opw arterial drainage

Report Control Sheet FORM 214 Rev 002

Business Management System

Natura Impact Statement Page i

Arterial Drainage Maintenance Works:

Kilcoo Arterial Drainage Scheme 2020 - 2024

Natura Impact Statement

November 2019

1 Galway Business Park, Dangan, Galway H91A3EF 173 Ivy Exchange, Granby Place, Parnell Square West, Dublin 1

Kilcoo Arterial Drainage Scheme - NIS

Natura Impact Statement Page ii

Client OPW

Project No. 2514

Project Title Kilcoo OPW Arterial Drainage Maintenance

Report Title Tender Submission

Rev. Status Authors Reviewed By Approved By Issue Date

- Draft A. Michaelides / S.

Gavin S. Gavin D. Bourke 06/11/2019

0 Draft A. Michaelides / S.


1 Final G. Kilbane/ S.



Natura Impact Statement Page i

Executive Summary

Ryan Hanley has been commissioned by the Office of Public Works (OPW) to provide

environmental consultancy services in relation to statutory arterial drainage maintenance activities

for 2019.

Following the methodology outlined in Ryan Hanley (2014a), a screening assessment was conducted

to assess the likely significant effects on European sites of the proposed drainage maintenance

activities in the Kilcoo Arterial Drainage Scheme in 2014 in accordance with Article 6(3) of the

Habitats Directive (Council Directive 92/43/EEC on the conservation of natural habitats and of wild

fauna and flora). Three “source > pathway > receptor” chains were examined to assess the likely

impact of drainage maintenance activities on European sites; surface water, land and air, and

groundwater pathways. The results of this screening exercise identified that significant adverse

impacts could not be excluded on the following European sites:

• Lough Melvin SAC (000428)

As a result, it was necessary to conduct a Stage 2 Appropriate Assessment to further examine the

potential direct and indirect impacts of the proposed works on the integrity and interest features

of the above European sites, alone and in-combination with other plans and projects, taking into

account the site's structure, function and conservation objectives.

Further examination of the potential sources of impact on the European sites above, looking at

surface water and land and air pathways and groundwater pathways, was conducted. Where

potentially significant adverse impacts were identified, a range of mitigation and avoidance

measures have been stipulated to help offset them.

As a result of this Appropriate Assessment it has been concluded, that given the avoidance and

mitigation measures suggested, the proposed drainage maintenance operations in the Kilcoo

Arterial Drainage Scheme will not have a significant adverse impact on the above European sites.

Natura Impact Statement Page 2

Contents

Executive Summary ........................................................................................................................................ i

1. Introduction ...................................................................................................................................... 1

1.1 Background ...................................................................................................................................................... 1

1.2 Legislative Context ......................................................................................................................................... 1

1.3 Appropriate Assessment Process ................................................................................................................. 1

1.3.1 Stage 1 - Screening for AA ..................................................................................................................... 2

1.3.2 Stage 2 - AA ............................................................................................................................................... 2

1.3.3 Stage 3 - Alternative Solutions ............................................................................................................... 2

1.3.4 Stage 4 - IROPI .......................................................................................................................................... 2

1.4 Methodology ................................................................................................................................................... 2

1.4.1 Ecological Walkover Surveys .................................................................................................................. 3

1.4.2 Screening ..................................................................................................................................................... 4

1.4.3 Consultation ................................................................................................................................................. 5

2. Arterial Drainage Maintenance ........................................................................................................ 6

2.1 Background ...................................................................................................................................................... 6

2.2 Drainage Maintenance Activities ................................................................................................................. 6

2.2.1 Channel Maintenance Activities ............................................................................................................... 7

2.2.2 Structural Maintenance Activities ............................................................................................................ 9

2.2.3 Maintenance works considered outside of the Scheme Design Standards and outside

of normal Arterial Drainage Maintenance Works ............................................................................................... 9

2.2.4 Plant and Machinery ................................................................................................................................. 9

2.2.5 Maintenance Access Corridors (MAC) and Working Zone ................................................................ 9

2.2.6 Site Compounds (Welfare Facilities), Access Routes and Haul Roads .......................................... 10

2.2.7 Waste Output/Disposal ......................................................................................................................... 10

2.2.8 Working Hours .......................................................................................................................................... 10

2.2.9 Environmental Training ............................................................................................................................ 11

2.2.10 Environmental Audits ................................................................................................................................ 11

2.2.11 Environmental Management Procedures (EPs) .................................................................................... 12

2.3 The Kilcoo Arterial Drainage Scheme ...................................................................................................... 12

2.4 Drainage Maintenance Works Proposed for the Kilcoo Arterial Drainage Scheme ...................... 13

3. Screening Assessment Results ....................................................................................................... 14

3.1 Introduction ..................................................................................................................................................... 14

3.1.1 Surface Water Pathways ....................................................................................................................... 15

3.1.2 Land & Air Pathways .............................................................................................................................. 15

3.1.3 Groundwater Pathways .......................................................................................................................... 16

3.2 Screening Assessment Conclusions ............................................................................................................. 17

4. European Sites within the Zone of Influence of Drainage Maintenance Activities ......................... 18



4.1 Introduction ..................................................................................................................................................... 18

4.2 Lough Melvin SAC (IRE 000428; UK0030047) ...................................................................................... 18

4.2.1 Qualifying Interests ROI and NI ............................................................................................................ 19

4.2.2 Conservation Objective .......................................................................................................................... 22

4.2.3 Site Vulnerabilities ................................................................................................................................... 22

4.3 Description of the receiving environment - Ecological Walkover Survey Results ............................ 23

4.3.1 Introduction ................................................................................................................................................ 23

4.3.2 Results ......................................................................................................................................................... 23

4.3.3 Consultation Responses ........................................................................................................................... 28

5. Appropriate Assessment ................................................................................................................ 28

5.1 Introduction ..................................................................................................................................................... 28

5.2 Identification of Potential Sources of Impact .......................................................................................... 28

5.2.1 Potential Sources of Impact via Surface Water Pathways ............................................................. 29

5.2.2 Potential Sources of Impact via Land and Air Pathways ................................................................. 30

5.2.3 Potential Sources of Impact via Groundwater Pathways ................................................................ 30

5.3 Impact Assessment ........................................................................................................................................ 31

5.3.1 Do nothing impact .................................................................................................................................... 32

5.3.2 In-Combination Effects............................................................................................................................. 32

6. Avoidance and Mitigation Measures ............................................................................................. 45

6.1 Introduction ..................................................................................................................................................... 45

6.2 Mitigation for Other Ecological Receptors .............................................................................................. 46

6.3 Mitigation for Bridge/Structure Works .................................................................................................... 47

7. Conclusions .................................................................................................................................... 48

Appendix A.............................................................................................................................

Maps of Channels within the Kilcoo 2020 – 2024 Programme................................................. ii

Kilcoo 2020 – 2024 Maintenance Programme............................................................................ iv



List of Figures

Figure 1-1 The Appropriate Assessment Process (from: Appropriate Assessment of Plans and Projects in Ireland - Guidance

for Planning Authorities, DEHLG, 2009) ...................................................................................................................................................... 2

Figure 1-2 Screening Assessment Process: Source Pathway Receptor Chain ................................................................................. 4

Figure 2-1 Medium to High Gradient Channels in the Kilcoo Arterial Drainage scheme ............................................................ 8

Figure 2-2: Map of the Extent of the Kilcoo Drainage Maintenance Scheme ............................................................................... 13

Figure 3-1 Channels with potential impacts via surface water pathways identified in AA Screening 2014 ......................... 15

Figure 3-2: Channels with potential impacts via land and air and b) groundwater pathways identified in AA Screening

2014 16

Figure 3-3: Channels with potential impacts via groundwater pathways identified in AA Screening 2014.................... 17

Figure 3-4 Map of all channels and structures where significant likely effects may arise as identified in AA Screening

18

Figure 4-1 Sample Habitat Map .......................................................................................................................................................... 26

List of Tables

Table 2-1 OPW Drainage Maintenance Subcategories ................................................................................................................... 6

Table 2-2 OPW Drainage Maintenance Types .................................................................................................................................. 6

Table 3-1 Screening Assessment Conclusions .................................................................................................................................... 17

Table 4-1 Qualifying Interests of Lough Melvin SAC (000428) in Ireland ................................................................................ 19

Table 4-2 Qualifying Interests of Lough Melvin SAC (UK0030047) in Northern Ireland....................................................... 20

Table 4-3 Habitats found along the County River .......................................................................................................................... 23

Table 4-5 Annex I Habitat within Kilcoo Arterial Drainage Scheme ........................................................................................... 24

Table 5-1 Potential Sources of Impact via Surface Water Pathways.......................................................................................... 30

Table 5-2 Potential Sources of Impact via Land and Air Pathways ............................................................................................. 30

Table 5-3 Potential Sources of Impact via Groundwater Pathways ............................................................................................ 31

Table 5-4 Impact Prediction ................................................................................................................................................................. 34

Table 6-1: Specific Mitigation Measures ............................................................................................................................................ 45

Table 6-2 Specific Mitigation Measures for other Ecological Receptors .................................................................................... 47



1. Introduction

1.1 Background

Ryan Hanley has been commissioned by the Office of Public Works (OPW) to provide environmental consultancy

services in relation to statutory arterial drainage maintenance activities that will take place over the five-year

period 2020 – 2024.

This Natura Impact Statement (NIS) provides the results of the Appropriate Assessment conducted for the Kilcoo

Arterial Drainage Scheme in accordance with Article 6(3) of the Habitats Directive (Council Directive 92/43/EEC

on the conservation of natural habitats and of wild fauna and flora).

A screening assessment was undertaken at this location for the purposes of Appropriate Assessment by JBA in

2014 (JBA 2014). This screening report defined the zone of influence of the works, screened European sites

within this zone of influence for potential to be significantly impacted by the proposed works, and identified the

potential for the proposed works to have significant impact. In accordance with Article 6(3) of the Habitats

Directive (Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora). Due

to the identification of potentially significant effects in relation to the proposed works at this location, this NIS

has been prepared to further assess the impacts on the integrity of the relevant European and devise appropriate

avoidance and mitigation measures where necessary. As part of this NIS, the 2014 AA Screening is reviewed

and updated within this NIS report as necessary.

1.2 Legislative Context

The Habitats Directive (Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna

and flora) aims to maintain or restore the favourable conservation status of habitats and species of community

interest across Europe. The requirements of this Directive are transposed into Irish law through the European

Communities (Birds and Natural Habitats) Regulations) 2011 (S.I. No. 477 of 2011).

Under the Directive a network of sites of nature conservation importance have been identified by each Member

State as containing specified habitats or species requiring to be maintained or returned to favourable

conservation status. In Ireland the network consists of Special Areas of Conservation (SACs) and Special Protection

Areas (SPAs), and also candidate sites, which form the Natura 2000 network.

Article 6(3) of the Habitats Directive requires that, in relation to European designated sites (i.e. SACs and SPAs

that form the Natura 2000 network), "any plan or project not directly connected with or necessary to the

management of the site but likely to have a significant effect thereon, either individually or in combination with

other plans or projects, shall be subject to appropriate assessment of its implications for the site in view of the

site's conservation objectives".

A competent authority (e.g. the OPW or Local Authority) can only agree to a plan or project after having

determined that it will not adversely affect the integrity of the site concerned.

Under article 6(4) of the Directive, if adverse impacts are likely, and in the absence of alternative options, a

plan or project must nevertheless proceed for imperative reasons of overriding public interest (IROPI), including

social or economic reasons, a Member State is required to take all compensatory measures necessary to ensure

the overall integrity of the European site. The European Commission have to be informed of any compensatory

measures adopted, unless a priority habitat type or species is present and in which case an opinion from the

European Commission is required beforehand (unless for human health or public safety reasons, or of benefit to

the environment).

1.3 Appropriate Assessment Process

Guidance on the Appropriate Assessment (AA) process was produced by the European Commission in 2002,

which was subsequently developed into guidance specifically for Ireland by the Department of Environment,



Heritage and Local Government (DEHLG) (2009). These guidance documents identify a staged approach to

conducting an AA, as shown Figure 1-1.

Figure 1-1 The Appropriate Assessment Process (from: Appropriate Assessment of Plans and Projects in Ireland - Guidance for Planning Authorities, DEHLG, 2009)

1.3.1 Stage 1 - Screening for AA

The initial, screening stage of the Appropriate Assessment is to determine:

a. whether the proposed plan or project is directly connected with or necessary for the

management of the European designated site for nature conservation

b. if it is likely to have a significant adverse effect on the European designated site, either

individually or in combination with other plans or projects

For those sites where potential adverse impacts are identified, either alone or in combination with other plans or

projects, further assessment is necessary to determine if the proposals will have an adverse impact on the integrity

of a European designated site, in view of the site’s conservation objectives (i.e. the process proceeds to Stage 2).

1.3.2 Stage 2 - AA

This stage requires a more in-depth evaluation of the plan or project, and the potential direct and indirect impacts

of them on the integrity and interest features of the European designated site(s), alone and in-combination with

other plans and projects, taking into account the site's structure, function and conservation objectives. Where

required, mitigation or avoidance measures will be suggested.

The competent authority can only agree to the plan or project after having ascertained that it will not adversely

affect the integrity of the site(s) concerned. If this cannot be determined, and where mitigation cannot be

achieved, then alternative solutions will need to be considered (i.e. the process proceeds to Stage 3).

1.3.3 Stage 3 - Alternative Solutions

Where adverse impacts on the integrity of European sites are identified, and mitigation cannot be satisfactorily

implemented, alternative ways of achieving the objectives of the plan or project that avoid adverse impacts

need to be considered. If none can be found, the process proceeds to Stage 4.

1.3.4 Stage 4 - IROPI

Where adverse impacts of a plan or project on the integrity of European sites are identified and no alternative

solutions exist, the plan will only be allowed to progress if imperative reasons of overriding public interest (IROPI)

can be demonstrated. In this case compensatory measures will be required.

The process only proceeds through each of the four stages for certain plans or projects. For example, for a plan

or project, not connected with management of a site, but where no likely significant impacts are identified, the

process stops at stage 1. Throughout the process, the precautionary principle must be applied, so that any

uncertainties do not result in adverse impacts on a site.

1.4 Methodology

This NIS has been prepared with regard to the following documents:

▪ Department of Environment, Heritage and Local Government (2009) Appropriate Assessment of

Plans and Projects in Ireland - Guidance for Planning Authorities

Stage 1

Screening for AA

Stage 2

AA

Stage 4

IROPI

Stage 3

Alternative Solutions



▪ Ryan Hanley (2014a) Office of Public Works Arterial Drainage Maintenance Environmental Services

2013. Stage 1: Appropriate Assessment Screening Methodology for the Maintenance of Arterial

Drainage Schemes. Methodology. Unpublished Report.

▪ Ryan Hanley (2014c) Office of Public Works Arterial Drainage Maintenance Service 2014-2018.

Source > Pathway > Receptor Chains for Appropriate Assessment. Unpublished Report.

▪ National Parks and Wildlife Service (NPWS) Site synopsis, Natura 2000 data forms and

Conservation Objectives

1.4.1 Ecological Walkover Surveys

To further inform the Appropriate Assessment process, the OPW selected a number of channels within the Kilcoo

Arterial Drainage Scheme for assessment through the undertaking of an ecological walkover survey. The selected

channels are those located in, or within 100m of, a European site.

The ecological walkover survey consisted of:

▪ Mapping and recording of habitats along the channels in accordance with the Fossitt Guidelines

(2010).

▪ As part of the habitat mapping, the location and extent of all Annex I habitats was also noted and

mapped.

▪ Any other habitat features that contributed to habitat diversity, including any spoil heaps, small

wetland areas or linear features with high species-richness, but that were not sufficient to warrant a

separate classification as part of the habitat mapping exercise, were identified and noted.

▪ The location of any areas of floating river vegetation were recorded, with notes made on abundance

and species composition.

▪ Recording the presence of any non-native invasive species.

▪ Recording the presence and location of all Annexed species, species protected under the Wildlife

Acts and Flora Protection Order, and any other notable floral or faunal species. Specifically, this

included:

▪ Recording of evidence of Otters (e.g. spraints, holts, couches, feeding remains, footprints)

▪ Recording of evidence of Badger activity (e.g. setts, latrines, footprints, runs, feeding signs or hairs)

▪ All bird activity observed during the survey was recorded, including species listed in Annex I of the

Birds Directive and Birds of Conservation Concern in Ireland (BoCCI).

▪ The locations of Kingfisher nests, Sand Martin nesting cliffs, or eroded sections of vertical bank

providing suitable nest sites was also noted and mapped.

▪ Habitats where rare or protected animal or plant species are present, or where the habitats are

suitable to support these species were also recorded.

The results of all of the above surveys have been compiled into a GIS geodatabase, which includes three layers:

▪ Habitats classified according to the Fossitt Guidelines

▪ Areas of Annex I habitats and other notable habitat areas not sufficient to warrant classification

under the Fossitt system

▪ The location of any species information (i.e. evidence of protected species, stands on non-native

invasive species).

A geo-referenced photographic record has also been compiled during the ecological survey, which consists of:



▪ Habitats present along the surveyed watercourses (where habitat type is continuous along a channel,

a minimum of one photograph for each kilometre stretch of channel corridor will be taken)

▪ Notable areas, such as ecologically valuable habitats and other ecological sensitivities

▪ Bridges encountered during the survey work

1.4.2 Screening

The screening assessment conducted for these works has been undertaken in line with recommended guidance

including that specifically produced for the OPW in 2014 (Ryan Hanley 2014b, 2014a). This methodology is

based on source > pathway > receptor chain principles and involves assessing likely significant effects on Natura

2000 sites within the zone of influence of the proposed drainage maintenance in relation to three pathways:

1. Surface water

2. Land & air

3. Groundwater

The screening assessment involves assessing the impacts of drainage maintenance operations within the arterial

drainage scheme, and its zone of influence, in relation to each of the three pathways individually. The results of

each pathway are then combined in a concluding section to identify if/where likely significant effects may arise.

Figure 1-2 Screening Assessment Process: Source Pathway Receptor Chain

The screening process uses a combination of GIS analysis and qualitative assessment to identify which drainage

maintenance activities, on which specific watercourses, are likely to have significant effects on the integrity of

European sites. The screening report, conducted by JBA ecologists in 2014, has been reviewed and updated as

necessary for the production of this NIS.



1.4.3 Consultation

To further enhance understanding of the baseline of the scheme area, consultation has been undertaken with local

representatives from Inland Fisheries Ireland (IFI) and the National Parks and Wildlife Service (NPWS). This

report has been produced on currently available information, with the most up-to-date versions used. Where

new, or updated, information becomes available the OPW will consider and review the findings of this

assessment, if necessary.

The findings of this assessment is subject to consultation with the NPWS and IFI.



2. Arterial Drainage Maintenance

2.1 Background

Between 1945 and 1995, under the Arterial Drainage Act (1945), the OPW completed 34 Arterial Drainage

Schemes on river catchments, along with five estuarine embankment schemes (over 11,500km of channel and

730km of embankments). The OPW is statutorily obligated to maintain arterial drainage channels under the

1945 Arterial Drainage Act, and since their completion, maintenance of these Arterial Drainage Schemes has

been ongoing, with the majority of channels maintained every five years. However, larger channels tend to be

only maintained every ten years, on average.

2.2 Drainage Maintenance Activities

Arterial Drainage Maintenance includes a range of operations such as silt and vegetation management, mowing

and structure maintenance, as detailed in Table 2-1, and listed as channel, embankment or structure maintenance

in Table 2-2 below. It is required to retain the arterial drainage scheme design capacity.

The following sections, taken from Ryan Hanley (2014c) and OPW (2019) Table 1.3 and 1.4, provide further

details on the types and nature of arterial drainage maintenance operations undertaken by the OPW.

Table 2-1 OPW Drainage Maintenance Subcategories

Drainage Maintenance Subcategories

A Silt and vegetation management

B Aquatic vegetation cutting

C Bank protection

D Bush cutting/Branch trimming

E Tree cutting

F Other Mulching embankment

Mowing embankment

Gate installation

Sluice maintenance

Bridge maintenance

Spraying with herbicide

Table 2-2 OPW Drainage Maintenance Types

Category Maintenance Type Code

Channel Maintenance Silt and vegetation management A

Aquatic vegetation cutting B

Bank protection C

Bush cutting/Branch trimming D

Tree cutting E

Other F



Category Maintenance Type Code

Embankment Maintenance Bush cutting/Branch trimming D

Tree cutting E

Mulching F

Mowing F

Gate installation F

Structural Maintenance Sluice maintenance F

Bridge maintenance F

Bank protection C

Bush cutting/Branch trimming D

Tree cutting E

The following sections, taken from Ryan Hanley (2014a) and OPW Environmental Guidance 2019, provide

further details on the types and nature of arterial drainage maintenance operations undertaken by the OPW.

2.2.1 Channel Maintenance Activities

The majority of drainage maintenance activities are focused on channel maintenance. While the frequency of

maintenance on an individual channel may vary, with some channels requiring maintenance annually and others

only requiring maintenance every twenty years, the average channel requires maintenance every four to six

years. In this regard, approximately 2,000km of channels are maintained annually and nearly all of the

11,500km of channels across Irelands Arterial Drainage Schemes will have been maintained at least once over

a period of five years. Channel maintenance is organised on a regional basis, with OPW Arterial Drainage

Maintenance Regional Offices in Limerick, Headford, Co. Galway and Trim, Co. Meath.

Scheme Design Standards

Arterial Drainage Schemes constructed under the Arterial Drainage Act, 1945 were designed to provide an

outfall for drainage of agricultural lands, and generally provided protection for a 3-year flood event. Where

the creation of an outfall dictated the design bed levels, greater protection than the 3-year flood event was

achieved as a consequence. In the case of modern flood relief schemes, flood protection for a 100-year flood

event would be the design objective.

The original Scheme designs including the outfall datum for each of the Arterial Drainage Schemes are available

in the relevant OPW Arterial Drainage Maintenance Regional Office. This includes the mapped Scheme design,

and the associated long sections and cross sections. These designs are used to inform channel maintenance.

Types of Channel Requiring Maintenance

In the years following the construction of a drainage scheme there is a tendency for the channel capacity to be

progressively reduced due mainly to the transportation and deposition of bed materials, the accumulation of silt

and the growth of in-channel vegetation. The resultant channel maintenance consists of repetitive works of a

cyclical nature, to restore the Schemes design levels i.e. outfall datum in order to maintain the channel's designed

capacity to convey water.

Channels are prioritised for maintenance based on the rate of deterioration and the risk arising. The selection

takes account of requests from the general public and potential flooding risk to roads, properties, Water

Treatment Plants and Waste Water Treatment Plants.



Plane Bed to Low Gradient Channels

Some 60 – 70% of maintained channels are of gentle longitudinal gradient and subject to relatively rapid

deposition of silt, especially those that are subject to prolific growth of in-channel vegetation. The majority of

maintenance works are therefore located on smaller lower-lying channels, with 90% of works in channels with a

base width of <3m. In such channels silt and in-channel vegetation may cause the low flow level to rise by 50-

300mm above the Scheme design level. In such circumstances, maintenance is focused on restoring both low-flow

and flood-flow water levels to original Scheme design.

Medium to High Gradient Channels

A smaller proportion of channels are steep and fast flowing and are subject to flash floods, bank erosion and

rapid movement of bed gravel. The steeper sections of channel normally require relatively little and infrequent

maintenance works as opposed to channels of low gradient which are subject to rapid accumulation of silt and

proliferation of vegetation. These channels will have a greater requirement for bank protection works.

Figure 2-1 Medium to High Gradient Channels in the Kilcoo Arterial Drainage scheme

Periods and Cycles of Maintenance

The average channel requires silt and vegetation management every four to six years. However, channels with

prolific weed growth may require maintenance annually, particularly where downstream bridges are at risk of

being blocked due to a flow of decaying vegetation in autumn. Conversely, some channels may only require in-

stream maintenance every twenty years due to the self-cleaning characteristics e.g. high gradient channels.

Where the period between previous channel maintenance works has been exceptionally long, dense scrub and

woody vegetation can establish along the channel and within the maintenance access corridor. In such

circumstances, drainage maintenance works will include the removal of scrub/transitional woodland (WS1) that

has developed along the banksides via bush cutting/branch trimming, tree cutting or mulching. This is undertaken

between the 1st September and 28th February to avoid the residential bird nesting season (from the 1st March

to 31st August as per the Wildlife Act (1976).

In contrast, in-stream works for silt and vegetation management are carried out outside of the salmonid spawning

season (May to September) and the times that early life stages of salmonid fish will be present as per Section

173 of the Fisheries (Consolidation) Act (1959) on channels with salmonid spawning habitat. Any works required

during this period are carried out in consultation with IFI. As a result, there may be a two-stage approach to the

works, with silt and in-stream vegetation management carried out during the open season (i.e. summer months),

while woody vegetation removal is carried out in the winter months.

Other restrictions on works may also apply in relation to the presence/absence of other protected species such

as White-clawed Crayfish and Sea, River and Brook Lamprey which will influence the timing of works.



2.2.2 Structural Maintenance Activities

Structural Design Standards

During the construction of the Arterial Drainage Schemes under the 1945 Act, some 18,500 No. accommodation

bridges were identified and modified, or replaced as required. These bridges provide farmers owning land on

both sides of a channels with farm vehicular and/or foot access from one side to the other. The type of bridge

provided depended on the width, depth and required flow capacity of the channel, and ranged from concrete

piped culverts to relatively large structures formed on concrete or masonry abutments spanned by structural steel

beams, or lattice girders together with concrete or timber decking.

Types of Structures Requiring Maintenance

In general, as channel maintenance proceeds, the bridges are examined by the supervisory industrial staff and

if required, repairs/replacements are scheduled. The type of bridge structures, which are most likely to have

fallen into a critical state of disrepair, are those with timber decking supported on steel beams, and those in

which abutment foundations are being undercut. There is a standard type of design for the replacement of these

structures, which consists essentially of mass concrete abutments with reinforced cast in-situ decking. This type of

structure is simple to construct and under normal circumstances, it will last for many years with little or no

maintenance. Where feasible Pre-cast concrete elements are also used for repair or replacement of structures.

On many occasions, it is not necessary to totally replace a bridge, and repairs such as underpinning the

foundation or replacement of wing-walls, parapets or sections of the deck may be all that is required to extend

the useful life of the structure. Where bridge maintenance may be required, a Bridge Inspection Form will be

filled out by the Foreman, prior to the works. This will determine the need for further assessment and potentially,

any mitigation measures that may be required. See EP4 of OPW (2019) Environmental Guidance: Drainage

Maintenance and Construction - Foreman’s Bridge Inspection Report Form.

2.2.3 Maintenance works considered outside of the Scheme Design Standards and outside of normal

Arterial Drainage Maintenance Works

Occasionally, works are required that can be considered outside of the scope of the normal Arterial Drainage

Maintenance Works to maintain a scheme. Works considered outside of the normal scope of statutory arterial

drainage maintenance works are not assessed for impacts in this report. Works that could be considered outside

of the normal scope of works include those involving extensive bank protection measures, removal of mature

woodland, or bridge replacement works that have not had any assessments completed, which are within the zone

of influence of a European site.

2.2.4 Plant and Machinery

The types of machinery typically utilised during maintenance works would include 3600 hydraulic excavators

(from 15-20 tonne excavators), mini-diggers, tractors and trailers, tipper lorries, hydraulic shears, weed cutting

equipment, chainsaws, mulchers and mowers; the machinery used is dependent on the maintenance activity being

conducted.

The removal of dense in-stream silt and vegetation requires the use of a hydraulic excavator with a 1.5m wide

(approximate) bucket (capacity approximate 500ltrs). For standard excavators, works progress at a rate of

700m to 900m per week. In relation to long-reach excavators, works progress at a slower rate of between

200m and 350m per week. Rates may change due to channel width or ground conditions.

2.2.5 Maintenance Access Corridors (MAC) and Working Zone

Maintenance sites are generally accessed via the public road and through farmland. A maintenance access

corridor is utilised along one side of a channel for maintenance purposes. These established routes are used to

track the hydraulic excavators for maintenance and for the disposal of spoil (see section 2.2.6). The same route



is generally followed every maintenance cycle. This approach avoids disturbance of habitats on the opposite

bank during works.

Where grasslands are present within the maintenance access corridor, the impact is predominantly temporary as

the grasslands are trampled by machinery and can recolonise following completion of the maintenance activities.

Within woodland and scrub habitats a linear path more typical of disturbed vegetation i.e. scrub/transitional

woodland (WS1) will be evident along the maintenance access corridor due to regular machine access. In this

regard, the disturbance regime associated with the tracking of plant machinery along the maintenance access

corridors on the channel bank arrests succession to mature woodland such that scrub/transitional woodland (WS1)

dominates. Where mature trees are present these are generally avoided by plant machinery.

Structures are generally accessed through farmland from the public road above. Plant machinery will utilise the

same maintenance access corridor used for channel maintenance to gain access to the structure. Where individual

immature or semi mature trees and scrub habitats are present at the location of the structure, these may be

removed to facilitate bridge inspection and works. Where mature trees are present these are generally avoided

by plant machinery.

The location of mobile short-term staff welfare facilities, plant storage and car parking agreed with local

landowners. There is no requirement for temporary site lighting.

There is a requirement for water supply and disposal of wastewater from the welfare facilities (see section 2.2.6

in relation to waste disposal).

2.2.6 Site Compounds (Welfare Facilities), Access Routes and Haul Roads

Haul roads are generally not required to facilitate drainage maintenance activities. Where access is required in

soft ground conditions, plant equipment will be brought in on tracks or temporary matting will be laid to provide

a corridor for machinery access. Where matting is utilised, it will be completely removed post completion of

works to allow vegetation to recolonise. All plant and machinery are confined to one defined access route to

minimise disturbance.

All plant and machinery are regularly maintained and serviced to minimise release of hydrocarbons. All hydraulic

excavators and other plant machinery use long life engine oil and biodegradable hydraulic oil. Fuelling and

lubrication are conducted a minimum of 50m away from all channels. Spill kits are present in all plant used in

maintenance activities. Integrated submersible pumps are also deployed in the event of structural maintenance

and the requirement for dewatering of excavations.

2.2.7 Waste Output/Disposal

The material removed from a channel during silt and vegetation management is normally spread thinly along the

bank or on top of existing spoil heaps where present within the access corridor. All dead wood material is left

on site to decompose or is removed off site and utilised as firewood under local landowner agreements. Where

mulchers or mowers are deployed, the arisings are left on site to decompose or the mulched material is buried.

Construction and demolition waste from structures includes broken concrete and stone. Steel railings are returned

to the depot for recycling. Used engine oil and hydraulic oil is disposed of by a licensed waste handler. Toilet

facilities are maintained by a licensed waste handler. Any waste generated on site is returned to the depot for

segregation and disposal by a licensed waste handler.

2.2.8 Working Hours

All maintenance activities are undertaken during daylight hours. Standard working hours are 8.00am to 4.30pm,

with lunch and tea breaks, Monday to Friday. There is no requirement for temporary site lighting to facilitate

works. Machines are powered down when not in use.



2.2.9 Environmental Training

Environmental training of all staff involved in drainage maintenance is an ongoing process through site visits and

audits. A useful forum for knowledge sharing is the Foreman’s meeting which is typically held annually, although

some years have been skipped. This meeting between IFI, the OPW’s environment section, and the on-site

foremen presents new information and allows for discussion on environmental issues.

Technical and Operational Staff have completed formal training in Environmental Drainage Maintenance (EDM)

in 2004. This training course was revised and expanded under the OPW’s Environmental River Enhancement

Programme (EREP) and was delivered to all staff in 2010. The training programme delivered included

presentations in river corridor ecology, the Environmental Drainage Maintenance Guidance Notes (Ten Steps to

Environmentally Friendly Maintenance), maintenance strategies involving both ‘enhanced maintenance’ and

‘capital enhancement’, and OPW’s Environmental Management Protocols and Standard Operating Procedures

(SOPs) (see section 2.2.10 for more details). Both sets of training were developed and delivered by Inland

Fisheries Ireland (IFI).

The formal approach to EDM Training was complimented with on-site training. Regular site visits with consultants

and OPW’s Environment Section provided further guidance and advice to operational staff. Auditing of

operational staff on the implementation of the Environmental Drainage Maintenance Guidance Notes (Ten Steps

to Environmentally Friendly Maintenance) was also carried out by the OPW’s Environment Section.

In addition, other environmental training takes place as deemed beneficial, e.g. in 2008, the majority of the

technical and operational staff were trained in Otter Awareness. This course, provided by the Department of

Zoology, Trinity College Dublin, included presentations on Otter ecology, and on-site identification of Otter signs

and suitable habitat.

More recently, an environmental training course was designed and provided by JBA to all OPW staff in 2017

and 2018. It was given in three different stages. Management staff were given a more detailed 2-day course

in Environmental and Ecological training. Ground staff were given 1.5 days of training in the environment and

ecology. Modules were designed to assist staff in understanding the relevant legislation, recognising ecologically

sensitive habitats and species, invasive non-native species identification and general environmental and

ecological training relevant to their work. This included a half day practical session where ecologists

demonstrated the identification of the elements taught in the classroom, in the field.

Training in the completion of an Environmental Risk Assessment and Bridge Inspections from an ecological

perspective, was designed and provided by JBA Consulting to OPW Foremen and selected engineering staff in

2018. Training with regard to the new OPW procedures, Environment Guidance: Drainage Maintenance and

Construction was delivered in house by OPW Environment Section in June 2019. All relevant staff were trained

in how to use the new Guidance and workshops on how to use Environmental Data EP6 proved useful.

2.2.10 Environmental Audits

A portion of operational crews are audited annually by the OPW Environment Section and OPWs Environmental

Consultants for the implementation of the Environmental Drainage Maintenance Guidance Notes (Ten Steps to

Environmentally Friendly Maintenance) and the OPW’s Environmental Guidance. Auditing is carried out

separately by OPW Environment Section and their Consultants on a rotational basis to ensure all operational

crews are audited at least once every three years. All audit results are forwarded to the relevant Engineer for

that Scheme within two working weeks. In the event of an audit showing elements of unreasonable non-compliance

with procedures, the relevant Engineer will be notified within one working day. Audit results are also forwarded

to OPW Systems Manager for inclusion in monthly regional benchmarking reports.



2.2.11 Environmental Management Procedures (EPs)

The OPW’s Environmental Guidance: Drainage Maintenance and Construction, Environmental Procedures set out

how regional management staff manage a range of environmental aspects, including programming of works to

accommodate certain environmental windows or restrictions on timing of works, and recording of data. A total

of 33 No. Environmental Procedures (EPs) are applied to the works. These EPs set out actions designed to

eliminate, or substantially reduce likely impacts to identified species and their associated habitats. Environmental

Procedures are broken down into the following:

Section 1A Drainage Maintenance Planning Procedures (EP 1- 5)

Section 1B, Drainage Maintenance Implementation Procedures (EP 6 – 13), including procures for the 10 Steps

to Environmentally Friendly Maintenance, River Enhancement and Tree and Vegetation Management.

Section 2 Construction Procedures (EP 14 – 18), including Construction and Environmental Management, Ecological

friendly culverts ad water pollution management);

Section 3 Invasive Species Procedures EP 18 A – D) including Procedures for general and high-level biosecurity

and treatments;

Section 4 Animal and Plant Procedures (EP 19-28)

▪ EP 19 Salmonid

▪ EP 20 Otter

▪ EP 21 Lamprey

▪ EP 22 Crayfish

▪ P 23 Badger

▪ EP 24 Bank Nesting Birds

▪ EP 25 Birds

▪ EP 26 Bats

▪ EP 27 Rare Plants

▪ EP 28 Fresh Water Perl Mussel

Section 5 Habitat Procedures EP 30 – 33):

▪ EP 30 Alluvial (Wet Woodland)

▪ EP 31 Wetland

▪ EP 32 Mudflat

▪ EP 33 Floating River Vegetation Habitat.

All Environmental Procedures are available in the OPW’s “Environmental Guidance Drainage Maintenance &

Construction” (OPW, 2019).

This document can also be downloaded from https://www.opw.ie/en/media/environmental-guidance-

drainage-maintenance-and-construction-2019.pdf.

2.3 The Kilcoo Arterial Drainage Scheme

The Kilcoo Arterial Drainage Scheme is located in County Leitrim on the border with County Fermanagh. It includes

13.5km of watercourse and 0km of embankment. The Kilcoo catchment has a total benefiting area of 166ha.

http://www.opw.ie/en/media/OPW%20Environmental%20Management%20Protocols%20%26%20SOPs%20April%202011.pdf



Figure 2-2: Map of the Extent of the Kilcoo Drainage Maintenance Scheme

The construction of the scheme started in 1969 and was completed in 1971 under the 1945 Arterial Drainage

Act. Maintenance has been ongoing since completion of the scheme.

2.4 Drainage Maintenance Works Proposed for the Kilcoo Arterial Drainage Scheme

Within the Kilcoo Arterial Drainage Scheme the exact location and type of required maintenance activity varies

over time. The screening assessment (JBA Consulting, 2014a) was conducted on the assumption that all channels

will be maintained during a 5-year maintenance cycle. However, this Appropriate Assessment is based on more

detailed information provided on the timing, frequency and nature of maintenance operations to be conducted

on each channel. During the period 2020 to 2024 maintenance activities proposed for the channels in the Kilcoo

Arterial Drainage Scheme, include:

▪ A - Silt and vegetation management

▪ D- Brush cutting/branch trimming

▪ E - Tree Cutting

▪ F- Other (See Section 2.2)

The frequency of the above listed maintenance works within the Kilcoo Arterial Drainage Scheme occur every 7-

8 years.

Selective tree maintenance will not result in a total removal of all trees from the channel banks. Trees that do not

obstruct the channel, and hence do not compromise flow, will not be removed. Any trees or branches that encroach

into the flow path will be removed. Where only branches reduce the flow, the low hanging branches will be

removed and the main tree will be retained. There will be no alterations to banks or exposure/stripping of soils



as part of the works. The removal of trees will not include the removal of tree roots from the bank. Vegetated

buffer zones will be retained along channel banks to retain the natural filtering system and prevent agricultural

run-off and other pollutants entering the river. The works will not significantly increase instream flow capacity

and will maintain design flows.

The removal of trees and woody vegetation along channel C1 will occur using a short reach excavator with tree

shears. The machine will operate on mats to reduce ground bearing pressure in areas of wet or soft ground.

There shall be no tracking of machinery within waterlogged areas adjacent to the river.

No aquatic vegetation cutting (activity B) or bank protection (activity C) are proposed to be undertaken during

the period 2020 to 2024.

As there are no embankments within the Kilcoo scheme area.

It is currently not known where structural maintenance operations activities as detailed in Tables 2.1 and 2.2 are

proposed, and therefore it will be assumed that potentially these activities could occur on all structures within the

scheme area during the period 2020 -2024.

The spreadsheet in Appendix A provides full details of the drainage maintenance activities proposed for the

Kilcoo Arterial Drainage Scheme for the period 2020 to 2024.

3. Screening Assessment Results

3.1 Introduction

An Appropriate Assessment screening assessment, addressing Stage 1 of the process, has already been

completed for Kilcoo Arterial Drainage Scheme (JBA Consulting, 2014a). This identified that likely significant

effects on Natura 2000 may occur as a result of the proposed maintenance activities and therefore a Stage 2

Appropriate Assessment is necessary.

The Stage 1 Screening Assessment was conducted in line with guidance produced for the OPW in 2019 (Ryan

Hanley, 2014a, b and c). This methodology is based on source > pathway > receptor chain principles and

involves assessing likely significant effects on European sites within the zone of influence of the proposed drainage

maintenance in relation to three pathways:

1. Surface water

2. Land & air

3. Groundwater

The screening assessment involved assessing the impacts of drainage maintenance operations within the arterial

drainage scheme, and its zone of influence, in relation to each of the three pathways individually. Conclusions

were then drawn to identify which channels within a scheme could impact upon European sites. Sites that had the

potential to be impacted by the maintenance works were determined to be within the ZOI and these sites require

further assessment. The review of the previous screening included a review of the ZOI and an assessment of any

new European sites, and/or any changes to current European sites within the ZOI. The screening assessment review

also took into consideration the up to date information on the upcoming programme of works where relevant.

The resulting assessment included the European sites potentially impacted as follows:

▪ Lough Melvin SAC (Site code UK0030049, Site code ROI 000428).

Lough Melvin is located within the boundary of Counties Leitrim and Counties Fermanagh and therefore is

designated as a European site (SAC) in both Northern Ireland and the Republic of Ireland.



3.1.1 Surface Water Pathways

As a result of the screening assessment (JBA Consulting, 2014a) maintenance activities on those watercourses

shown in Figure 3-1 were identified as potentially resulting in significant adverse impacts on European sites via

surface water pathways. Specifically, the European sites that may be adversely impacted upon are:

▪ Lough Melvin SAC

Figure 3-1 Channels with potential impacts via surface water pathways identified in AA Screening 2014

3.1.2 Land & Air Pathways

As a result of the screening assessment (JBA Consulting, 2014a) maintenance activities on those watercourses

shown in Figure 3-2 were identified as potentially resulting in significant adverse impacts on European sites via

land and air water pathways. Specifically, the European site that may be adversely impacted upon is:

▪ Lough Melvin SAC (000428)



Figure 3-2: Channels with potential impacts via land and air and b) groundwater pathways identified in AA Screening 2014

3.1.3 Groundwater Pathways

As a result of the screening assessment (JBA Consulting, 2014a) maintenance activities on those watercourses and

embankments shown in Figure 3-3 were identified as potentially resulting in significant adverse impacts on

European sites via groundwater pathways. Specifically, the European site that may be adversely impacted upon

is:

▪ Lough Melvin SAC (000428)



Figure 3-3: Channels with potential impacts via groundwater pathways identified in AA Screening 2014

3.2 Screening Assessment Conclusions

The Screening Assessment (JBA Consulting, 2014a) identified that the sites detailed in Table 3-1 were likely to

be significantly affected by drainage maintenance operations undertaken within the Kilcoo Arterial Drainage

Scheme. These conclusions are based on the assumption that all drainage maintenance activities are to be

undertaken on all watercourses and structures during the life of the plan (2020-2024).

Table 3-1 Screening Assessment Conclusions

Site

Pathway of Impact Comment

Surface

Water

Land

and Air

Ground

water

Lough

Melvin

SAC

(000428)

This screening exercise identified that Lough Melvin SAC may be

adversely impacted upon via all pathways. Surface water

pathways could impact upon suspended solid and nutrient

loadings and water levels and affect all qualifying interests.

Noise, visual and physical disturbance could impact on Salmon

and Otter populations via land and air pathways. Groundwater

pathways could impact on the lake habitats through nutrient

release and impacts on groundwater levels.

Note:

Red = likely significant effect



Figure 3-4 Map of all channels and structures where significant likely effects may arise as identified in AA Screening

4. European Sites within the Zone of Influence of Drainage Maintenance

Activities

4.1 Introduction

This chapter provides baseline information on the European sites within the Zone of Influence of the drainage

maintenance activities (i.e. those screened into the assessment as detailed in Table 3-1). A short description for

each site is provided, along with details of the qualifying interest/special conservation interests, conservation

objectives, the attributes used to define favourable conservation status and site vulnerabilities. However, for

many sites, site specific conservation objectives have not yet been developed for the qualifying interest/special

conservation interest present. In these instances, attributes have been taken from similar or nearby sites where

the same qualifying interest/special conservation interests, or from similar habitats/species, and these are

assumed to be appropriate for the sites detailed.

4.2 Lough Melvin SAC (IRE 000428; UK0030047)

Lough Melivn covers an area of 2,1258ha located in the Counties of Leitrim and Fermanagh. The site is

designated as a candidate Special Area of Conservation (SAC) under the EU Habitats Directive (82/43/EEC) in

both Northern Ireland and the Republic of Ireland. Lough Melvin is an oligo-mesotrophic lake approximately

13km long by 3km wide in County Leitrim. It varies in depth, with average depths of 8.5m, with 45m the maximum

depth. The designation includes a number of inflowing and outflowing watercourses, including the Drowes River

which links the lake to Donegal Bay (NPWS, 2016).

The lake contains a good diversity of aquatic plants including Quillwort Isoetes lacustris, Shoreweed Littorella

uniflora, Alternate Water-milfoil Myriophyllum alternifolium and Water Lobelia Lobelia dortmanna. Marginal



areas contain some sparse patches of swamp vegetation, consisting of Common Reed Phragmites australis,

Common Spike-rush Eleocharis palustris and Common Club-rush Schoenoplectus lacustris (NPWS, 2016a).

Grassland ascribable to the E.U. Habitats Directive Annex I type Molinia Meadows has been reported by the

Irish Semi-natural Grasslands Survey (2009) from Gubacreeny and Gubalaun. Drier woodland exists in other

areas, with Hazel (Corylus avellana), Ash (Fraxinus excelsior), Holly (Ilex aquifolium) and Hawthorn (Crataegus

monogyna). Some stands have a rich ground flora that includes Primrose (Primula vulgaris), Wood-sorrel (Oxalis

acetosella), Bluebell (Hyacinthoides non-scripta), Honeysuckle (Lonicera periclymenum) and Sanicle (Sanicula

europaea).

Four plant species which are listed in the Irish Red Data Book, Globeflower (Trollius europaeus), Marsh

Helleborine (Epipactis palustris), Blue-eyed-grass (Sisyrinchium bermudiana) and Tea-leaved Willow (Salix

phylicifolia), are found in this site. Globeflower is also protected under the Flora (Protection) Order, 2015. The

main interest of the site is the unique fish community which the lake supports. Lough Melvin is an excellent example

of a natural, post-glacial salmonid lake. A relict population of the Arctic Char (Salvelinus alpinus) occur there, as

does the Atlantic Salmon (Salmo salar). Lough Melvin has three races of Brown Trout (Salmo trutta) - Ferox,

Sonaghen and Gillaroo - which have distinctive characteristics and separate spawning grounds. The lake’s

inflowing and outflowing streams which are used for spawning by these Brown Trout races are included in the

site. Otter have been recorded from the Drowes River and the main inflowing rivers and are likely to be

widespread throughout the site (NPWS, 2016a).

The lake is used for boating, fishing and water abstraction, while much of the terrestrial part of the site is used

for grazing. Consequently, the main threats to the site are from agricultural pollution and recreational pressure

(NPWS, 2016a).

The lake which is also located within the boundary of Northern Ireland is also designated by Department of

Agriculture, Environment and Rural Affair (DAERA) in Northern Ireland as Lough Melvin Site Code UK0030047.

4.2.1 Qualifying Interests ROI and NI

Table 4-1 Qualifying Interests of Lough Melvin SAC (000428) in Ireland

Code Qualifying Interests Attributes

1106 Salmon Salmo salar

Rep. Ireland and UK

(identified in by JNCC

designation as present as

a qualifying feature but

not a primary reason for

designation)

- Distribution: extent of anadromy

- Adult spawning fish

- Salmon fry abundance

- Out-migrating smolt abundance

- Number and distribution of redds

- Water quality

From: Lower Shannon SAC (002165) Site Specific Conservation Objectives (NPWS,

2012)

1355 Otter

Lutra lutra

Rep. Ireland only

- Habitat area

- Distribution

- Extent of terrestrial habitat

- Extent of freshwater (river) habitat

- Extent freshwater (lake/lagoon) habitat

- Couching sites and holts

- Fish biomass available

- Barriers to connectivity


2012)




3130 Oligotrophic to

mesotrophic standing

waters with vegetation of

the Littorelletea uniflorae

and/or of the Isoeto-

Nanojuncetea

Rep Ireland and UK

- Habitat area

- Habitat distribution

- Typical species

- Vegetation composition: characteristic zonation

- Vegetation distribution: maximum depth

- Hydrological regime: water level fluctuations

- Lake substratum quality

- Water quality: transparency

- Water quality: nutrients

- Water quality: phytoplankton biomass

- Water quality: phytoplankton composition

- Water quality: attached algal biomass

- Water quality macrophyte status

- Acidification status

- Water colour

- Dissolved organic carbon

- Turbidity

- Fringing habitat: area and condition

From: Lough Corrib SAC (000297) Site Specific Conservation Objectives (NPWS,

2017)

6410 Monlinia meadows on

calcareious peaty or

clayey silt laden soils

(Molinion caeruleae)

- Habitat area

- Habitat distribution

- Vegetation structure: broadleaf herb: grass ratio

- Vegetation structure: sward height

- Vegetation composition: typical species

- Vegetation composition: notable species

- Vegetation composition: negative indicator species

- Vegetation composition: negative indicator moss species

- Vegetation structure: woody species and bracken (Pteridium aquilinum)

- Physical structure: bare ground


2012)

Table 4-2 Qualifying Interests of Lough Melvin SAC (UK0030047) in Northern Ireland


3130 Oligotrophic to mesotrophic

standing waters with

vegetation of the

Littorelletea uniflorae

and/or of the Isoeto-

Nanojuncetea

- Water Open water area to remain stable and water level regime to

follow a natural cycle.

- The lake water to remain poor in plant nutrients and not to fluctuate

outside normal limits.

- The lake water alkalinity not to fluctuate outside normal limits.

- The degree of peat staining of the lake water to remain at low levels

- Characteristic aquatic vegetation to remain present, including zones of

isoetid vegetation.




- Hard basin substrate not to become buried below soft sediments. Inflows

not to carry an abnormal sediment load.

- Minimal negative impacts from artificial structures.

- Minimal negative impacts from recreation.

- Co-ordinate monitoring efforts north and south of the border, and

correlate the results

6410 Monlinia meadows on

calcareious peaty or clayey

silt laden soils (Molinion

caeruleae)

- Maintain and expand the extent of existing fen meadow but not at the

expense of other SAC (ABC) features. (There are area of degraded heath,

scrub, and damp grassland which have the potential to develop into fen

meadow)

- Maintain and enhance fen meadow species diversity including the

presence of notable or rare species.

- Maintain the diversity and quality of habitats associated with the fen

meadow, e.g. wet grasslands, wet heath, wet woodland and scrub,

especially where these exhibit natural transition to fen meadow.

- Seek nature conservation management over suitable areas immediately

outside the SAC where there may be potential for restoring fen meadow

Old sessile oak

woods with Ilex and

Blechnum in the

British Isles

- Maintain and expand the extent of existing oak woodland but not at

the expense of other SAC (ABC) features. (There are area of degraded

heath, wetland and damp grassland which have the potential to develop

into oak woodland)

- Maintain and enhance Oak woodland species diversity including the

presence of notable or rare species.

- Maintain and enhance Oak woodland structure

- Maintain the diversity and quality of habitats associated with the Oak

woodland, e.g. fen meadow, grasslands, wet heath wet woodland and

scrub, especially where these exhibit natural transition to Oak woodland

- Seek nature conservation management over adjacent forested areas

outside the SAC where there may be potential for woodland rehabilitation.

- Seek nature conservation management over suitable areas immediately

outside the SAC where there may be potential for woodland expansion

1106 Salmon Salmo salar

- Maintain and if possible, expand existing population numbers and

distribution

- Maintain and where possible, enhance the extent and quality of suitable

Salmon habitat, in particular the chemical and biological quality of the

water)



4.2.2 Conservation Objective

The Conservation Objective for the Lough Melvin SAC (ROI and NI) is to maintain or restore the favourable

conservation condition of the Annex I habitat(s) and/or the Annex II species for which the SAC has been selected

(as detailed in Table 4-1 above).

Favourable conservation status of a habitat is achieved when:

▪ its natural range, and area 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 favourable conservation status of a species is achieved 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.

4.2.3 Site Vulnerabilities

NPWS (2017a) identify that the ROI Lough Melvin SAC 000428 is vulnerable to:

▪ Removal of hedges and copses or scrub

▪ Forest and Plantation management & use

▪ Fertilisation

▪ Invasive non-native species

▪ Diffuse pollution to surface waters due to agricultural and forestry activities

▪ Grazing

The Conservation Objectives for Lough Melvin SAC UK0030047 in Northern Ireland identify the

following threats:

▪ Open water impacts

▪ Nutrient enrichment

▪ Recreational pressure

▪ Alien Species (Canadian pondweed, zebra mussel)

▪ Woodland Impacts

▪ Grazing / Poaching / Tree barking and Browsing

▪ Woodland Clearance

▪ Deadwood Removal

▪ Invasion by exotics

▪ Fly-tipping

▪ Species Impacts

▪ Human induced changes such as stocking of trout or non-Melvin origin or non-indigenous species

▪ Grassland Impact

▪ Grassland dereliction



▪ Nitrogen Deposition

4.3 Description of the receiving environment - Ecological Walkover Survey Results

4.3.1 Introduction

To further inform the Appropriate Assessment process, the OPW selected channels within the Kilcoo Arterial

Drainage Scheme for assessment through the undertaking of an ecological walkover survey. The selected channels

are those located in, or within 100m of, a European site. This section summarises the methodology and findings

of these surveys. See Appendix A for map of Channels and SAC boundaries.

All data collected on site has been inputted into a GIS system and provided to OPW to enhance understanding

of the baseline environment and inform future works. See Section 1.4 for detail of the methodology used for

walkover surveys.

Lough Melvin SAC is within the zone of influence of the works. The County River is within the SAC designation for

directly upstream of the lake. This channel is included within the Maintenance Programme, therefore a walkover

of approximately 2.2km of the river channel (encompassing the SAC and a 100m buffer) was included in the

field survey.

4.3.2 Results

Habitats

The County River surveyed forms the boundary between the North and the South of Ireland. The survey covers

the area between the townland of Cornagawna to Lough Melvin.

The river gradient throughout the surveyed reach is gentle for the most part, at the time of survey the river was

found to be in spate. The river substrate is a mixture of large cobbles and bedrock. The river is a mix of

eroding/upland river (FW1) and depositing/lowland river (FW2) types. Some pools are present, but few areas

have gravel.

The bankside habitats are primarily riparian woodland (WN5), but are non-flooding (i.e. the banks are strong)

and there is a wooded valley along the river. The river valley is steep on the southern banks, but not as steep on

the northern side for most of the distance surveyed, and so the area was more suitable for agricultural

improvement. For much of the distance surveyed on the northern bank, a small (10-120m) riparian woodland

(WN5) separated the river from either improved agricultural grassland (GA1) or wet grassland (GS4). Closer

to Lough Melvin, on the northern banks, the riparian woodland begins to thin and is reduced to a treeline (WL2),

particularly in the townlands of Carran West and Rocktown.

The bankside habitat on the south is also primarily riparian woodland (WN5), but in two large sections this is

bordered by Sitka spruce coniferous forestry (WD4). In some areas, especially closer to Lough Melvin areas

farmland (either GA1 or GS4) borders the riparian woodland, but for the majority of the area surveyed the

river valley was wooded (>20m) on the southern bank.

Fourteen Fossitt habitats were identified during the ecological walkover survey. The most common habitats present

are wet grassland and riparian woodland. Habitat found along the Kilcoo Scheme are as follows:

Table 4-3 Habitats found along the County River

Code Habitat Code Habitat

BL3 Buildings and artificial

surfaces

ED1 Exposed sand, gravel or

till

FS1 Reed and large sedge

swamps

GS4 Wet grassland



Code Habitat Code Habitat

GS1 Dry calcareous and neutral

grassland

WN5 Riparian woodland

WN2 Oak-ash-hazel woodland ER1 Exposed siliceous rock

WD4 Conifer plantation FL5 Eurtophic lakes

GA1 Improved agricultural

grassland

WN1 Oak-birch-holly woodland

WN6 Wet willow-alder-ash

woodland

WS5 Recently felled woodland

Of the habitats identified there were two possible Annex I habitats described: alluvial forest and floating river

vegetation.

Annex I Habitats

As part of the habitat mapping process, those habitats considered to represent habitat types listed on Annex I

of the Habitats Directive were noted. While Alluvial Woodlands and potential suitable Floating River Vegetation

habitats were present during the site visit these habitats are not qualifying features of Lough Melvin SAC.

Information on habitat areas that have been identified as representing Annex I habitats is detailed within the

provided GIS shapefiles, however, a summary of the Annex I habitats found, and their location is detailed below.

Table 4-4 Annex I Habitat within Kilcoo Arterial Drainage Scheme

Annex I

Habitat Type

Description (From: NPWS, 2014h and JNCC, 2014) Equivalent

Fossitt Habitats

Location Found

in Kilcoo Scheme

Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-padion, Alnion incanae, Salicion albae)

(91E0)

Comprises woods dominated by Alder Alnus glutinosa and Willow Salix spp. on flood plains in a range of situations from islands in river channels to low-lying wetlands alongside the channels. The habitat typically occurs on moderately base-rich, eutrophic soils subject to periodic inundation.

Many such woods are dynamic, being part of a successional series of habitats. Their structure and function are best maintained within a larger unit that includes the open communities, mainly fen and swamp, of earlier successional stages. On the drier margins of these areas other tree species, notably Ash Fraxinus excelsior and Elm Ulmus spp., may become abundant.

WN4: Wet

pedunculate

oak ash

woodland,

WN5 Riparian

woodland

In isolated pockets along the County River largely on the north and south side of the bank.

Floating River Vegetation

The Annex I habitat of watercourses of plain to montane levels with the Ranunculion fluitantis and Callitricho-

Batrachion vegetation [3260] under the Habitats Directive is very broad, especially when the presence of aquatic

mosses is considered; using this broad definition the 'Floating River Vegetation' habitat type will be found in most

watercourses in Ireland (NPWS, 2014h). They are typically watercourses characterised by the abundance of

water-crowfoots Ranunculus spp., subgenus Batrachium (i.e. Ranunculus fluitans, R. penicillatus ssp. penicillatus, R.

penicillatus ssp. pseudofluitans, and R. peltatus and its hybrids), which form floating mats. However, there is no

satisfactory definition of this habitat type and its sub-types and its distribution in Ireland. It can occur over a wide

range of physical conditions from acid, oligotrophic, flashy upland streams dominated by bryophytes to more

eutrophic, slow flowing streams dominated by Ranunculus and water-starwort Callitriche species. The Ranunculus

species can be associated with a wide assemblage of other aquatic plants, such as Water-cress Rorippa



nasturtium-aquaticum, waterstarworts Callitriche spp., water-parsnips Sium latifolium and Berula erecta, water-

milfoils Myriophyllum spp. and Water Forget-me-not Myosotis scorpioides. In some rivers, the cover of these

species may exceed that of Ranunculus species (NPWS, 2014h). Other associated species with this habitat type

can include Horned Pondweed Zannichellia palustris, pondweed species Potamogeton spp. and the moss Fontinalis

antipyretica. Opposite-leaved Pondweed Groelandia densa may also be present, with Flowering Rush Butomus

umbellatus potentially present as part of the bank flora (OPW, 2007).

Floating river vegetation was not recorded during the walkover survey though it was noted that there is potential

for this Annex I habitat to be present in the area as previous records of aquatic mosses dominated the riverine

flora, occasional patches of Water-crowfoot Ranunculus spp. were present.

A sample habitat map illustrating the nature of the habitat data collected during the ecological walkover survey

is given in Figure 4-1 below.



Figure 4-1 Sample Habitat Map

Non-native Invasive Species

No evidence of non-native invasive species was recorded during the survey.

Protected Flora and Fauna

Protected fauna recorded during ecological walkover surveys included:

▪ Otter Lutra lutra - evidence of the presence of this species on the County River was noted at a

number of locations; otter is likely to use the river for foraging. It is likely to be present throughout

the scheme

▪ Badger Meles meles- evidence of this species, including latrines and snuffle holes, were noted at a

number of locations during the 2018 survey and it is likely to be present throughout



▪ Red Deer Cervus elaphus- evidence of Red Deer was identified throughout the site (stripped bark

and droppings) during the 2018 survey

▪ Red Squirrel Sciurus vulgaris- evidence of Red Squirrel feeding (split hazel nuts) were found

throughout the site during the 2018 survey

Out of the above listed species only otter is a qualifying feature of Lough Melvin SAC. Locations of otter records

along the channels are shown in Figure 4.2 below. Specific details on protected species records are provided

within the GIS database.

Figure 4 2 Otter record locations from walkover surveys



No plant species listed on the Flora (Protection) Order 1999 were recorded during the survey.

Bird Activity

The bird species recorded during the ecological surveys conducted in the Kilcoo Arterial Drainage Scheme are

detailed below.

Table 4-3: Bird Species Recorded in Kilcoo Arterial Drainage Scheme

Common Name Latin Name Comment on Location Recorded

Dipper Cinclus cinclus Several points throughout surveyed reach

Grey Heron Ardea cinerea Alongside the County river

4.3.3 Consultation Responses

The table below summarises the responses provided during the consultation phase undertaken as part of this

project in 2014. Where relevant, this information has been used to inform the Appropriate Assessment detailed

in section 5.3. No response was received from the IFI to date. Consultation is ongoing.

Table 4-5: Consultation Responses

Consultee Comment

NPWS There is unlikely to be kingfishers in the first 600m stretch of the river upstream from the

Bridge near Lough Melvin as the habitat is unsuitable, although there is uncertainty

regarding the habitat suitability elsewhere.

NPWS noted that there are quite a few mature oak and ash trees along the surveyed

section, and these should be left along with any other mature trees of other species.

Invasive species were not noted during NPWS visits to the river.

5. Appropriate Assessment

5.1 Introduction

The following chapter assesses the proposed drainage maintenance activities on those channels screened into the

assessment (see section 3) in relation to the European sites detailed in Section 4. AA Screening (2014) of impacts

on Lough Melvin SAC identified, one habitat potentially impacted by the project (Oligotrophic-mesotrophic

lakes). Since the publication of the Screening Report (2014), the SAC has been designated for one further Annex

I habitat (Molinia meadows), this habitat is included in the assessment of impact. Furthermore, the designation of

Lough Melvin in Northern Ireland is considered in this report, with regard the potential impact on the qualifying

interests and conservation objectives under its NI designation.

5.2 Identification of Potential Sources of Impact

This section further examines the “source > pathway > receptor” chains that could potentially result in adverse

impacts arising on the screened in European sites in the Kilcoo Arterial Drainage Scheme; this is informed primarily

by Ryan Hanley (2014c).

Table 3-1 details which of the possible pathways of impact (i.e. surface water, groundwater and land and air)

have been identified as potentially affecting the screened in European site.

Figure 3-4 illustrates which of the channels and structures within the Kilcoo Arterial Drainage Scheme are those

which could potentially impact upon the identified European sites and are consequently screened into the

assessment; all other channels and structures within the Kilcoo Arterial Drainage Scheme have been screened out

of the assessment.



Drainage Maintenance Activities include the following (to be carried out on all channels included within the

programme):

▪ A Silt and vegetation management

▪ E Tree cutting.

5.2.1 Potential Sources of Impact via Surface Water Pathways

One European site was identified as potentially being impacted upon by drainage maintenance activities via

surface water pathways; Lough Melvin SAC. All qualifying interests in the site are identified as potentially being

at risk from sources of impact via surface water pathways.

The following sources of impact are identified as potentially impacting upon the above Natura 2000 site through

surface water pathways:

▪ Release of suspended solids - this can arise from a variety of drainage maintenance activities, including

removal of in-stream silt and vegetation and tree cutting. It can impact on surface water dependent

habitats, such as the oligo-mesotrophic lake habitat, indirectly through increased turbidity, which can

reduce photosynthesis levels. This can then impact upon species within the lake (i.e. Otter and Salmon) by

reducing food availability through changed water quality. Adjoining grassland habitats may also be

impacted during flood and highwater conditions.

▪ Release or changes in nutrient levels - this can arise from a variety of drainage maintenance activities,

including removal of in-stream silt and vegetation and tree cutting. It can impact on surface water

dependent habitats indirectly through causing eutrophication. This can then impact upon species within

the lake (i.e. Otter and Salmon) by reducing food availability through changed water quality or

adjoining grassland habitats by increased nutrient deposition.

▪ Changes in water levels/channel morphology - this can arise from a variety of drainage maintenance

activities, including removal of in-stream silt and vegetation and tree cutting. It can occur from

maintenance activities that deepen and widen the channel back to the original design level. This can

impact on surface water dependent habitats, such as the oligo-mesotrophic Lough Melvin itself, through

increased capacity and flow in the channel leading to hydrological impacts. It can impact on Molinia

meadows by changes in groundwater and surface water available. It can also impact on the species for

which the SAC is designated for by causing a loss of suitable habitat and impacting upon food chains.



Table 5-1 Potential Sources of Impact via Surface Water Pathways

Potential Sources of Impact Vulnerable European Sites Applicable OPW Channels

Release of suspended solids

Release or changes in nutrient levels

Changes in water levels/channel morphology

Lough Melvin SAC C1

C2

C3

C4

C5

C6

Maintenance works on bridges and sluices located on the above channels are similarly considered to result in

potential adverse effects.

5.2.2 Potential Sources of Impact via Land and Air Pathways

One European site was identified as potentially being impacted upon via land and air pathways; Lough Melvin

SAC. All qualifying interests in the SAC were identified as potentially being at risk from sources of impact via

land and air pathways.

The following sources of impact are identified as potentially impacting upon the above European Site through

land and air pathways:

▪ Physical disturbance of habitats (and loss of wood vegetation cover) - this can arise from a variety

of drainage maintenance activities, including removal of in-stream silt and vegetation, branch cutting and

trimming, tree cutting and bridge and sluice maintenance. It can impact on habitats directly, although

temporarily, as a result of machines tracking along the bankside and as a result of the deposition of

spoil on the bankside. This can result in a loss of habitat from in-stream/bankside areas and maintenance

access corridors, direct mortalities or the displacement of sensitive species, such as Otter. It can also

impact on species through machines tracking along the banskide, reducing vegetation as a food source.

▪ Noise and visual disturbance - this can arise from a variety of drainage maintenance activities, including

removal of in-stream silt and vegetation, branch cutting and trimming, tree cutting and bridge and sluice

maintenance. It can occur as a result of noise emissions and visual disturbance from machinery and the

presence of machine drivers and other OPW staff at the site of works. It can result in the flight and

displacement of sensitive species from suitable habitat locations. It is not considered relevant in relation

to designated habitat types, although it is relevant for the species which these habitats support, such as

Otter and salmon for which Lough Melvin SAC is designated.

Table 5-2 Potential Sources of Impact via Land and Air Pathways

Potential Sources of Impact Vulnerable European Site Applicable OPW Channels

Physical disturbance of habitats (and loss of

wood vegetation cover)

Lough Melvin SAC C1

Maintenance works on bridges and sluices located on the above channels are similarly considered to result in

potential adverse effects.

5.2.3 Potential Sources of Impact via Groundwater Pathways

One European sites was identified as potentially being impacted upon via groundwater pathways; Lough Melvin

SAC. Two qualifying interests are identified as potentially being at risk from drainage maintenance activities via

this pathway; the oligo-mesotrophic lake habitat and Molinia Meadows habitat. The lake habitat is a surface



water dependent habitat with connectivity to groundwater, while Molinia meadows is a groundwater dependant

habitat. The Otter and Salmon populations for which this SAC is also designated are not identified as

groundwater dependent qualifying interests and will therefore not be impacted upon via groundwater pathways.

The following sources of impact are identified as potentially impacting upon the above European sites through

groundwater pathways:

The following sources of impact are identified as potentially impacting upon the above European sites through

groundwater pathways:

▪ Release of suspended solids - this can arise from a variety of drainage maintenance activities, including

removal of in-stream silt and vegetation, branch cutting and trimming, tree cutting and bridge and sluice

maintenance. It can impact on groundwater dependent habitats indirectly through increased turbidity,

which can reduce photosynthesis levels, which could impact on groundwater from aquifer recharge.

▪ Release or changes in nutrient levels - this can arise from a variety of drainage maintenance activities,

including removal of in-stream silt and vegetation, branch cutting and trimming, tree cutting and bridge

and sluice maintenance. It can impact on groundwater dependent habitats indirectly through causing

eutrophication (from mobile inorganics N03 and low mobility inorganics P04), which could impact on

groundwater from aquifer recharge.

▪ Changes in water levels/channel morphology - this can arise from a variety of drainage maintenance

activities, including removal of in-stream silt and vegetation, branch cutting and trimming, tree cutting

and bridge and sluice maintenance. It can also occur from maintenance activities that deepen and wide

the channel back to the original design level. This could impact on groundwater the dependent habitat

indirectly through:

▪ Increased capacity and flow in the channel leading to a reduction in water levels and

hydrogeological impacts.

▪ Lowering of water levels due to increased channel conveyance, which can increase the

hydraulic gradient between the bankside unconfined groundwater table. This can

potentially increase discharge to the channel and change the absolute value and pattern of

variation in groundwater levels and potentially the location of groundwater divides. The

distance from the channel at which an impact occurs is dependent on the subsoil and bedrock

aquifer characteristics.

Table 5-3 Potential Sources of Impact via Groundwater Pathways

Potential Sources of Impact Vulnerable Natura 2000 Site

Release of suspended solids

Release or changes in nutrient levels

Changes in water levels/channel morphology

Lough Melvin SAC

5.3 Impact Assessment

Table 5-4 assesses each of the screened in European sites in more detail and examines where potentially adverse

impacts may arise from the sources of impact identified above. Where potentially significant adverse impacts

are identified, avoidance and mitigation measures are proposed to offset these impacts.



5.3.1 Do nothing impact

Should the Kilcoo drainage works not be carried out at this site, it is likely that natural succession would occur

throughout the location. This is likely to include increased sedimentation in the channels over time, and increased

vegetation growth along channel edges and on the islands. Reduction in channel width due to increase size of

vegetated islands, may slow the flow of water and cause flooding in susceptible areas during periods of high

rainfall. Erosion occurring along the edge of the banks may contribute further to the sediment loading.

5.3.2 In-Combination Effects

Projects and Plans that have the potential to contribute in-combination impacts and cumulative impacts upon

European designated sites are considered in this section, as described in the Guidelines for the Assessment of

Indirect and Cumulative Impacts, as well as Impact Interactions (Walker and Johnston 1999). Key points to

consider when assessing cumulative and in-combination impacts include the nature and scale of the potential

impacts including their potential magnitude and significance, the availability and quality of data and the impacts

that may have occurred with similar projects in the area, where available or observed. Potential sources of in-

combination effects identified as part of this assessment include:

Agricultural activities: Farmers and landowners may also undertake general agricultural operations in areas

adjacent to the rivers and drainage ditches included in the proposed Kilcoo drainage maintenance works, which

could potentially give rise to impacts of a similar nature to those arising from the planned OPW works. This could

potentially result in additional periods of disturbance and a risk to water quality. Many agricultural operations

are periodic, not continuous in nature, and qualify as a Notifiable Action that requires consultation with NPWS in

advance of the works e.g. reclamation, infilling or land drainage within 30m of the river, removal of trees or any

aquatic vegetation within 30m of the river, and harvesting or burning of reed or willow (NPWS 2019).

Agricultural operations must also comply with the EC (Environmental Impact Assessment) (Agriculture) Regulations

2011 and amendment 2017 S.I. No. 456/2011 and 407/2017 in relation to activities covered by the

regulations:

▪ restructuring of rural land holdings,

▪ commencing use of uncultivated land or semi-natural areas for intensive,

▪ land drainage works on lands used for agriculture.

A NIS is required under Regulation 9 if it is likely to have a significant effect on a Natura 2000 site. The drainage

or reclamation of wetlands is controlled under the Planning and Development (Amendment) (No. 2) Regulations

2011 and the European Communities (Amendment to Planning and Development) Regulations 2011. Therefore,

the in-combination effects of the proposed works and agricultural operations is not likely to be significant.

OPW arterial drainage maintenance operations: Maintenance operations have been ongoing since the

construction of the schemes following the 1945 Arterial Drainage Act, potentially resulting in adverse cumulative

effects. However, as the maintenance operations are undertaken to restore the design level only, the hydrological

and hydrogeological impact should be no greater than originally occurred upon the scheme's construction; no

further deepening or widening will occur. On a regional scale, neighbouring Arterial Drainage Schemes could be

considered to have an adverse impact on European sites, particularly where large sites fall across two, or more

scheme areas. However, this is not considered to be an issue for the Kilcoo Scheme works. The closest schemes

are on the Duff and River Bonet, Co. Leitrim. The Kilcoo Scheme is within a separate surface water catchment and

separate groundwater body so the potential for adverse in-combination impacts are minimal. Thus, the potential

for adverse in-combination impacts from either of these schemes are minimal. Appropriate Assessment screening

exercises have been conducted for both the Bonet and Duff schemes (JBA Consulting, 2014b and 2014c). Neither

screening exercise for the Bonet or Duff identified likely significant effects on Lough Melvin SAC. As no adverse



impacts will arise on this site from works in the Bonet and Duff drainage schemes no cumulative or in-combination

effects with works in the Duff scheme can arise.

The Leitrim County Development Plan 2015-2021 aims to adopt a precautionary principle in respect of

development proposal where significant environmental implications are involved and recognise the importance

of Leitrim’s natural heritage. A NIR was completed for the Plan identifying threats to the SAC and objectives of

the plan which have potential impact on the protection of Lough Melvin SAC. Cumulative and in combination

effects were also considered in relation to other plans and programmes of relevance as set out in the NIR of the

CDP. Therefore, considering the Plan and Measures included to the CDP to prevent impact, it was found that no

direct, indirect or cumulative significant effects on the Natura 2000 network of sites or its integrity were likely to

occur.

The River Basin Management Plan for Ireland 2018-2021 sets out the actions that Ireland will take to improve

water quality and achieve ‘good’ ecological status in water bodies (rivers, lakes, estuaries and coastal waters)

by 2027. The County River has been classified as "Probably at risk", however the River Basin Management Plan

for Ireland 2018-2021 aims to improve the management and water quality of the Border Region Catchments.

Therefore, the plans outlined above would not significantly adversely impact on the European sites in combination

with the proposed arterial drainage maintenance works.



Table 5-4 Impact Prediction

Site Name

(site code)

Qualifying Interests/

Special Conservation

Interests

Potential

Source of

Impact

Pathway Impact on Attribute and Target Prior to

Mitigation / Avoidance 1

Avoidance /

Mitigation Measures

Residual

Impact

Lough

Melvin

SAC

(ROI

000428)

(NI

UK0030047)

Salmon Salmo salar

Otter Lutra lutra

Molinia meadows on

calcareous peaty or

clayey-silt-laden

soils (Molinia

caeruleae)

Oligotrophic to


waters with

vegetation of the


and/or of the

IsoëtoNanojuncetea

Physical disturbance of habitats (and loss

of wood

vegetation

cover)

Land and Air Physical disturbance can impact on habitat-

related attributes for oligo-mesotrophic waters,

primarily in relation to habitat area and

vegetation composition. Where works encroach

into lake habitats on the margins of Lough Melvin

physical disturbance may occur, which could

impact locally on habitat area and vegetation

composition. However, as identified by the

ecological survey, Lough Melvin at the location

where the County River connects was considered

to be a eutrophic lake (FL5) and not

representative of an acidoligotrophic lake (FL4)

at this location.

Physical disturbance can also impact on habitat-

related attributes for Molinia meadows in relation

to habitat area and vegetation composition.

Where works or access routes encroach into

Molinia meadow habitats physical disturbance

may occur, which could impact locally on habitat

area and vegetation composition. However, as

identified by the ecological survey, no Molinia

meadow habitats were identified along the

channels where works are proposed.

Drainage maintenance activities can also result in

physical disturbance impacts to Salmon

populations via land and air pathways, primarily

Where protected habitats and species are present, limit works and physical disturbance to prevent deterioration of supporting habitat, prevent deterioration of protected habitats and prevent unnecessary impact to protected species that depend on both protected and unprotected habitats. Follow Environmental Procedures in OPW (2019) - specifically EP7 Environmental Drainage Maintenance including; Carrying out maintenance in compliance with the 10-point plan for protecting bank slopes, restricting maintenance to channel, spoil management, selective vegetation removal, leaving sections untouched, management of trees, management of berms, replacement of stones and boulders and working in gravel bed channels EP19 Salmon including; Programme instream maintance works on salmonoid channels between July and September with IFI consultation, rake spawning gravels, protect or enhance river enhancement works, consideration of fish passage with regard to temporary or new

No



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

through impacting upon the number and

distribution of redds through in-stream working

which can result in their removal/damage.

Similarly, physical disturbance can impact on

Otter through reducing the extent of habitat

(terrestrial, river, or lake) and availability of

couching or holt sites (Otters need lying up areas

throughout their territory where they are secure

from disturbance; NPWS, 2012). Removal of

woody vegetation along the river corridor, along

with riparian and in-channel vegetation, can

make a watercourse less optimal for Otter,

potentially displacing them from a particular

location. However, given that maintenance

activities are conducted along watercourses that

have been periodically subject to such activities,

and that the bank of operation remains consistent,

there will be a working corridor along the

channels which has been subject to periodic

physical disturbance. The habitats supporting

Otter and Salmon populations are also subject to

regular periods of maintenance and there will be

a period of habitat recovery upon completion of

an activity within which species will re-colonise

areas they have potentially been displaced from.

structures and manage construction pollution EP20 Otter including; A walkover of the works area in advance, recording areas of dense cover or new burrows. Consult with ecologist and cut dense vegetation by hand to reduce disturbance. Works should follow those as describes in guidance under the Silt Management EP10, including but not limited to working upstream, skipping sections and leaving buffer zones both instream and along the banks. Machinery Related Procedures should be followed to include leaving a natural vegetation buffer strip along the bank Follow EP 9 for Tree Management Procedures, particularly when removing fallen trees and clearing Machine Access Corridor to minimise physical disturbance during the works.

See Table 6-1

Drainage maintenance works will

not encroach into the Molinia



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

meadows or acid-oligotrophic

waters of Lough Melvin itself to limit

physical disturbance to this habitat

type.

Salmon Salmo salar

Otter Lutra lutra

Noise and

visual

disturbance

Land and Air Both Otter and Salmon are sensitive species that

can be disturbed by the noise and movements

created by certain activities, such as drainage

maintenance operations, which can displace these

species from a particular location. This could

impact on the distribution of a species in a

particular area. However, drainage maintenance

operations are undertaken on a periodic basis

and only generate noise and visual disturbance

on a short-term, temporary basis. Consequently,

whilst these species may be displaced from a

working area during the actual period of works,

they are unlikely to be permanently displaced

and so no long-term significant impacts are likely

on these species as a result of drainage

maintenance operations.

Follow Environmental Procedures in OPW (2019) specifically EP7 Environmental Drainage Maintenance including; Carrying out maintenance in compliance with the 10-point plan for protecting bank slopes, restricting maintenance to channel, spoil management, selective vegetation removal, leaving sections untouched, management of trees, management of berms, replacement of stones and boulders and working in gravel bed channels EP19 Salmon including; Programme instream maintance works on salmonoid channels between July and September with IFI consultation, rake spawning gravels, protect or enhance river enhancement works, consideration of fish passage with regard to temporary or new structures and manage construction pollution EP20 Otter including; A walkover of the works area in advance, recording areas of dense cover or new burrows. Consult with



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

ecologist and cut dense vegetation by hand to reduce disturbance.

See Table 6-1

Salmon Salmo salar

Otter Lutra lutra

Molinia meadows on

calcareous peaty or

clayey-silt-laden

soils (Molinia

caeruleae)

Oligotrophic to


waters with

vegetation of the


and/or of the

IsoëtoNanojuncetea

Release of

suspended

solids

Surface

Water

It is a target for some SAC watercourses

supporting Salmon populations that water quality

is at least Q4 at all sites sampled by EPA.

Drainage maintenance operations can result in

the release of suspended sediments and nutrients

which could reduce water quality and result in the

target for this attribute not being met. Whilst

there are no specific water quality attributes

relating to Otter, available fish biomass is an

attribute used to assess the conservation status of

Otter populations (NPWS, 2012); water quality

can be adversely impacted upon by drainage

maintenance activities through the release of

suspended solids and nutrients and this could

impact on fish populations upon which Otter feed.

Molinia meadows are nutrient dependant but are

not surface water dependant, they are ground

water dependant and not impacted by surface

water nutrient status.

Oligo-mesotrophic waters are also sustained by

a specific water quality and trophic status, which

is a key aspect of their conservation importance.

The release of suspended sediments or nutrients

Follow Environmental Procedures in OPW (2019) - specifically EP7 Environmental Drainage Maintenance including; Carrying out maintenance in compliance with the 10-point plan for protecting bank slopes, restricting maintenance to channel, spoil management, selective vegetation removal, leaving sections untouched, management of trees, management of berms, replacement of stones and boulders and working in gravel bed channels EP19 Salmon including; Programme instream maintance works on salmonoid channels between July and September with IFI consultation, rake spawning gravels, protect or enhance river enhancement works, consideration of fish passage with regard to temporary or new structures and manage construction pollution EP20 Otter including; A walkover of the works area in advance, recording areas of dense cover or new burrows. Consult with

No

Release or

changes in

nutrient levels



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

as a result of drainage maintenance activities

could adversely impact on water quality of the

lake habitats, which could then impact on habitat

area and vegetation composition.

ecologist and cut dense vegetation by hand to reduce disturbance.

EP17 Water Pollution including;

Monitoring the weather forecast

during all works, isolate the works

area from aquatic environment

where possible, ensure measures are

taken to prevent cement or concrete,

fuel or oil entering waterbody, store

and remove wastewater from site

Works should follow those as

describes in guidance under the Silt

Management EP 10, including but

not limited to working upstream,

skipping sections and leaving buffer

zones both instream and along the

banks. Machinery Related

Procedures should be followed to

include no refuelling within 50m of a

watercourse, use of biodegradable

oils, ensure availability of spill kits

and leave natural vegetation buffer

strip along the bank.

See Table 6-1

The above measures will control

sediment mobilisation and reduce

the risk of pollution incidents thereby

reducing the potential significance of



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

this source dependent habitats within

this SAC.

Changes in

water

levels/channel

morphology

Surface

Water

Oligo-mesotrophic lake habitats are dependent

on a

specific hydrological regime to ensure their

conservation status. Drainage maintenance

activities can impact on hydrological regime

attributes and could cause changes in water levels

which could then impact on habitat area and

vegetation composition. Changes in water levels

and channel morphology as a result of drainage

maintenance operations within scheme

watercourses could also impact upon the riparian

and in-channel habitats that support Otter and

Salmon populations.

Follow Environmental Procedures in OPW (2019) - specifically EP7 Environmental Drainage Maintenance including; Carrying out maintenance in compliance with the 10-point plan for protecting bank slopes, restricting maintenance to channel, spoil management, selective vegetation removal, leaving sections untouched, management of trees, management of berms, replacement of stones and boulders and working in gravel bed channels EP19 Salmon including; Programme instream maintance works on salmonoid channels between July

No



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

Molinia meadows habitats are dependent on

groundwater and a specific hydrological regime

to ensure their conservation status. Drainage

maintenance activities can impact on hydrological

regime attributes and could cause changes in

water levels which could then impact on habitat

area and vegetation composition.

Changes in water levels and channel morphology

as a result of drainage maintenance operations

within scheme watercourses could also impact

upon the riparian and in-channel habitats that

support Otter and Salmon populations. Whilst no

attributes specifically relating to water levels are

available for Salmon, changes to channel

morphology could impact upon the number and

distribution of redds. For Otter, changes to water

levels/channel morphology could impact on the

extent of freshwater habitat available, and

potentially the availability of fish biomass.

However, significant changes to the hydrological

regime are unlikely as the works will restore the

system to the design standard only. The drainage

maintenance activates are therefore unlikely to

impact significantly on habitat area, vegetation

composition or hydrological regime of the

qualifying interests.

and September with IFI consultation, rake spawning gravels, protect or enhance river enhancement works, consideration of fish passage with regard to temporary or new structures and manage construction pollution EP20 Otter including; A walkover of the works area in advance, recording areas of dense cover or new burrows. Consult with ecologist and cut dense vegetation by hand to reduce disturbance.



Management EP 10.

The above measures will control

sediment mobilisation and reduce the

risk of pollution incidents thereby

reducing the potential significance of

this source dependent habitats within

this SAC. See Table 6-1

This will ensure that drainage

maintenance works do not change

water levels/channel morphology

beyond the existing design level,



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

which has been in existence since

1971.

Molinia meadows on

calcareous peaty or

clayey-silt-laden

soils (Molinia

caeruleae)

Oligotrophic to


waters with

vegetation of the


and/or of the

IsoëtoNanojuncetea

Release of

suspended

solids

Groundwater Oligo-mesotrophic waters are sustained by a

specific water quality and trophic status, which is

a key aspect of their conservation importance.

The release of sediment and/or nutrients as a

result of drainage maintenance activities could

adversely impact on water quality of the lake

habitats if groundwaters which are connected to

the lake habitat become contaminated through

aquifer recharge. This could then impact on

habitat area and vegetation composition

attributes.

Molinia meadows influenced by a specific ground

water quality and trophic status, which is a key

aspect of their conservation importance. The

release of sediment and/or nutrients as a result

of drainage maintenance activities could

adversely impact on groundwaters which are

connected to the grasslands that become

contaminated through aquifer recharge. This

could then impact on habitat area and

vegetation composition attributes

Surface water and groundwater

pathway connections are not always

obvious. In order to prevent impact

to this habitat from the release of

suspended solids, changes in nutrient

levels/ pollutants.

Follow Environmental Procedures in OPW (2019) - specifically EP7 Environmental Drainage Maintenance including; Carrying out maintenance in compliance with the 10-point plan for protecting bank slopes, restricting maintenance to channel, spoil management, selective vegetation removal, leaving sections untouched, management of trees, management of berms, replacement of stones and boulders and working in gravel bed channels EP19 Salmon including; Programme instream maintance works on salmonoid channels between July and September with IFI consultation, rake spawning gravels, protect or enhance river enhancement works, consideration of fish passage with regard to temporary or new

No

Release or

changes in

nutrient

levels



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

structures and manage construction pollution EP20 Otter including; A walkover of the works area in advance, recording areas of dense cover or new burrows. Consult with ecologist and cut dense vegetation by hand to reduce disturbance.



Management EP 10, including but

not limited to working upstream,

skipping sections and leaving buffer

zones both instream and along the

banks. Machinery Related

Procedures should be followed to

include no refuelling within 50m of a

watercourse, use of biodegradable

oils, ensure availability of spill kits

and leave natural vegetation buffer

strip along the bank.

EP17 Water Pollution including;

Monitoring the weather forecast

during all works, isolate the works

area from aquatic environment

where possible, ensure measures are

taken to prevent cement or concrete,



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

fuel or oil entering waterbody, store

and remove wastewater from site

See Table 6-1. The above measures

will control sediment mobilisation

and reduce the risk of pollution

incidents thereby reducing the

potential significance of this source

of impact on the groundwater

dependent habitats within this SAC

Changes in

water

levels/channel

morphology

Oligo-mesotrophic lake habitats and Molinia

meadows are dependent on a specific

hydrological regime to ensure their conservation

status. As this habitat type has connectivity to

groundwater, drainage maintenance activities

can impact on hydrogeological regime which

could then impact on water levels within the lake,

which could then impact on attributes such as

habitat area and vegetation composition.

However, works in the Kilcoo scheme are

upstream of the Oligo-mesotrophic lake and,

given the likely resilience of this large waterbody,

drainage maintenance activities will not impact on

any regional groundwater flow pathways into the

lake, nor the stage of the lake. As works are

confined to the County River and no adjoining

Molinia habitat was identified, significant changes

Follow Environmental Procedures in OPW (2019) - specifically EP7 Environmental Drainage Maintenance including; Carrying out maintenance in compliance with the 10-point plan for protecting bank slopes, restricting maintenance to channel, spoil management, selective vegetation removal, leaving sections untouched, management of trees, management of berms, replacement of stones and boulders and working in gravel bed channels EP19 Salmon including; Programme instream maintance works on salmonoid channels between July and September with IFI consultation, rake spawning gravels, protect or enhance river enhancement works,

No



Site Name

(site code)



Interests

Potential

Source of

Impact



Avoidance /

Mitigation Measures

Residual

Impact

to the hydrogeological regime are unlikely as the

works will restore the system to the design

standard only. Significant impacts on attributes

including habitat area, vegetation composition or

hydrological regime are therefore unlikely.

consideration of fish passage with regard to temporary or new structures and manage construction pollution EP20 Otter including; A walkover of the works area in advance, recording areas of dense cover or new burrows. Consult with ecologist and cut dense vegetation by hand to reduce disturbance. See Table 6-1

This will ensure that drainage

maintenance works do not change

water levels/channel morphology

beyond the existing design level,

which has been in existence since

1971.



6. Avoidance and Mitigation Measures

6.1 Introduction

The Environmental Guidance and Eps developed by OPW (2019) are routinely followed by OPW operational

staff undertaking drainage maintenance works and help to provide a baseline level of environmental protection,

with a specific focus on certain species (i.e. Brook, River and Sea Lamprey, White-clawed Crayfish, Otter,

Freshwater Pearl Mussel, invasive species and Zebra Mussel) and habitats (woodlands, wetlands). In addition to

the measures contained within these documents, Table 6-1 provides specific avoidance and mitigation measures

that should be followed in order to offset the identified potential impacts on European sites.

Table 6-1: Specific Mitigation Measures

Potential Impact Applicable OPW

Channels Avoidance and Mitigation Measures2

Release of suspended

solids

All channels

EP 7 Environmental Drainage Maintenance, EP 9 Tree and

Vegetation Management. Follow EP’s 14 – 17.

When removing aquatic vegetation instream, maximise the

use of a weed-cutting bucket where possible to minimise the

amount of silt being disturbed/suspended into the water

column from the river substrate or bank.

All aquatic vegetation or branch cuttings shall be removed

from the channel and the channel bank and placed in an

area where they cannot re-enter the water

Release or changes in

nutrient levels

Changes in water

levels/ channel

morphology

All channels


Vegetation Management and EP 31 Wetlands:

Given that the works taking place along the channel involve

the removal of instream vegetation and silt, which will

ultimately result in increased instream flow capacity

potentially effecting the groundwater levels within the Lough

Melvin SAC; it is of particular importance that works strictly

adhere to Steps 2.1 - 2.3 of EP 7 Environmental Drainage

Maintenance. By retaining marginal vegetation alongside the

channel, a partial canopy shading of the channel is

maintained reducing excessive evapotranspiration from the

channel, and thus preventing any unnecessary water loss from

the area. Additionally, Step 5. of EP 7, will be implemented

along certain sections of the channel in order to mitigate

against excessive draining of sensitive groundwater

dependent habitats. Due to the low permeability of the

subsoils that surround the river waterbody and the distance

between the river waterbody and the groundwater aquifer,

localised removal of silts and vegetation will not significantly

increase the discharge of groundwater to the river channel.

Any impact on groundwater levels will be very localised and

confined to within the subsoils layers and will not impact on

the bedrock aquifer. The impact on the groundwater within



Potential Impact Applicable OPW

Channels Avoidance and Mitigation Measures2

the Lough Melvin SAC will therefore not be significant and

groundwater dependent qualifying interests such as

Oligotrophic to mesotrophic standing waters with vegetation

of the Littorelletea uniflorae and/or Isoeto-Nanojuncetea will

not be impacted by the works. For more information see

Appendix B.

Physical disturbance of

habitats (and loss of

wood vegetation

cover)

All

channels


Vegetation Management, EP 25 Birds and EP 31 Wetlands:

The site layout and activities will be designed in such a

manner that the sensitive habitat (Molinia meadows) will be

excluded from all foot traffic, machinery access and activity.

Works and access will be restricted to the existing

maintenance access corridor. Drainage maintenance works

will not encroach into the oligotrophic waters of Lough Melvin

itself to limit physical disturbance to this habitat type.

Where general maintenance works are required, works will

not take place within 30m of an Otter holt. Where

construction works are required a buffer of 150m applies

and the need for a derogation licence considered within this

zone. EP20

In relation to non-breeding holts, no wheeled or tracked

vehicles will be permitted within 20m of active holts or scrub

clearance by hand within 15m.

Noise and visual

disturbance

All channels Works and access will be restricted to the existing

maintenance access corridor.

1 Maintenance works on bridges and sluices located on the above channels are also subject to the detailed

mitigation/avoidance measures.

2 It should be noted that these avoidance and mitigation measures are required in addition to those standard

practices detailed in the OPWs Environmental Guidance: Drainage Maintenance &Construction (OPW, 2019).

6.2 Mitigation for Other Ecological Receptors

The ecological walkover surveys (see Section 4.3) identified a number of other potential ecological constraints to

arterial drainage maintenance works, for which European sites are not designated, which should be taken into

account during maintenance operations. Table 6-2 details proposed mitigation measures to offset impacts on

these identified receptors.



Table 6-2 Specific Mitigation Measures for other Ecological Receptors

Receptor

Applicable

OPW

Channels

Specific Avoidance and Mitigation Measures1

Trout

All channels

Refuelling will not be undertaken within 50m of a watercourse.

Avoid closed season for Salmonids (October-April) in relation to in-stream silt and

vegetation management on channels with salmonid spawning habitat.

Where Salmonids are absent, undertake in-stream removal of silts and gravels

in an upstream direction for lamprey and crayfish. Where Salmonids are present,

undertake in-stream removal of silts in a downstream direction allowing solids to

settle out naturally and/or become trapped in vegetation.

In relation to structural maintenance activities, spawning gravels located

downstream of the structure will be tossed post completion of works to remove

any silts present.

Lamprey

species

Bats All masonry

bridges

Where masonry bridges require maintenance, a bat roost potential assessment

will be conducted in advance of works as per EP4 Where bridges are identified

as being of moderate or above suitability for roosting, nocturnal activity surveys

may then be required.

The bat survey and mitigation measures will be in full accordance with Bat

Mitigation Guidelines for Ireland (Irish Wildlife Manual No. 25).

Nesting Birds All channels

For the protection of resident birds during the bird nesting season 1st March to

the 31st August, EP 24 and 25 in relation to Birds will be deployed to protect

riverbank vegetation and species during woody vegetation cutting.

Prior to work on bridges the potential for nesting birds to be present, in particular

Sand Martin and Dipper, will be taken into account as per EP4. The incorporation

of holes and ledges will be considered in the design of repairs and replacement

structures as they can provide potential nesting habitat for bird species.

Fox and

Badger All channels

A buffer of 30m in relation to the use of plant machinery will be deployed on

Badger setts to allow for associated tunnels. Fox dens are often also used by

badgers and the same standard should apply.

Mature trees All channels Avoid removal where possible. Mature tree species along the river bankside

habitats will be left in situ if feasible.

1It should be noted that these avoidance and mitigation measures are required in addition to those standard

practices detailed in the OPWs Environmental Guidance: Drainage Maintenance &Construction (OPW, 2019).,

in particular Section 4 – Animal and Plant Procedures

6.3 Mitigation for Bridge/Structure Works

As discussed in section 2.4 it is currently unknown where and when structural drainage maintenance operations

will be required in relation to bridges. This Natura Impact Statement considers the potential impact of

maintenance operations on bridges and other structures on those watercourses screened into the assessment (see

Figure 3-4 and JBA Consulting, 2014a). To ensure that adverse impacts do not arise on European sites and other

protected species as a result of structural maintenance operations undertaken during the period 2020-2024, the

EP 4 will be complied with and the Foreman Bridge Inspection Report filled out. The environmental procedures

outlined in EP’s 14, 15, 16 & 17 will also be applied as necessary.



7. Conclusions

This Natura Impact Statement details the findings of the Stage 2 Appropriate Assessment conducted to further

examine the potential direct and indirect impacts of proposed drainage maintenance works in the Kilcoo Arterial

Drainage Scheme on the following European sites:

▪ Lough Melvin SAC

▪ ROI designation 000428

▪ NI designation UK0030047

The above sites were identified by a screening exercise that identified likely significant effects in relation to the

above sites. This screening exercise was conducted following the methodology outlined in Ryan Hanley (2014a),

which examines three “source > pathway > receptor” chains; surface water, land and air, and groundwater

pathways.

The Appropriate Assessment investigated the potential direct and indirect impacts of the proposed works on the

integrity and interest features of the above European sites, alone and in combination with other plans and

projects, taking into account the site's structure, function and conservation objectives. The three pathways of

potential impact were again used as a framework of assessment.

Where potentially significant adverse impacts were identified, a range of mitigation and avoidance measures

have been stipulated to help offset them.

As a result of this Appropriate Assessment it has been concluded, that the avoidance and mitigation measures

suggested, the proposed drainage maintenance operations in the Kilcoo Arterial Drainage Scheme will not have

a significant adverse impact on the above European sites.

To confirm this conclusion, the following checklist, taken from DEHLG (2009) has been completed.

Table 7-1: Integrity of Site Checklist (From: DEHLG, 2009)

Conservation objectives: does the project

or plan have the potential to:

Y/N

Cause delays in progress towards

achieving the conservation objectives of the

sites?

N - Following mitigation, no significant adverse residual impacts

have been identified that will prevent achievement of the

conservation objectives of the identified sites.

Interrupt progress towards achieving the

conservation objectives of the sites?

N - Following mitigation, no significant adverse residual impacts

have been identified that will prevent achievement of the

conservation objectives of the identified sites.

Disrupt those factors that help to maintain

the favourable conditions of the site?

N - Potential adverse impacts identified during the screening

process can be mitigated against.

Interfere with the balance, distribution and

density of key species that are the

indicators of the favourable condition of

the site?

N - Potential adverse impacts on the Salmon and Otter

populations of Lough Melvin SAC can be avoided by

appropriate timing of the maintenance works and avoiding

working in appropriate buffer zones for sensitive locations.



Conservation objectives: does the project

or plan have the potential to:

Y/N

Cause changes to the vital defining aspects

(e.g. nutrient balance) that determine how

the site functions as a habitat or ecosystem?

N - Potential adverse impacts from suspended solids and

nutrient release can be effectively mitigated.

Change the dynamics of the relationships

(between, for example, soil and water or

plants and animals) that define the

structure and/or function of the site?

N - Potential adverse impacts relating to hydrological status

and water quality have been identified which could impact on

the functioning and dynamics of the site however these can be

effectively mitigated.

Interfere with predicted or expected

natural changes to the site (such as water

dynamics or chemical composition)?

N - Potential adverse impacts from changes to the

hydrological regime, suspended solids and nutrient release can

be effectively mitigated.

Reduce the area of key habitats? N - Potential adverse impacts on SAC habitats can be

effectively mitigated to ensure no loss of key habitats.

Reduce the population of key species? N - Potential disturbance impacts Otter and Salmon

populations can be effectively mitigated to ensure populations

are not reduced. Mitigation can also be implemented to protect

populations of key species present, but for which the SAC is not

designated (e.g. bats, Badger, Lamprey, eel).

Change the balance between key species? N - Potential disturbance impacts to Otter and Salmon

populations can be effectively mitigated to ensure population

dynamics are not adversely affected. Mitigation can also be

implemented to protect populations of key species present, but

for which the SAC is not designated (e.g. bats, Badger,

Lamprey, eel).

Reduce diversity of the site? N - The identified mitigation measures to protect designated

habitats and species will ensure that the current diversity of the

sites is maintained.

Result in disturbance that could affect

population size or density or the balance

between key species?

N - Potential disturbance impacts to Otter and Salmon

populations can be effectively mitigated to ensure populations

are not reduced. Mitigation can also be implemented to protect

populations of key species present, but for which the SAC is not

designated (e.g. bats, Badger, Lamprey, eel).

Result in fragmentation N - The proposed works will be undertaken along existing

maintenance access corridors and therefore no fragmentation

will occur.

Result in loss or reduction of key features

(e.g. tree cover, tidal exposure, annual

flooding etc.)?

N - Potential adverse impacts on SAC habitats can be

effectively mitigated to ensure no loss of or reduction of key

features.


Natura Impact Statementl

References

Brew, T., Gilligan, N., 2019, Environmental Guidance: Drainage Maintenance and Construction. Series

of Ecological Assessments on Arterial Drainage Maintenance No 13. Environment Section, Office of

Public Works, Trim, Co. Meath, Ireland.

Department of Environment, Heritage and Local Government (2009) Appropriate Assessment of Plans

and Projects in Ireland - Guidance for Planning Authorities

DOENI (2015) Lough Melvin Sac Conservation Objectives https://www.daera-

ni.gov.uk/sites/default/files/publications/doe/land-information-lough-melvin-conservation-objectives-

2015.pdf

Fossitt, J.A. (2000) A Guide to Habitats in Ireland. The Heritage Council, Dublin

JBA Consulting (2014a) Duff Arterial Drainage Scheme: Stage 1 Appropriate Assessment Screening.

Unpublished Report.

JBA Consulting (2014b) Bonet Arterial Drainage Scheme: Stage 1 Appropriate Assessment Screening.

Unpublished Report.

JBA Consulting (2014c) Kilcoo Arterial Drainage Scheme: Stage 1 Appropriate Assessment Screening.

Unpublished Report.

JNCC (2016) Natura 2000 – Standard Data Form Lough Melivn UK30047 https://jncc.gov.uk/jncc-

assets/SAC-N2K/UK0030047.pdf

JNCC (2014) Annex I Habitat Accounts.

http://jncc.defra.gov.uk/ProtectedSites/SACselection/SAC_habitats.asp [accessed: 11th September

2019]

Kelleher, C. and Marnell, F. (2006) Bat Mitigation Guidelines for Ireland. Irish Wildlife Manuals, No.

25. National Parks and Wildlife Service, Department of Environment, Heritage and Local Government,

Dublin, Ireland.

Kilroy, G., Dunne, F., Ryan, J., O'Connor, A., Daly, D., Craig, M., Coxon, C., Johnston, P. and Moe, H.

(2008) A Framework for the Assessment of Groundwater – Dependent Terrestrial Ecosystems under the

Water Framework Directive. Environmental Protection Agency.

NPWS (2019a). The Status of EU Protected Habitats and Species in Ireland. Volume 1: Summary

Overview.

Unpublished NPWS report. Available at https://www.npws.ie/sites/default/files/publications/pdf/N

PWS_2019_Vol1_Summary_Article17.pdf [accessed: 11th September 2019]

NPWS (2019b). The Status of EU Protected Habitats and Species in Ireland. Volume 2: Habitat

Assessments.


PWS_2019_Vol2_Habitats_Article17.pdf [accessed: 11th September 2019]

NPWS (2019c). The Status of EU Protected Habitats and Species in Ireland. Volume 3: Species

Assessments.


PWS_2019_Vol3_Species_Article17.pdf [accessed: 11th September 2019]

NPWS (2018) Conservation Objectives for Lough Melvin SAC (000428)

https://www.npws.ie/sites/default/files/protected-sites/conservation_objectives/CO000428.pdf

[accessed: 11th September 2019]

https://www.daera-ni.gov.uk/sites/default/files/publications/doe/land-information-lough-melvin-conservation-objectives-2015.pdf



https://jncc.gov.uk/jncc-assets/SAC-N2K/UK0030047.pdf

https://jncc.gov.uk/jncc-assets/SAC-N2K/UK0030047.pdf

http://jncc.defra.gov.uk/ProtectedSites/SACselection/SAC_habitats.asp

https://www.npws.ie/sites/default/files/publications/pdf/NPWS_2019_Vol1_Summary_Article17.pdf

https://www.npws.ie/sites/default/files/publications/pdf/NPWS_2019_Vol1_Summary_Article17.pdf

https://www.npws.ie/sites/default/files/publications/pdf/NPWS_2019_Vol2_Habitats_Article17.pdf

https://www.npws.ie/sites/default/files/publications/pdf/NPWS_2019_Vol2_Habitats_Article17.pdf

https://www.npws.ie/sites/default/files/publications/pdf/NPWS_2019_Vol3_Species_Article17.pdf

https://www.npws.ie/sites/default/files/publications/pdf/NPWS_2019_Vol3_Species_Article17.pdf

https://www.npws.ie/sites/default/files/protected-sites/conservation_objectives/CO000428.pdf


Natura Impact Statement

NPWS (2017a) Arroo Mountain SAC Natura 2000 Data Form.

https://www.npws.ie/sites/default/files/protected-sites/natura2000/NF001403.pdf [accessed: 11th

September 2019]

NPWS (2017b) Ben Bulben, Gleniff and Glenade Complex SAC Natura 2000 Data Form.

https://www.npws.ie/sites/default/files/protected-sites/natura2000/NF000623.pdf [accessed 11th

September 2019]

NPWS (2017c) Lough Melvin SAC Natura 2000 Standard Data form

https://www.npws.ie/sites/default/files/protected-sites/natura2000/NF000428.pdf [accessed: 11th

September 2019]

NPWS (2016a) Arroo Mountain SAC Site Synopsis. https://www.npws.ie/sites/default/files/protected-

sites/synopsis/SY001403.pdf [accessed: 11th September 2019]

NPWS (2016b) Ben Bulben, Gleniff and Glenade Complex SAC Site

Synopsis. https://www.npws.ie/sites/default/files/protected-sites/synopsis/SY000623.pdf [accessed:

11th September 2019]

NPWS (2016c) Bunduff Lough and Machair/ Trawalua/ Mullaghmore SAC Site Synopsis.

https://www.npws.ie/sites/default/files/protected-sites/synopsis/SY000625.pdf [accessed: 11th

September 2019]

NPWS (2016d) Conservation Objectives: Arroo Mountain SAC 001403. Version 1. National Parks and

Wildlife Service, Department of Arts, Heritage, Regional, Rural and Gaeltacht Affairs. [accessed: 11th

September 2019]

NPWS (2016e) Arroo Mountain SAC Site Synopsis. https://www.npws.ie/sites/default/files/protected-

sites/synopsis/SY001403.pdf. [accessed: 13th September 2019]

NPWS (2016f) Conservation Objectives: Caha Mountains SAC 000093. Version 1. National Parks and

Wildlife Service, Department of Arts, Heritage, Regional,Rural and Gaeltacht Affairs.

NPWS (2016f) Site Synopsis Lough Melvin SAC 00428

https://www.npws.ie/sites/default/files/protected-sites/synopsis/SY000428.pdf [accessed: 13th

September 2019]

NPWS (2012a) Conservation Objectives: Lower River Shannon SAC 002165. Version 1.0. National

Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht. Available at

https://www.npws.ie/sites/default/files/protected-sites/conservation_objectives/CO002165.pdf.

[accessed: 11th September 2019]

NPWS (2012b) Lower River Shannon SAC 002165. Conservation Objectives Supporting Document

Water courses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion

vegetation (habitat code 3260). National Parks and Wildlife Service, Department of Arts, Heritage and

the Gaeltacht. Available

at https://www.npws.ie/sites/default/files/publications/pdf/002165_Lower%20River%20Shannon%

20SAC%20Water%20Courses%20Supporting%20Doc_V1.pdf. [accessed: 18th September 2019]

OPW (2014) The Office of Public Works Arterial Drainage Maintenance Activities 2014: Duff Arterial

Drainage Scheme Natura Impact Statement (NIS). Unpublished Report.

OPW (2007) Ecological Impact Assessment (EcIA) of the Effects of Statutory Arterial Drainage

Maintenance Activities on Water Courses of Plain to Montane levels with Aquatic Vegetation (Floating

River Vegetation).

http://www.opw.ie/media/Issue%20No.%205%20EcIA%20floating%20river%20vegetation.pdf

[date accessed 20th September 2019]

https://www.npws.ie/sites/default/files/protected-sites/natura2000/NF001403.pdf


http://www.npws.ie/media/npwsie/content/images/protectedsites/natura2000/NF000623.pdf%20accessed%2022nd%20September%202014




http://www.npws.ie/media/npwsie/content/images/protectedsites/sitesynopsis/SY000623.pdf



https://www.npws.ie/sites/default/files/protected-sites/synopsis/SY000428.pdf


Natura Impact Statementlii

Ryan Hanley (2014a) Office of Public Works Arterial Drainage Maintenance Environmental Services


Drainage Schemes. Methodology. Unpublished Report.

Ryan Hanley (2014b) Office of Public Works Arterial Drainage Maintenance Environmental Services


Drainage Schemes. Moy Validation Report. Unpublished Report.

Ryan Hanley (2014c) Office of Public Works Arterial Drainage Maintenance Service 2014-2018.

Source > Pathway > Receptor Chains for Appropriate Assessment. Unpublished Report.


Natura Impact Statement i

Appendix A


Natura Impact Statementii

Maps of Channels within the Kilcoo 2020 – 2024 Programme


Natura Impact Statement iii


Natura Impact Statementiv

Kilcoo 2020 – 2024 Maintenance Programme

Natura Impact Statementv

Unique

ID

Channel

_Ref Scheme

Frequency of

Maintenance

(years)

Last

Maintenance

Timing of

Works

Machine

Type A B C D E F Notes

2468 C 1 Kilcoo 7/8 years 2007, 2002

Summer –

Instream

Works / Tree Cutting

Winter

Long

Reach/ Short Reach

X X X

A number of areas of Riparian Woodland (WN5 with 91E0 links) have been recorded; have regards for EP 30 Alluvial (Wet

Woodland). Approximate start and finish chainages for these

locations are; 20-360, 510-730,800-1980 and 2140-2250

2469 C 2 Kilcoo 7/8 years 1999

Summer – Instream

Works / Tree

Cutting Winter

Short Reach X X X Channel is assessed every 7/8 years.

2470 C 3 Kilcoo 7/8 years 2015, 2007

Summer –

Instream Works / Tree

Cutting

Winter

Short Reach X X X

2471 C 4 Kilcoo 7/8 years 2015, 2007

Summer – Instream

Works / Tree

Cutting Winter

Short Reach X X X

2472 C 5 Kilcoo 7/8 years 2015, 2007

Summer –

Instream Works / Tree

Cutting

Winter

Short Reach X X X Gravelly. Spawning channel

2473 C 6 Kilcoo 7/8 years 2015, 2007

Summer – Instream

Works / Tree

Cutting Winter

Short Reach X X X Channel not on the GIS “Channel Scheme V2 issue” layer. Channel also know as C85/356/15

Natura Impact Statementvii

Appendix B

Screening Assessment of Groundwater Impact due to arterial drainage works within the Lough

Melvin SAC.

1. Introduction

The NIS report is for routine maintenance works on the County River which flows into Lough Melvin on the

Leitrim / Fermanagh Border. The report assesses the impact on Oligotrophic lakes and salmon as a result of

cutting back trees, removing some trees from the bank and removing silt where it has built up/ aggradated.

Further to a previous screening assessment carried out by JBA which stated:

“Given that the works taking place along the channel involve the removal of instream vegetation and silt, which

will ultimately result in increased instream flow capacity potentially effecting the groundwater levels within

the Lough Melvin SAC”

we propose to undertake here an assessment which screens out any significant hydrological impact on

groundwater levels within the Lough Melvin SAC arising from arterial drainage works on the County (Kilcoo)

River upstream of the lake and therefore negates the need for any further hydrological assessment.

2. Study Area

Figure 1,2 and 3 present the study area location of the channels and the European sites. The assessment is for

the channels within and 100m upstream of the SAC., i.e. the 2.0km reach of the County River upstream of its

discharge to Lough Melvin.

Figure 1: Study Area

Arterial Drainage Channel

upstream of Lough Melvin

Lough Melvin County (Kilcoo)

River

Drowes River

Works Area with

the SAC

Natura Impact Statementix

Figure 2: Study Area and SAC extents

Figure 3: Study Area with the SAC (2km long)

Works Area

within the SAC

3. Hydrology

The border between the Republic of Ireland and Northern Ireland (UK) runs along the County River within the

study area. The OPW and EPA maintains water level gauges on the outlet of Lough Melvin. The river agency

maintains a gauge (235052) on the County River within the study reach. The reported Lough Melvin catchment

area (FSU Portal database, Gauge 35071) is 247km2 and the peak estimated discharge flow for the record

period 1974 to 2005 from the lake was 37.9m3/s and the Qmed is 26.3m3/s. The County River catchment area

at the outfall to Lough Melvin is approximately 50km2 based on available gauge catchment extents. The

seasonal annual average rainfall for the catchment is 1380mm/annum and the potential evapotranspiration is

530mm/annum. This gives an effective rainfall on the catchment is approximately 850mm/annum. The mean

flow in the study reach is approximated at 1.35m3/s.

The upper reach of the study area has a relatively steep gradient while the lower reach is expected to be less

steep and affected by backwatering as it approaches its outfall with Lough Melvin.

4. Hydrogeology

Figure 4: Study Area Groundwater Aquifers

The study reach is located in area reported on GSI groundwater and OPW FSU database as having the following

characteristics:

• Groundwater Body

o A. Tullaghan-Lough Melvin GWB – 0km to 1 km reach

▪ The main groundwater discharges are to the streams, rivers, Lough Melvin and any

springs within the GWB. The baseflow proportion of the total streamflow is

expected to be relatively high in this GWB as a) higher transmissivities are generally

A

B

C

Natura Impact Statementxi

associated with Lm aquifers, and b) a large proportion of this GWB is likely to

constitute a discharge zone.

▪ Recharge will occur diffusely through the thinner and/or more permeable subsoil

and rock outcrops, although is limited by any thicker low permeability subsoil and

bedrock.

o B. Rossinver Groundwater Body (GWB) – 1 km to 2km reach

▪ Groundwater will discharge locally to streams and rivers crossing the aquifer and

also to small springs and seeps. Owing to the poor productivity of the aquifers in this

body it is unlikely that any major groundwater - surface water interactions occur.

Baseflow to rivers and streams is likely to be relatively low.

▪ Recharge occurs diffusely through the subsoil and rock outcrops, although is limited

by any thicker low permeability subsoil and the bedrock itself. Most of the effective

rainfall is not expected to recharge the aquifer.

o Kilcoo GWB – 0km length [not applicable]

• Aquifer

o A. Lm – Locally Important Aquifer – Bedrock which is Generally Moderately Productive

o B. LI – Locally Important Aquifer- Bedrock which is Moderately productive only in Local

Zones.

o C. The river reach upstream of the study reach is Rkc – Regionally important Aquifer –

Karstified Conduit

• Bedrock

o A. Sandstone, siltstone & shale - Mullaghmore Sandstone Formation

o B. Calcareous shale with minor calcarenite- Benbulben Shale Formation

o C. Karstified Limestone

• Soils and Subsoils:

o Teagasc Soils Sandstone and Shale Till - Surface water Gleys, Ground water Gleys, and

Alluvium

o Subsoil are Till derived from Namurian and Carboniferous sandstones and shales (TNCSSs)

• Low Permeability Subsoils and Low groundwater vulnerability (See Figure 5)

o Depth to bedrock >10m

• There are no boreholes or wells or springs of significance reported in the area.

• The Winter Rainfall Acceptance Potential of the soils and subsoils is classed as Type 5, very low

surface water acceptance, very high surface run-off.

Figure 5: Groundwater Vulnerability (within the republic of Ireland shown)

It is expected due to low permeability of the subsoil and depth to bedrock that groundwater discharge in the

area will be to the river channels and limited or very low recharge to the bedrock aquifer will occur.

It is expected, based on the GSI database, that the river channel is located in the subsoil strata. During flood

conditions the river may contribute/ discharge to adjacent subsoils and increase bank storage ,however, due

to the low soil permeability this contribution is not expected to be significant. During periods of low flow the

groundwater in the saturated bank subsoils may recharge the river but the baseflow to rivers from the subsoils

and bedrock aquifer is likely to be relatively low.

5. Proposed Groundwater Impact Assessment

As set out above, the proposed arterial drainage works will comprise very localised removal of silt aggradation

(the deposition of material by a river, stream, or current) and instream vegetation clearance in order to

reinstate the channel to the original post-arterial channel works condition. It is not proposed to widen,

deepen, realign or reshape the river channel as part of these works.

Removal of silt aggradation and in stream vegetation will, in effect, reduce the effective roughness of the

channel and increase the effective channel cross-sectional area and therefore increase the river channel

capacity. In effect, in the upper steeper gradient sections which are not affected by backwatering from Lough

Melvin, water depths would be expected to be shallower in the post-maintenance condition for the same

equivalent flow in the pre-maintenance condition. Due to the low permeability of the subsoils, localised

removal of silts and vegetation will not significantly increase the discharge of groundwater to the river channel

due to the reduced water levels in the channel. Any impact on groundwater levels will be very localised and

confined to within the subsoils layers and will not impact the bedrock aquifer. The impact on the groundwater

within the Lough Melvin SAC will therefore not be significant.

opw arterial drainage

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