EN Official Journal of the European Union C 213/1

Commission notice: ‘Guidance document on the requirements for hydropower in relation to EU nature legislation’

(2018/C 213/01)

This document reflects the view of the European Commission and is not of a binding nature.

European Commission, May 2018

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Reproduction is authorised provided the source is acknowledged.

This document has been prepared with the assistance of N2K GROUP EEIG — Ecosystems Ltd, Brussels and Beleco, Czech Republic.

TABLE OF CONTENTS

Purpose of the document 3

1. Overview of EU Policy and Legislative framework 4

1.1. The Birds and Habitats Directives 4

1.2. The Water Framework Directive (WFD) 6

1.3. Coordination between the WFD and the Nature Directives 6

1.4. The Floods Directive 8

1.5. The SEA and EIA Directives 9

1.6. The relationship between SEA, EIA and Article 6 10

2. Freshwater ecosystems and hydropower in the EU 10

2.1. The status of the EU's river and lake ecosystems 10

2.2. Pressures and threats of Europe's freshwater ecosystems 12

2.3. The effects of hydropower on freshwater ecosystems 14

2.4. Cumulative effects 19

2.5. Distinguishing between significant and insignificant effects 21

3. Good practice examples in mitigating effects and applying ecological restoration measures to hydropower 23

3.1. Aiming for the best practicable ecological condition of rivers in the context of hydropower 23

3.2. Dealing with existing hydropower having a negative effect on a Natura 2000 site 24

3.3. Introducing ecological measures and restoration measures 25

3.4. Good practice examples of ecological restoration 29

4. Good practices in applying an integrated planning approach to hydropower 36

4.1. The benefits of integrated planning 36

4.2. Integrated national and regional plans 40

4.3. Wildlife sensitivity and zoning 41

4.4. Early consultation 44

5. The assessment procedure under the Habitats Directive 46

5.1. Introduction 46

5.2. When is the Article 6 procedure required 46

5.3. A step by step procedure for carrying out appropriate assessments 47

5.4. Exceptions under Article 6.4 57

Abbreviations 61

PURPOSE OF THE DOCUMENT

This document offers guidance and presents a series of practical case studies on how hydropower can be made to operate in accordance with the requirements of the Habitats and Birds Directives. It examines the types of effects that might occur from hydropower activities and illustrates, through a series of practical experiences, how the effects of hydropower can be avoided or at least minimised under a range of different conditions.

More generally, it aims to act as a conduit for fostering synergies between EU policies and practices on energy, nature and water in order to achieve EU targets in a more coordinated, and wherever possible, mutually supportive manner.

Chapter 1 provides an overview of the EU policy and legislative framework in which hydropower is expected to operate in Europe. The key provisions of the Habitats and Birds Directives are briefly summarised as is their relationship with the Water Framework Directive and the EIA and SEA Directives.

Chapter 2 outlines the generally poor state of the EU's river and lake ecosystems, as well as their main pressures and threats, before going on to examine the range of effects hydropower can have on freshwater ecosystems, stressing the importance of potential cumulative effects in particular.

A significant number of Europe's wild fauna and flora species, including some 400 freshwater species protected under the Birds and Habitats Directives, depend on river and lake ecosystems for their survival. However, today most of Europe's rivers are in a highly degraded state and under immense pressure from a wide range of socio-economic activities (including hydropower).

From the latest State of Environment reports (1) it is clear that much still needs to be done to meet the objectives of the Water Framework Directive and the two Nature Directives. This can only be achieved if priority is given not just to preventing a further deterioration of our rivers but also to actively restoring their ecological status and removing, or at least significantly reducing, the pressures and threats they face.

Chapter 3 explores the ways in which this can be achieved, illustrating this with good practice examples of ecological restoration from across the EU.

Particular attention is given in Chapter 4 to the need for strategic planning and to designing more integrated hydropower plans and projects that take account of the river's ecological requirements early on in the planning process and wherever possible also include measures to improve the ecological status of the river.

The document goes on to describe in detail (Chapter 5) the procedure to follow when carrying out an appropriate assessment for a hydropower plan or project under Article 6 of the Habitats Directive. Clarification is provided on certain key aspects of this approval process and of its relation with other EU environmental assessment procedures. Experience has shown, time and again, that problems with the Article 6 approval process are very often caused by poor quality and incomplete appropriate assessments.

The guidance is designed primarily for use by competent authorities, developers and consultants. It will also be of interest to non-governmental organisations and other stakeholders who are working in the hydropower sector. The document has been written in consultation with Member state authorities as well as a range of key stakeholder and interest groups all of whom have provided valuable feedback on the various drafts.

The document is intended to be bound by, and faithful to, the text of the Birds and Habitats Directives and to the wider principles underpinning EU policy on the environment and hydropower. The good practice procedures and proposed methodologies are not prescriptive in their intent; rather they aim to offer useful advice, ideas and suggestions based on discussions with industry representatives, national and international authorities, NGOs, scientific experts and other stakeholders.

The document reflects only the views of the Commission and is not of a legally binding nature. It rests with the European Court of Justice to provide definitive interpretation of EU directives. Wherever relevant, existing European case law has been included. The present guide is therefore best read in conjunction with the existing general guidance and relevant European Court of Justice rulings on the two directives (2).

1. EU POLICY AND LEGISLATIVE FRAMEWORK

Hydropower plays a key role in the implementation of the Renewable Energy Directive (3) and in contributing to the EU energy targets for 2020-2030. As with all other water-based activities, hydropower must conform to the requirements of EU environmental law, which has been introduced to protect and restore Europe's rivers and lakes. These legal requirements are laid down in the Water Framework Directive, the Floods Directive, the Birds and Habitats Directives, and the Environmental Assessments Directives (Environmental Impact Assessment - EIA and Strategic Environmental Assessment - SEA Directives).

This chapter outlines some of the key provisions of these EU laws that are relevant for hydropower. The focus is on the two Nature Directives in particular, as this is the main topic of the present document.

1.1. The Birds and Habitats Directives

Europe's rivers are a major source of biodiversity and an important part of our rich natural heritage. They have, however, undergone major changes over the decades. This has reduced their resilience and capacity to provide for nature and wildlife. Most rivers are now in a degraded state and in need of restoration.

Recognising the alarming loss of biodiversity in Europe, the EU Heads of State and Government set themselves the ambitious target of halting, and reversing, this loss by 2020. In May 2011, the Commission adopted an EU biodiversity strategy to 2020 (4) setting out a policy framework for achieving this. In April 2017, it launched a new action plan (5) to rapidly improve the practical implementation of the Habitats and Birds Directives and accelerate progress towards the EU 2020 goal of halting and reversing the loss of biodiversity and ecosystem services.

The Birds and Habitats Directives are the cornerstones of the EU's nature and biodiversity policy. They enable all EU Member States to work together, within a common legislative framework, to conserve Europe's most endangered, vulnerable and valuable species and habitats across their entire natural range within the EU, irrespective of political or administrative boundaries.

The overall objective of the two Directives is to ensure that the species and habitat types they protect are maintained and restored to a favourable conservation status (6) throughout their natural range within the EU.

This target is defined in positive terms, oriented towards a favourable situation which needs to be reached and maintained. It therefore goes beyond the basic requirement of avoiding deterioration.

Definition of favourable conservation status (FCS) under the Habitats Directive Article 1 The conservation status of a natural habitat means the sum of the influences acting on a natural habitat and its typical species that may affect its long-term natural distribution, structure and functions as well as the long-term survival of its typical species within the territory of the EU. The conservation status of a natural habitat will be taken as ‘favourable’ when: — Its natural range and the areas it covers within that range are stable or increasing, and — the specific structure and functions which are necessary for its long-term maintenance exist and are likely to continue to exist for the foreseeable future, and — the conservation status of its typical species is favourable. The conservation status of a species means the sum of the influences acting on the species concerned that may affect the long-term distribution and abundance of its populations within the territory of the EU. The conservation status will be taken as ‘favourable’ when: — population dynamics data on the species concerned indicate that it is maintaining itself on a long-term basis as a viable component of its natural habitats, and — the natural range of the species is neither being reduced nor is likely to be reduced for the foreseeable future, and — there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis.

To achieve this objective, the EU Nature Directives require Member States to implement two main types of measures in particular:

— The designation and conservation of core sites for the protection of species and habitat types listed in Annex I and II of the Habitats Directive and Annex I of the Birds Directive, and for the protection of all regularly occurring migratory birds. These sites make up the EU-wide Natura 2000 Network which currently contains over 27 500 sites. Lake and river ecosystems cover around 4 % of the total surface area of Natura 2000 (European Environment Agency, 2010, for EU 27).

— The establishment of a species protection regime for all wild European bird species and other species listed in Annex IV of the Habitats Directive. These measures apply across the species' entire natural range within the EU, i.e. both within and outside protected sites such as Natura 2000.

Natura 2000 site protection provisions

The protection and management of Natura 2000 sites is governed by the provisions of Article 6 of the Habitats Directive, which also determines the relationship between the site's conservation and other land-uses, such as hydropower, in and around the area (7).

Article 6 is divided into two types of measures:

— The first concerns the conservation management of all Natura 2000 sites and the setting of conservation objectives for these sites. It requires Member States to: (a) elaborate and implement positive conservation measures which correspond to the ecological requirements of the habitat types in Annex I and the species in Annex II present on the sites (Article 6.1); and (b) take appropriate measures to avoid any deterioration of habitat types and habitats of species or any significant disturbance of the species present (Article 6.2). The Habitats Directive recommends the development of Natura 2000 management plans as a means of identifying the necessary conservation measures for Natura 2000 sites in an open and transparent manner. They are useful tools for setting conservation objectives and helping to build a consensus view on the management solutions for the site amongst all stakeholders and interest groups. They also provide a mechanism for integrating conservation measures for Natura 2000 into the wider Water Framework Directive's programme of measures.

— The second type of measure (governed by Article 6.3) concerns the assessment procedure for any plan or project that could affect one or more Natura 2000 site (see Chapter 5 for full details). In essence, the assessment procedure requires that any plan or project that is likely to have a significant effect on a Natura 2000 site undergoes an appropriate assessment (AA) to study these effects in detail, in view of the site's conservation objectives. The competent authority can only agree to the plan or project if, based on the findings of the AA, it has ascertained that it will not have an adverse effect on the integrity of the site concerned. It is important to note that the onus is on demonstrating the absence (rather than the presence) of significant negative effects. In exceptional circumstances, a derogation (Article 6.4) may be invoked to approve a plan or project having an adverse effect on the integrity of a Natura 2000 site if it can be demonstrated that there is an absence of less damaging alternatives and the plan or project is considered to be necessary for imperative reasons of overriding public interest. In such cases, adequate compensation measures will need to be secured to ensure that the overall coherence of the Natura 2000 network is protected. It is important to note that the assessment procedure under the Habitats Directive is not the same as that foreseen under the EIA or SEA Directives (8) and Article 4.7 of the WFD even if they should ideally be integrated with one another or at least coordinated.

Species protection provisions

The second set of provisions of the Nature Directives concerns the protection of certain species across their entire natural range within the EU, i.e. regardless of whether they are inside or outside Natura 2000 sites. The species protection measures apply to species listed in Annex IV of the Habitats Directive and all wild bird species in the EU. The exact terms are laid down in Article 5 of the Birds Directive and Articles 12 (for animals) and 13 (for plants) of the Habitats Directive.

In essence Member States are required to prohibit, for these species:

— their deliberate disturbance during breeding, rearing, hibernation and migration;

— the deterioration or destruction of breeding sites or resting places;

— the deliberate destruction of nests or eggs, or the uprooting or destruction of protected plants.

Derogations to the species protection provisions are only allowed in restricted cases — such as to prevent serious damage to crops or livestock or in the interests of public health and safety — provided that there is no other satisfactory solution and the consequences of these derogations are not incompatible with the overall aims of the Directives. The conditions for applying derogations are set out in Article 9 of the Birds Directive and Article 16 of the Habitats Directive (9).

The species protection provisions are highly relevant to hydropower facilities operating also outside Natura 2000 sites. They aim to ensure that any new developments do not destroy the breeding and resting sites of any wild bird or any species listed under Annex IV of the Habitats Directive unless they have sought from the competent authorities a derogation in accordance with the terms of the Directives. This provision can be especially important for hydropower situated on a river harbouring migratory species, such as migratory birds or fish (e.g. European sea sturgeon Acipenser sturio or the apron Zingel asper both listed in Annex IV of the Habitats Directive).

1.2. The Water Framework Directive

The Water Framework Directive (WFD) establishes a framework for the protection and sustainable management of inland surface waters (rivers and lakes), transitional waters (estuaries), coastal waters and groundwater. It aims to ensure that all water bodies meet ‘good status’ as a rule by 2015 (except for heavily modified and artificial water bodies where the objective is to achieve a good ecological potential). Like the Nature Directives, the WFD goes beyond the basic requirement of preventing the further deterioration of water bodies and the terrestrial ecosystems and wetlands directly depending on the aquatic ecosystem.

To help achieve this objective, the WFD requires Member States to establish a river basin management plan for each river basin district. The Directive envisages a cyclical process where river basin management plans are prepared, implemented and reviewed every 6 years.

1.3. Coordination between the WFD and the two Nature Directives

The Water Framework Directive and the two Nature Directives are closely interlinked as they both aim to protect and restore Europe's freshwater ecosystems. They should therefore be implemented in a coordinated way to ensure that they operate in an integrated manner. The following highlights some of the key points of interaction between the WFD and the two Nature Directives that are relevant for hydropower plants in particular, derived from the Commission's FAQ on links between the Water Framework Directive and the Nature Directives (10).

Distinct objectives of the WFD and Nature Directives

The WFD and the Nature Directives all operate, at least in part, on the same environment and have broadly similar ambitions of ensuring the non-deterioration of rivers and improving the status of aquatic ecosystems. However, while their overall objectives are similar, their specific aims are nevertheless distinct even if they are closely interlinked.

The WFD aims to protect and improve all surface waters and groundwater so that they reach good status or potential and to avoid deterioration. The Birds and Habitats Directives, on the other hand, aim to protect, maintain and restore particular species and habitat types in order to bring them up to a favourable conservation status across their natural range within the EU.

Achieving good ecological status under the WFD usually helps to achieve the conservation objectives of water-dependent habitats and species in Natura 2000, and vice versa. However, the requirement of ‘good ecological status’ refers to water bodies while favourable conservation status refers to specific habitat types and species.

Thus, reaching good ecological status is not necessarily sufficient for reaching favourable conservation status, even if all water bodies would reach good ecological status. There may therefore be a need to implement additional conservation measures in order to achieve the Natura 2000 site's conservation objectives for the species and habitat types for which it is designated.

This is explicitly recognised in the WFD. Article 4.2 of the WFD states that ‘where more than one of the objectives […] relates to a given body of water, the most stringent shall apply ’. For instance, if a Natura 2000 site is designated for otters or freshwater pearl mussels, it may also be necessary to regulate overfishing even if this is not necessary to achieve good ecological status under the WFD.

These additional requirements should ideally be included, or at least referred to, in the WFD river basin management plan via specific provisions regarding protected areas to ensure coherence (and avoid conflicts) between the WFD measures and the Natura 2000 measures (see Article 4.1.c).

Heavily modified water bodies or artificial water bodies and Natura 2000

According to Article 4.3 of the WFD, some water bodies that are significantly modified by human activities in their physical characteristics may be designated as heavily modified water bodies provided they fulfil all the provisions of Article 4.3 (11). Water bodies that have been created by human activity where there was no water body before (e.g. a man-made reservoir or an artificial navigation canal) can be designated as artificial water bodies.

For heavily modified water bodies and artificial water bodies the WFD objective of ‘good ecological potential’ applies (instead of good ecological status) if the requirements for less stringent objectives such as ‘moderate ecological potential’ are not applicable. In plain words this means the best practicable ecological condition that is compatible with the legitimate use which was the basis for its designation as a heavily modified water body or artificial water body (12).

A heavily modified water body or artificial water body may also be designated as a Natura 2000 site, if it harbours a species or habitat type listed in Annex I of the Birds Directive or in Annexes I or II of the Habitats Directive. In such cases, appropriate conservation measures will need to be implemented for that species or habitat as well, in accordance with the conservation objectives of the site. Again, these measures may be stricter than those required for achieving ‘good ecological potential’. They should also be integrated into the WFD river basin management plans by specific provisions on protected areas (see Article 4(1)c in conjunction with Article 4(2)).

Assessing new developments under the WFD

Like the Nature Directives, the WFD has specific provisions for assessing new developments on water bodies. According to Article 4.7 of the WFD, exemptions can be approved by the authorities for new modifications and sustainable human development activities that result in the deterioration of the status of the water body or that prevent the achievement of good ecological status or potential, or good groundwater status under certain conditions. This potentially includes new developments related to hydropower (13).

If the development potentially affects both a WFD objective and a Natura 2000 site then both the Article 4(7) procedure under the WFD and the Natura 2000 assessment procedure under Article 6.3 of the Habitats Directive must be undertaken (ideally in a coordinated or integrated manner). Each has a different legal focus: one will assess if the project is likely to compromise the primary objectives of the WFD, the other will assess whether it will adversely affect the integrity of a Natura 2000 site. However, this does not prevent certain aspects of the assessment being coordinated, e.g. through surveys and consultations.

The WFD makes it clear that a development cannot go ahead if it is not consistent with other EU environmental legislation. In other words, if the project does not compromise the objectives of the WFD but does adversely affect the integrity of a Natura 2000 site then it cannot be approved under the WFD unless an exemption under Article 6.4 of the Habitats Directive has also been accepted. Clarification on the application of WFD Article 4(7), on the exemptions to the environmental objectives, including the linkage to the Nature Directives, is provided in CIS Guidance Document No 36 on WFD Article 4.7 which was endorsed in 2017 (14).

Conserving the freshwater pearl mussel in Ireland's sub-river basins The freshwater pearl mussel Margaritifera margaritifera is one of the longest-living invertebrates on earth. Owing to its complicated life history and its need for near natural, clean flowing waters, it is a key biological indicator species for the quality of river ecosystems. The species is protected under the EU Habitats Directive but is in an unfavourable conservation status throughout Ireland. Sedimentation or sedimentation with nutrient enrichment has been identified as the main causes of this. In 2009, national legislation was developed to support the achievement of favourable conservation status for the freshwater pearl mussel. This legislation set obligatory environmental quality objectives for freshwater pearl mussel habitats within Natura 2000 sites. It also required that sub-basin management plans be prepared along with a programme of measures. The purpose of these plans was to address the catchment-wide issues that are contributing to the species decline. The format used mirrored that of the river basin management plans under the WFD so that the sub-basin management plans could operate under the umbrella of the river basin management plans later on. In Ireland, the close linkages between the Habitats and Birds Directives, and the WFD were highlighted at an early stage. In 2009, the National Technical Coordination Group for the Water Framework Directive established a subcommittee — the National Conservation Working Group, — to work on the development of nature conservation aspects of the WFD. The Working Group's core objective was to ensure that this development of the nature conservation aspects of the Water Framework Directive were well coordinated and supported within Ireland and to facilitate effective communication between the relevant government agencies involved. For the sub-basin plans for the freshwater pearl mussels, the Group played a key role in refining and further developing a national set (‘toolkit’) of standard catchment measures for freshwater pearl mussels that are practical, functional and cost effective. It also reviewed the plans to ensure their practicality and effectiveness, and identified policy and guidance gaps, which would hinder their implementation. http://www.wfdireland.ie/docs/5_FreshwaterPearlMusselPlans/ http://kerrylife.ie http://www.environ.ie/en/Environment/Water/WaterQuality/WaterFrameworkDirective/

1.4. The Floods Directive

In November 2007, Directive 2007/60/EC was adopted. It establishes a framework for assessing and managing flood risks and requires Member States to draw up:

— Flood hazard and flood risk maps, that map out the identified flood risk areas per river basin (or other agreed unit area of management). These maps should also show the potential adverse consequences associated with different flood scenarios, including information on potential sources of environmental pollution as a consequence of floods, as well as protected areas such as Natura 2000 sites in those areas (deadline December 2013).

— Flood risk management plans for managing and reducing the potential adverse consequences of flooding. These plans should include a prioritised set of measures, addressing all aspects of flood risk management from prevention and protection to preparedness, taking into account the characteristics of the particular river basin or sub-basin (deadline December 2015).

Activities under the Floods Directive must be in line with the requirements of the Nature Directives. For instance, if a flood protection measure risks affecting one or more Natura 2000 sites, it too, must follow the procedure under Article 6 of the Habitats Directive, and an appropriate assessment should be carried out to assess the potential effects of the plan or project on the integrity of the Natura 2000 site(s).

1.5. The SEA and EIA Directives

The SEA Directive

Directive 2001/42/EC on the assessment of the effects of certain plans and programmes on the environment (the ‘SEA Directive’) aims to provide for a high level of protection of the environment. It aims to do this by ensuring that the environmental consequences of certain plans and programmes are identified, assessed and taken into account during their preparation and before their adoption.

A strategic environmental assessment is mandatory for a variety of plans and programmes which set the framework for future consent of the development of projects listed in the EIA Directive. It is also mandatory for any plans or programmes, which, because of their likely significant effect on Natura 2000 sites, require an assessment pursuant to Article 6.3 of the Habitats Directive.

Under the SEA process, Member States are required to prepare an environmental report that assesses the likely significant environmental effects of the plans and programmes, and the effects of any reasonable alternatives. In addition, they must consult the authorities, which by reason of their specific environmental responsibilities, are likely to be concerned by the environmental effects of implementing plans and programmes (i.e. environmental authorities) and the public.

The consultation should be early and effective, allowing the environmental authorities and the public to express their opinion on the draft plan or programme, and on the accompanying environmental report before the plan or programme is adopted. The process of developing the SEA is intended to be coordinated with the plan's development leading to the inclusion of environmental considerations into the final version of this plan.

Ultimately, the SEA aims to encourage a more integrated and efficient approach to territorial planning where environment, including biodiversity considerations, are taken into account much earlier on in the planning process and at a much more strategic level. This should lead to fewer conflicts further down the line at the level of individual projects. It also allows for a more appropriate siting of future developments away from areas of potential conflict such as in Natura 2000 sites.

The EIA Directive

While the SEA process is for plans and programmes, EIA Directive 2011/92/EU, as amended by Directive 2014/52/EU (commonly referred to as the ‘EIA Directive’), is for individual public and private projects. Thus, the consent to develop a project (15) which is likely to have significant effects on the environment should be granted only after the project's likely environmental effects have been assessed.

The EIA Directive distinguishes between projects requiring a mandatory EIA (‘Annex I projects’ (16)) and those where Member State authorities must determine if projects are likely to have significant effects (‘Annex II projects’). This is done through a ‘screening’ procedure that takes into account criteria in Annex III of the Directive. Most installations for hydroelectric energy production are Annex II projects (17).

1.6. The relationship between SEA, EIA and Article 6.3 of the Habitats Directive

According to the EIA Directive (as amended by Directive 2014/52/EU), a coordinated and/or joint procedure should be undertaken if an assessment of a project is required under both the EIA Directive and the Nature Directives. The Commission issued guidance on setting up any coordinated and/or joint procedures for projects (18) that simultaneously have to be assessed under the EIA, Habitats, Birds, Water Framework, and Industrial Emissions Directives.

Under the coordinated procedure, Member States must coordinate the various individual assessments of the environmental impact of a particular project, required by the relevant Union legislation, by designating an authority for this purpose. Under the joint procedure, Member States have to provide for a single assessment of the environmental impact of a particular project required by the relevant Union legislation.

The appropriate assessment under EU nature legislation should nevertheless remain a clearly distinguishable and identifiable part of the overall environmental report. This is because the Habitats Directive's appropriate assessment measures different aspects of the natural environment and has different criteria for determining ‘significance’ than the EIAs/SEAs. The EIA/SEAs consider all aspects of the environment, including biodiversity, whereas the Nature Directives' assessment focuses specifically on possible effects on the species and habitat types for which the Natura 2000 site has been designated.

There is also a distinction for the outcome of each assessment. The assessments under the SEA and EIA lay down procedural requirements but do not establish obligatory environmental standards. The outcome of assessment under the Habitats Directive, on the other hand, is immediately binding for the competent authority and conditions its final decision.

In other words, if the appropriate assessment cannot ascertain that the plan or project will not adversely affect the integrity of a Natura 2000 site, the authority cannot agree to the plan or project as it stands unless, in exceptional cases, they meet the conditions of the derogation procedure under Article 6.4.

If an assessment has to be made under the Habitats Directive, the Court of Justice of the European Union clarified that the SEA Directive would apply on its own merits for plans and programmes (19).

Guidance Document ‘Streamlining environmental assessment procedures for energy infrastructure “projects of common interest”’ (PCIs) Like all other development projects, hydropower is subject to a number of environment assessment procedures. The Commission has issued guidance on how to streamline these various procedures, in particular for projects of community interest (PCIs) under the Ten-E Regulation, while ensuring the maximum level of environmental protection in accordance with EU environmental law. The Commission guidance makes a series of recommendations, which, although designed with PCIs in mind, are also relevant for all energy plans or projects, including hydropower developments. The recommendations focus in particular on: — Early planning, ‘road mapping’ and scoping of assessments; — Early and effective integration of environmental assessments and of other environmental requirements; — Procedural coordination and time limits; — Data collection, data sharing and quality control; — Cross-border cooperation, and — Early and effective public participation. http://ec.europa.eu/environment/eia/pdf/PCI_guidance.pdf

2. FRESHWATER ECOSYSTEMS AND HYDROPOWER IN THE EU

2.1. Status of the EU's river and lake ecosystems

The structural complexity and highly dynamic nature of rivers and lakes make them exceptionally rich ecosystems, bringing lifeblood, or in this case water, to large parts of the surrounding countryside. As well as being valuable habitats in their own right, they act as vital ecological corridors, encouraging the dispersal and migration of species over long distances. They are also responsible for the development of a rich mosaic of interconnected, water dependent wetlands such as floodplain forests, marshes, fens, wet meadows, all of which further enhance their overall biodiversity.

A significant number of Europe's wild fauna and flora species, including some 400 freshwater species protected under the Birds and Habitats Directives, depend on river and lake ecosystems for their survival. Altogether, lakes and rivers cover around 4 % of the land surface of Natura 2000 (some 31 560 km2 — an area larger than Belgium) having been designated for species such as the Atlantic salmon Salmo salar, otter Lutra lutra, kingfisher Alcedo atthis, white-clawed crayfish Austropotamobius pallipes, thick-shelled river mussel (Unio crassus) as well as habitat types such as water courses of plain to montane levels, alluvial forests, wet meadows, humid grasslands and fens.

In addition, rivers are also a vital multi-functional resource for Europe's economy and social well-being, servicing a large number of different sectors and delivering many important goods and services to society. However their intensive use has put immense pressure on this valuable resource over the last 150 years, with the result that few of the major rivers are now in an entirely natural state. In addition to being subjected to varying degrees of pollution and high nutrient loads, which has led to a significant degradation in water quality, many rivers have also undergone major changes to their hydro-morphology, natural flow dynamics and ecological connectivity.

In 2015, the European Environment Agency's report on the State of Europe's environment (20) concluded that more than half of the rivers and lakes in Europe had not reached a good ecological status or potential. In 2009, only 43 % of surface water bodies were in a good or high ecological status. The situation was not expected to improve much by 2015 with only 53 % of water bodies expected to reach a good ecological status. This is far removed from the targets set by the WFD.

In terms of EU protected freshwater species and habitats, the situation is even more severe. According to the Commission's latest State of Nature report on the conservation status of habitats and species protected under the two Nature Directives for 2007-2012 (21), almost three quarters of freshwater species (74 %) and freshwater habitat types (73 %) had an unfavourable-inadequate or unfavourable-bad status. By contrast, only 17 % and 16 % respectively had a favourable status.

Conservation status

Conservation status

(a) Species (5615 assessments)

(b) Habitats (94 assessments)

Favourable

Unknown

Unfavourable-inadequate

Unfavourable-bad

Conservation status and trends of species (a) and habitats (b) (Habitats Directive) associated with rivers and lakes ecosystem. Source EEA, 2015b, Article 17 reports and assessments.

The overall poor status of Europe's rivers is a significant cause for concern. It is clear that many of Europe's rivers are in a highly degraded state and that much still needs to be done to meet the objectives of the WFD and the two Nature Directives. This can only be achieved if the priority is not just to prevent their further deterioration but also to actively improve their ecological condition.

2.2. Pressures and threats of Europe's freshwater ecosystems

Water bodies are under pressure from a wide variety of activities. Hydro-morphological pressures in particular have had a major effect and affect more than 40 % of river and transitional water bodies. Based on the first characterisation of river basins in relation to the WFD (22), most EU Member States indicated that pressures from urban development, flood defence, power generation including hydropower, inland water navigation, straightening and land drainage for agriculture are the strongest and affect the hydro-morphological status of water bodies to the highest degree.

Rivers pressures

Rivers impacts

No pressures (22)

No impacts (19)

Point sources (22)

Organic enrichment (16)

Diffuse sources (22)

Nutrient enrichment (19)

Contamination (18)

Water abstraction (19)

Acidification (10)

Hydromorphology (22)

Altered habitats (16)

Other pressures (19)

Other impacts (14)

Percentage of water bodies

Percentage of water bodies

Significant pressures (left) and impacts (right) for rivers; the number of Member States included is indicated in parentheses (European waters — assessment of status and pressures 2012)

As regards the threats and pressures on Natura 2000 freshwater bodies, the State of Nature report identifies ‘changes in water bodies conditions’ as the most frequent by far, as compared to other threats and pressures.

Figure 4.37 Top 10 (% of frequency) reported high-ranked pressures and threats for species (Habitats Directive) associated with rivers and lakes ecosystem

J02 Changes in water bodies conditions

J03 Other changes to ecosystems

H01 Pollution to surface waters

I01 Invasive alien species

A02 Modification of cultivation practices

K03 Interspecific faunal relations

F02 Fishing and harvesting aquatic resources

A07 Use of 'pesticides' in agriculture

D01 Roads, railroads and paths

K02 Vegetation succession/Biocenotic evolution

Pressures

Threats

State of Nature report, EEA 2015

Hydropower in the EU Around 23 000 hydropower installations were recorded in the EU in 2011. The vast majority (91 %) are small (less than 10 MWH) and generate around 13 % of the total electricity production from hydropower. Large hydropower plants, on the other hand, represent only 9 % of all hydropower facilities but generate about 87 % of the total electricity production from hydropower (23). Hydropower facilities are often concentrated in mountainous areas for technical reasons but have major far reaching effects on both large and small rivers and lakes across all kinds of different regions. In smaller rivers, even a small flow depletion or disruption to natural ecological conditions can have major negative implications for the river. The following hydropower facilities are most frequently used: Run-of-river hydropower plants . In the run-of-river hydropower systems, electricity production is driven by the existing flow and drop in elevation of a river. This type of installation uses the natural flow of a watercourse in order to generate electricity. There is no intention to store water and to use it later on. This type is most common for small hydropower stations but can also be found with large stations. Storage run-of-the-river hydropower schemes : A storage reservoir offers the opportunity to store water during periods of low demand and release it during peak periods. The generating capacity is therefore less dependent on availability of the water flow. Such reservoirs can comprise daily, seasonal or yearly storage, thus allowing it to meet peak electricity demands and facilitating the integration of variable renewable energy productions e.g. from wind energy into the energy system. Reservoir hydropower plants . The conventional reservoir plant has a reservoir of a big enough size to permit the storage of water during both wet and dry seasons. Water is stored behind the dam and is available to the plant as and when required. Such a plant can be used efficiently throughout the year, either as a base load plant or as a peak load plant as required. Pumped-storage hydropower plants . These are based on reservoirs at different elevations, which make it possible to generate supplementary electricity during high peak demands. The water is pumped to the higher reservoir at the time of a lower demand and released down through turbines when the demand is high. Pumped-storage hydroelectric power stations are not excluded from the Renewable Energy Directive but they are not taken into consideration for renewable energies statistics.

2.3. The effects of hydropower on freshwater ecosystems

The range of effects a hydropower facility can have on species and habitat types protected under the two EU Nature Directives will vary considerably from one site to another. It will depend on the individual characteristics of the river, its physical and ecological state — whether already degraded or still pristine, large or small, mountainous or lowland etc. — as well as on the type and scale of hydropower facilities and the species and habitats for which the site has been designated. There is therefore a need to look at each facility on a case-by-case basis.

The effects can occur at any stage of the life cycle of a hydropower installation, from its initial construction to its renovation, decommissioning or their day-to-day operation and management. They can result in the loss, degradation and fragmentation of natural habitats and populations of species that depend on these habitats for their existence. The significance of loss depends on the scale of the effects as well as on the rarity and vulnerability of the habitats and species affected.

The remainder of this chapter outlines the range of effects that hydropower can have on habitats and species under the EU Nature Directives in particular. Operators who are aware of the types of effects and who have an understanding of the complexities of the riverine ecosystems will be better placed to ensure that their activities are compatible with the requirements of the WFD and Nature Directives. They will also be better placed to identify potential win-win situations to help restore already degraded rivers wherever possible.

Changes in river morphology and riverine habitats

Any physical modification to water bodies will affect the normal hydrological processes and disrupt the ecological continuity (24) of freshwater systems both longitudinally and laterally, e.g. by disconnecting rivers from their surrounding floodplains and wetlands, or by creating a ponding effect around power plants.

The most obvious form of habitat loss is the direct physical destruction of the habitats themselves upstream or downstream or in the surrounding area (e.g. land take, inundation, removal of riparian vegetation or physical structures in the river). But even without physical land take, the disruption of natural hydromorphological processes can also disrupt or alter the biotic and abiotic conditions that are vital for the habitat's structure and functioning. Additionally, it can lead to the colonisation of degraded habitats by invasive species that could end up displacing the natural fauna.

Barriers to migration and dispersal of protected species

Rivers, lakes and riparian zones play an important role in the dispersal and migration of freshwater species and in more localised movements between different feeding, breeding, resting and nesting areas. They act as vital ecological corridors or stepping stones across the landscape. Any barriers or impediments to their free movement up or down stream, however small, can have important consequences for the survival of these species.

Range of impacts caused by different hydropower facilities Source: Veronika Koller-Kreimel

Hydropower installations can either directly or indirectly disrupt or prevent species dispersal and migration. The most obvious are dams and impounded areas which present physical barriers to fish migration, preventing the fish from travelling up and down the river. This has major effects on the survival of a wide range of freshwater species, resulting in the fragmentation, isolation and ultimate disappearance of some freshwater fish populations in particular.

The barrier effect is especially severe when there is more than one obstacle on a river stretch. Even with very small structures or physical barriers, rivers can rapidly become un-passable. Artificial canals can also act as barriers to species movement because they cut through and consequently fragment terrestrial habitats. They may also create artificial connections between catchments which can enhance the spread of non-native species, to the detriment of native species.

Although up- and downstream migration is important for all fish species, continuity is essential for diadromous species in particular. Upstream migration is most important for populations of anadromous fish and lamprey species like Salmo salar, sea lampreys Petromyzon marinus and Lampetra fluviatilis or some sturgeons as Acipenser sturio because of their need for periodical (optimally annual) long-distance migrations. Downstream migrations are essential for their juveniles and for adults of catadromous fish such as the eel Anguilla anguilla, which is protected under the Eel Regulation (25).

Disruption of sediment dynamics

Sediments are a natural part of aquatic ecosystems and are essential for the hydrological, geomorphological and ecological functioning of these systems. Sediment forms a variety of habitats which directly and indirectly support a broad range of species. Under natural conditions, there is a permanent downstream transport of sediments (mainly gravel) which maintains the ecological structure and function of the rivers. Transverse structures such as weirs or dams tend to disrupt the natural sediment dynamics.

Large reservoirs can trap over 90 % of incoming sediment which can lead to increased erosion of the river bed and banks downstream as well as the local destruction of important hydromorphological structures such as gravel bars. Maintenance works on weirs and dams involving the periodic flushing of sediments (especially in summer when there is water scarcity) can also be detrimental for habitats and species if not managed properly.

Upstream of a dam, in a reservoir or in impounded sections, the reduction of the sediment transport capacity causes sediment to accumulate which can have a negative effect on both species and habitats, e.g. by promoting the growth of algae and other aquatic weeds that crowd out the protected species. The accumulation of gravel or other silty sediments on the riverbed or in the water column may be especially detrimental to lithophile species, such as grayling Thymallus thymallus, which use these areas as spawning grounds for the freshwater pearl mussel Margaritifera margaritifera and the thick shelled river mussel Unio crassus. It is also detrimental for bird species, such as the plover or sandpiper that use dry gravel beds as nesting places.

Removing barriers on the Danube River Basin District Hydropower generation accounts for around 45 % of river and habitat continuity interruptions in the Danube River Basin District. A total of 1 688 barriers are located in the District's rivers with catchment areas of more than 4 000 km. 600 of these barriers are dams/weirs, 729 are ramps/sills and 359 are classified as other types of interruptions. 756 are currently indicated to be equipped with functional fish migration aids. 932 continuity interruptions (55 %) have been a hindrance to fish migration since 2009 and are currently classified as significant pressures. According to the latest Danube Basin River Management Plan, the Danube countries plan to significantly reduce the continuity interruption by dams by 2021. Danube River Basin District: River and habitat continuity interruption – (above) current situation 2015; (1st map) expected improvements by 2021 (2nd map). Source: DRBMP. https://www.icpdr.org/main/management-plans-danube-river-basin-published

Changes of the ecological flow regime

Ecological flows are a vital mechanism for maintaining essential processes of healthy river ecosystems upon which EU protected species and habitats depend and to ensure a good ecological status of the water bodies (26). A change in ecological flow can reduce or degrade the extent of the aquatic habitat as well as its connectivity with riparian habitats.

Too little water flow for instance can have a wide range of negative effects including the drying out of spawning sites for fish and lamprey species or preventing the development of fish eggs and juveniles. Fish migration upstream can also be hampered in the depleted reach, either because of blockages from the low flows or because of insufficient stimuli encouraging fish to migrate.

Inadequate flow rates in the original riverbed can also cause the water to overheat and contain insufficient oxygenation (as described above). This creates unsuitable living conditions for a whole range of species such as fish, crayfish and lamprey species, bivalve molluscs, or dragonflies dependent on flowing water habitats.

Changes of the flow regime by peaking hydropower plants

Strong oscillations in water flow can cause major damage to both species and their habitats, especially in small rivers. Hydropeaking stresses organisms living in affected parts of the watercourse, especially those unable to handle sudden changes in water levels, like juvenile fish, or other slow moving or static organisms (especially plant species). The hydropeaking regime influences also the behaviour of the prey of protected species and consequently affects their fitness levels.

The effect of hydropeaking is especially acute during sensitive periods (e.g. periods of drought or frost) and is increasingly relevant in view of climate change. Another adverse consequence of peaking hydropower plants is often a significantly different (much lower) temperature of water discharged during the peaking period. Species that are adapted to regular water temperatures cannot survive sudden changes lasting for several hours a day.

Changes in seasonal flood cycles

Measures are sometimes used to modify streambeds in order to be able to control better the flow of water. Interventions in flow control can result in the disruption of the seasonal flood cycles, causing sometimes the complete disappearance of the target habitat types and species connected to these cycles. Examples of affected habitats include alluvial forests, temporary ponds and oxbow lakes and rivers as well as their associated species.

RIPEAK — EU RESEARCH PROJECT: Responses of RiParian forests to hydroPeaking: towards a sustainable hydropower management Hydropeaking refers to short-term changes in river flow occurring within the span of a day caused either by turning on or off hydro-turbines to generate electricity according to variations in the market demand. As a result, downstream and upstream river hydrology, hydraulic parameters, water quality, river morphology, and ultimately the fluvial ecosystem, are modified. Scientific studies on the effects of hydropeaking are scarce and most of them have focused on fish fauna. Moreover, there are no studies on riparian vegetation. Hydropeaking might result in a failure of riparian species recruitment and hence affects the maintenance of riparian populations. Thus, by analysing seed germination and seedling performance, it might be possible to define hydropeaking — vegetation responses relationships that make it possible to quantify, correlate and predict biological responses to hydropeaking. Such relationships are crucial to objectively define thresholds which help to minimise ecological effects of hydropower generation without causing significant production losses. This project aims to shed some light on the sustainable management of rivers subjected to hydropower production. For this goal, an in-depth literature review, analysis of sub-daily flow series, field experiments and computer modelling are planned. The final contributions from the project expected are: (1) new hydrological and ecological (i.e. riparian vegetation) metrics of hydropeaking impact, (2) new hydrology-ecology models to quantify such effects and (3) new effective measures for a sustainable operation of hydropower dams. http://www.emg.umu.se/english/research/research-projects/responses-of-riparian-forests-to-hydropeaking/

Water chemical and temperature changes

Dams can fundamentally change the chemical quality, mineral composition and the pH of the river both up and downstream, for instance by accumulating contaminants in sediments. All these changes influence the composition of plant and animal communities present. Organisms are also influenced by changes of water temperature and connected alterations of oxygen concentration. Reservoirs can lead to an important increase of temperature but also to a reduction in temperature if the water is taken from the bottom.

Injuries and killing of individual animals

Fish and other species passing through a hydropower plant can be injured or killed. A hydropower plant can cause (27):

— injuries through physical contact with guide vanes, turbine runner or turbine casing

— damage from pressure fluctuations during the turbine passage

— wedging onto intake screens or injuries caused by cleaning machines

— injuries caused by intense flow and constructions of overflow in spillways

— susceptibility to predation due to the disorientation.

The degree of mortality can vary from 0 to 100 % at a single hydro power plant (28). Much depends on the type of fish present and on the type of hydropower construction and the mitigation measures used. The mortality rate of turbines increases with the velocity and number of rotor blades and with decreasing distance between the blades (Kaplan). Mortality can reach 100 % when fish pass through turbines that are mainly in high-pressure plants (e.g. with a Pelton turbine).

Displacement and disturbance

River engineering works may cause disturbance to certain species and disrupt their life cycles both inside and outside Natura 2000 sites, especially in the case of benthic fauna and flora which rely on a good water quality. This may affect the species ability to breed, feed, rest or disperse and migrate.

If the disturbance reaches significant levels it can lead to the exclusion of the species from that area and hence the loss of habitat use or it can result in poorer survival and/or breeding success. In the case of rare and endangered species even small or temporary disturbances can have serious repercussions for their long-term survival in the region. Such situations would be incompatible with the species protection provisions of the two Nature Directives.

Effects on terrestrial species and habitats

Hydropower may have effects not just on freshwater species and habitats but also on terrestrial species and habitats. Again this can occur at any time e.g. during the construction, decommissioning or renovation of hydropower. It can also be caused by associated infrastructures such as access roads, pipe routes, or powerlines designed to connect the hydropower facility to the electricity grid.

In addition to the loss, degradation or fragmentation of the habitats involved, these structures could cause the death or significant disturbance of terrestrial species. Birds for instance might collide with and be electrocuted by overhead electricity wires or their breeding sites could be severely disturbed by regular traffic on the access roads. Such effects may be especially significant when the hydropower plant and associated infrastructures are located along migration routes or along narrow valleys with cliffs used by raptors, or next to important bird wetlands.

2.4. Cumulative effects

As the EEA's State of the Environment report illustrated, most European rivers are now in a degraded state and the majority have reached a saturation point where they can no longer host any new developments or activities without causing a further significant deterioration of the river's status. Special consideration must therefore be given to assessing the potential cumulative effects of any new activities, including those for hydropower plants, on rivers in general and on Natura 2000 site(s) in particular.

The assessment of cumulative effects is especially important on near natural rivers, particularly small rivers, that are vulnerable to any changes in their hydromorphology. Even one or two small installations may bring about unacceptably high effects that are in conflict with the legal requirements of the WFD and the two Nature Directives.

The assessment of cumulative effects should consider all of the hydropower plants and other developments in the catchment area, irrespective of whether they are situated in or outside the Natura 2000 sites. It may be that one hydropower project, taken on its own, will not have a significant effect, but if its effect is added to those of other already existing activities or approved projects their combined effects can become significant.

Cumulative effects will often only occur over time. It is therefore important to consider all plans or projects during the assessment. This includes any plans and projects which have been approved in the past but which have not yet been implemented or completed, as well as any existing pressures and threats. In this context, information available in the WFD river basin management plans and Natura 2000 management plans may be useful for this.

Also, it is important to note that an already approved plan or project does not create a presumption in favour of any other plans or projects that may be proposed in the future. For example, if a hydropower development does not give rise to a significant effect and is therefore approved, the approval does not create a presumption in favour of further hydropower developments in the future. On the contrary, the approval of this project may mean that the river will have reached its carrying capacity and will not be able to tolerate any further developments, however small.

In addition, the assessment of cumulative and in combination effects is not restricted to the assessment of similar types of plans or projects in the same sector. Any other types of plans or projects that could, in combination with the plan or project under investigation, have a significant effect, should be taken into account during the assessment. Potential cumulative effects should be assessed using sound baseline data and not rely on qualitative criteria only. They should be assessed as an integral part of the overall assessment and not be treated as an ‘afterthought’ at the end of the assessment process.

Lastly, a cumulative assessment must also consider already existing installations on the river (the so called ‘pre-load’) (29). For instance, if a new project is planned with a new turbine, its effect must be assessed in light of the existing hydropower plant even if this was built decades ago. If the cumulative effects are significant, the new project will be refused.

Recommendations on small hydropower plants, Federal Environment Agency, Germany In Germany, around 80 % of the usable hydropower potential has already been exploited. The technological potential was also largely exhausted. This was reflected in the relatively low rates of support available for hydropower use in support programmes. The remaining exploitable potential therefore mainly concerns small, previously undeveloped, virtually undisturbed waters. Yet the possible harmful ecological effects on the few remaining small undisturbed watercourses in Germany are likely to be considerable. Macro-economic cost-benefit analysis has also shown that the economic costs can be considerable, compared with the benefit. The smaller the installation's capacity and the more natural the watercourse, the less favourable the cost-benefit analysis is. Economic evaluations show that, especially with small hydroelectric power plants with a capacity of up to 100 kW, in all three cases of new construction, modernisation and reactivation, the cost of producing energy is higher than the rates of payment under the Renewable Energy Act. Therefore in many cases, even in favourable circumstances, electricity can hardly be produced economically. Economic considerations show that a subsidy that covers the operating costs of small hydroelectric power plants — in particular plants with a capacity of under 100 kW — leads to high macro-economic costs for the avoidance of CO2 emissions. Against the background of negative ecological effects, further exploitation of the potential of small hydroelectric power plants is not a priority for climate protection. Considering prevailing legal provisions and the requirements of the EC Water Framework Directive, the following recommendations have been put forward: — On account of their higher efficiency, large hydroelectric power plants are generally to be given preference to small and micro-installations for secondary use on waters already developed and impounded. When developing hydropower capacity attention should be focused on their optimisation. — With virtually undisturbed waters, or those where re-naturalisation is planned, the use of hydropower should be renounced. — The construction and reactivation of small hydroelectric power plants is unproblematic at existing weirs that cannot be demolished, in particular when, at the same time, ecological improvements — for instance, restoring free passage — can be achieved. — With the reactivation of installations currently not in operation, and the renewal of water rights, concerns of water protection should be more strongly considered and conditions laid down (for example, functional fish ladders, structurally-guaranteed dynamic minimum water flow, exclusion of flash floods downstream dams). — In the case of new installations, impounding of a water body for diversion is to be avoided. Constructional methods should be chosen, which divert the water used in such a way that the free passage and character of the watercourse is maintained (e.g. lateral water intake with a diversion structure in the water body). Requirements are to be issued on minimum flow and on measures for the avoidance of damage to fish from turbines. Flash floods downstream of dams are to be prohibited. Abstract from: Hydroelectric Power Plants as a Source of Renewable Energy - legal and ecological aspects – Umweltbundesamt, November 2003 http://www.umweltbundesamt.de/sites/default/files/medien/publikation/long/2544.pdf

2.5. Distinguishing between significant and insignificant effects

Identifying the range of effects on the species and habitats that are likely to be affected by a hydropower development plan or project is the first step of any impact assessment. After that, it is necessary to determine whether the effect is significant or not in view of the Natura 2000 site's conservation objectives. Clearly, the assessment of significance needs to be done on a case-by-case basis, in function of the site-relevant species and habitats and of the precise characteristics of the project itself and on the basis of sound scientific expertise (see Chapter 5).

The loss of a few individuals may be insignificant for some species but may have serious consequences for others. Population size, distribution, range, reproductive strategy and life-span will all influence the significance of the effects, and this will vary from one Natura 2000 site to another, even if they are designated for the same species. The interconnectivity of effects should also be taken into account. For instance, land take on its own may not be significant for a particular species, but when combined with major disruptions to natural river flows, the impact may become significant.

The assessment of significance should be considered over an appropriate geographical scale. For migratory species that move over very long distances (such as Atlantic salmon Salmo salar), the effect at a specific site may have consequences for the species over a larger geographical area (river basin). Likewise, for resident species with large territories or changing habitat uses, it may be necessary to consider potential effects on a regional, rather than a local scale.

The conservation objectives of the Natura 2000 sites are also essential for helping to determine if there is a likely significant effect. This is confirmed by the European Court of Justice Waddenzee ruling (30) paragraph 49, ‘… where a plan or project not directly connected with or necessary to the management of a site is likely to undermine the site's conservation objectives, it must be considered likely to have a significant effect on that site. The assessment of that risk must be made in the light inter alia of the characteristics and specific environmental conditions of the site concerned by such a plan or project.’

The appropriate assessment must be based on the best available data. This may require dedicated field surveys or monitoring programmes some time in advance of the project. The investors have to be able to anticipate this in their planning and ensure the relevant data from biological and hydrological surveillance includes information on all important aspects (life cycle and seasonal variability). Such studies can sometimes take several years before they are able to capture sufficiently the life cycle of the species and habitat types concerned (see Chapter 5 for details).

Guidance on setting thresholds of significance in Germany In Germany, as elsewhere, because of a high level of subjectivity, it was difficult to assess the significance of effects on Natura 2000 target features, which is the core of the appropriate assessment. As a result, the competent authorities often did not have the reasonable scientific certainty they needed to back their decisions on whether or not to authorise a plan or project. It also left them open to legal challenges. To address this problem and ensure a more uniform and consistent approach when assessing the impact significance in practice, the German Federal Agency for Nature Protection (BfN) commissioned a research project to provide scientifically tested rules and conventions for all habitat types and species listed in the Birds and Habitats Directives that occur in Germany (31). The resulting guidance document was published in 2007. The starting premise for the guide is that any permanent loss of habitat types and habitats for species in a Natura 2000 site should be considered a significant impact. However, a certain level of loss could nevertheless be treated as insignificant for some habitat types and species under certain conditions. The guide provides scientifically agreed thresholds and criteria for determining significance, which are based on qualitative as well as functional aspects — not just quantitative criteria. Thus, for an impact to be considered insignificant all the following conditions must be met: — Specific features of the given habitat/ habitat for species or key habitats of the typical species must remain unaltered, — Orientation values of ‘quantitative — absolute area loss’ are not exceeded, — Supplementary values of ‘quantitative — relative area loss’ of 1 % are not exceeded, — Cumulative effects with other projects do not exceed the above threshold values, and — Cumulative effects with other factors do not occur. For the 2nd indent, 7 size classes for habitats and 8 for species were developed, providing ranges in which the threshold values for every habitat type/species lie; 3 threshold degrees for each class were set. In practice this means that for 21 of the 91 habitat types occurring in Germany, no loss is acceptable, while for the remaining habitats some loss may be considered insignificant if it is scaled according to size classes and degrees. As for the 53 species from Annex II, no tentative threshold values exist for 16 of them, nor for 20 of the 98 Birds Directive species. In other words, no impact is likely to be acceptable. All these conclusions/ figures/ thresholds are intended to act as guidance only. This means that a case-by-case approach within each AA is still required. Since its publication, the guidance document has been successfully tested in the German courts and is now applied across the country. http://www.bfn.de/0306_ffhvp.html

Scales used by experts licensed for AA in the Czech Republic A practical issue is the scale used for evaluation of the significance of effects during the AA. There is no prescription, but based on long practical experience, the following scale has been recommended to be used by AA experts licensed by law in the Czech Republic (32): Impact significance is to be assessed against each target feature of the given site. If the impact on even a single target feature is marked with ‘-2’ it automatically means the site integrity is adversely affected and such a project must not be granted a permit within the Article 6.3 procedure. Value Term Description Examples -2 Significant adverse impact Significant adverse impact. Excludes plan/project implementation Significant disturbance or destructive impact on habitat or species population or its substantial part; significant disturbance of ecological demands of the habitat or species; significant impact on the habitat or natural development of a species. Under certain conditions, the impact can be lowered by mitigation measures. Disruption of migration routes to spawning places of anadromous species Destruction of habitat by inundation because of new dam. Hydrological changes because of derivation significantly influencing population. -1 Moderately adverse impact Limited/moderate/non-significant adverse impact. Plan/project implementation is not excluded. Moderate troublesome impact to habitat or species population; moderate disruption of ecological demands of habitat or species; marginal impact on habitat or natural development of a species. Its elimination through mitigation measures is possible but application of mitigation measures cannot be enforced, unless national legislation requires differently. Modernisation — using technology less damaging to fish, building fish passes on existing barriers. Impact on margin parts of population. Influence on habitat common in surrounding area. 0 Zero impact The plan/project has no demonstrable impact. Outside area of occurrence. +1 Moderately positive impact Moderate favourable impact on habitat or species population; moderate improvement of ecological demands of the habitat or a species; moderate favourable impact on the habitat or on the natural development of a species. Reconstruction of peaking hydropower to run-of-river hydropower without weir or dam. +2 Significantly positive impact Significant favourable impact on habitat or species population; significant improvement of ecological demands of habitat or a species, significant favourable impact on the habitat or natural development of a species. Demolition of hydropower plant.

3. GOOD PRACTICE EXAMPLES IN MITIGATING EFFECTS AND APPLYING ECOLOGICAL RESTORATION MEASURES TO HYDROPOWER

3.1. Aiming for the best practicable ecological condition of rivers in the context of hydropower

As stated in the previous chapter, few of Europe's large rivers remain in a relatively natural state, having been physically altered over the years for a wide variety of reasons, including for hydropower generation. The modernisation of existing hydropower plants should therefore be prioritised over the construction of new ones, to improve their ecological footprint.

A range of measures can be taken to mitigate hydropower plants' negative effects on river ecosystems and surrounding habitats and species, and to help improve their conservation status. This is a major part of achieving the objectives of the WFD and the two Nature Directives.

Opportunities should also be sought to decommission inefficient or obsolete installations and remove them entirely from the river system. It should be noted that the default action to be taken under the WFD if a body of water has been degraded by an existing installation is to restore the river to good ecological status. Significant physical modifications can only be made if they also serve a legitimate purpose that cannot be achieved by other better environmental options (see WFD Article 4.3 for more details on the requirements for HMWB/AWB designation and respective guidance).

The possibilities for technically upgrading hydropower installations and introducing ecological restoration measures must be evaluated on a case-by-case basis taking account of their cumulative effects. The type of ecological measures that can be implemented will depend very much on local circumstances, such as the condition of the river, other ongoing pressures along the river and the facilities already in place, as well as the type of species and habitats present.

3.2 Dealing with existing hydropower plants having a negative effect on a Natura 2000 site

Existing hydropower facilities located in or near, or having negative effects on, Natura 2000 sites must at all times conform to the provisions of Article 6.2 of the Habitats Directive. More specifically, Article 6.2 imposes an obligation to ensure that the site does not deteriorate as compared to the state it was in when it was first designated under Natura 2000. This means that Member States should take all appropriate action that they may be reasonably expected to take to ensure that there is no deterioration of habitats and/or significant disturbance of species.

This means that Member States are legally obliged to:

— investigate the threats and pressures brought about by the presence of hydropower facilities on the species and habitat types for which the site was designated, and

— take the necessary remedial measures if these existing pressures are causing a decline or degradation of the targeted species and habitats present.

The European Court of Justice confirmed this requirement in the Owenduff Case (C-117/00) (33), where it ruled that Article 6.2 was infringed because measures had not been adopted to prevent the deterioration of habitats of the species for which an SPA was designated. Several CJEU Cases (34) have further clarified the type of legal protection regime that needs to be put in place for the purposes of Articles 4.1 and 4.2 of the Birds Directive and Article 6.2 of the Habitats Directive. They stress in particular the need for the legal regime to be specific, coherent and complete, capable of ensuring the sustainable management and the effective protection of the sites concerned (C-293/07).

The Court also identified infringements in cases where the regime in place was ‘too general and did not concern specifically the SPA or the species that live in it’ (C-166/04), measures taken were ‘too partial, isolated measures, only some of which promote conservation of the bird populations concerned, and so did not constitute a coherent whole’ (C-418/04), or SPAs were submitted to ‘heterogeneous legal regimes which did not confer on the SPAs a sufficient protection’ (C-293/07). It also considered that purely administrative or voluntary measures were not sufficient for the purposes of Article 6.2 (C-96/98).

It should be noted that, for Natura 2000 sites, Article 6.1 of the Habitats Directive also requires Member States to put in place conservation measures that correspond to the ecological requirements of the habitat types in Annex I and the species in Annex II present on the sites. This means that hydropower installations must also comply with any more ambitious conservation objectives going beyond non-deterioration set under Article 6.2. They should also be integrated into the programme of measures within the RBMP.

Although not obligatory, the Habitats Directive encourages nature authorities to develop Natura 2000 management plans in close cooperation with local stakeholders and land owners concerned to identify the threats and pressures on each Natura 2000 site and to jointly determine the necessary conservation measures that need to be implemented.

Hydropower operators' good communication with authorities and/or bodies in charge of management planning is essential and can lead to the inclusion of measures which can benefit both the conservation objectives and the hydropower operation.

3.3. Introducing ecological mitigation and restoration measures

A wide range of measures can be introduced for both existing and new hydropower plants to reduce their ecological effects (35). These can either mitigate potential effects before they happen or restore damage that has already been done. Such measures can for instance involve:

— the restoration of river continuity and fish migration, for example by removing old or obsolete structures or building fish passes;

— reducing fish mortality for example by installing screens at inlets and specially adapted turbines;

— the restoration of an adequate variable ecological flow (including mitigation of low flows, dynamic flows, fish flows and rapidly changing flows) and sediment dynamics that improves the structure and functioning of freshwater habitats.

A wide range of measures can also be introduced to actively restore, reconnect or recreate valuable natural riverine habitats and habitats for rare and endangered species in order to make a net positive contribution to improving a river's ecological condition in line with the objectives of the WFD and the Nature Directives. The type of measure chosen will very much depend on the ecological condition of the body of water in question, the type of hydropower facility present, other pressures and threats, and the overall cost and potential for improving the hydropower facility's efficiency and generating capacity.

Once the measures have been implemented, monitoring systems should be put in place to ensure that they have the desired effect and, where this is not the case, remedial measures should be taken to address any failings.

Distinguishing between mitigation, compensation and ecological restoration Mitigation measures are directly linked to the likely effects and form part of the project, or are introduced by the authority as a condition for authorising a plan or project. Based on the precautionary principle, they are designed to remove likely negative effects, pre-empt them or reduce them to a level where they will no longer adversely affect the integrity of the site. At the date of the decision authorising the project's implementation, the mitigation measures under the project must ensure that there is no reasonable scientific doubt as to the absence of adverse effects on the integrity of the site in question (36). Compensatory measures are intended to compensate for any damage that may be caused by the project. They can only be considered under Article 6.4 if the plan or project has been accepted as being necessary for imperative reasons of overriding public interest and where no alternatives exist (see Section 5). Ecological restoration measures are not necessarily linked to an environmental impact assessment and are designed to make a net positive contribution to improving the ecological condition of an already degraded river in line with the objectives of the WFD and the Nature Directives.

Table

Overview of the most widespread measures to mitigate water storage

Hydromorphological alterations Main ecological impact Mitigation of … Mitigation measure options River continuity for upstream fish migration reduced or interrupted Fish: populations of migratory and other riverine fish absent or abundance reduced Upstream continuity for fish — Ramp — Fish pass — By-pass channel River continuity for downstream fish migration reduced or interrupted Fish: Populations of migratory and other riverine fish absent or abundance reduced Downstream continuity for fish — Less damaging turbines for fish — Fish screens — By-pass channel — Fish pass Artificially extreme low flows or extended low flows Reduced abundance of plant & animal species. Alterations to composition of plant & animal species Low flow — Provide additional flow — River morphology changes Loss of or reduction in flows so that they are not sufficient to trigger and sustain fish migrations Migratory fish absent or abundance reduced Fish flow Provide fish flow Loss, reduction or absence of variable flows sufficient for flushing Alteration/reduced abundance of fish and invertebrate species Variable flow — Passive flow variability — Active flow variability Rapidly changing flows (including hydro peaking) Reduction in abundance of animal and plant species due to stranding and wash out Rapidly changing flows — Balancing reservoir(s) (internal) — Relocate tailrace — Reduce rate — Modify river morphology — Balancing reservoirs (external) Alteration of general physico-chemical conditions both up- and downstream (e.g. temperature, super saturation etc.) Altered composition or growth of macro invertebrate communities and fish or fish mortality Physico-chemical alteration — Flexible intake — Multiple intakes — Management of reservoir level River continuity for sediment disrupted or reduced leading to changes in substrate composition Reduction in fish and invertebrate abundance and alterations in species composition Sediment alterations — Mechanical break-up of bed armouring — Removal of sediment — Re-introduce sediment (intake structures) — Re-introduce sediment (reservoirs) — Restore lateral erosion processes — Introduce mobilising flows Artificially extreme changes in lake level, reductions in quality and extent of shallow water and shore zone habitat Reduction in abundance of plant and animal species. Alterations to species composition. Lake level alteration — Reduce abstraction — Increase inflows — Create embayment(s) — Manage shore/shallow habitats — Connectivity to tributaries — Artificial floating islands Dewatered shore line and reduced river flow — ponded river Alterations to plant and animal species composition (e.g. favouring disturbance-intolerant species/still water species) Ponded rivers (impoundments) — Bypass channel — Reduce storage level — In-channel habitat improvements — Lateral reconnection Source: Adapted from Table 3 in ECOSTAT working group report on a common understanding of using mitigation measures for reaching good ecological potential for heavily modified water bodies, part 2: Impacted by water storage (37)

In hydropower facilities, particular attention is often paid to the potential range of techniques that can be used to restore or facilitate the upstream and downstream movement of fish and other aquatic fauna within river systems. This is an evolving science in which a wide variety of techniques and innovative solutions are regularly trialled out and re-evaluated. It is not however a cure-all.

There are too many examples of fish migration aides that have been put in place as a supposed mitigation measure but which have turned out to be either ineffectual or even detrimental to the fish populations they are supposed to help. This may be because the devices were ill conceived and not fit for purpose, or that they did not take account of the cumulative effects of other already existing obstacles along the river stretch. It may also be because the conditions for device maintenance or management were not respected or that there was no monitoring system to check whether or not the device was actually doing the job it was designed to do.

This is why it is important to ensure not only that the fish pass or adapted turbine is built according to state-of-the-art developments in this sector and current best practices, but also that a sound monitoring system is in place to provide feedback on its effectiveness. In general, monitoring should show that the device makes it possible for all riverine species to enter the pass and that the vast majority (e.g. 85 %) can also exit alive.

In the case of a fish pass, where possible, nature-like passes should be preferred, because the general rule is that the more nature-like a pass is, the better it works. The choice of the most suitable type of fish pass (e.g. vertical slot, bypass, rock-ramp, lift) strongly depends on local conditions (height of barrier, character of the stream, usability of neighbouring sites, etc.) and requires careful study on a case-by-case basis.

Likewise, the impact of turbines on fish is usually significant but can sometimes be reduced by making certain adaptations to the turbine geometry and their mode of operation. However, such adapted turbines have so far not proven to be a guarantee that no fish will be killed or that the turbine is not still a barrier for migration. Once again, effectiveness must be assessed and monitored on a case-by-case basis.

The planning of fish passes or adapted turbines should also be dependent on evaluation of the cumulative effect of the barriers in the wider river system. Building one fish pass along a river riddled with barriers may prove to be both expensive and inefficient. It is therefore important to look more strategically at all the barriers on the river stretch in question in order to decide on the best course of remedial action.

Finally, it is essential to have a regular maintenance plan for all new constructions. Many fish passes or turbines will no longer be effective over the medium- to long-term if they are not maintained regularly enough.

When is a fish ladder deemed an adequate mitigation measure? Findings of the ECJ Ruling 142/16 on the Moorburg coal-fired powerplant The Moorburg coal-fired power plant is situated within the port of Hamburg, on the south bank of the southern section of the Elbe river. This is a migratory route for certain fish species listed in Annex II to the Habitats Directive and as such plays an important role in a number of Natura 2000 areas situated upstream of the Geesthacht weir (Germany) whose conservation objectives cover these species. These areas are situated up to a distance of approximately 600 km from the plant. The Geesthacht weir is situated on the Elbe corridor, in between the Moorburg power plant and the Natura 2000 areas. Before authorisation for construction of the Moorburg plant was granted on 30 September 2008, an environmental impact assessment was conducted under German water legislation. This assessment concluded that the authorisation was compatible with the conservation objectives of the Natura 2000 areas because the operator had agreed to install a second fish ladder approximately 30 km from the plant, by the Geesthacht weir. There was therefore an intention to compensate for fish killed during the operation of the cooling mechanism, which draws large quantities of water from the river in order to cool the Moorburg plant (‘the fish ladder’). In addition, the impact assessment prescribed multi-phase monitoring in order to verify the effectiveness of the fish pass. The Commission considered that the authority concerned had wrongly classified the fish ladder as a mitigating measure. Findings of the Court: ‘In order to ensure that the construction of the Moorburg plant would not adversely affect the integrity of the Natura 2000 areas concerned, it was the responsibility of the German authorities to take account of the protective measures included in that construction project. In that regard, it is settled case-law that the application of the precautionary principle in the context of the implementation of Article 6(3) of the Habitats Directive requires the competent national authority to take into account, inter alia, the protective measures forming part of that project aimed at avoiding or reducing any direct adverse effects on the site, in order to ensure that it does not adversely affect the integrity of the protected site (… C-521/12,..C-387/15 and C-388/15 …). In the present case, it is clear from the file submitted to the Court that … the fish ladder was intended to increase migratory fish stocks by allowing those species to reach their breeding areas, along the middle and upper reaches of the Elbe, more quickly. Increasing stocks in this manner was expected to compensate for the fish deaths near the Moorburg plant so that the conservation objectives of the Natura 2000 areas upstream of the plant would not be significantly affected. However, it is clear that the impact assessment itself did not contain definitive data regarding the effectiveness of the fish ladder, and merely stated that its effectiveness could only be confirmed following several years of monitoring . It must therefore be held that, at the time the authorisation was granted, the fish ladder, even though it was intended to reduce direct significant effects on the Natura 2000 areas situated upstream of the Moorburg plant, could not guarantee beyond all reasonable doubt , together with the other measures referred to in paragraph 35 of the present judgment, that that plant would not adversely affect the integrity of the site, within the meaning of Article 6(3) of the Habitats Directive. As regards the estimates on which the impact assessment was based, it should be pointed out that the data relating to the years 2011 to 2014 was collected by the Federal Republic of Germany after the granting of the authorisation of 30 September 2008. In that regard, it should be noted that it is at the date of adoption of the decision authorising implementation of the project that there must be no reasonable scientific doubt remaining as to the absence of adverse effects on the integrity of the site in question (judgment of 26 October 2006, Commission v Portugal, C-239/04, EU:C:2006:665, paragraph 24 and the case-law cited).’ The Commission also stated that the city of Hamburg granted the authorisation without taking into account, in the impact assessment for the Moorburg plant, the potential cumulative effects with those stemming from the Geesthacht pumped-storage power plant, which dates back to 1958 and does not have any specific fish protection mechanisms. According to the Commission, it is irrelevant that the Geesthacht pumped-storage power plant was constructed before the transposition period of the Habitats Directive expired, for the provisions of Article 6(3) of that directive are not limited to plans and projects approved or completed after this deadline. Findings of the Court Under Article 6(3) of the Habitats Directive, when assessing cumulative effects national authorities are required to take into account all projects which, in combination with the project for which an authorisation is sought, are likely to have a significant effect on a protected site in the light of the objectives pursued by that directive, even where those projects precede the date of transposition of that directive. Projects which, like the Geesthacht pumped-storage power plant, are likely to cause, as a result of their combination with the project to which the impact assessment relates, deterioration or disturbance likely to affect the migratory fish present in the river and consequently result in the deterioration of the site concerned in the light of the objectives pursued by the Habitats Directive, are not to be excluded from the impact assessment required under Article 6(3) of the Habitats Directive. http://curia.europa.eu/juris/liste.jsf?num=C-142/16

ICPDR technical paper: Measures for ensuring fish migration at transversal structures This document aims to inform the Danubian countries about existing technical solutions for restoring river continuity for fish migration. All guidelines currently available in the upper Danube catchment were considered. Their comparison showed that their overall structure and content is basically consistent and that deviations are only marginal in most cases. Since most guiding documents are only available in the German language, this document aims to provide the most important facts in English. https://www.icpdr.org/main/practical-advice-building-fish-migration-aids

3.4. Good practice examples of mitigation and/or ecological restoration

The following good practice examples illustrate how various types of mitigation and/or ecological restoration measures have been introduced to hydropower installations under a range of different circumstances.

The management of freshwater Natura 2000 sites in England, with particular reference to hydropower and river Special Areas of Conservation (SAC) Natural England is the statutory agency responsible for providing advice on protected sites in England, including Natura 2000 sites. Natural England's approach to decision-making on protected freshwater sites is habitat-led but species-aware. Objectives are based on natural ecosystem function, with freshwater species conserved as characteristic components of the naturally functioning ecosystem wherever possible. A holistic view of protected freshwater habitat features is taken - river habitat (for instance, Habitats Directive Annex II feature H3260: watercourses with Ranunculion and Callitricho-Batrachion vegetation) comprises the whole river corridor, encompassing all of the small-scale biotopes within it. The key components of natural habitat function (flow regime, natural morphology and sediment regime, water chemistry and an absence of direct biological stresses such as non-native species) are an intrinsic part of the objectives agreed for the habitat feature. Target levels of naturalness for these components are set out in the UK guidance for protected sites. Effects on these components of natural function are addressed through a range of protection and restoration measures. The approach has much in common with the principles of ecological status objectives in the Water Framework Directive, but differs in terms of the level of precaution applied to decision making, the level of ambition for protecting natural function and addressing historical damage, and the level of consideration of effects on natural ecosystem functioning. The approach is also in tune with climate change adaptation principles for freshwater ecosystems, which require a focus on the restoration of natural function. The English surface water network (including freshwater SACs) contains many thousands of in-channel structures, considerably affecting natural river and lake ecosystem function. Some are large structures with major ecological effects, whilst others are small and numerous, creating considerable cumulative effects. Many are associated with existing abstraction licences, which may or may not be used. Some were built for hydropower whilst many could be retrofitted. Restoration plans have been drawn up to remove physical modifications to river SACs wherever possible, in order to restore natural habitat function. This is an ambitious and long-term programme, initiated ten years ago (Wheeldon et al. 2015). There are also programmes to alleviate abstraction stress and pollution, and tackle non-native species. A joint regulators' statement on hydropower has been drawn up with the water regulator in England (the Environment Agency) to set out decision-making processes relating to protected sites. This recognises the need for environmental precaution, proper consideration of cumulative effects, and decisions to be taken in the light of the specific conservation objectives of the site and associated restoration plans. Where a Natura 2000 river restoration plan considers an in-channel structure to be immovable, or where it will take a long time period to remove it, then there may be scope for hydropower generation (permanent or temporary). However, the structure should be modified to minimise its impact on natural habitat function, and target values for the natural flow regime should be met (including limits on the cumulative extent of depleted reaches caused by abstraction). Given the objectives of protected freshwater sites in England, and the precaution and ambition associated with restoring natural habitat function, the freshwater Natura 2000 network is not a natural focus for hydropower development. Whilst there may be local circumstances where hydropower would be compatible with Natura 2000 objectives, greater opportunities exist outside of the protected site series in the wider surface water network. If hydropower developments are particularly important on the Natura 2000 network but conflict with conservation objectives, then a case for overriding public interest can be made. However, alternative solutions involving other forms of renewable energy with less nature conservation impact are likely to be more cost-effective. http://publications.naturalengland.org.uk/publication/5478339747774464?category=5605910663659520

Release of controlled floods from hydropower plants in the Ebro River (Spain) In Spain, controlled floods were legally established in 2008. Since that time, a number of flooding events have been carried out in Mediterranean rivers. For example, controlled flood rates have been calculated and released in the Lower Ebro River (Northeast Spain) since 2002, from the dam complex that regulates the river (Mequinenza-Ribarroja-Flix Dams). The main goal of these floods has been to control macrophyte populations and improve sedimentary activity in the channel (Tena et al., 2013). The dam complex was constructed between 1948 and 1969 and has a total storage capacity of ca. 1 700 hm3. The reservoir system was created with several goals in mind: hydropower generation, water supply (including supply to a downstream nuclear power plant), and flood control. Flood releases from the dams were managed by the hydroelectric operator (Endesa Generación S.A.) and controlled by the Ebr