/l

Figure 3. A groundwater body with two ecosystems differing in sensitivity. In the north east part of this groundwater body, the concentration of a substance is naturally high. The ecosystem there is adapted to high concentrations.

Page 20 7 Status assessment

7.1 Classification or status assessment Classification of the status of groundwater body under the GWDTE test, for both quantitative and chemical status, is a decision based on the information available from the risk assessment, the characterisation process. There may be different levels of certainty in the risk assessment depending on the amount and type of evidence available about the site itself, linkages to the groundwater body and pressures acting on the groundwater body. Only those deemed to be 'at risk' under the characterisation process should be considered as potentially putting a groundwater body at poor status.

The process set out in figure 5 and 6 below (from CIS Guidance 18) highlight the need to take a decision on whether environmental supporting conditions being met on GWDTEs identified as 'at risk'. However, there may be insufficient information on the site, its function or the contribution from the groundwater body to determine with certainty these environmental supporting conditions. As detailed in CIS 18, in this instance, the groundwater body will be of good status under this test but will remain 'at risk'. These sites will also be prioritised for further investigation to enable improvements in future risk assessments and decisions for classification for this test to use this improved information.

For those groundwater bodies where there is still significant risk of significant damage of a GWDTE, after the characterisation process CIS Guidance 18 (section 2.6) recognises that additional investigation and monitoring may be required to inform classification. For groundwater bodies where a threshold value is exceeded, but significant uncertainty exists, this may trigger a more detailed site-specific assessment as part of the classification of the groundwater body or alternatively may rely on a weight-of-evidence approach and expert judgement, where information is available.

It is important to carry out any form of detailed investigation in a cost-effective way. The investigation should always be guided by the conceptual model (CIS Guidance 26, Annex II). It is recommended to prepare a ‘site-works plan’ with partner organisations and shared between technical specialism’s to scope the work. Methods that may be cost-effective and help to reduce uncertainty in source-pathway-receptor links for GWDTEs include:

 Targeted ecological surveys (e.g. vegetation surveys to detect changes in abundance of species indicative of chemical damage such as nutrient enrichment);  Walkover hydro-ecological surveys to determine the location of springs and seepages in relation to critical groundwater-dependent ecological features, and ascertain hydraulic relationships between groundwater and surface water features such as ditches, ponds and other watercourses;  Chemical sampling of groundwater and surface water features along the source-pathway-receptor gradient to improve knowledge of the transfer of pollutants from the source to the wetland;  Establishment of shallow dipwells to measure water levels in the near-surface deposits and their hydraulic relationships with the underlying groundwater body.

Other techniques that may be required include:  Geophysical surveys e.g. resistivity, ground-penetrating radar to confirm stratigraphic relationships and location of water-bearing/conductive strata;

Page 21  Drilling of deeper piezometers into the underlying groundwater body;  For chemical pressures, age-dating and isotope sampling of groundwater (e.g. nitrogen isotopes to give information about the likely source such as agricultural fertiliser application);  Measurement of other sources of chemical pressure e.g. atmospheric nitrogen deposition that may cause a critical loading to be exceeded.

This further investigation should be used to underpin whether or not a GWDTE is significantly damaged and that the damage is caused by the pressure exerted by the groundwater body. The result of this will therefore inform the classification of the groundwater body.

7.2 Status assessment and magnitude of damage to GWDTE CIS 12 explains how the expression ‘significant damage’ is based upon: a. the magnitude of the damage and b. the socio-economic significance of the terrestrial ecosystem.

The magnitude of the damage needs to be related to the capacity of the terrestrial ecosystem to continue fulfil its socio-economic function (i.e. the function for which it was identified as being significant).

CIS guidance document 18 ‘Guidance on groundwater status and trend assessment’ provides the outline of tests for quantitative (section 5.3.3.) and chemical damage (section 4.4.5) to GWDTEs (Figures 5 and 6).

It is important to apportion the source of the pressure into groundwater and non-groundwater (such as rain, surface water or aerial) components.

Look out! ‘In-combination’ effects may be important in causing actual ecological damage to GWDTEs. For example, even if the chemical loading of nitrates from groundwater does not exceed a concentration which causes ecological damage, aerial deposition of nitrates (from atmospheric pollution or incineration for example) may cause a critical loading for the catchment to be exceeded (see for example, the case of Merthyr Mawr, reported by Jones et al. 2006). This may need to be investigated if a site is failing to meet the function for which it was deemed significant.

In case of combined effects, it is necessary to identify the share of the contribution of groundwater compared to the overall contribution to assign a GW-body as beeing of poor status.

7.3 Staus assessment and size of GW body versus GWDTE When assessing a GWDTE, it is not specifically the scale (i.e. the size) of that GWDTE that is important in relation to the groundwater body. If a GWDTE has been identified as significant (and is therefore important) and is significantly damaged from groundwater pressures such that it can no longer perform the function for which it was identified as significant, the groundwater body should be at poor status.

Page 22 Terrestrial ecosystem Is a terrestrial ecosystem No Significantly damaged significantly damaged and Interaction with GWB interacting with the GWB?

Yes

Relevant TV Is any relevant monitoring point No Damage to GWDTE in the GWB exceeding a relevant GW-QS or TV by its mean value for a parameter responsible for the damage of the GWDTE?

Yes

Pollutants transfer Is the exceedance located in an No area where pollutants might be transferred to the GWDTE?

Yes

Pollution load transfer Is the pollution load transferred No from the GWB and the resulting concentration causing harm to the Yes GWDTE?

GWB is not of good GWB is of good chemical status for this chemical status for this test. test. *

Consider the conceptual understanding (e.g. pressure, vulnerability, impact situation) of the groundwater body at each step within the assessment. * Proceed according to Article 4(5) GWD

Figure 5: Proposed procedure for test of significant damage of terrestrial ecosystems directly dependent on the groundwater body caused by the chemical pressure of the groundwater body (From CIS Guidance No.18)

Page 23 Data preparation Data testing

Associate each GWDTE with a Are GWDTE within the No GWB and establish whether GWB damaged, or at directly dependant. risk of being damaged?

GWDTE damaged

Are the required environmental Yes supporting conditions relating to water level and flow being met?

Determine the magnitude of the departure from required conditions within the GWDTE

Is the departure from the required environmental conditions the result of groundwater abstraction? Yes No

GWB is not of good GWB is of good quantitative status quantitative status for this test. for this test.

Note:

If the proportion of failure due to anthropogenically impacted groundwater is significant, and a dependent community is not damaged, the groundwater body is deemed to be of good status for his test, but is at risk of failing the relevant good status requirements in the future.

Figure 6: Outline of procedure for the GWDTE element of quantitative status assessment (from CIS Guidance Document No.18)

Page 24 8 Recommendations

1. Is is advisable that multi-disciplinary teams (hydro-geologists and ecologists) work together in determining the risk to the GWDTE and the level of damage to the GWDTE caused by the groundwater. 2. It is advisable that ground and surface water organisations work together when dealing with GWDTE 3. It is advisable to develop a working group under WG-C to further develop GWDTE –issues and share knowledge and pragmatic and practical solutions 4. It is advisable that a technical paper on groundwater dependent surface waters (aquatic) is written.

9 Summary of Case Studies  as presented in Bruges (presenters to be asked for approval in advance) presenters  Uk contribution (already published paper on this from Mark Whiteman etc.+ investigation sites (e.g. in Scotland, also Wales and England - Wybunbury, Cors Bodeilio, Merthyr Mawr etc) UK

Insert Case Study: tiered risk assessment – Wybunbury

 UNESCO-IHP suggests to include a brief description of two case studies outside the EU region, i.e. South Africa and Jordan and from the network of IAH UNESCO (remark: to be checked, if the procedure applied in the case studies are in line with WFD/GWD requirements and the procedure finally outlined in the guidance)

FAQ: Frequently Asked Questions about relationship between Water Framework Directive and Natura 2000 (Contribution to the document ‘Links between the Water Framework Directive (WFD 2000/60/EC) and Nature Directives (Birds Directive 79/409/EEC and Habitats Directive 92/43/EEC)’ which was distributed as a draft in summer/autumn 2010). All

10 References (to update)

Other relevant documents:  FAQ WFD – N2000  guidance 7 monitoring  guidance 12 wetlands  CIS Guidance No.12 ‘Horizontal Guidance on the Role of Wetlands in the Water Framework Directive’  guidance 18 status/trends  guidance 26 risk assessment & conceptual models

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