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Bund für Umwelt und Naturschutz Deutschland eV, by R. Nebelsieck, Rechtsanwalt,

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Bundesrepublik Deutschland, by W. Ewer, Rechtsanwalt,

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Freie Hansestadt Bremen, by P. Schütte, Rechtsanwalt,

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the Czech Government, by M. Smolek, acting as Agent,

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the French Government, by S. Menez, acting as Agent,

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the Netherlands Government, by M. Bulterman, B. Koopman and J. Langer, acting as Agents,

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the Polish Government, by B. Majczyna, acting as Agent,

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the United Kingdom Government, by J. Beeko, acting as Agent, and G. Facenna, Barrister,

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the European Commission, by E. Manhaeve and G. Wilms, acting as Agents,

1

This request for a preliminary ruling concerns the interpretation of Article 4(1)(a)(i) to (iii) of 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 (OJ 2000 L 327, p. 1).

2

The request has been made in proceedings between Bund für Umwelt und Naturschutz Deutschland eV (German federation for the environment and the conservation of nature) and Bundesrepublik Deutschland (the Federal Republic of Germany) concerning a scheme to deepen various parts of the river Weser in the north of Germany, intended to enable larger container vessels to call at the German ports of Bremerhaven, Brake and Bremen.

3

Recitals 16, 25 and 32 in the preamble to Directive 2000/60 state:

...

…

4

Article 1 of Directive 2000/60, headed ‘Purpose’, provides:

‘The purpose of this Directive is to establish a framework for the protection of inland surface waters, transitional waters, coastal waters and groundwater which:

...’

5

Article 2 of Directive 2000/60, headed ‘Definitions’, states in paragraphs 9, 17 and 21 to 23:

‘For the purposes of this Directive the following definitions shall apply:

...

...

...

...’

6

Article 3 of Directive 2000/60, headed ‘Coordination of administrative arrangements within river basin districts’, provides in paragraph 1:

‘Member States shall identify the individual river basins lying within their national territory and, for the purposes of this Directive, shall assign them to individual river basin districts. Small river basins may be combined with larger river basins or joined with neighbouring small basins to form individual river basin districts where appropriate. Where groundwaters do not fully follow a particular river basin, they shall be identified and assigned to the nearest or most appropriate river basin district. Coastal waters shall be identified and assigned to the nearest or most appropriate river basin district or districts.’

7

Article 4 of Directive 2000/60, headed ‘Environmental objectives’, states in paragraphs 1(a), 2 and 6:

‘1.   In making operational the programmes of measures specified in the river basin management plans:

2.   Where more than one of the objectives under paragraph 1 relates to a given body of water, the most stringent shall apply.

...

6.   Temporary deterioration in the status of bodies of water shall not be in breach of the requirements of this Directive if this is the result of circumstances of natural cause or force majeure which are exceptional or could not reasonably have been foreseen, in particular extreme floods and prolonged droughts, or the result of circumstances due to accidents which could not reasonably have been foreseen, when all of the following conditions have been met:

8

Article 4(7) of Directive 2000/60 provides:

‘Member States will not be in breach of this Directive when:

and all the following conditions are met:

9

Article 11 of Directive 2000/60, headed ‘Programme of measures’, states in paragraph 1:

‘Each Member State shall ensure the establishment for each river basin district, or for the part of an international river basin district within its territory, of a programme of measures, taking account of the results of the analyses required under Article 5, in order to achieve the objectives established under Article 4. Such programmes of measures may make reference to measures following from legislation adopted at national level and covering the whole of the territory of a Member State. Where appropriate, a Member State may adopt measures applicable to all river basin districts and/or the portions of international river basin districts falling within its territory.’

10

Article 13 of Directive 2000/60, headed ‘River basin management plans’, provides in paragraph 1:

‘Member States shall ensure that a river basin management plan is produced for each river basin district lying entirely within their territory.’

11

Article 14 of Directive 2000/60, headed ‘Public information and consultation’, states in paragraph 1:

‘Member States shall encourage the active involvement of all interested parties in the implementation of this Directive, in particular in the production, review and updating of the river basin management plans. ...’

12

Paragraph 27 of the federal Law on the management of water resources (Wasserhaushaltsgesetz) of 31 July 2009 (BGBl. 2009 I, p. 2585) in the version applicable at the material time (‘the WHG’), which is headed ‘Management objectives for surface waters’, provides:

‘(1)   In so far as they are not classified as artificial or heavily modified in accordance with Paragraph 28, surface waters shall be managed in such a way as:

(2)   Surface waters which are classified as artificial or heavily modified in accordance with Paragraph 28 shall be managed in such a way as:

13

The first sentence of Paragraph 31(2) of the WHG states:

‘If good ecological status of surface water is not achieved or if its status deteriorates, that shall not be contrary to the management objectives under Paragraphs 27 and 30 provided that:

1.   it is the result of a new modification to the physical characteristics of the water or to the groundwater level;

2.   the reasons for the modification are of overriding public interest or the benefits of the new modification for human health or safety or for sustainable development outweigh the benefits for the environment and the community of achieving the management objectives;

3.   the objectives pursued by the modification to the water cannot be achieved using other appropriate measures which have a significantly less adverse impact on the environment, which are technically achievable and the cost of which is not disproportionately high; and

4.   all measures appropriate in practice are taken to reduce the adverse impact on water status.

...’

14

The third sentence of Paragraph 12(7) of the Law on federal waterways (Bundeswasserstraßengesetz) of 2 April 1968 (BGBl. 1968 II, p. 173), in the version applicable at the material time, states:

‘Development measures must take account of the management objectives applicable under Paragraphs 27 to 31 of the [WHG].’

15

The second sentence of Paragraph 14(1) of that law provides:

‘In the context of planning approval, the public and private interests affected by the project must be taken into consideration, including the impact of the project on the environment.’

16

By planning decision of 15 July 2011 (‘the planning approval’), the Waterways and Navigation Directorate for the North-West Region (Wasser- und Schiffahrtsdirektion Nordwest), a federal administrative authority, granted consent for three projects concerning the development of the river Weser, which is a federal waterway. The developer for each of those projects, which can be carried out independently of each other, is the Federal Waterways and Navigation Authority (Wasser- und Schifffahrtsverwaltung des Bundes).

17

The first project seeks to develop the outer Weser from the high sea to Bremerhaven. The depth of its navigable channel is to be increased by up to 1.16 metres (m) so that large container vessels with a loaded draught of up to 13.5 m can reach the port of Bremerhaven irrespective of the tide. The project is connected with a deepening of the vessel turning area in the port of Bremerhaven, the developer for which is Freie Hansestadt Bremen, the joined party in the main proceedings.

18

The second project concerns the development of the lower Weser from Bremerhaven upstream to Brake; the depth of the navigable channel is to be increased by up to 1 m so that vessels with a maximum loaded draught of 12.8 m can reach that port, depending on the tide.

19

The third project seeks to develop the lower Weser from Brake upstream to Bremen. In this section of the river, the depth of the navigable channel is to be increased so that vessels with a loaded draught of up to 11.1 m can, depending on the tide, reach the port of Bremen. At present, the port of Bremen can, depending on the tide, be reached by vessels with a loaded draught of up to 10.7 m.

20

Implementation of the projects at issue involves dredging the river bed in the channels. After the initial excavation to the depth planned in the development, regular dredging for maintenance purposes will be necessary. Most of the dredged material arising from the development and from maintenance of the river is proposed to be discharged into the outer and the lower Weser at locations that have already been used for that purpose.

21

In addition to the direct effects of dredging and of discharging the dredged material, the projects at issue have, according to the referring court, other hydrological and morphological consequences for the sections of river concerned. In particular, current speeds will increase on a rising tide and on an ebb tide, tidal high water levels will rise, tidal low water levels will fall, salinity will increase in parts of the lower Weser, the brackish water limit in the lower Weser will move upstream and, finally, silting-up of the river bed will increase outside the navigable channel.

22

Of the bodies of water concerned, the Weser transitional waters and the tidal area above Brake are classified as heavily modified within the meaning of Article 2(9) of Directive 2000/60. The outer Weser area is classified as a natural body of water in so far as it forms part of the coastal waters. Also, a number of bodies of water falling within tributaries are concerned, some of which are classified as natural and some as heavily modified.

23

On that basis, the Waterways and Navigation Directorate for the North-West Region examined in the planning approval whether the projects at issue were compatible with the objective laid down by Directive 2000/60 of preventing deterioration of the status of the bodies of water. It concluded that deterioration within the meaning of the directive was not to be expected so far as concerns the coastal waters.

24

On the other hand, it considered that the present status of certain bodies of water of the Weser would tend to be adversely modified by the effects of the development projects at issue, without that resulting in a change in the status class in accordance with Annex V to Directive 2000/60. According to the Waterways and Navigation Directorate for the North-West Region, such deterioration within a status class is not to be regarded as a deterioration of the ecological potential or the status of the body of water concerned.

25

By way of alternative, that authority examined whether the conditions, laid down in Paragraph 31(2) of the WHG and Article 4(7) of Directive 2000/60, for a derogation from the prohibition of deterioration in the status of bodies of water were met and concluded that that was the case.

26

Bund für Umwelt und Naturschutz Deutschland eV challenges the planning approval, pleading in particular — in addition to infringements of the legislation relating to planning consent, of the Law on environmental impact assessment (Gesetz über die Umweltverträglichkeitsprüfung) and of environmental protection legislation, especially legislation relating to fauna, flora, habitats and the protection of birds — a failure to comply with provisions for the protection of water which have their origin in Directive 2000/60.

27

The referring court considers that the outcome of the main proceedings depends on the interpretation of several provisions of Directive 2000/60.

28

In those circumstances, the Bundesverwaltungsgericht (Federal Administrative Court) decided to stay the proceedings and to refer the following questions to the Court for a preliminary ruling:

29

By its first and fourth questions, which it is appropriate to deal with together, the referring court asks, in essence, whether Article 4(1)(a)(i) to (iii) of Directive 2000/60 must be interpreted as meaning that the Member States are required — unless a derogation is granted — to refuse authorisation for a project where it may cause a deterioration of the status of a body of surface water or where it jeopardises the attainment of good surface water status or of good ecological potential and good surface water chemical status by the date laid down by the directive.

30

In accordance with settled case-law of the Court, the scope of those provisions must be determined by taking into account both the terms in which they are couched and their context, as well as the objectives pursued by the legislation of which they form part (see, in particular, judgments in Lundberg, C‑317/12, EU:C:2013:631, paragraph 19; SFIR and Others, C‑187/12 to C‑189/12, EU:C:2013:737, paragraph 24; and Bouman, C‑114/13, EU:C:2015:81, paragraph 31) and, in the circumstances of this case, the history of that legislation.

31

It should be noted that, contrary to the submissions of Bundesrepublik Deutschland and the Netherlands Government, the wording of Article 4(1)(a)(i) of Directive 2000/60, which provides that ‘Member States shall implement the necessary measures to prevent deterioration of the status of all bodies of surface water’, attests to the binding force of that provision. The words ‘shall implement’ involve an obligation on the Member States to act to that effect.

32

It is necessary, as the referring court has done, to construe authorisation of an individual project as such implementation.

33

Furthermore, as provided in Article 4(1)(a) of Directive 2000/60, it is ‘[i]n making operational the programmes of measures specified in the … management plans’ that the Member States adopt the measures necessary in order to achieve the objectives of preventing deterioration of the status of bodies of surface water and protecting and enhancing their status. The use of the words ‘[i]n making operational’ supports an interpretation of that provision to the effect that it entails obligations which must be complied with by the competent authorities when approving individual projects in the context of the legal regime governing the protection of waters.

34

It should also be pointed out that Directive 2000/60 is a framework directive adopted on the basis of Article 175(1) EC (now Article 192(1) TFEU). It establishes common principles and an overall framework for action in relation to water protection and coordinates, integrates and, in a longer perspective, develops the overall principles and the structures for protection and sustainable use of water in the European Union. The common principles and overall framework for action which it lays down are to be developed subsequently by the Member States by means of the adoption of individual measures in accordance with the timescales laid down in the directive. However, the directive does not seek to achieve complete harmonisation of the rules of the Member States concerning water (judgments in Commission v Luxembourg, C‑32/05, EU:C:2006:749, paragraph 41, and Commission v Germany, C‑525/12, EU:C:2014:2202, paragraph 50).

35

Recital 25 in the preamble to Directive 2000/60 confirms that the environmental objectives should be set to ensure that good status of surface water and groundwater is achieved throughout the European Union and that deterioration in the status of waters is prevented at EU level.

36

According to Article 1(a) of Directive 2000/60, the purpose of the directive is to establish a framework for the protection of inland surface waters, transitional waters, coastal waters and groundwater which prevents further deterioration and protects and enhances the status of aquatic ecosystems and terrestrial ecosystems directly depending on the aquatic ecosystems.

37

Accordingly, the ultimate objective of Directive 2000/60 is to achieve, by coordinated action, ‘good status’ of all EU surface waters by 2015.

38

The environmental objectives that the Member States are required to achieve are specified in Article 4(1) of Directive 2000/60.

39

That provision imposes two objectives that are separate, although intrinsically linked. First, in accordance with Article 4(1)(a)(i) of Directive 2000/60, the Member States are to implement the necessary measures to prevent deterioration of the status of all bodies of surface water (obligation to prevent deterioration). Second, pursuant to Article 4(1)(a)(ii) and (iii), the Member States are to protect, enhance and restore all bodies of surface water with the aim of achieving good status by the end of 2015 at the latest (obligation to enhance).

40

The origin of those two objectives is apparent from the drafting history of Directive 2000/60. So far as concerns in particular the obligation to prevent deterioration of the status of surface waters, the provisions at issue, in their initial version, could be interpreted as allowing bodies of water classified above ‘good status’ to deteriorate to that class once Directive 2000/60 was adopted. It is for that reason that the European Parliament proposed an amendment enabling a distinction to be drawn between the obligation to achieve ‘good status’ and that of preventing any deterioration by the insertion in Article 4(1) of the directive of a new indent laying down the latter obligation separately.

41

Both the obligation to enhance and the obligation to prevent deterioration of the status of bodies of water are designed to attain the qualitative objectives pursued by the EU legislature, namely the preservation or restoration of good status, good ecological potential and good chemical status of surface waters.

42

In order to ensure that the Member States attain the environmental objectives referred to above, Directive 2000/60 lays down a series of provisions, in particular Articles 3, 5, 8, 11 and 13 and Annex V, establishing, as the Advocate General has noted in points 43 to 52 of his Opinion, a complex process involving a number of extensively regulated stages, for the purpose of enabling the Member States to implement the necessary measures, on the basis of the specific features and the characteristics of the bodies of water identified in their territories.

43

These matters confirm the interpretation that Article 4(1)(a) of Directive 2000/60 does not simply set out, in programmatic terms, mere management-planning objectives, but has binding effects, once the ecological status of the body of water concerned has been determined, at each stage of the procedure prescribed by that directive.

44

The derogation regime provided for in Article 4(7) of Directive 2000/60, the conditions for the application of which have been examined by the defendant in the main proceedings but are not the subject of the referring court’s questions, likewise constitutes a matter which confirms the interpretation that prevention of deterioration of the status of the bodies of water is binding in nature.

45

That regime includes several categories. In particular, under Article 4(7) ‘Member States will not be in breach of this Directive when failure … to prevent deterioration in the status of a body of surface water or groundwater is the result of new modifications to the physical characteristics of a surface water body or alterations to the level of bodies of groundwater’.

46

That derogation is, however, applicable only on condition that all practicable steps have been taken to mitigate the adverse impact on the status of the body of water concerned and that the programmes of measures and management plans have been adapted accordingly.

47

The structure of the categories of derogation which are laid down in Article 4(7) of Directive 2000/60 permits the inference that Article 4 of the directive does not contain solely basic obligations, but that it also concerns individual projects. As the Advocate General has observed in point 78 of his Opinion, the grounds for derogation apply in particular where failure to comply with the objectives follows new modifications to the physical properties of the body of surface water, resulting in adverse effects. That may occur following new authorisations for projects. Indeed, it is impossible to consider a project and the implementation of management plans separately.

48

Consequently, those projects are covered by the obligation, laid down in Article 4 of Directive 2000/60, to prevent deterioration of the status of bodies of water. However, the projects may be authorised pursuant to the system of derogations provided for in Article 4.

49

The European Commission submits in its written observations that the prohibition of deterioration of the status of bodies of water is an objective of the duty to enhance their status. In that regard, it must be held that the obligation to prevent deterioration of the status of bodies of water was granted autonomous ranking by the EU legislature and is not merely an instrument placed at the service of the obligation to enhance the status of bodies of water.

50

It follows that, unless a derogation is granted, any deterioration of the status of a body of water must be prevented, irrespective of the longer term planning provided for by management plans and programmes of measures. The obligation to prevent deterioration of the status of bodies of surface water remains binding at each stage of implementation of Directive 2000/60 and is applicable to every surface water body type and status for which a management plan has or should have been adopted. The Member State concerned is consequently required to refuse authorisation for a project where it is such as to result in deterioration of the status of the body of water concerned or to jeopardise the attainment of good surface water status, unless the view is taken that the project is covered by a derogation under Article 4(7) of the directive.

51

In the light of all the foregoing considerations, the answer to the first and fourth questions is that Article 4(1)(a)(i) to (iii) of Directive 2000/60 must be interpreted as meaning that the Member States are required — unless a derogation is granted — to refuse authorisation for an individual project where it may cause a deterioration of the status of a body of surface water or where it jeopardises the attainment of good surface water status or of good ecological potential and good surface water chemical status by the date laid down by the directive.

52

By its second and third questions, which it is appropriate to deal with together, the referring court asks, in essence, whether the concept of ‘deterioration of the status’ of a body of surface water in Article 4(1)(a)(i) of Directive 2000/60 must be interpreted as covering only detrimental changes which result in classification of that body of water in a lower class in accordance with Annex V to the directive (the status classes theory). If the answer is in the negative, that is to say, if that concept covers any detrimental change to the body of water at issue (the status quo theory), the referring court wishes to ascertain the criteria for concluding that there is a deterioration of the status of a body of surface water.

53

The concept of ‘deterioration of the status’ of a body of surface water is not defined in Directive 2000/60.

54

In the absence of such a definition in EU law, the meaning and scope of that concept must, in accordance with settled case-law of the Court, be determined by taking into account both the terms in which the provision of EU law concerned is couched and its context (see, in particular, judgments in Lundberg, C‑317/12, EU:C:2013:631, paragraph 19; SFIR and Others, C‑187/12 to C‑189/12, EU:C:2013:737, paragraph 24; and Bouman, C‑114/13, EU:C:2015:81, paragraph 31).

55

The wording of Article 4(1)(a)(i) of Directive 2000/60 supports an interpretation according to which the concept of ‘deterioration of the status’ of a body of surface water also covers deterioration which does not result in classification of that body of water in a lower class. That provision expressly states that deterioration of the status of all bodies of surface water should be prevented. According to the definition in Article 2(17) of the directive, surface water status is the general expression of the status of a body of surface water, determined by the poorer of its ecological status and its chemical status. Thus, Article 4(1)(a)(i) of Directive 2000/60 imposes in a general manner the obligation to prevent deterioration of the status of bodies of surface water and does not mention any change of class; only Article 4(1)(a)(ii) and (iii) of the directive refers to Annex V thereto, in respect of the obligation to enhance the status of bodies of surface water.

56

Before establishing whether that literal interpretation is borne out by the context within which the concept of ‘deterioration of the status’ of a body of surface water falls and by the objectives of Directive 2000/60, it should be noted, as the Advocate General has stated in points 91 to 97 of his Opinion, that the assessment of surface water status is based on analysis of the ecological status, which covers five classes.

57

It is at the stage of drawing up ecological quality ratios that the Member States divide the ecological quality ratios for each surface water category into five classes, by means of a limit value for the biological quality elements which shows the boundary between those different classes, namely high, good, moderate, poor and bad. The limit values are to be established following an intercalibration exercise, which involves comparing the classification results of the national monitoring systems for each biological element and for each common surface water body type among Member States in the same geographical intercalibration group, and assessing the consistency of the results with the normative definitions set out in Section 1.2 of Annex V to Directive 2000/60.

58

However, as is apparent from point 1.4.1(iii) of Annex V to Directive 2000/60, the intercalibration exercise serves only to define the limits of the classes for ‘high’, ‘good’ and ‘moderate’ status. The Member States’ limit values are set out in Commission Decision 2013/480/EU of 20 September 2013 establishing, pursuant to Directive 2000/60/EC of the European Parliament and of the Council, the values of the Member State monitoring system classifications as a result of the intercalibration exercise and repealing Decision 2008/915/EC (OJ 2013 L 266, p. 1).

59

Finally, in accordance with point 1.4.2(i) of Annex V to Directive 2000/60, for surface water categories, a body of water is to be classified in the class immediately below as soon as the ratio of one of the quality elements falls below the level for the current class. This ‘one out all out’ rule is linked to the definition of ‘surface water status’ in Article 2(17) of the directive, which must be determined by the poorer of the ecological status and the chemical status of the body of surface water.

60

By virtue of Article 2(21) of Directive 2000/60, ecological status is an expression of the quality of the structure and functioning of aquatic ecosystems associated with surface waters, classified in accordance with Annex V thereto, which refers to those classifications of ecological status as ‘normative definitions’.

61

However, as the Advocate General has observed in point 99 of his Opinion, determination of the limit values between the classes results in the adoption of wide ranges. The classes are thus merely an instrument which limits the discretion of the Member States when determining the quality elements which reflect the actual status of a specific body of water. It is in particular for that reason that Article 4(1)(a)(i) of Directive 2000/60 does not refer to Annex V thereto, as the concept of ‘deterioration of the status’ of a body of surface water is a concept of general scope.

62

A different interpretation of that concept would, on the other hand, deter the Member States from preventing deterioration of the status of a body of surface water within a status class. Since classification of a body of surface water depends on the poorest value of the applicable parameters, all the other values could be reduced without that having legal consequences.

63

Application of the ‘one out all out’ rule in conjunction with the status classes theory would also result in waters in the lowest class being excluded from the scope of the obligation to prevent deterioration of their status. After classification of a body of water in that status class, further deterioration of its status would legally no longer be possible. However, given the purpose of Directive 2000/60, that type of body of water calls for particular attention in the context of water management.

64

That interpretation is borne out by Article 4(5)(c) of Directive 2000/60, which expressly lays down a prohibition of all further deterioration as regards heavily modified bodies of surface water for which the Member States may aim to achieve less stringent environmental objectives.

65

Furthermore, application of the status classes theory would result in a weakening of the protection of waters falling within the highest classes. Given that the classification of waters is determined by the poorest value of the applicable parameters, clear deterioration of other elements would not change the classification of the body of water concerned at all as long as it did not result in classification in a lower class.

66

By contrast, as the Advocate General has observed in point 105 of his Opinion, if the concept of ‘deterioration’ is interpreted by reference to a quality element or a substance, the obligation to prevent deterioration of the status of a body of water retains all its practical effect, since it encompasses all changes liable to undermine achievement of the principal objective of Directive 2000/60.

67

As regards the criteria for concluding that there is a deterioration of the status of a body of water, it is clear from the scheme of Article 4 of Directive 2000/60, in particular Article 4(6) and (7), that a deterioration of the status of a body of water, even if transitory, is authorised only subject to strict conditions. It follows that the threshold beyond which breach of the obligation to prevent deterioration of the status of a body of water is found must be low.

68

Contrary to the submissions of Bundesrepublik Deutschland, an interpretation that only ‘serious impairment’ constitutes a deterioration of the status of a body of water, an interpretation which is founded, in essence, upon the weighing up of, on the one hand, the adverse effects on waters and, on the other, water-related economic interests, cannot be inferred from the wording of Article 4(1)(a)(i) of Directive 2000/60. Furthermore, as the applicant in the main proceedings observes, such an interpretation does not respect the difference established by the directive between the obligation to prevent deterioration of the status of a body of water and the grounds of derogation laid down in Article 4(7) of the directive, since only the latter involve some weighing up of interests.

69

That said, the view should be taken, as the Commission has done, that there is ‘deterioration of the status’ of a body of surface water, within the meaning of Article 4(1)(a)(i) of Directive 2000/60, as soon as the status of at least one of the quality elements, within the meaning of Annex V to the directive, falls by one class, even if that fall does not result in a fall in classification of the body of surface water as a whole. However, if the quality element concerned, within the meaning of that annex, is already in the lowest class, any deterioration of that element constitutes a ‘deterioration of the status’ of a body of surface water, within the meaning of Article 4(1)(a)(i).

70

In the light of all the foregoing considerations, the answer to the second and third questions submitted is that the concept of ‘deterioration of the status’ of a body of surface water in Article 4(1)(a)(i) of Directive 2000/60 must be interpreted as meaning that there is deterioration as soon as the status of at least one of the quality elements, within the meaning of Annex V to the directive, falls by one class, even if that fall does not result in a fall in classification of the body of surface water as a whole. However, if the quality element concerned, within the meaning of that annex, is already in the lowest class, any deterioration of that element constitutes a ‘deterioration of the status’ of a body of surface water, within the meaning of Article 4(1)(a)(i).

71

Since these proceedings are, for the parties to the main proceedings, a step in the action pending before the referring court, the decision on costs is a matter for that court. Costs incurred in submitting observations to the Court, other than the costs of those parties, are not recoverable.

On those grounds, the Court (Grand Chamber) hereby rules: