Indicator Specification

Ecological status or potential

Indicator Specification
  Indicator codes: WFD 003
Published 09 Apr 2013 Last modified 10 Feb 2021
8 min read
This page was archived on 10 Feb 2021 with reason: Other (Entry created by a failure)
Ecological status or potential in rivers, lakes, transitional waters and coastal waters. The indicator can be used to illustrate variations between different water categories and geographical variations.

Assessment versions

Published (reviewed and quality assured)
  • No published assessments


Justification for indicator selection

Diffuse and point source pollution, along with hydromorphological alterations causes deterioration of the structure and function of surface water ecosystems, as expressed by their ecological status or potential. The main objective of the WFD is that all surface waters should be in good or high ecological status or potential by 2015. The current classification is the baseline from which the improvements objective of the WFD is measured

Scientific references

  • No rationale references available

Indicator definition

Ecological status or potential in rivers, lakes, transitional waters and coastal waters. The indicator can be used to illustrate variations between different water categories and geographical variations.


The ecological status or potential is presented as percentage of total classified water bodies by count.


Policy context and targets

Context description

The indicator presents the main results on ecological status and potential, as reported in the first river basin management plans reported under the WFD. The WFD came into force on 22 December 2000, and according to the directive the first river basin management plans should be published at the latest nine years after the directive entered into force. There are however serious delays in some parts of the EU, and in some Member States consultations are still on-going.


The indicator is directly linked to the objective of the WFD. The main objective of the WFD is that all surface waters should be in good or high ecological status or potential by 2015, or 15 years after the entry into force of the directive. The indicator shows the number of water bodies where management measures are needed, and for which water categories and in which regions the need for measures is highest.

Related policy documents

  • Water Framework Directive (WFD) 2000/60/EC
    Water Framework Directive (WFD) 2000/60/EC: Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy.


Methodology for indicator calculation

Source of data: The WISE-WFD database contains the data as reported in the River Basin Management Plans (RBMPs). The indicator is based on an extract of the WISE-WFD database as of May 2012, with addition of Slovenian data as of June 2012.

Type of data: The data presented are ecological status or potential of single water bodies. The WFD defines "good ecological status" in terms a healthy ecosystem based upon classification of the biological elements (phytoplankton, phytobenthos, benthic fauna, macrophytes and fish) and supporting hydromorphological, physico-chemical quality elements and non-priority pollutants. 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. 

Ecological status is assigned to natural water bodies, whereas ecological potential is applied for heavily modified water bodies (HMWBs) and artificial water bodies (AWBs). The classification of ecological potential is either based on the same biological, chemical and hydromorphological quality elements as for ecological status after adjusting for the impacts of the hydromorphological pressures underlying the designation of the water body as being HMWB or AWB, or on the level of measures taken to mitigate the impacts of all other pressures on those water bodies. In the analyses in this indicator, no distinction has been made between ecological status and potential. The criteria for classification of natural and heavily modified or artificial water bodies vary, but the ecological conditions they reflect are assumed to be comparable having the same deviation from reference conditions or from maximum ecological potential, after adjusting for the effects of the physical modifications in case of the HMWBs or AWBs.

Ecological status or potential is recorded on the scale of high, good, moderate, poor or bad.´High´denotes largely undisturbed conditions and the other classes represent increasing deviation from this natural condition. The ecological status classification for the water body, is determined by the worst scoring biological quality element (one out – all out principle), with adjustments using the supporting quality elements according to certain rules (Solheim et al., 2012). The WFD requires that the good/moderate status class boundaries for each biological quality element are intercalibrated across Member States sharing similar types of water bodies, to ensure that the classification is consistent (ref intercalibration report). The classification is supposed to represent the ecological status or potential at the time of reporting, but in practice the classification is based on monitoring or other types of evaluation over the last few years prior to reporting.

Data coverage: The Member States are required to classify all their surface water bodies above a certain size. The data included in this indicator covers all Member States, but there are some limitations in the reporting:

For certain RBDs there is either no reporting or all water bodies are reported as unclassified (see Fig. 2): The Wallonian and Brussels regions in Belgium, parts of Spain, Sardinia and Sicily in Italy, and a few other very small RBDs. Norway and Iceland (European Economic Area countries) and will not report until 2015.

A substantial proportion of water bodies are delineated, but not classified. Poland (79%), Finland (51%) and Italy (48%) have the highest percentage of unclassified water bodies. Overall the proportion of unclassified water bodies are:

        • Rivers: 13%
        • Lakes: 23%
        • Transitional waters: 30%
        • Coastal waters: 21%

Calculation: The percentage of water bodies in the different status or potential classes is calculated against the total number of classified water bodies. Hence, the figures represent the classified water bodies in the 27 Member States only. When results are shown as percentage in less than good status or potential, this means the percentage of water bodies in bad, poor or moderate ecological status or potential.

Methodology for gap filling

No methodology for gap filling has been specified. Probably this info has been added together with indicator calculation.

Methodology references

No methodology references available.


Data specifications

EEA data references

Data sources in latest figures



Methodology uncertainty

There are several sources of uncertainty in the classification of ecological status or potential. First of all the classification system itself is uncertain. 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 RBMPs. 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. This reduces the comparability across Member States and RBDs.

Secondly, classification is in many cases not based on monitoring. An overview of the proportion of monitored water bodies shows that this is low for most quality elements and water categories, usually around 20% (ref technical report). One reason for this is classification by grouping, which according to the WFD CIS guidance on monitoring this is WFD compliant, if applied to water bodies of the same type exposed to the same type and level of pressures. Still, this type of classification will introduce some uncertainty. Another reason is that many water bodies have been assessed using expert judgement based on the information compiled in the pressure and impact analyses (WFD article 5). In many cases this was the only solution, due to gaps in the classification system, and probably also incomplete implementation of the WFD monitoring systems. The level of uncertainty introduced by expert judgement is highly variable.
The uncertainty in the classification is to some extent reflected in the Member States own assessment of confidence. Overall only 35% of the water bodies are reported as classified with medium or high confidence.

Data sets uncertainty

The percentage of water bodies in different classes of ecological status or potential is calculated against the total number of classified water bodies. In using this calculation to represent the situation in all EU Member States it is assumed that the distribution of water bodies to status classes would have been similar in the unclassified water bodies had they been classified. This is not necessarily the case. For instance a large proportion of the unclassified lake water bodies are found in Finland, where the ecological status or potential is likely to be higher than in EU as a whole. Nonetheless, this approach is chosen, as the proportion of classified water bodies is generally far higher than the proportion of unclassified water bodies. Moreover, it would be difficult to interpret the figures if the unclassified water bodies were included. However, it should be taken into account that all water bodies in the 27 EU Member States are not represented by the figures shown.

Rationale uncertainty

No uncertainty has been specified

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

General metadata

Responsibility and ownership

EEA Contact Info

Peter Kristensen


European Environment Agency (EEA)


Indicator code
WFD 003
Version id: 1

Frequency of updates

Updates are scheduled every 6 years


DPSIR: State
Typology: Performance indicator (Type B - Does it matter?)


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