Directive 2000/60/EC requires the Member States to protect enhance and restore all bodies of surface waters with the aim of achieving good ecological and chemical status. It furthermore requires Member States to protect and enhance all artificial and heavily modified bodies of water, with the aim of achieving good ecological potential and good chemical status.

In order to define one of the main environmental objectives of Directive 2000/60/EC, namely good ecological status, that Directive provides for a process to ensure the comparability between the biological monitoring results of Member States and their monitoring system classifications. Member States’ biological monitoring results and their monitoring system classifications are to be compared through an intercalibration network comprised of monitoring sites in each Member State and in each ecoregion of the Union. Directive 2000/60/EC requires the Member States to collect, as appropriate, the necessary information for the sites included in the intercalibration network, in order to enable the assessment of the consistency of the national monitoring system classifications with the normative definitions of Section 1.2 of Annex V to Directive 2000/60/EC. In order to carry out the intercalibration exercise Member States are organised in Geographical Intercalibration Groups, consisting of Member States sharing particular surface water body types, as defined in Section 2 of the Annex to Commission Decision 2005/646/EC.

In accordance with Directive 2000/60/EC the intercalibration exercise is to be carried out at biological element level, comparing the classification results of the national monitoring system for each biological element and for each common surface water body type among Member States and ensuring the consistency of the results with the normative definitions set out in Section 1.2 of Annex V to that Directive.

The Commission has facilitated three phases of the intercalibration exercise through the Joint Research Centre. Under the Water Framework Directive Common Implementation Strategy four guidance documents (No 6, 14 (two versions) and 30) were prepared to facilitate the intercalibration process. They provide an overview of the key principles of the intercalibration process and the options for carrying out the exercise including timescales, and reporting requirements. They also provide a procedure to fit new or revised national classification methods to the harmonised definition of good ecological status.

By 2007 the Commission had received intercalibration results for a number of biological quality elements. They were included in Commission Decision 2008/915/EC, which sets out the values of the boundaries between classes that Member States were to use in their national monitoring system classifications. The results of the first phase of the intercalibration exercise were incomplete, in so far as not all biological quality elements were covered. It was necessary however to adopt the available results of the intercalibration exercise to inform the development of the first river basin programme of measures and the first river basin management plans in accordance with Articles 11 and 13 of Directive 2000/60/EC.

In order to close the gaps and improve the comparability of the intercalibration results in time for the second river basin management plans due in 2015, the Commission initiated a second phase of the intercalibration exercise. The results of this exercise were included in Commission Decision 2013/480/EU. The results revealed that in some cases intercalibration was only partially achieved. There were also Geographical Intercalibration Groups and biological quality elements for which there were no intercalibration results for inclusion in that Decision.

A third phase of the intercalibration exercise was therefore necessary in order to close these gaps and improve the comparability of the intercalibration results in time for the third river basin management plans due in 2021. The results of this third phase of the intercalibration exercise are included in the Annex to this Decision.

The Annex to this Decision sets out the results of the intercalibration exercise. For the results in Part 1 of the Annex all steps of the intercalibration process set out in the guidance documents have been fully completed. Part 2 of the Annex contains the national classification methods and their respective boundary values for which it has not been technically feasible to complete the comparability assessment due to a lack of common types, different pressures addressed or different assessment concepts. Since the results set out in Part 1 and Part 2 of the Annex are consistent with the normative definitions set out in Section 1.2 of Annex V to Directive 2000/60/EC, the respective boundary values should be used in Member States monitoring systems classifications.

Where water bodies corresponding to the intercalibrated types are designated as artificial or heavily modified water bodies in accordance with Article 4(3) of Directive 2000/60/EC, Member States should be allowed to use the results presented in the Annex to this Decision to derive their good ecological potential, taking into account their physical modifications and their associated water use in accordance with the normative definitions in point 1.2.5 of Annex V to Directive 2000/60/EC.

Member States should apply the results of the intercalibration exercise to their national classification systems in order to set the boundaries between high and good status and between good and moderate status for all their national types.

The information that is made available through the establishment of the monitoring programmes provided for in Article 8 of Directive 2000/60/EC and the review and update of the characteristics of river basin districts provided for in Article 5 of that Directive could bring new evidence that may lead to the adaptation to scientific and technical progress of the Member States’ monitoring and classification systems. Member States may also develop new national classification methods covering biological quality elements or sub biological quality elements and respective boundary values for which the consistency with the normative definitions set out in Section 1.2 of Annex V to Directive 2000/60/EC should be assessed. These matters may lead to a review of the results of the intercalibration exercise to close gaps and improve the quality and comparability of the intercalibration results which in turn may warrant an update of the results contained in the Annex to this Decision.

Decision 2013/480/EU should therefore be repealed and replaced accordingly.

The measures provided for in this Decision are in accordance with the opinion of the Committee referred to in Article 21(1) of Directive 2000/60/EC,