Report on Harmonisation of freshwater biological methods

Annex IX: WFD Common Metric1. In order to ensure comparability of the Ecological Quality Ratio (EQR) scalesbetween the different EU countries and to obtain a common understanding of thegood ecological status of surface waters all over EU, the WFD requires for theintercalibration of the classification results of the biological monitoring systems. Inpractice, the intercalibration exercise must establish the values for the boundarybetween the classes of high and good status, and for the boundary between good andmoderate status, which shall be consistent with the normative definitions of thoseclass boundaries given in Annex V of the WFD.2. As in the WFD the intercalibration is a two-phase process, which starts with theestablishment of an intercalibration network consisting of sites representing theboundaries between the quality classes ‘High-Good’ and ‘Good-Moderate’, as basedon the WFD normative definitions. In a second phase each Member State’sassessment method must be calibrated both in the ecoregion and for the surface watertype to which the system is applicable. The results of the second phase must be usedto set (EQR) values for relevant class boundaries for each Member States biologicalassessment system.3. The intercalibration exercise will focus on specific type/biological qualityelement/ pressure combinations, which were selected based in data availability withinthe time constrains of the exercise. For rivers, the intercalibration will focus on sitesimpacted by organic and/or nutrient loading, river modification and acidification asassessed making use of macroinvertebrates, fish and benthic algae. For lakes, thefocus will be on eutrophication and acidification as assessed using, respectively, ofphytoplankton and macrophytes, and macroinvertebrates and fish respectively. Thedifferent combinations of pressures/ biological quality elements are, both for river andlakes, dependant of the GIG, the pressure and the type.4. Guidance on the intercalibration process was developed within a drafting groupthat is part of the ECOSTAT WG 2A. The guidance foresees an intercalibrationprocess based in the selection from three different options, and several hybrids ofthese options, all firmly based on the definition of a protocol for deriving goodecological status class boundary values from the normative definitions. The choice of111