## 6.5.5. European Water Framework Directive

Author: Piet Verdonschot

Reviewers: Peter von der Ohe, Michiel Kraak

Learning objectives:

After this finishing this module, you should be able to:

- summarize the key aspects of the Water Framework Directive, its objectives and philosophy;
- explain the methodological reasoning behind the Water Framework Directive;
- understand the role of toxic substances in the Directive and the relation to other stressors.

Key words:

EU Water Framework Directive, water types, quality elements, ecological quality ratio, priority substances

Introduction

Early water legislation on the European level only began in the seventies with standards for rivers and lakes used for drinking water abstraction and aiming to control the discharge of particular harmful substances. In the early eighties, quality targets were set for drinking water, fishing waters, shellfish waters, bathing waters and groundwater. The main emission control instrument was the Dangerous Substances Directive. Within a decade, the Urban Waste Water Treatment Directive (1991), the Nitrates Directive (1991), the Drinking Water Directive (1998) and the Directive for Integrated Pollution Prevention and Control (1996) followed. Finally, on 23 October 2000, the "Directive 2000/60/EC of the European Parliament and of the Council establishing a framework for the Community action in the field of water policy" or, in short, the EU Water Framework Directive (WFD) was adopted (European Commission, 2000). The key aim of this directive is to achieve good ecological and good chemical status for all waters by 2027. This is captured in the following objectives:

- expanding the scope of water protection to all waters (not only waters intended for particular uses), surface waters and groundwater;
- achieving "good status" for all waters by a set deadline;
- water management based on river basins;
- combined approach of emission limit values and water quality standards;
- ensuring that the user bears the true costs of providing and using water;
- getting the citizen involved more closely;
- streamlining legislation.

Instead of administrative or political boundaries, the natural geographical and hydrological unit (the river basin) was set as the unit of water management. For each river basin, independent from national frontiers, a river basin management plan needs to be established and updated every six years. Herein, the general protection of ecological water quality, specific protection of unique and valuable habitats, protection of drinking water resources, and protection of bathing water are integrated, assessed and, where necessary, translated into an action plan. Basically, the key requirement of the Directive is that the environment as an entity is protected to a high level, in other words the protection of the ecological integrity applies to all waters. Within five months after the WFD came into force, the Common Implementation Strategy (CIS) was established. The CIS includes, for instance, guidance documents on technical aspects, key events and additional resource documents related to different aspects of the implementation. The links at the end of this chapter provide access to these additional key documents.

WFD Methodology

The WFD integrated approach to manage water bodies consists of three key components of aquatic ecosystems: water quality, water quantity, and physical structure. Furthermore, it implies that the ecological status of water bodies must be determined with respect to the near-natural reference conditions, which represent a ‘high ecological status’. The determination of the ‘good ecological status’ (Figure 1) is based on the quality of the biological community, the hydrological characteristics and the chemical characteristics that may slightly deviate from these reference conditions. To describe reference conditions, a typology of water bodies is needed. In the WFD, water bodies are categorized as rivers, lakes, transitional or coastal waters. Within each of these categories, the type of water body must be differentiated, based on an ecoregion approach in combination with at least three additional factors: altitude, catchment area and geology (and depth for lakes). The objective of the typology is to ensure that type-specific biological reference conditions can be determined. Furthermore, it may be necessary or is allowed to use additional descriptors (called optional descriptors) to achieve sufficient differentiation. Waters in each category can be classified as natural, heavily modified or artificial dependent on their origin and human-induced changes.

The WFD requires to include ecological status and chemical status classification schemes for surface water bodies that differ for the four major water types, i.e. rivers, lakes, transitional waters and coastal waters. Rivers and lakes are assessed in relation to their ecological and chemical reference status, and heavily modified and artificial water bodies in relation to their ecological potential and chemical status. The classification schemes of ecological status and potential make use of several quality elements (QEs; Annex V):

- Biological quality elements; composition and abundance of algae, macroalgae, higher water plants, benthic invertebrates, and fish;
- Hydro-morphological quality elements (e.g. water flow, substrate, river morphology);
- General physicochemical quality elements (e.g. nutrients, chloride, oxygen condition, temperature, transparency, salinity, river basin-specific pollutants);
- Environmental Quality Standards (EQSs) for synthetic and non-synthetic pollutants.

For the ecological status and ecological potential classification schemes, the Directive provides normative definitions of the degree of human disturbance to each relevant quality element that is consistent with each of the classes for (potential) ecological status (Figure 1). These definitions have been expanded and used in the development of classification tools (assessment systems) and appropriate numeric class boundaries for each quality element. The results of applying these classification tools or assessment systems are used to determine the status (quality class) of each water body or group of water bodies.

Once reference conditions are established, the departure from these can be measured. Boundaries have been defined for the degree of deviation from the reference conditions for each of the WFD ecological status classes. Annex V 1.4.1 of the Directive states: “the results of the (classification) system shall be expressed as ecological quality ratios (EQRs) for the purposes of classification of ecological status. These ratios shall represent the relationship between the values of the biological parameters observed for a given body of surface water and the values for these parameters in the reference conditions applicable to that body. The ratio shall be expressed as a numerical value between zero and one, with high ecological status represented by values close to one and bad ecological status by values close to zero.” (Figure 1). Boundaries are thus the values that separate the 5 classes.

The reference conditions form the anchor point for the whole ecological assessment. The outcome or score of all WFD Quality Elements is combined to inform the overall quality classification of a water body. Hereby, the one-out-all-out principle applies, meaning that the lowest score for an individual Quality Element decides the final score.

Figure 1. Ecological Quality Ratio (altered after Vincent et al., 2002).

Priority substances

The values of the environmental quality standards (values for specific pollutants) are set to ensure that the water body is not exposed to acute and chronic toxicity for aquatic organisms, no accumulation in the ecosystem and losses of habitats and biodiversity occurs, as well as there is no threat to human health. Substances that were identified to present significant risks to or via the aquatic environment are listed as priority substances. According to the Directive on Environmental Quality Standards (Directive 2008/105/EC) good chemical status is reached for a water body when it complies with the Environmental Quality Standard (EQS) for all priority substances and eight other pollutants that are not in the priority substances list. The EQSs define a limit on the concentrations of 33 priority substances, 13 of them designated as priority hazardous substances in surface waters. These concentration limits are derived following the methodologies explained in Section 6.3.4. Furthermore, the Directive on EQSs offers the possibility of applying EQSs for sediment and biota, instead of those for water. It opens the possibility of designating mixing zones adjacent to discharge points where concentrations of the priority substances might be expected to exceed their EQS. Furthermore, authorities can add basin or catchment specific EQSs.

Environmental Quality Standards (EQSs) can be expressed as a maximum allowable concentration (EQS-MAC) or as an annual average value (EQS-AA). For all priority substances, Member States need to establish an inventory of emissions, discharges and losses. To improve the legislation, the EU also 1) introduced biota standards for several substances, 2) provided improvements on the efficiency of monitoring and the clarity of reporting with regard to certain substances behaving as ubiquitous persistent, bioaccumulative and toxic (PBT) substances, and 3) added a watch-list mechanism designed to allow targeted EU-wide monitoring of substances of possible concern to support the prioritization process in future reviews of the priority substances list.

Status classification

Together the classification of surface water bodies follows the scheme provided in Figure 2.

Figure 2. Elements of ‘good status’ of surface waters.

In summary, under the WFD, the ecological quality status assessment of surface water bodies is primarily based on biological quality elements phytoplankton, fish, and benthic flora and fauna. In the Netherlands, the worst Biological Quality Element score is taken as the overall final score (one-out-all-out principle). Furthermore, adequate assessment of stream and river hydro-morphology requires the consideration of any modifications to flow regime, sediment transport, river morphology, lateral channel mobility (or channel migration), and river continuity. For (groups of) substances, the WFD requires assessment of their relevance. A substance is relevant, when it exceeds its Environmental Quality Standard, meaning the boundary between good and moderate status is exceeded and a de-classification takes place when. The overall assessment follows the scheme given in Figure 3.

Figure 3. Decision tree for determining the ecological status of surface water bodies based on biological, hydromorphological and physicochemical quality elements according the normative definitions in Annex V: 1.2. (WFD).

References

European Commission (2000). Directive 2000/60/EC. Establishing a framework for community action in the field of water policy. European Commission PE-CONS 3639/1/100 Rev 1, Luxembourg.

Vincent, C., Heinrich, H., Edwards, A., Nygaard, K., Haythornthwaite, J. (2002). Guidance on typology, reference conditions and classification systems for transitional and coastal waters. CIS working group, 2, 119.