Methodology

3.1.     Basis for classification of ecological status

3.1.1.      Principles on classification of ecological status or potential

The WFD defines “good ecological status” in terms a healthy ecosystem based upon classification of the biological elements (phytoplankton, phytobenthos, benthic fauna and fish) and supporting hydromorphological, physico-chemical quality elements and non-priority pollutants. Biological elements are especially important, since they reflect the quality of water and disturbance of environment over longer period of time. The ecological status is reported for each water body. Water bodies are classified by assessment systems developed for the different water  categories (river, lake, transitional and coastal waters) and  the different natural type characteristics within each water category..

WFD has different requirements for natural waters and for artificial or heavily modified waters. ‘Artificial water bodies’ are those, created by human activity (e.g. an artificial lagoon in the area where there was naturally no water before). ‘Heavily modified water bodies’ (HMWB) are waters, where significant human induced physical alterations have changed  of their hydro-geomorphological character to the extent that habitats are negatively affected (e.g. large harbours, hydropower reservoirs, major reductions of natural river flow, etc.). For natural water bodes the ecological status is standard for classification, while for heavily modified and artificial water bodies the ecological potential should be determined. Member States will need to meet the good ecological potential (GEP) criterion for ecosystems of HMWBs and AWBs rather than good ecological status as for natural water bodies.  The objective of GEP is similar to good status but takes into account the constraints imposed by social and/or economic uses. 

The ecological status classification scheme includes five status classes: high, good, moderate, poor and bad. ‘High status’ is defined as the biological, chemical and morphological conditions associated with no or very low human pressure. This is also called the ‘reference condition’ as it is the best status achievable - the benchmark. These reference conditions are type-specific, so they are different for different types of rivers, lakes or coastal waters in order to take into account the broad variation of ecological conditions in Europe.

The Directive requires that the overall ecological status of a water body be determined by the results for the biological or physicochemical quality element with the worst class determined by any of the biological quality elements. This is called the “one out - all out” principle.

At “good” ecological status, none of the biological quality elements can be more than slightly altered from their reference conditions. At “moderate” status, one or more of the biological elements may be moderately altered. At poor status, the alterations to one or more biological quality elements are major and, at bad status, there are severe alterations such that a large proportion of the reference biological community is absent.

The class boundaries for the biological classification tools are expressed as ecological quality ratios (EQRs). EQRs are a means of expressing class boundaries on a common scale from zero to one. The boundary EQR values represent particular degrees of deviation from the corresponding reference values. High status is represented by values relatively close to one (i.e. little or no deviation) and bad status by values relatively close to zero (i.e. substantial deviation).

The process of ecological classifications is described in Figure 3.1.

Figure 3.1: Classification of ecological status (from WFD CIS Guidance on classification)

WFD requires that standard methods are used for the monitoring of quality elements, and that the good status class boundaries for each biological quality element are intercalibrated across member states sharing similar types of water bodies. The aim of the intercalibration has been to ensure that the good status class boundaries given by each country’s biological methods are consistent. Further information on the intercalibration process and results are given in the text box below.

Text box: Inter-calibration of national classification systems for assessment of ecological status or potential

Chemical and physicochemical quality elements

The general chemical and physicochemical quality elements describe water quality and are considered as supporting elements to biological community. General chemical and physicochemical quality elements relevant for rivers and lakes are transitional and coastal waters are (i) transparency (not for rivers), (ii) thermal conditions, (iii) oxygenation conditions,  (iv) nutrient conditions and (v) acidifying substances (for rivers and lakes only). At high ecological status, the condition of each element must be within the range of conditions normally associated with undisturbed conditions. At good ecological status, the Directive requires that the general physicochemical quality elements comply with standards established by the Member State to protect the functioning of the ecosystem and the achievement of the values specified for the biological quality elements at good status.

Specific pollutants

Member States are required to identify 'specific pollutants' (i.e. those pollutants being discharged in significant quantities) from the Directive's general list of the main types of pollutants. For good ecological status, the environmental quality standards established for specific pollutants must not be exceeded. Environmental quality standards for the specific pollutants have been set in such a way that, where the standards are met, no adverse effects on aquatic plants and animals should occur.

Hydromorphological quality elements

For high status to be achieved, the Directive requires that there are no more than very minor human alterations to the hydromorphological quality elements. At good, moderate, poor and bad status, the required values for the hydromorphological quality elements must be such as to support the required biological quality element values for the relevant class. Each of the four surface water categories is ascribed specific hydromorphological quality elements (Table 3.1).

Table 3.1: Hydromorphological quality elements to be used for the assessment of ecological status or potential based on the list in WFD Annex V. 1.1.

3.1.2.      Results of classification of status and Biological Quality Elements, confidence and data quality

European overview

Due to delays in the development of national classification systems in many member states, only a few biological quality elements could be used for assessing ecological status of water bodies for the first river basin management plans. The assessment systems available at the time of delivering the RBMPs were mainly for benthic invertebrates in rivers and coastal waters, for diatoms in rivers and for phytoplankton chlorophyll a in lakes. Most of the assessment systems are relevant mainly to assess impacts of pollution pressures causing nutrient and organic enrichment, whereas hydromorphological pressures causing altered habitats have mainly been assessed in rivers using fish as indicator of ecological status. For transitional waters there were almost no assessment systems available in time to be used in the first RBMPs. There were also large differences in the level of development of assessment methods across Europe, with the most serious gaps found in the Mediterranean and Eastern Continental / Black Sea regions. For more information, see:

 http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:332:0020:0044:EN:PDF .

An additional weakness in the national systems used for ecological status assessment of water bodies in the first RBMPs is that the class boundaries for the supporting quality elements (e.g. nutrients, organic matter etc.) in many cases are not well linked to the class boundaries for the biological quality elements, and in some cases are quite relaxed compared to the responses of the biological quality elements (ref. to Ulli Claussen and Jens Arle’s comparison of nutrient standards).

For ecological potential of heavily modified and artificial water bodies, the assessment systems applied have either been the same as those for ecological status (for example in terms of phytoplankton chlorophyll in Mediterranean reservoirs or fish in Alpine rivers), or been based on expert judgement considering possible measures that could be used to improve the ecological potential.

The overview of quality elements used for assessing the ecological status or potential of water bodies (Figure 3.2), reflects the level of development of the national assessment systems described above, and also shows that the proportion of water bodies monitored are less than the proportion classified for most quality elements in most of the water categories. The latter is explained by grouping of water bodies, using a few representative monitored water bodies to classify a larger group of non-monitored water bodies. If this grouping is applied for water bodies of the same type exposed to the same type and level of pressures, the classification of non-monitored water bodies would still be WDF compliant, according to the WFD CIS guidance on monitoring. 

However, also expert judgement based on the information compiled in the pressure and impact analyses (WFD article 5) has probably also been used for classification of water bodies in this first cycle of RBMPs.

For rivers, the most commonly used quality elements are macroinvertebrates and fish, as well as the supporting quality elements for hydromorphology, for general physico-chemical and for non-priority specific pollutants. The proportion of classified water bodies is much larger than the proportion of monitored water bodies illustrating the practice of grouping and/or expert judgement for classifying non-monitored water bodies. This grouping is justified by the very large number of river water bodies. The phytobenthos (mainly diatoms) are monitored in less than 10% of all water bodies and used for classification of less than 20%, while macroinvertebrates are monitored in more than 20% and classified in more than 40% of all river water bodies. This is surprising, considering the high sensitivity of phytobenthos to nutrient enrichment, but propably reflects the traditional use of macroinvertebrates to assess organic enrichment (saprobic indices) in rivers.

For lakes, phytoplankton is the most commonly used biological quality element. In many cases the phytoplankton classification is based only on chlorophyll a, which was the only part of this quality element that was fully developed for classification by most member states for the first RBMPs. Also for lakes, the supporting quality elements, especially the general physico-chemical ones, are most commonly monitored and used for classification. As for rivers, the classification of lakes is based on grouping and/or expert judgement for the majority of the classified water bodies; less than 20% of  the water bodies are monitored for one or more quality elements, while close to 80% is classified for general physico-chemical quality elements.

For transitional waters, the picture is quite different from that of  rivers and lakes. Almost the same proportion of water bodies is monitored as that classified. For angiosperms, as well as for hydromorphological and non-priority specific pollutants, the proportion monitored is even higher than the proportion of classified water bodies. The explanation may be that some member states did not have their assessment systems in place at the time of the first RBMPs, and thus collected monitoring data to be able to develop their assessment systems. The total number of transitional water bodies reported is also much lower than for rivers and lakes, and they may be less comparable in terms of types and pressures, thus grouping and expert judgement is less needed and also less easy to apply for classifying the transitional waters.  The biological quality elements most commonly used for monitoring and classification of transitional waters are phytoplankton, macroinvertebrates and fish, as well as the supporting quality elements.

For coastal waters, phytoplankton and macroinvertebrates are the most commonly used biological quality elements and is monitored in ca. 30% of all water bodies, and classified in more than half of all coastal water bodies. The supporting quality elements are also monitored and classified in almost the same proportions as the biological quality elements. As for lakes, the use of phytoplankton is probably dominated by chlorophyll a measurements, while the use of macroinvertebrates reflects the traditional use of this biological quality element to assess organic enrichment (and secondary impacts of nutrient enrichment) in soft-bottom sediments.

Figure 3.2. European overview of the different quality elements reported by Member States to be used for monitoring and classification of water bodies in the different water categories.

Notes: The percentage is calculated against the total number of classified water bodies, i.e. total number of water bodies reported where quality elements were identified are for rivers: 75763, for lakes: 13849, for transitional waters: 629, for coastal waters: 2225. “Monitored” means WBs with at least one monitoring station for that particular QE. This percentage is most likely underestimated, because a) some member states have not reported monitoring stations (Poland, Hungary, Ireland, Latvia, Lithuania, Slovakia and Estonia (transitional and coastal only)) and b) it seems to be an underreporting of monitoring stations where only non-BQEs are monitored. “Classified” means WBs with status information for that particular QE. Here too this may be an incorrect estimate, as the member states have interpreted this reporting differently. The member states were asked only to report status class for WBs were the QE was monitored. Status can also be set based on grouping or expert judgement (see text). In practice, some member states have reported status class also when the QE has not been monitored, others have not. Hence, if regarding “Classified” as all WBs with status information on a particular QE, regardless of method for setting that status, the results shown are likely to be underestimated. If possible, the Member States should help clarifying how they have reported monitoring stations and classification of single QEs.

3.1.3.      Confidence in classification of ecological status or potential in different countries

Most member states have classified all their water bodies (figure 3.3), although a few countries have a substantial proportion of water bodies that are delineated, but not classified. At the EU level 86% of a total of 103663 river and lake water bodies are classified, while 76% of a total of 3764 transitional and coastal water bodies are classified.   The member states with a substantial proportion of unclassified water bodies for rivers and lakes are Poland (79%), Finland (54%), Italy (48%), Hungary (39%), Greece (38%), Cyprus (23%) and Spain (22%), while for transitional and coastal waters only three countries have a substantial proportion of unclassified water bodies: Italy (90%), Ireland (66%) and the Netherlands (25%).

The reasons for not classifying all water bodies are unclear, but may be related to low confidence or gaps in assessment systems for certain quality elements or certain types of water bodies.

Figure 3.3. Proportion of classified water bodies of the total number of water bodies for rivers and lakes (left) and for transitional and coastal waters (right). The member states are ranked by the percentage of classified water bodies.

Notes: The total number of water bodies is given in brackets for each member state. The total number of water bodies does not include water bodies in countries/RBDs for which there is no reporting (see table 2.1). “Classified” means WBs with status class bad to poor. “Unclassified” means WBs with status class “Unknown” or “Not applicable”.

Due to inconsistencies of reporting the RBMP data in WISE in terms of which quality elements have been used for classification, it has not been possible to obtain reliable results across member states for comparison of the proportion of water bodies classified with at least one BQE and those classified with only supporting QEs or without any monitoring data (see also notes for figure 3.2).    

Member states have reported the confidence of classification as high, medium or low, but the basis for choosing these confidence categories is not harmonised across the EU. However, from the descriptions reported by the member states on how these categories have been used, there are  some general principles applied by many member states:

• high confidence: classification based on monitoring of at least one biological quality element and some supporting quality elements
• medium confidence: classification based on monitoring of at least one supporting quality element
• low confidence: classification is done without monitoring data, based on expert judgement

 For some water bodies no information of confidence is reported.

Figure 3.4. Member states own assessment of confidence in classification of ecological status or potential of classified rivers and lakes (left) and classified transitional and coastal waters (right). The Member States are ranked by the proportion of water bodies classified with high or medium confidence.

Notes: The number of classified water bodies is given in brackets for each member state.

Poland has reported high confidence for all their classified water bodies, whereas they have only classified 21 % of their water bodies in rivers and lakes. This indicates that Poland has only classified a water body if they have high confidence in the classification. Some member states have a majority of water bodies classified with high or medium confidence both for rivers and lakes, as well as for transitional and coastal waters, e.g. Latvia, Estonia, Germany, UK, and some land-locked member states like Austria, Hungary and Luxembourg report high and medium confidence for most of their classified river and lake water bodies. 

On the other hand, some member states have not provided information on confidence for all or almost all of their classified water bodies, e.g. the Netherlands, Belgium, Ireland and Greece.

The reasons for reporting low confidence may be related to gaps in assessment systems for certain quality elements or certain types of water bodies, or lack of monitoring data.

At the EU level, only 39% of the classified river and lake water bodies and 44% of the classified transitional and coastal water bodies are reported to be classified with medium or high confidence. This suggests that the classification results are quite uncertain for the majority of water bodies in these first RBMPs.  In many cases the classification is probably based merely on expert judgement and/or on results of the pressure and impact analyses (article 5) rather than on biological monitoring data and WFD-compliant classification systems.

3.2.     Pressures and impact analysis

The WFD defines “good ecological and chemical status” in terms of low levels of chemical pollution as well as a healthy ecosystem. To achieve good ecological status, Member States will have to address the factors affecting water eco-systems. Pollution is one, so are morphological changes such as dams built on rivers. The extraction of water for irrigation or industrial uses can also harm ecosystems if it reduces water levels in rivers or lakes below a critical point.

The status of a water body is greatly influenced by the characteristics of its catchment area (Figure 3.5). The climatic conditions, for example rain, bedrock geology and soil type, all influence the water flow. In addition, soil type impacts on the mineral content of the water. Similarly, human activity affects surface water and groundwater through afforestation, urbanisation, land drainage, pollutant discharge, morphological changes and flow regulation.

Figure 3.5: Conceptual overview of activities in river basins.

Identifying significant pressures: The WFD requires that Member States collect and maintain information on the type and magnitude of significant pressures to which water bodies are liable to be subject. The common understanding of a ‘significant pressure’ is that it is any pressure that on its own, or in combination with other pressures, may lead to a failure to achieve one of the WFD objectives of achieving good status. Annex II of the Directive provides lists of some of the different types of pressures that may be significant.

Published in 2005, the WFD Article 5: Characterisation and impacts analyses reports were the first step in identifying pressures and impacts in the river basin management planning process. This pressure and impact analysis reviewed the impact of human activity on surface waters and on groundwater and identified those water bodies that are at risk of failing to meet the WFDs environmental objectives.

‘at risk’ means that: the pressure and impact assessment shows that there is a likelihood that a water body will fail to meet the WFD´s environmental objectives by 2015 unless appropriate management action is taken.

“At risk” does not necessarily mean that the water bodies are already suffering poor status, but it does highlight areas where appropriate management measures should be applied to ensure that good status is maintained or to ensure it is achieved in the future.

The first identification of pressures and impact (Article 5) was the basis for the overview of Significant Water Management Issues (SWMI) that was reported in 2007 and was the basis for establishing the first RBMPs. The identification of significant pressure and impact were further developed in the RBMPs.

3.2.1.      Significant pressures and impacts

Several factors contribute to surface water bodies being at risk. These include point sources - for example pollution from urban areas and industries as well as diffuse sources such as agriculture. In addition, the influence of water extraction and of morphological changes are important pressures. Changes in habitats can result from the physical disturbance through damming, channelisation and dredging of rivers, construction of reservoirs, sand and gravel extraction in coastal waters, bottom trawling by fishing vessels etc. Below is described the main pressures and impacts affecting Europe’s surface waters.

One major pressure is pollution. Pollution is harmful to aquatic plants and animals, and may threaten drinking water and water supplies. Pollution can be anything from hazardous substances to a nutrient which can result in excessive plant growth or even silt that can smother fish spawning beds. Pollution comes from one of two types of source:

• point sources, e.g. pipes discharging effluents from urban wastewater treatment plants, industrial sites, or mines; and
• diffuse sources, e.g. land use activities such as farming, forestry and urban areas.

During the last decades, significant progress has been made in reducing the point source pollution: improved wastewater treatment, reduced volume of industrial effluents, and reduced or banned phosphate content in detergents as well as reduced atmospheric emissions. Over the last 30 years the urban and industrial wastewater treatment has progressively improved and in many parts of Europe a large proportion of the pollutants are today removed (see chapter 7). However, pollution caused by inadequately treated wastewater is still in some areas an important source of river pollution and an important source for transitional and coastal waters.  Main impacts related to point source pollution are organic pollution, nutrient enrichment and contamination by hazardous substances. Severe organic pollution may lead to rapid de-oxygenation of water, a high concentration of ammonia and the disappearance of fish and aquatic invertebrates.

Diffuse water pollution is a serious problem in many parts of Europe (see chapter 7). Diffuse sources of pollution include run-off from farmland, run-off from roads or scattered dwellings. Diffuse pollution is closely linked to land use (e.g. the application of fertiliser or pesticides to farmland; livestock manure; use of chemicals and leakage from old waste storage and polluted industrial sites). Diffuse pollution is also linked to air emissions, for example acid rain or deposition of nitrogen, impacts of traffic emissions or other air transported pollutants.

Some of the main impacts related to diffuse pollution are high levels of nutrients in rivers, lakes, estuaries and coastal waters, which can cause eutrophication; nitrate and pesticide contamination of groundwater; hazardous chemicals leaking into rivers, lakes and groundwater from industrial sites; and air pollution causing acid rain, deposition of nitrogen on sensitive waters and deposition of hazardous chemicals (e.g. mercury and PAHs).

Figure 3.6: Overview of different diffuse sources

Source: Environment Agency 2007

http://www.environment-agency.gov.uk/static/documents/Research/geho0207bzlvee_1773088.pdf

During the last centuries European mining for coal, metal ores, and other minerals have affected water bodies. Many thousands of mines have been abandoned and now discharge mine-water containing acid water, heavy metals and other pollutants into water bodies. Other mines are still filling up with groundwater or have heavy regulation of water level affecting the surrounding groundwater aquifers or surface waters. Abandoned mines in several areas of Europe are today a significant pollution pressure. For example, eight of the twelve River Basin Districts in the UK have identified abandoned mines as a significant problem (Johnson and Rolley, 2008). Nine per cent of rivers in England and Wales, and 2% in Scotland are at risk of failing to meet their WFD targets of good chemical and ecological status because of abandoned mines. These rivers cause some of the biggest discharges of metals such as cadmium, iron, copper, and zinc to rivers and the seas around Britain.

Aquaculture has grown substantially in a number of European countries over recent years such as Atlantic salmon in Scotland, Norway and Ireland, seabass and seabream in the Mediterranean and mussel farming in Ireland, Spain and France. In particular, marine aquaculture of finfish has become more intensive over the last 25 years resulting and can generate considerable amounts of effluent, such as waste feed and faeces, medications and pesticides, which can have undesirable impacts on the environment.

The abstraction of too much water from rivers, lakes or groundwater is harmful to the environment and can compromise the water resources needed by other water users. Water abstraction may reduce the amount of water available to dilute discharges and therefore makes pollution worse. In extreme cases, rivers and reservoirs can dry up or salt water can be drawn into groundwater.  Transfers of water from one catchment to another and flow-controlling structures, such as dams may also have major influences on water flows.

Hydrological alterations refer to pressures resulting from water abstraction and water storage affecting the flow regime such as change in daily flow (hydropeaking) and seasonal flow. In addition, river stretches may dry up and water levels of lakes and reservoirs may be heavily regulated. The flow regime of a water body may be significantly altered downstream of an impoundment or an abstraction, and the biology may impacted. Alterations to the flow regime degrade aquatic ecosystems through modification of physical habitat and of erosion and sediment supply rates.

Morphology is the physical structure of a river, lakes, estuary or coast including, for example, the banks and bed of a river and the shore of lakes or coastal waters. Engineering or the way the land is managed can change the morphology of these waters. This has a direct impact on animals and plants and can lead to increased flooding or erosion.

Land reclamation, shoreline reinforcement or physical barriers (such as flood defences, barrages and sluices) can affect all categories of surface waters. Weirs, dams and barrages can alter water and sediment movements, and may impede the passage of migratory fish such as salmon. Using water for transport and recreation often requires physical alteration to habitats and affects the flow of water. Activities such as maintenance and aggregate dredging and commercial fishing using towed bottom-fishing gear can also damage physical habitats.

Biological pressures related to Invasive Alien Species (IAS) have been identified as a significant pressure in several of the RBMPs. IAS are non-native plants or animals which compete with, and may even over-run, our natural aquatic plants and animals. Introduction of IAS may alter both species composition and the numbers of different species in surface waters. Escaped farmed salmon for instance, represents a serious risk to wild salmon stocks.

It is increasingly being recognised that climate change will have a significant impact on the aquatic environment in Europe (EEA 2008; CEC 2009; IPCC, 2007, 2008). Climate change is projected to lead to major changes in yearly and seasonal precipitation and water flow, flooding and coastal erosion risks, water quality, and the distribution of species and ecosystems. Models indicate that at a general level the south of Europe will show a significant drying trend and the north of Europe one of wetting. There are many indications that water bodies, which are already under stress from human activities, are highly susceptible to climate change impacts and that climate change may hinder attempts to prevent deterioration and/or restore some water bodies to good status. Although climate change is not explicitly included in the text of the WFD, the step-wise and cyclical approach of the river basin management planning process makes it well suited to adaptively manage climate change impacts.

3.3.     Methodology issues in relation to data handling

In the following is described some of the methodology issues, quality issues and shortcomings in relation to analysing the data in the WISE-WFD database. A set of information is reported for each water body (Figure 3.7).  A surface water body have information on:

• the ecological status/potential and chemical status. This information is based on more detailed information on biological quality elements (e.g. macroinvertebrates; phytoplankton); general physiochemical conditions (general water quality information e.g. nitrate and phosphorus); and hydromorphological conditions.
• Significant pressures such as pressures related to diffuse sources or water flow regulation. More than one pressure may apply to a water body. Significance is in relation to the failure of a water body to achieve environmental objectives.

• Significant impacts such as nutrient enrichment; contamination by priority substances; acidification; and alteration of habitats etc. A water body may be subject to more than one impact.

A water body may have no significant pressure or impact because it is in good (or high) status. However, no reported pressures or impacts may also mean that pressures and impacts have not been reported or identified.

Figure 3.7: Conceptual overview of reported information in relation to a water body

Notes

Significant pressures: Member States are required to report on the significant pressures on surface and groundwater water bodies. Significance is in relation to the failure of a water body to achieve environmental objectives. More than one pressure may apply to a water body.

Significant pressures have been reported at different levels of aggregation. For example, point source discharges might be reported at three levels of aggregation: 1 Point Source, 1.1 Point - UWWT_General and 1.1.1 Point - UWWT_2000.

Significant impacts: Number and percentage of water bodies that are reported as being subject to the indicated significant impacts. A water body may be subject to more than one impact.

3.3.1.      Assumption made in relation to data handling

Unclassified water bodies – unknown status, pressure and impact

Some water bodies have been reported with unknown or not applicable ecological status/potential (unclassified water bodies), or no information on significant pressures (no pressures) or impacts (no impacts). In most cases unclassified water bodies do not have information on pressure and impacts. All analyses done in the following chapters are based on water bodies which are classified with respect to ecological status or potential only.

No differentiation between ecological status and potential

In the analysis, no distinction has been made between ecological status and potential. The criteria for classification of natural (status) and artificial or heavily modified water bodies (potential) vary, but the ecological conditions they reflect are assumed to be comparable. 

3.3.2.      How to read the diagrams

The basic information unit is water bodies. For each water body is attached information on status, pressures and impact. This information has been aggregated to European, country and RBD level and is presented as:

• Percentage, number or length/area of water bodies in the different classes of ecological and chemical status.
• Percentage, number of water bodies affected by different significant pressures and impacts.

Figure 3.8: Aggregation of status to European overviews (upper panel) and for country comparison.

The diagrams are based on only water bodies with classified ecological status or potential.

• The percentage high and good status (blue or green colour) or water bodies without pressures or impacts (blue colour) are always presented to the right of the bar charts.
• Diagrams with country comparison are always ranked by the percentage of water bodies not achieving good status (red, orange and yellow colour).
• This ranking by percentage of water bodies not achieving good status are kept when presenting percentage of water bodies affected by different pressures or impacts.
• Pressure information has been aggregated to main pressure groups (see the notes to the diagrams).

References

CEC 2009;

EEA 2008;

IPCC, 2007, 2008

Johnston D. and Rolley S. 2008: Abandoned Mines and the Water Framework Directive in the United Kingdom. Paper available at http://www.imwa.info/docs/imwa_2008/IMWA2008_128_Johnston.pdf

Environment Agency 200x: Abandoned mines and the water environment. Science report from the Environment Agency. Available at http://publications.environment-agency.gov.uk/PDF/SCHO0508BNZS-E-E.pdf