Irish Water Uisce Éireann
June 2014
CARLINGFORD WASTEWATER DISCHARGE LICENCE APPLICATION (REG NO. D0268-01) Stage 2 Appropriate Assessment for the
purposes of the Waste Water Discharge
(Authorisation) Regulations, 2007 (S.I. No
684 of 2007)
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IRISH WATER
CARLINGFORD WASTEWATER DISCHARGE LICENCE APPLICATION (REG. NO D0268-01)
STAGE 2 APPROPRIATE ASSESSMENT FOR THE PURPOSES OF THE
WASTEWATER DISCHARGE (AUTHORISATION) REGULATIONS, 2007 (S.I. NO 684 OF 2007)
Nicholas O’Dwyer Ltd.,
Consulting Engineers,
Nutgrove Office Park,
Nutgrove Avenue,
Dublin 14. June 2014
PROJECT NO. 20542
Revision Reason for Revision Prepared by Reviewed by Approved by Issue Date
- Initial Report NOD / TN SH/CAS CAS 10/06/2014
A Report for Client Review NOD / TN SH/CAS CAS 11/06/2014
B Incorporating Client Comments NOD / TN SH/CAS CAS 12/06/2014
C
D
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Carlingford WwTP Reg. No. D0268-01 Stage 2 Appropriate Assessment
Nicholas O’Dwyer Ltd. i June 2014
CONTENTS 1. INTRODUCTION 1
1.1 Background 1
1.2 Appropriate Assessment Legislation 2
1.3 Waste Water Discharge (Authorisation) Regulations, 2007 3
1.4 Methodology 3
1.5 Sources of Information 5
1.6 Consultation 6
2. STAGE 2 APPROPRIATE ASSESSMENT 7
2.1 Introduction 7
2.2 Project and Site Information 7
2.2.1 Site Location 7
2.2.2 Existing Carlingford WwTP 9
2.2.3 Effluent Discharge 9
2.3 Natura 2000 Sites 11
2.3.1 Description of Natura 2000 Sites 11
2.3.2 Qualifying Interests 14
2.4 Baseline Environment 18
2.4.1 Water Framework Directive Assessment 18
2.4.2 WFD Register for Protected Areas 21
2.5 Impact of Carlingford WwTP Primary Discharge 21
2.5.1 Coastal Dilution and Dispersion 21
2.5.2 Dilution and Dispersion Calculations 21
2.5.3 Initial Dilution 22
2.5.4 Horizontal Transport and Dispersion 23
2.5.5 Overall Dilution 23
2.5.6 Impact of Wastewater Parameters 24
2.5.7 Summary of Predicted Dispersion Results 26
2.6 Conservation Objectives 28
2.6.1 Conservation Objectives of Carlingford Shore SAC 28
2.6.2 Conservation Objectives of Carlingford Lough SPA 31
2.7 Assessment of Potential Impacts on the Conservation Objectives 31
2.8 In Combination Effects with Other Plans and Projects 35
2.9 Mitigation Measures 39
2.10 Concluding Statement 39
3. REFERENCES 40
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APPENDICES
Appendix I: Natura 2000 Site Synopses
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Carlingford WwTP Reg. No. D0268-01 Stage 2 Appropriate Assessment
Nicholas O’Dwyer Ltd. 1 June 2014
1. INTRODUCTION
1.1 Background
Louth County Council submitted a Waste Water Discharge Licence Application to the EPA
on 3rd March 2009 to comply the Waste Water Discharge (Authorisation) Regulations,
2007 (S.I. No 684 of 2007).
The Water Services (No.2) Act 2013 provided for the transfer of water services functions
from the 34 Local Authorities to Irish Water. It also provided for the transfer of the water
services infrastructure assets to Irish Water. With this transfer of assets and functions,
Irish Water has now become the licensee for all EPA Waste Water Discharge Licences
and Certificate of Authorisation applications.
This Stage 2 Appropriate Assessment, prepared by Nicholas O’Dwyer Ltd. and Associate
Ecologist, Tony Nagle on behalf of Irish Water, supports the Waste Water Discharge
Licence application for the Carlingford agglomeration (EPA Application Register Number
D0268—01) and forms a response to the EPA correspondence of 21st March 2014 which
requested the following:
“A screening for Appropriate Assessment was undertaken to assess, in view of best
scientific knowledge and the conservation objectives of the site, if the activity,
individually or in combination with other plans or projects is likely to have a significant
effect on a European Site(s). In this context, particular attention was paid to the
European sites at Carlingford Shore SAC (002306) and Carlingford Lough SPA (004078)
and the Agency considered, for the reasons set out below, that the activity is not directly
connected with or necessary to the management of those sites as European Sites and
that it cannot be excluded, on the basis of objective scientific information following
screening under this Regulation, that the activity, individually or in combination with
other plans or projects, will have a significant effect on a European site and accordingly
determined that an Appropriate Assessment of the activity is required. This
determination is based on the proximity of the primary discharge to the Carlingford
Shore SAC (002306) and the direct discharge of effluent to the Carlingford Lough SPA
(004078).
You are thereby required to submit a Natura Impact Statement, as defined in Regulation
2(1) of the European Communities (Birds and Natural Habitats) Regulations (S.I. No.
477 of 2011)”.
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This Stage 2 Appropriate Assessment Natura Impact Statement will consider the impact
on the integrity of the Carlingford Shore SAC (002306) and the Carlingford Lough SPA
(004078) from the current discharged effluent from the agglomeration. This effluent is
discharged directly into the aforementioned SAC and SPA. This assessment will consider
alone or in combination impacts, with respect to the site’s structure and function and the
conservation objectives. Any negative impacts on the integrity of the sites will require
the implementation of avoidance or mitigation measures to avoid progression to Stages
3 and 4 of the Appropriate Assessment process.
1.2 Appropriate Assessment Legislation
Directive 92/43/EEC on the Conservation of Natural Habitats and Wild Fauna and Flora -
the “Habitats Directive” - provide legal protection for habitats and species of European
importance. The Directives requires the maintenance or restoration of habitats and
species of European Community interest, at a favourable conversation status and
provides the legislation to protect habitats and species of community interest
through the establishment and conservation of an EU-wide network of sites known as
Natura 2000 sites.
Natura 2000 sites are Special Areas of Conservation (SAC) designated under the
Habitats Directive and Special Protection Areas (SPA) designated under the Conservation
of Wild Birds Directive (79/409/EEC). Articles 6(3) and 6(4) of the Habitats Directive sets
out the decision-making tests for plans or projects affecting Natura 2000 sites.
Article 6(3) establishes the requirement for Appropriate Assessment:
“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. In the light of the
conclusions of the assessment of the implications for the site and subject to the
provisions of paragraph 4, the competent national authorities shall agree to the plan or
project only after having ascertained that it will not adversely affect the integrity of the
site concerned and, if appropriate, after having obtained the opinion of the general
public”.
Article 6(4) of the Directive deals with alternative solutions, the test of “imperative
reasons of overriding public interest” (IROPI) and compensatory measures:
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“If, in spite of a negative assessment of the implications for the site and in the absence
of alternative solutions, a plan or project must nevertheless be carried out for imperative
reasons of overriding public interest, including those of social or economic nature, the
Member State shall take all compensatory measures necessary to ensure that the overall
coherence of Natura 2000 is protected. It shall inform the Commission of the
compensatory measures adopted”.
1.3 Waste Water Discharge (Authorisation) Regulations, 2007
The Wastewater licensing and certification process gives effect to a number of EU
Directives by the imposition of restrictions or prohibitions on the discharge of dangerous
substances and thus preventing or reducing the pollution of waters by wastewater
discharges.
All discharges to the aquatic environment from sewerage systems owned, managed and
operated by water service authorities (now Irish Water) require Waste Water Discharge
Licences or Certificate of Authorisations from the EPA.
This process provides for the EPA to place stringent conditions on the operation of
discharges from WwTPs to ensure that potential effects on the receiving water bodies are
strictly limited and controlled. In overall terms the aim is to achieve good surface water
and ground water status in addition to complying with standards and objectives
established for associated protected areas, including Natura 2000 sites.
1.4 Methodology
An Appropriate Assessment is an assessment of the potential adverse or negative
impacts of a plan or project, in combination with other plans or projects, on a European
site. An Appropriate Assessment must be carried out before any decision is made to
allow that plan or project to proceed. The obligation to undertake Appropriate
Assessment derives from both Article 6(3) and 6(4) of the Habitats Directive.
The European Commission (2002) has provided guidance on addressing the provisions of
Article 6(3) and 6(4) of the Habitats Directive and identifies four main stages in the
process as follows:
Stage One: Screening for Appropriate Assessment
The process identifies the likely significant effects upon a Natura 2000 site of a project or
plan, whether alone or in combination with other projects or plans, and considers
whether these impacts are likely to be significant. This Stage 1 has been completed by
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the Competent Authority, the EPA and it was determined that a Stage 2 NIS would need
to be completed for the current discharge as it cannot be excluded, on the basis of
objective scientific information following screening, that the discharge, individually or in
combination with other plans or projects, will have a significant effect on the Carlingford
Shore SAC and the Carlingford Lough SPA.
Stage Two: Appropriate Assessment
This stage considers whether the project or plan, alone or in combination with other
projects or plans, will have adverse effects on the integrity of a Natura 2000 site, and
includes any mitigation measures necessary to avoid, reduce or offset negative effects.
Stage Three: Assessment of Alternative Solutions
This process examines alternative ways of achieving the objectives of the project or plan
that avoid adverse impacts on the integrity of the Natura 2000 site.
Stage Four: Assessment where no Alternative Solutions Exist and where
Adverse Impacts Remain.
This process is an assessment of compensatory measures, where in the light of an
assessment of imperative reasons of over-riding public interest, it is deemed that the
project or plan should proceed.
The Habitats Directive promotes a hierarchy of avoidance, mitigation and compensatory
measures. First, the project should aim to avoid any negative impacts on European sites
by identifying possible impacts early in the planning stage and designing the project in
order to avoid such impacts. Second, mitigation measures should be applied, if
necessary, during the AA process to the point where no adverse impacts on the site(s)
remain. If the project is still likely to result in adverse effects, and no further practicable
mitigation is possible, then it is rejected. If no alternative solutions are identified and the
project is required for imperative reasons of overriding public interest (IROPI test) under
Article 6(4) of the Habitats Directive, then compensation measures are required for any
remaining adverse effects.
This document bring together all of the information necessary to determine if the current
discharges from the Carlingford WwTP to the Carlingford Lough is adversely affecting the
integrity of the Carlingford Shore SAC and the Carlingford Lough SPA.
This Stage 2 Appropriate Assessment has been prepared in accordance with the following
guidelines:
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• EPA (2012) Note on Appropriate Assessments for the purposes of the Waste
Water Discharge (Authorisation) Regulations, 2007 (S.I. No. 684 of 2007), as
amended;
• Managing Natura 2000 Sites: the provisions of Article 6 of the “Habitats” Directive
92/43/EEC (EC, 2000);
• Assessment of plans and projects significantly affecting Natura 2000 sites:
Methodological guidance on the provisions of Article 6(3) and (4) of the Habitats
Directive 92/43/EEC (EC, 2002);
• Appropriate Assessment of Plans and Projects in Ireland: Guidance for Planning
Authorities (DoEHLG, 2009);
• Department of the Environment Heritage and Local Government Ireland
(DOEHLG) Circular L8/08 (September 2008).
The structure of this NIS broadly follows the methodology as recommended in the EPA
guidance note: Waste Water Discharge Licensing – Appropriate Assessment,
Version 2.2 2012).
1.5 Sources of Information
The data used in this assessment has been drawn mainly from following sources:
• Carlingford WWDLA Application and Further Information Request (Reg. No.
D0268-01)
• EPA Monitoring Data
• Louth County Council/Irish Water Monitoring Data
• Neagh-Bann International River Basin District Management Plan and Associated
Reports
• NPWS Data and Mapping
• NPWS (2013) The Status of EU Protected Habitats and Species in Ireland. Habitat
Assessments Volume 2. Version 1.0
• NPWS (2013) Conservation Objectives: Carlingford Shore SAC 002306 Version 1
• NPWS (2013) Conservation Objectives: Carlingford Lough SPA 004078 Version 1
• NPWS (2013) Carlingford Lough Special Protection Area (Site Code 4078)
Conservation Objectives Supporting Document Version 1
• NPWS (2013) Carlingford Shore SAC (Site Code 2306) Conservation Objectives
Supporting Document - Coastal Habitats
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1.6 Consultation
Consultation was sought with the NPWS Divisional Ecologist (North Eastern Region),
Linda Patton, on the 9th of June 2014. No responses were received at the time of writing
this Report.
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2. STAGE 2 APPROPRIATE ASSESSMENT
2.1 Introduction
In Stage 2 of the Appropriate Assessment process the impact of a project or plan (i.e. in
this case the primary discharge from the Carlingford WwTP to Carlingford Lough) on the
integrity of a European Site(s) (i.e. the Carlingford Shore SAC and the Carlingford Lough
SPA) is considered with respect to the conservation objectives of the sites. This involves
acquiring adequate information on the project, predicting the likely effects (direct,
indirect, short and long term, isolated, interactive and cumulative) and identifying the
impacts on the conservation objectives and status of the European Sites. Finally,
mitigation measures need to be identified and assessed against the adverse effects the
project is likely to cause.
2.2 Project and Site Information
2.2.1 Site Location
Carlingford is a coastal town in Northern Louth, located on the east of Ireland between
Dublin and Belfast. The town it situated adjacent to Carlingford Lough and the base of
the Slieve Foy Mountains and the Mourne Mountains.
The existing Wastewater Treatment Works is located south of the village centre. The
treatment works site is approximately 0.67 ha in area and access to the site is via a local
road adjacent to the R173.
A location plan of the area around the Carlingford WwTP is shown on Fig. 2.1 below. The
location of the primary discharge location is shown in Fig. 2.2.
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WwTP
Figure 2.1: Carlingford WwTP Location (Source: NPWS Mapping)
Figure 2.2: WwTP and Primary Discharge Location (Source: EPA Mapping)
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2.2.2 Existing Carlingford WwTP
A full description of the existing Carlingford Sewerage Scheme and associated WwTP is
provided in the 2009 WWD application (Reg. No. D0268-01). A brief overview of the
WwTP and primary discharge is provided in the sections below.
The existing treatment works was built in the late 1990s and consists of an inlet pump
station, a screening chamber with balancing tank, two aeration tanks, two clarifiers, a
sludge return pump station, a sludge thickener, a sludge press building and a sludge
storage area. The existing Wastewater Treatment Works is located south of the village
centre.
The treated effluent is pumped from the treatment works to a chamber located along the
coast line and flows then by gravity through a sea outfall pipe about 1500 m long,
discharging into Carlingford Lough via a diffuser. The treatment works is designed on the
basis of a population equivalent of 1,500 assuming Total BOD5 90 kg/d, Total Suspended
Solids 105 kg/d, Total Dry Weather Flow 270 m3/day, Total peak design flow to be
treated (3DWF) 34 m3/h.
The quality of the current effluent discharge and its compliance with the UWWT
Regulations are discussed in Section 2.2.3 below.
2.2.3 Effluent Discharge
As mentioned above in Section 2.2.2, Carlingford wastewater receives secondary
treatment before being discharged to Carlingford Lough by a diffuse outfall with an
approximate length of 1500 m. The treated effluent from the Carlingford WwTP must
comply with the Urban Wastewater Treatment Regulations, 2001 (S.I. No. 254 of 2001)
i.e. the treated effluent quality standards must achieve 25 mg/l BOD5, 35 mg/l SS and
125mg/l COD.
Data obtained from Louth County Council was assessed for compliance with the above
effluent standards. A summary of the 2013-2014 effluent concentrations is shown in
Table 2.1. Where data were recorded as less than the limit of detection a worst case
scenario was assumed and data were considered to be equal to the limit of detection.
The effluent monitoring results for 2013 and 2014 indicates that the Carlingford WwTP is
in compliance with the required BOD, COD and SS standards of Urban Waste Water
Treatment Regulations. The impact of the effluent on the receiving environment (in the
context of meeting the surface water objectives standards) is discussed in Section 2.5
of this Report.
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Table 2.1: Carlingford WwTP Effluent Monitoring Data (mg/l) (2013-2014) (Data Source: Louth County Council)
Sample Date Nitrates
(N)
Ammonia
as N
Total
Nitrogen BOD
COD
(O2)
Total
Suspended
Solids
Ortho-
phosphate
(P)
Total
Phosphorus
as P
Nitrites
(N)
Nitrates
(NO3) DIN *
16-Jan-13 5.91 2.34 6.2 1.76 44.1 21 <0.18 0.21 0.279 - 8.529
20-Feb-13 - 2.19 4.3 3.97 30.8 5 0.29 0.74 0.386 0.095 2.672
20-Mar-13 7.42 2.84 10.6 15.8 72.1 35 0.25 1.2 0.59 - 10.85
17-Apr-13 5 1.57 5.9 7.95 44.9 13 0.91 1.4 0.492 - 7.062
22-May-13 4.3 4.55 10.2 6 46.1 21 0.85 1.4 0.828 - 9.678
19-Jun-13 1.21 8.1 8.4 7.36 37.4 25 0.71 1 1.21 - 10.52
17-Jul-13 0.802 16.9 19.7 9.21 53.3 25 0.62 1.3 0.792 - 18.494
21-Aug-13 2.81 14 17 6.35 60 17 3.04 3.4 0.994 - 17.804
18-Sep-13 7.1 6.84 14.6 6.19 50.4 13 2.74 3 1.33 - 15.27
16-Oct-13 14.7 4.06 18.4 4.8 36.9 18 2.67 2.9 1.12 - 19.88
13-Nov-13 6.53 2.17 8.9 3.72 27.8 13 1.34 1.42 0.599 - 9.299
18-Dec-13 6.31 4.31 9.1 8.65 72 24 1.54 2 0.673 - 11.293
12-Feb-14 0.652 10.7 10.8 8.37 40.6 9 1.17 1.97 0.231 - 11.583
19-Mar-14 0.068 18.5 16.6 4.89 43.7 17 1.84 2.33 0.128 - 18.696
Max 14.7 18.5 19.7 15.8 72.1 35 3.04 3.4 1.33 - 19.88
Mean 4.8 7.1 11.5 6.8 47.2 18.3 1.4 1.7 0.7 - 12.3
Min 0.068 1.57 4.3 1.76 27.8 5 0.25 0.21 0.128 - 2.672
Urban Wastewater Treatment Regulation
Standards 25 125 35
*DIN calculated: DIN = nitrite + nitrate + ammonia
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2.3 Natura 2000 Sites
2.3.1 Description of Natura 2000 Sites
The Carlingford WwTP discharges into Carlingford Lough. Carlingford Lough is designated
as an SAC (Carlingford Shore SAC) and SPA (Carlingford Lough SPA). The SAC
designation covers the southern shore line of Carlingford Lough and extends around the
peninsula to Templetown (Fig. 2.3). The SPA designation comprises the outer part of t
Lough, at Carlingford and Greenore (see Fig. 2.4). The location of both designated sites
in relation to the treated effluent discharge point is shown in Fig. 2.5 and 2.6.
Figure 2.3: Carlingford Shore SAC (Mapping Source: NPWS)
Figure 2.4: Carlingford Lough SPA (Mapping Source: NPWS)
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Figure 2.5: Carlingford WwTP and Discharge Location relative to the SAC and SPA
(Source: NPWS)
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Figure 2.6: View of Carlingford WwTP Discharge Point (at sea) and surrounding habitat
Carlingford Shore SAC (Site Code: 002306)
Carlingford Shore stretches for approximately 15 km along the shoreline to the Low
Water Mark of Carlingford Lough which is also the estuary of the Newry River. It is
flanked by glacial moraines and mountains - the Mourne Mountains to the north and
Carlingford Mountain to the south-west. The underlying rock within the SAC is mainly
Carboniferous limestone. This outcrops over sections of the SAC in the form of bedrock
shore or reefs. Granite boulders are occasionally found. Intertidal mudflats and
sand/gravel banks also occur.
The site is a candidate SAC selected for perennial vegetation of stony banks and drift
lines, both habitats listed on Annex I of the E.U. Habitats Directive. The stony banks or
shingle found along much of the site vary in width from less than a meter to
approximately 50 m south of Ballagan Point. The best examples are found in this area.
The perennial vegetation of the upper beach of these shingle banks is widely ranging,
well developed and often stable. In places lichens encrust the stones farther back from
the sea and a small brackish lake is present on the landward side of the railway line.
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Relatively extensive expanse of intertidal flats - more a sand rather than mud dominant
type - occurs, particularly between Greenore Point and Carlingford Harbour. The flats in
this area are broken by outcropping reefs and some shingle deposits and saltmarsh on
the drier higher rocks. These flats are very important feeding grounds for wildfowl and
waders. Eelgrass (Zostera) beds are found on the flats – the main food source for the
internationally important population of Pale-bellied Brent Geese at the site. Small tufts of
Cord-grass (Spartina) are also found.
A site synopsis for this site is appended to Appendix I.
Carlingford Lough SPA (Site Code: 004078)
This SPA site, most of which is in the intertidal zone, primarily includes the relatively
extensive expanse of sand and mudflats, broken by outcropping reefs and some shingle
deposits. These flats are very important feeding grounds for internationally important
numbers of Light-bellied Brent Geese and large numbers of wintering wildfowl including
nationally important numbers of Cormorant and Ringed Plover. Although there are no
breeding Terns on the site, Common Terns, and particularly Sandwich Terns feed in the
SPA. The site also forms part of an extended cross-border site which supports
internationally important numbers of over-wintering Light-bellied Brent Geese Branta
bernicla hrota.
While the numbers of wintering birds are relatively low, the site does support a good
range of species. The presence of Bar-tailed Godwit is of particular note as this species is
listed on Annex I of the E.U. Birds Directive.
The site synopsis for this site is appended to Appendix I.
2.3.2 Qualifying Interests
2.3.2.1 Carlingford Shore SAC
The qualifying interest/features of the Carlingford Shore SAC are outlined and discussed
below):
• Annual vegetation of drift lines [1210]
• Perennial vegetation of stony banks [1220]
Annual vegetation of drift lines [1210]
This type of vegetation occurs on sandy, shingle or stony substrate at the upper part of
the strand, around the high tide mark. Water-borne material including organic matter is
deposited on the shore and provides nutrients and a seed source for vegetation. The
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vegetation predominantly consists of annual species, such as Atriplex species, Cakile
maritima and Salsola kali, which are highly specialised to deal with the harsh conditions
of high salinity, wind exposure and drought. This habitat is generally very species-poor,
fragmented and tends not to occupy large areas due to its narrow, linear nature. It
exists in a state of instability and may be absent in some years due to natural and/or
anthropogenic causes. In Ireland, the habitat includes drift line vegetation on sandy
substrates as well as drift line vegetation dominated by annuals found on shingle.
In the Article 17 Assessment the Range of this habitat was assessed as “Favourable”
(stable) as there has been no change in the assessment since 2007. Future prospects
were assessed as “Unfavourable-Inadequate” (stable). The most serious threats to the
habitat were associated with recreation and coastal defences, and these were consistent
with the Structure and Function assessment results. The overall conservation status of
1210 was assessed as “Unfavourable-Inadequate” in the NPWS 2013 report.
Perennial vegetation of stony banks [1220]
This habitat occurs along the coast where shingle (cobbles and pebbles) and gravel have
accumulated to form elevated ridges or banks above the high tide mark. Most of the
rocky material should be less than 250 mm in diameter to be considered in this
category. The vegetation tends to be dominated by perennial species, typically including
Honckenya peploides, Rumex crispus, Beta vulgaris ssp. maritima, Crithmum maritimum
and Tripleurospermum maritimum. The rare plants Crambe maritima and Mertensia
maritima are also associated with this community (Fossitt, 2000). Species diversity is
determined by the degree of exposure and by substrate stability, coarseness and size.
The presence of lichens indicates long term stability.
The ‘Status of EU Habitats and Species in Ireland’ (NPWS, 2013) states that the overall
national conservation status of this habitat is considered as ‘inadequate’ but the national
conservation status trend is considered as “stable”. The future prospects are
considerable “Inadequate”.
2.3.2.2 Carlingford Lough SPA
The qualifying interest/features of the Carlingford Lough SPA are outlined and discussed
below:
• Light-bellied Brent Goose (Branta bernicla hrota) [A046]
• Wetlands [A999]
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Light-bellied Brent Goose (Branta bernicla hrota) [Species Code A046]
The Light-bellied Brent Goose population winters almost entirely in Ireland. As the entire
population is considered to be relatively small (c. 40,000 (2010)), the Light-bellied Brent
Goose is considered the most important waterbird species in Ireland, based on numbers
alone. The species is Amber-listed as the majority of the population which winter here
are located at less than ten sites around Ireland. The European population is considered
vulnerable as some important populations have seen a decline.
The main factors which affect the population are as follows:
• Food availability, the species are dependent on intertidal eelgrasses, Zostera
spp., Reduction in this food source could see decline in species numbers
• Habitat loss and fragmentation, the population are threatened by loss of inter-
tidal habitat and/or anthropogenic degradation (e.g. aquaculture and
infrastructure)
• Disturbance, human activity can impact the species and prevent site utilisation
A recent waterbird survey (2010/11) was conducted at Carlingford Lough SPA (Detailed
in the Carlingford Lough SPA Conservation Objectives Supporting Document). Waterbirds
were counted within two survey zones (zone 1 and 2) both contained within the
Carlingford Lough SPA. This survey focused on Light-bellied Brent Goose numbers,
distribution, behaviour and movements. Table 2.2 details the peak zone counts within
the Carlingford Lough SPA from October 2010 to March 2011.
Table 2.2: Carlingford Lough SPA Peak zone counts and the peak site count (Source:
NPWS, 2013)
Date Count in Zone 1
(Occurrence Frequency %)
Count in Zone 2
(Occurrence Frequency %) Site*
Oct 2010 126 (53) 92 (100) 218
Nov 2010 109 (33) 317 (100) 411**
Dec2010 275 (53) 412** (100) 687**
Jan 2011 177 (47) 132 (91) 271
Feb 2011 346 (56) 176 (100) 522**
Mar 2011 438** (42) 282 (100) 572**
* Numbers in Zone 1 and Zone 2 combined within any one 60—minute period
** Exceeds international threshold of 400 after Wetlands International (2012)
Based on the long-term population trend for the site, Light-bellied Brent Goose are
determined as “Intermediate-Unfavourable” Conservation Condition (Table 2.3).
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Table 2.3: Carlingford Lough SPA Current Site Conservation Condition (Source: NPWS)
Special
Conservation
Interest
BoCCI
Category a
Site
Population
Trend b
Site
Conservation
Condition
Current all-
Ireland
Trend c
Current
International
Trend d
Light-bellied
Brent Goose Amber
-1 Intermediate
Unfavourable +62.3 Increase
a After Lynas et al. (2007); b Site Population Trend; see Table 4.2 in the Carlingford Lough SPA Supporting
Information Document1; c All-Ireland trend calculated for period 1994/95 to 2008/09 (I-WeBS); d International
trend after Wetland International (2012)
Wetlands [Habitat Code [A999]
The wetlands of northwest Europe are a vital resource for millions of northern and boreal
nesting waterbird species that overwinter on these wetlands or visit them when
migrating further south. To acknowledge this importance of Ireland's wetlands to
wintering waterbirds the term Wetland and Waterbirds can be included as a Special
Conservation Interest for a Special Protection Area that has been designated for
wintering waterbirds, and is or contains a wetland site of significant importance to one or
more of the species of Special Conservation Interest.
The boundary of Carlingford Lough SPA was defined to include the primary wetland
habitats of this site. The designation seeks to maintain the permanent extent of these
wetland habitats, which constitute an important resource for regularly-occurring
migratory waterbirds.
The wetland habitats can be categorised into three broad types: subtidal, intertidal and
supratidal. Over time and through natural variation these subcomponents of the overall
wetland complex may vary due to factors such as changing rates of sedimentation,
erosion etc. Waterbird species may use more than one of the habitat types for different
reasons (behaviours) throughout the tidal cycle. Subtidal areas refer to those areas
contained within the SPA that lie below the mean low water mark and are predominantly
covered by marine water. Tidal rivers, creeks and channels are included in this category.
For Carlingford Lough SPA this broad category is estimated to be 304 ha. Subtidal areas
are continuously available for benthic and surface feeding ducks (e.g. Shelduck,
Shoveler) and for the listed species Light-bellied Brent Geese. Various waterbirds roost
in subtidal areas. The intertidal area is defined, in this context, as the area contained
between the mean high water mark and the mean low water mark. For Carlingford
Lough SPA this is estimated to be 282 ha. When exposed or partially exposed by the
1http://www.npws.ie/publications/archive/004078_Carlingford%20Lough%20SPA%20Supporting%20Doc_V1.p
df
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tide, intertidal habitats provide important foraging areas for many species of waterbirds,
especially wading birds, as well as providing roosting/loafing areas. When the intertidal
area is inundated by the tide it becomes available for benthic and surface feeding ducks,
geese and piscivorous/other waterbirds. During this tidal state this area can be used by
various waterbirds as a loafing/roosting resource. The supratidal category refers to areas
that are not frequently inundated by the tide (i.e. occurring above the mean high
watermark) but contain shoreline and coastal habitats and can be regarded as an
integral part of the shoreline. For Carlingford Lough SPA this is estimated to be 9 ha.
supratidal areas are used by the listed species Light-bellied Brent Geese and a range of
other waterbird species as a roosting resource as well as providing feeding opportunities.
2.4 Baseline Environment
This section of the NIS gives a brief outline of the general baseline of the aquatic
environment.
2.4.1 Water Framework Directive Assessment
The Water Framework Directive was adopted by the EU in order to halt and reverse the
decline in water quality. The Directive sets very strict deadlines for meeting water quality
objectives, especially in protected areas. The WFD’s objectives can be best summarised
as: maintaining “high status” of waters where it exists; preventing any deterioration in
the existing status of waters; and achieving at least “good status” in all waters by 2015
(or 2027 at the latest where a derogation has been applied to a waterbody).
Carlingford Lough (NB_030_0000) is located in the Neagh-Bann International River Basin
District (NB IRBD). The NB IRBD Plan sets out how it is aimed to achieve the objectives
of the WFD Directive in this district. The NB IRBD Plan establishes four core
environmental objectives to be achieved by 2015 or in specific cases a timeframe set by
derogation:
• Prevent deterioration
• Restore good status
• Reduce chemical pollution
• Achieve water related protected areas objectives
The NB IRBD Transitional and Coastal Waters Action Programme sets out the current
status of Carlingford Lough. Details of the current status are shown in Fig. 2.7 below.
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Figure 2.7: Neagh-Bann IRRBD Transitional and Coastal Waters Designations and
Discharge Locations (Source: NB IRBD Transitional and Coastal Waters Action
Programme)
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A breakdown of the overall status of Carlingford Lough is shown below:
Figure 2.8: Reasons for status for the water bodies within the Carlingford and Newry
LMA March 2014 Version No.1 (Source: NIEA)
As seen on Fig. 2.7 and 2.8, Carlingford Lough is designated as “Moderate” status. The
monitoring data for Carlingford Lough indicates that the key limiting parameter for this
waterbody to achieve “Good” status is DIN. The specific source of the adverse pressure
or combination of pressures on this water body, causing deterioration in status, has yet
to be determined, however, possible contributors to the DIN status have been identified
as agricultural nutrient input, WwTPs and shellfish dredging.
As a result of the above, Carlingford Lough was identified as “at risk” or “probably at
risk” of not achieving good status by 2015. Derogation has been applied to this
waterbody and the WFD objective of the Carlingford Lough water body is to restore to
good status by 2021.
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2.4.2 WFD Register for Protected Areas
In accordance with the requirements of the Water Framework Directive and the
associated national regulations, the Environmental Protection Agency (EPA) has compiled
Registers of Protected Areas in Ireland. The protected areas are identified as those
requiring special protection under existing national or European legislation, either to
protect their surface water or groundwater, or to conserve habitats or species that
directly depend on those waters.
These Protected Areas include sites designated under the Birds Directive (79/409/EEC)
and the Habitats Directive (92/43/EEC) e.g. Carlingford Shore SAC and Carlingford
Lough SPA. There are no nutrient sensitive waters within the vicinity of the effluent
discharge location.
2.5 Impact of Carlingford WwTP Primary Discharge
2.5.1 Coastal Dilution and Dispersion
The Water Framework Directive (WFD) which established a new framework for
Community action in the field of water policy (2000/60/EC) came into effect in December
2000. The primary objective of the Water Framework Directive, as mentioned in Section
2.4.1 above, is to maintain the “high status” of waters where it exists, prevent
deterioration in existing status of waters and to achieve at least “good status”.
Carlingford Lough is located within the Neagh-Bann International River Basin District
(IRBD). The Transitional and Coastal Waters Action Programme for the Neagh-Bann
IRBD identified the water quality status as moderate with high nitrogen levels noted.
Taylor et al. (1999) calculated that the total annual loading of dissolved inorganic
nitrogen (DIN: NO‐3 + NH4+, of which <2% was NH4+) to Carlingford Lough was 1,311
tonnes. Approximately 77% (1,016 tonnes) of the DIN originated from the
Newry/Clanrye catchment, 1.196 tonnes (<0.12%) was identified as originating from the
Carlingford Wastewater Treatment Plant.
The calculations below have been completed using the design PE for the actual effluent
data (2013-2014) and the design standards.
2.5.2 Dilution and Dispersion Calculations
There are several mechanisms which govern the dilution characteristics of a coastal
outfall. These are usually considered separately in three phases:
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i. Initial dilution which occurs in the first few minutes as the wastewater leaves the
outfall diffuser and rises in the water column
ii. Kinetic reactions which take place in the sea (the principal reaction for design is
the die-off of indicator bacteria (coliforms))
iii. Horizontal transport and dispersion of the wastewater plume
The calculations below consider dilution within the immediate vicinity of the outfall only
and as such kinetic reactions and die-off are not considered.
2.5.3 Initial Dilution
Initial dilution occurs due to three effects:
• Jet mixing due to the momentum of the sewage stream as it leaves the diffuser
port
• The buoyancy effect resulting from density differences between the wastewater
and the ambient ocean water (temperature and salinity differences) which causes
the wastewater plume to rise upward in the water column as an expanding
plume, thus mixing with the sea water
• The current effect causing the lateral entrainment of fresh sea water into the
plume. The plume may rise to the water surface, or may be trapped below the
surface depending on the degree of stratification of the water column.
The initial dilution equations developed by the WRc (WRc Design Guide for Marine
Treatment Schemes) are as follows:
Where,
Q = Total discharge flow (m3/s) = 0.012 m3/s (3DWF@1,500pe, 225
l/pe/day)
N = number of diffusers (=1)
Qj = Diffuser discharge flow = (Q/n) (m3/s) = 0.012 m3/s
ua = ambient velocity (m/s) = 0.05m/s – estimated low current
ua = ambient velocity (m/s) = 1.0m/s – estimated high current
C3 = dilution constant for equation (1) above = 0.34 (reference WRc)
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C1 = dilution constant for equation (2) above = 0.34 (reference WRc)
B = Buoyancy flux = Qj.g (ρa – ρe) / ρa = 0.0031
ρa = ambient density (kg/m3) = 1,028kg/m3
ρe = effluent density (kg/m3) = 1,000kg/m3
g = Gravity (9.81 m/s2).
H = Depth of the discharge point (m) = 4.1m (average)
5B/ua3 = 125.25 (≥ H) at low current velocities therefore equation (1) above is used.
5B/ua3 = 0.02 (< H) at high current velocities therefore equation (2) above is used
At low currents:
Initial dilution, D1 = 0.34 x 0.00311/3 x 4.15/3 = _____
0.012
At high currents
Initial dilution, D1 = 0.34 x 1.0 x 4.12 = _______
0.012
2.5.4 Horizontal Transport and Dispersion
The horizontal transport and dispersion are governed by the local current regime and
eddy diffusion (lateral mixing due to eddy currents). The Brooks19 four-thirds power law
is used to calculate secondary (horizontal) dilution at a time interval, t using the
following equation:-
Where:
α = diffusion co-efficient = 0.0003 m2/3/sec (normal range: 0.0001 to 0.0005)
t = travel time of sewage field to bathing area
B = initial plume width (0.3 to 0.9 times the water depth depending on current speed. B
increases depending on current speed)
t = travel time to set distance from outfall (50 m and 200 m assessed)
2.5.5 Overall Dilution
The overall dilution achieved and the anticipated concentration at varying locations is
summarised in Table 2.4 for low and high currents using the following equations:
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DT = D1 x D2
CT =. Co .
D1 x D2
Table 2.4: Summary of Dilutions at 50m and 200m from Outfall in Carlingford Lough
Parameter
Concentration at 50 m from
outfall
Concentration at 200 m from
outfall
At low current At high current At low current At high current
D1 = Initial dilution 40.6 460 40.6 460
D2 = Horizontal
dispersion 2.08 1.0 9.2 1.06
DT = Total dilution 84.4 460 372.6 488
2.5.6 Impact of Wastewater Parameters
The impact of the effluent from the Carlingford WwTP primary discharge on the receiving
aquatic environment is discussed below. Using the calculations detailed in the above
sections, predicted concentrations have been calculated based for BOD and DIN as well
as TN, OP and COD. The concentrations of pollutants for low and high dilutions in
combination with the initial discharge location, 50m from the discharge location and 200
m from the discharge location has been examined.
Table 2.5 below details the average effluent concentrations for BOD and DIN (2013-
2014 data) and the allowable concentrations based on the Surface Water Objectives (i.e.
S.I. No. 272 of 2009).
Table 2.5: Average Effluent Concentrations and Allowable Concentrations
Parameter Effluent Concentration
(Initial Concentration)
Maximum Allowable
Concentration
cBOD (mg/l) 6.8 41
Dissolved Inorganic Nitrogen
(mg.N/l) 12.3 0.252
1 Transitional standard for good status
2 Coastal water stand for good status
Table 2.6 provides a summary of the predicted BOD and DIN concentrations along with
predicted Ortho-Phosphate (P), COD and Total Nitrogen concentrations for (i) after initial
dilution, (ii) 50m from the discharge location and (iii) 200m from discharge location.
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These predicted concentrations are based on design standards (i.e. BOD 25mg/l; COD
125mg/l; TN 40mg/l; DIN 30mg/l; OP 10mg/l)
Table 2.6: Predicted Concentrations based on Design Standards at Low and High Current
Dilutions
Parameters Low Current High Current
Following Initial Dilution
BOD 0.62 0.05
COD 3.08 0.27
Total Nitrogen 0.98 0.09
Dissolved Inorganic Nitrogen 0.74 0.07
Ortho-Phosphate (P) 0.25 0.02
Concentrations at distance of 50m from discharge (mg/l)
BOD 0.30 0.05
COD 1.48 0.27
Total Nitrogen 0.47 0.09
Dissolved Inorganic Nitrogen 0.36 0.07
Ortho-Phosphate (P) 0.12 0.02
Concentrations at distance of 200m from discharge (mg/l)
BOD 0.07 0.05
COD 0.33 0.25
Total Nitrogen 0.11 0.08
Dissolved Inorganic Nitrogen 0.08 0.06
Ortho-Phosphate (P) 0.03 0.02
The horizontal dispersion dilution factor, D2, increases from 9.2 at 200 m for low currents to 31 at 500 m.
Table 2.7 provides a summary of the predicted BOD and DIN concentrations along with
predicted Ortho-Phosphate (P), COD and Total Nitrogen concentrations for (i) after initial
dilution, (ii) 50m from the discharge location and (iii) 200m from discharge location
based on the mean effluent concentrations from 2013-2014.
Table 2.7: Predicted Concentrations based on Mean Effluent Concentrations (2013-2014)
at Low and High Current Dilutions
Parameters Low Current High Current
Following Initial Dilution
BOD 0.17 0.01
COD 1.16 0.10
Total Nitrogen 0.28 0.02
Dissolved Inorganic Nitrogen 0.30 0.03
Ortho-Phosphate (P) 0.03 0.00
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Parameters Low Current High Current
Concentrations at distance of 50m from discharge (mg/l)
BOD 0.08 0.01
COD 0.56 0.10
Total Nitrogen 0.14 0.02
Dissolved Inorganic Nitrogen 0.15 0.03
Ortho-Phosphate (P) 0.02 0.00
Concentrations at distance of 200m from discharge (mg/l)
BOD 0.02 0.01
COD 0.13 0.10
Total Nitrogen 0.03 0.02
Dissolved Inorganic Nitrogen 0.03 0.02
Ortho-Phosphate (P) 0.00 0.00
2.5.7 Summary of Predicted Dispersion Results
Design Standards and Low Currents
The level of BOD following initial dilution will be a maximum of 15% of the maximum
allowable concentration; at 50m the level of BOD will be 7.5% of the maximum allowable
concentration and at 200m the level of BOD will be 1.75% of the maximum allowable
concentration.
In terms of DIN, following initial dilution and at 50m the level will exceed the
concentration in the Surface Water Regulations (0.25mg/l). At 200m the level of dilution
will be 32% of the maximum allowable concentration.
Design Standards and High Currents
The level of BOD following initial dilution will be a maximum of 1.25% of the maximum
allowable concentration after initial dilution.
At high currents, the level of DIN will be approximately 28% of the maximum allowable
concentrations after initial dilution and 50m. At a distance of 200 m from the outfall
location the maximum DIN will be approximately 24% of maximum allowable
concentration at high currents.
The mixing zone within Carlingford Lough where the effluent discharge may impact the
DIN levels is approximately 200m at low tidal conditions. Outside this area, any impacts
will be negligible.
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Mean Effluent Concentration (2013-2014 Data) and Low Currents
The level of BOD following initial dilution will be a maximum of 4.25% of the maximum
allowable concentration; at 50m the level of BOD will be 2% of the maximum allowable
concentration and at 200m the level of BOD will be 0.5% of the maximum allowable
concentration.
In terms of DIN, following initial dilution the level will exceed the concentration in the
Surface Water Regulations (0.25mg/l). At 50m the level of dilution will be 60% of the
maximum allowable concentration and at 200m the level of DIN will be 12% of the
maximum allowable concentration.
Table 2.8 below shows the % allowable concentrations of DIN in relation to the distance
from the discharge point (i.e. point of initial dilution) at low tidal conditions.
Table 2.8 Percentage Allowable Concentrations of DIN in relation to the Distance from
the Discharge Point at Low Tidal Conditions
DIN Concentration (mg/l) Distance from Discharge
Point (m)
Percentage of Allowable
Concentration (%)
0.300 0 120
0.2438 20 97.5
0.2025 30 81
0.1705 40 68.20
0.1500 50 60
0.1263 60 48
0.0879 85 32
0.0792 95 31
0.0477 150 18.8
0.0390 170 15.6
0.0367 185 14.68
0.0346 190 13.84
0.0327 200 13.08
Based on the current mean effluent data and low tidal conditions, the mixing zone within
Carlingford Lough where the actual effluent discharge may impact the DIN levels is up to
approximately 100m from the outfall, where the DIN will be approximately 28% of
maximum allowable concentration. Outside this area, any impacts will be negligible.
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Mean Effluent Concentration (2013-2014 Data) and High Currents
The level of BOD following initial dilution will be a maximum of 0.25% of the maximum
allowable concentration after initial dilution.
At high currents, the level of DIN will be approximately 12% of the maximum allowable
concentrations after initial dilution and 50m. At a distance of 200 m from the outfall
location, DIN concentrations will be approximately 8% of maximum allowable
concentration at high currents.
2.6 Conservation Objectives
A site's conservation objectives are a statement of the overall nature conservation
requirements for a site, expressed in terms of the favourable condition required for the
qualifying features.
According to the EU Habitats Directive, favourable conservation status of a habitat is
achieved when:
• Its natural range and area it covers within that range, is stable or increasing;
• the ecological factors that 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 as defined below.
The favourable conservation status of a species is achieved when:
• Population data on the species concerned indicate that it is maintaining itself;
• The natural range of the species is neither being reduced or 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.
The conservation objectives for the two Natura 2000 sites are set out below.
2.6.1 Conservation Objectives of Carlingford Shore SAC
The conservation objectives for the qualifying interests (SAC) are detailed in the 2013
NPWS Conservation Objectives document (ISSN 2009-4086). The natural condition of
the qualifying interest should be preserved with respect to their area, distribution, and
extent. Habitat availability should be maintained for qualifying species and disturbances
should not adversely affect such species.
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The features, conservation objectives and key targets of each of the qualifying interests
within the SAC are listed in Table 2.9 overleaf.
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Table 2.9 Conservation Objectives and Key Targets for Marine Habitats and Species in Carlingford Shore SAC (Source: NPWS, 2013)
Qualifying Interest
[Habitat Code]
Conservation
Objective Target
Annual Vegetation of
drift lines [1210]
Maintain the favourable
conservation condition
of annual vegetation of
drift lines
• Habitat area stable or increasing, subject to natural processes including erosion and
succession
• No decline, or change in habitat distribution, subject to natural processes
• Maintain the natural circulation of sediment and organic matter, without any physical
obstructions
• Maintain the range of coastal habitats including transitional zones, subject to natural
processes including erosion and succession
• Maintain the presence of species-poor communities with typical species: sea rocket (Cakile
maritima), sea sandwort (Honckenya peploides), prickly saltwort (Salsola kali) and orache
(Atriplex spp.)
• Negative indicator species (including non-natives) to represent less than 5% cover
Perennial vegetation of
stony banks [1220]
Maintain the favourable
conservation condition
of perennial vegetation
of stony banks
• Area stable or increasing, subject to natural processes, including erosion and succession
• No decline, or change in habitat distribution, subject to natural processes. (Greenore,
Ballagan Point, Whitestown to Cooley Point)
• Maintain the natural circulation of sediment and organic matter, without any physical
obstructions
• Maintain range of coastal habitats including transitional zones, subject to natural processes
including erosion and succession
• Maintain the typical vegetated shingle flora including the range of sub-communities within
the different zones
• Negative indicator species (including non-natives) to represent less than 5% cover
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2.6.2 Conservation Objectives of Carlingford Lough SPA
The overarching Conservation Objective for Carlingford Lough SPA is to ensure that the
waterbird populations and their wetland habitats are maintained at, or restored to,
favourable conservation condition. This includes, as an integral part, the need to avoid
deterioration of habitats and significant disturbance; thereby ensuring the persistence of
site integrity.
The site should contribute to the maintenance and improvement where necessary, of the
overall favourable status of the national resource of waterbird species, and continuation
of their long-term survival across their natural range.
Conservation Objectives for Carlingford Lough SPA, based on the principles of favourable
conservation status, are described below.
Objective 1: to maintain the favourable conservation condition of Light-bellied Brent
Goose in Carlingford Lough SPA.
This Conservation Objective target aims to maintain the population trend as stable or
increasing and aims to result in no significant decrease in the range, timing or intensity
of use of areas by Light-bellied Brent Goose, other than that occurring from natural
patterns of variation.
Objective 2: to maintain the favourable conservation of the wetland habitat in
Carlingford Lough SPA as a resource for the regularly occurring migratory waterbirds
that utilise the site.
This Conservation Objective target aims to ensure that the permanent area occupied by
wetland habitat should be stable and not significantly less than 595 ha, other than that
occurring from natural patterns of vegetation succession or natural processes of erosion.
2.7 Assessment of Potential Impacts on the Conservation Objectives
This stage of the Stage 2 Appropriate Assessment assesses the impact of the effluent
discharge on the conservation objectives of the Carlingford Shore SAC and Carlingford
Lough SPA qualifying interests as detailed in Sections 2.3.
An assessment under the Habitats Regulations must be appropriate to the potential level
of impact and the likely receptors. Therefore designated SAC and SPA qualifying features
which have no potential of being impacted by the wastewater treatment plant discharge,
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either because they do not occur within the area likely to be affected or because they are
not sensitive to changes in water quality, are excluded from this assessment. In the case
of Carlingford WwTP discharge all of the qualifying features of the SAC and SPA, as
detailed in the above Sections, have the potential to be impacted and have been brought
forward to this assessment.
The Transitional and Coastal Waters Action Programme for the Neagh-Bann IRBD
identified the water quality status of Carlingford Lough as moderate with high nitrogen
levels noted. Taylor et al. (1999) have shown that Carlingford WwTP is the source of a
small but significant proportion of the total dissolved inorganic nitrogen (DIN) loading to
Carlingford Lough. In low tidal conditions, Carlingford WwTP does not reach permissible
DIN levels in emissions to a limited area of Carlingford Lough (up to 100 m from the
emission point).
Carlingford Shore SAC
The qualifying interest/features of the Carlingford Shore SAC are Annual vegetation of
drift lines [1210] and Perennial vegetation of stony banks [1220], as detailed above. The
assessment of potential impacts on the conservation objectives of these habitats are
detailed below.
Annual vegetation of drift lines [1210]
Annual vegetation of drift lines, or strandline vegetation, is found on beaches along the
high tide mark, where tidal litter accumulates. Decaying detritus in the tidal litter
releases nutrients into what would otherwise be a nutrient-poor environment. It is
possible that enhanced nutrient levels from effluent discharged into Carlingford Lough by
the Carlingford WwTP may have contributed to increased algal growth and hence the
amount of detritus accumulating on sandy shores. The conservation objectives set for
the annual vegetation of drift lines are based in part on the findings of the Coastal
Monitoring Project (CMP) (Ryle et al., 2009). However, as the CMP did not visit this
particular site, the conservation objectives for the entire SAC are based on generic
findings from other sites that have been visited and therefore the overall objective for
‘Annual vegetation of drift lines’ in Carlingford Shore SAC is to ‘maintain the favourable
conservation condition’. The exact current extent of this habitat in Carlingford Shore is
unknown but it is thought to coincide with that of ‘perennial vegetation of stony banks’
with which it is likely to occur in a mosaic. The known extent of this habitat has been
mapped (NPWS, 2013) and the principal conservation objective is that there should be
no decline or change in the distribution of this habitat, unless it is the result of natural
processes, including erosion and succession.
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The main pressures and threats to this habitat relate to sand and gravel extraction,
removal of beach materials, walking, horse-riding and use of non-motorised vehicles,
trampling, garbage and solid waste disposal at habitat sites. The top-ranking pressures
are amenity/recreational use and coastal protection works at habitat sites (NPWS,
2013). This largely terrestrial habitat is not likely to be impacted by the WwTP at
Carlingford.
Perennial vegetation of stony banks [1220]
The conservation objectives set for this habitat are based primarily on the findings of the
National Shingle Beach Survey (NSBS), which was carried out in 1999 on behalf of the
National Parks and Wildlife Service (NPWS) (Moore and Wilson, 1999). Profiles and
transects were recorded from each shingle beach and each site was assigned a
High/Medium/Low interest ranking. At Carlingford Shore, all three sub-sites were rated
‘medium’ interest. The overall conservation objective for perennial vegetation of stony
banks in Carlingford Shore SAC is to ‘maintain the favourable conservation condition’.
The exact current extent of this habitat in Carlingford Shore SAC is unknown. The
National Shingle Beach Survey recorded vegetated shingle ridge from three sub-sites:
Cooley Point to Whitestown, Ballagan Point and Greenore, but did not map the extent
(Moore and Wilson, 1999) and there may be additional areas of shingle within the SAC.
The known extent of this habitat has been mapped (NPWS, 2013) and the principal
conservation objective is that there should be no decline or change in the distribution of
this habitat, unless it is the result of natural processes, including erosion and succession.
The main pressures and threats to this habitat are removal of beach materials, sea
defence and coastal protection measures and sand and gravel extraction, horse-riding
and use of non-motorised vehicles, trampling, garbage and solid waste disposal at
habitat sites. This largely terrestrial habitat is not likely to be impacted by the WwTP at
Carlingford.
Carlingford Lough SPA
As detailed above, the qualifying interest/features of the Carlingford Shore SAC are
Light-bellied Brent Goose (Branta bernicla hrota) [A046] and Wetlands [A999].
Favourable conservation conditions for the Light-Bellied Brent Goose in Carlingford
Lough are inextricably linked to the favourable conservation of the wetland habitat of the
Lough and as such, both objectives are assessed together.
Carlingford Lough SPA supports internationally important numbers of Light-bellied Brent
Goose i.e. numbers regularly exceed the international threshold of 400 (Wetlands
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International, 2012). In addition, the site holds a wide variety of waterbirds all of which
depend on wetland habitats. The main pressures on Brent Geese in terms of disturbance
relate to walkers and dog walkers, shellfish gatherers and aquaculture activities (NPWS,
2013).
Sewage outfalls are widely known to provide significant food sources for a variety of bird
species either directly as a source of edible matter or indirectly by artificially enhancing
nutrient availability (Burton et al. 2001). It is likely that nutrient delivery via Carlingford
and other treatment plants (and also agriculture sources) has led to increased nutrient
levels accumulating in the sediments of Carlingford Lough which in turn leads to
increases in certain invertebrate populations and algal growth. Increased numbers of
invertebrates benefit over-wintering waterbirds such as Black-tailed Godwit, Curlew and
Redshank, whereas increases in algal growth benefit grazing species such as Brent
Goose and Wigeon.
Excessive levels of nitrogen however, can have serious impacts on Zostera noltii
(Eelgrass), a vital food source for Brent Geese in Carlingford Lough between September
and December (NPWS, 2013) and high nitrogen levels have been implicated as one of
the primary causes of global Eelgrass decline (Katwijk et al. 1997; Van der Heide et al.
2008).
Conversely, high nitrogen levels can enhance the growth of algae such as Sea Lettuce,
also an important food source for Brent Geese. Continued high nitrogen levels in
Carlingford Lough could eventually lead to the establishment of eutrophic conditions
resulting in an ecological imbalance caused by excessive algal growth. This phenomenon
has already occurred in several estuaries along the south coast (e.g. Clonakilty Bay and
Courtmacsherry Bay in County Cork) and in nearby Dublin Bay where excessive growth
of sea lettuce is jeopardizing environmental conditions for important invertebrate species
with likely negative consequences for some wetland bird species at these sites (Sea
Lettuce Task Force Report, 2010).
Carlingford WwTP is largely meeting its emission targets and falls short with DIN
emissions only at low current periods. The WwTP at Carlingford is contributing to
nutrient enrichment in Carlingford Lough by exceeding the level of dissolved inorganic
nitrogen (DIN) emissions following initial dilution in low current situations up to 100 m
from the emission point and as such, it is having a negative impact on the wetland
habitat of Carlingford Lough. In the short term, nutrient enhancement may benefit the
Brent Goose population by contributing to enhanced algal growth but continued high
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levels of nitrogen could potentially threaten the existence of Eelgrass, the primary food
source for the Brent Goose population in the Lough. Excessive algal growth also has the
potential to negatively impact on the wetland habitat of Carlingford Lough.
2.8 In Combination Effects with Other Plans and Projects
In addition to the wastewater discharge from Carlingford, other relevant projects and
plans in the relevant region must also be considered in terms of in-combination impacts.
Cumulative impacts are incremental changes in the environment that result from
numerous manmade small-scale alterations. In-combination impacts can result from
individually minor but collectively significant changes taking place over a period of time.
The consequences of these changes are defined as in-combination effects.
Cumulative impacts resulting from projects of this nature relate primarily to the potential
for disturbances to key qualifying interests/features of a site and the degradation of
water quality, both of which have the potential to alter the integrity (structure and
function) of any Natura 2000 site.
Existing plans and projects which have been examined include:
• Louth County Development Plan 2012-2018
• Neagh-Bann International River Basin Management Plan
• Carlingford Water Management Unit Action Plan
• Other Discharge Sources
The above plans have been assessed in accordance with Article 6(3) of the Habitats
Directive and Part XAB of the Planning and Development Act, 2000, and are not
envisaged to result in significant effects on the integrity of the Natura 2000 network.
It is essential that the functioning of the Carlingford WwTP is not operating in conflict
with any of the aims, objectives and policies of the above plans.
Louth County Council Development Plan 2009-2015
The Louth County Development Plan 2009-2015 contains environmental policies and
objectives to protect Natura 2000 sites and the aquatic environment in County Louth
including Carlingford Louth.
A key Natural Heritage objective of the County Development Plan is to conserve and
protect where appropriate the County’s natural heritage for future generations and
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encourage appreciation and enjoyment of these resources (As per the Naturals Heritage
Plan 2002).
The key policies and objectives of the Plan relevant to the Scheme considering Natura
2000 sites and the WFD are listed below.
CON 11: To resist any development that would be harmful to or that would result in a
significant deterioration of habitats or disturbance of species.
CON 13: To ensure that an appropriate assessment of the implications of any proposed
development on a SAC or development likely to impact on a SAC that is outside the
designated area or any other SAC identified during the period of this plan is undertaken
in view of the site’s conservation objectives.
CON 14: To resist any development that would be harmful or that would result in a
significant deterioration of habitats or disturbance of species in a SAC.
CON 15: To ensure that an appropriate assessment of the implications of any proposed
development on a SPA or development likely to impact on a SPA that is outside the
designated area or any other SPA identified during the period of this plan is undertaken
in view of the sites conservation objectives.
ENV 1: To implement European, national and regional policy in relation to the protection
of the environment and the pursuance of sustainable development principles in respect
of the council’s policies and procedures.
ENV 3: To promote and maintain the highest achievable standards of air, noise and
water quality in the county.
ENV 7: To implement the recommendations contained in the River Basin District
Management Plans for the Neagh Bann and the Eastern River Basin Districts, in so far as
they relate to County Louth.
ENV 16: To adhere to the guidance document setting out the requirements and
information to be submitted with a planning application for an on-site wastewater
treatment systems.
WS 4: To ensure that the provision and operation of water and wastewater treatment
facilities is undertaken in accordance with EU policies and directives, relevant national
legislation, national and regional policies.
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WS 8: To undertake measures recommended in the River Basin Management Plans
relevant to County Louth to mitigate the impacts of water abstraction and discharges of
treated effluent from wastewater plants and storm drains, on a prioritised basis, subject
to affordability.
WS 28: To prevent discharges of untreated sewage from overflows.
Neagh-Bann International River Basin Management Plan and the Carlingford
Water Management Unit Action Plan
The principal suspected causes of less than satisfactory water in the state are
discharges, principally of nutrients, from agricultural activities and from municipal
wastewater treatment works. Industrial discharges, wastewater from unsewered
properties and discharges from several other activities have also been identified as
contributing.
This Neagh Bann River Basin Management plan identifies a programme of measures to
protect and restore water status by addressing the main pressures (that is sources of
pollution or status impact) in the district. Many of the measures are already provided for
in national legislation and are being implemented. These include, for example, the Urban
Waste Water Treatment Regulations 2001 to 2010 and the Good Agricultural Practice for
the Protection of Waters Regulations of 2009. Other measures have been recently
introduced e.g. the Bathing Water Regulations, 2008.
More detailed information is also set out in a series of water management unit (WMU)
action plans. WMUs are at a smaller geographical scale than river basin districts, and
allow for more focussed planning and implementation. There are seven water
management units for the rivers and lakes in the Neagh Bann IRBD plus action plans
focusing on groundwaters and estuary and coastal waters. For estuary and coastal water
there is a Transitional and Coastal Waters Action Programme which identifies the key
pressure and threats with the transitional and coastal waters of the Neagh Bann region
and outlines the action programmes for the waters to ensure that the objective and aims
of the WFD are met.
The relevant WMU Plan for Carlingford Lough and the Carlingford WwTP are the
Carlingford Water Management Unit Action Plan and the Neagh Bann IRBD Transitional
and Coastal Waters Action Programme. In this plan the Carlingford WwTP is considered
as a point pressure, however the Plan notes that “No water bodies at risk from WwTP or
industrial discharges”.
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Any impacts from the Carlingford WwTP discharge on the receiving coastal waters are in
conflict with the above plans’ policies and objectives. The WwTP is currently operating in
compliance with the UWWT Regulations.
The monitoring data for Carlingford Lough indicates that the key limiting parameter for
this waterbody in terms of achieving “Good” status is DIN. The specific source of the
adverse pressure or combination of pressures on this water body, causing a deterioration
in status, has yet to be determined. Based on the current mean effluent data and at low
tidal conditions, the mixing zone within Carlingford Lough where the actual effluent
discharge may impact the DIN levels is up to approximately 100 m from the outfall. It is
considered that outside this area the impact will be negligible. At low flow condition the
WwTP is therefore having a localised effect on the Lough in terms of DIN and is
contributing to the waterbody not achieving the surface water objective for this
parameter. It is considered that agricultural input and shellfish dredging are also
contributors to the DIN status (NIEA, 2014).
Other Sources/Discharges
As part of this in combination assessment the other discharges to the Lough were
considered.
As stated above, there are two other municipal wastewater discharges into Carlingford
Lough i.e. Omeath and Greenore. These sites are removed from the Carlingford treated
effluent discharge location and are subject to separate Licence applications.
Nevertheless, there is the potential for in combination impacts with the above
discharges, should the above WwTPs not be in compliance with the UWWT Directive,
Surface Water Objectives and EPA Certificate conditions.
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2.9 Mitigation Measures
With regard to the cumulative impacts of the Carlingford discharge as a whole and the
operational impacts, the wastewater discharge effluent standards must be in line with
the Urban Waste Water Treatment Regulations (2001) and the functioning of the WwTW
must be in compliance with any future EPA Waste Water Discharge Licence conditions to
ensure the environmental quality standards for the receiving waters are always met. In
terms of additional discharges from other municipal sources into Carlingford Lough, it is
imperative that the EPA Certificate conditions relating to their discharges to the aquatic
environment are stringently met.
A number of mitigation measures will be put in place further to the issuing of the
Wastewater Discharge Licence Application from the EPA for the existing Carlingford
WwTP. These will ensure that significant effects on Carlingford Lough will not occur or
will be minimised. The key mitigation measure will be the continued treatment of sewage
effluent to acceptable standards and will include measures to ensure nutrient emissions
will fall within maximum allowable concentrations. This will ensure the maximum water
quality output to the receiving water body and minimise adverse effects on Carlingford
Lough and therefore the Carlingford Lough SPA and Carlingford Shore SAC.
2.10 Concluding Statement
After completing this Natura Impact Statement and the Stage 2 Appropriate Assessment
process, it can be concluded that, as long as the mitigation measures of Section 2.9 are
implemented, no significant adverse effects on the conservation objectives and qualifying
interests/features of Carlingford Lough SPA and Carlingford Shore SPA are likely from
the discharge effluent from the existing Carlingford WwTP.
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3. REFERENCES
Burton, N.H.K., Maskell, J.M., Armitage, M.J.S, Hutchings, C.J., Rehfisch, M.M. 2001.
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Estuaries and Coastal Waters of England and Wales. Interim Report. British Trust
for Ornithology, The Nunnery, Thetford, Norfolk.
Circular L8/08 (September 2008) Water Services Investment and Rural Water
Programmes – Protection of Natural Heritage and National Monuments
Department of the Environment Heritage and Local Government Ireland
(DOEHLG).
DEHLG (2009) Appropriate Assessment of Plans and Projects in Ireland – Guidance for
Planning Authorities.
Drew D.P. and Daly D. (1993) Groundwater and Karstification in Mid-Galway, South
Mayo and North Clare. A Joint Report. Department of Geography, Trinity College
Dublin and Groundwater Section, Geological Survey of Ireland. Geological Survey
of Ireland Report Series 93/3 (Groundwater), 86 pp
EPA (2012) Note on Appropriate Assessments for the purposes of the Waste Water
Discharge (Authorisation) Regulations, 2007 (S.I. No. 684 of 2007), as amended.
European Commission: Assessment of plans and projects significantly affecting Natura
2000 sites Methodological guidance on the provisions of Article 6(3) and (4) of
the Habitats Directive 92/43/EEC.
European Commissions Managing Natura 2000 Sites. The provisions of Article 6, of the
‘Habitats’ Directive 92/43/EEC.
Moore D. and Wilson, F. (1999) National Shingle Beach Survey of Ireland 1999.
Unpublished report to the National Parks and Wildlife Service, Dublin.
NIEA (2005) Northern Ireland Species Action Plan, Light-bellied Brent Goose, Branta
bernicla hrota.
NIEA (2014) Reasons for status for the water bodies within the Carlingford and Newry
LMA March 2014 Version No.1.
NPWS (2013) Conservation Objectives: Carlingford Shore SAC 002306. Version 1.
National Parks and Wildlife Service, Department of Arts, Heritage and the
Gaeltacht.
NPWS (2013) Conservation Objectives: Carlingford Lough SPA 004078. Version 1.
National Parks and Wildlife Service, Department of Arts, Heritage and the
Gaeltacht.
NPWS (2013) The Status of EU Protected Habitats and Species in Ireland. Habitat
Assessments Volume 2. Version 1.0. Unpublished Report, National Parks and
Wildlife Services. Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland.
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NPWS (2013) Carlingford Lough Special Protection Area (Site Code 4078) Conservation
Objectives Supporting Document Version 1.
Ryle, T., Murray, A., Connolly, K. and Swann, M. (2009). Coastal Monitoring Project
2004-2006. Unpublished report to the National Parks and Wildlife Service, Dublin.
Sea Lettuce Task Force Report. 2010. Available at:
http://www.environ.ie/en/Foreshore/ApplicationsandDeterminations/CorkCoCl-
RemovalSeaLettuce/ApplicationDetails/FileDownLoad,30556,en.pdf
Van der Heide, T., Smolders, A.J.P., Rijkens, B.G.A., Van Nes, E.H., Van Katwijk, M.M.,
Roelofs, J.G.M. 2008. Toxicity of reduced nitrogen in eelgrass (Zostera marina) is
highly dependent on shoot density and pH. Oecologia, 158:411-419.
Van Katwijk, M.M., Vergeer, L.H.T., Schmitz, G.H.W., Roelofs, J.G.M. 1997. Ammonium
toxicity in eelgrass Zostera marina. Marine Ecology Progress Series, 157:159-
173.
Western RBD / ESBI / Eleanor Mayes (2008) Report Protected Areas: Water Dependent
Habitats and Species.
Wetlands International (2012) Waterfowl Population Estimates – Fifth Edition. Wetlands
International, Wageningen, The Netherlands.
Key Online Sources
EPA Online Mapping ENVision
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Carlingford WwTP Reg. No. D0268-01 Stage 2 Appropriate Assessment
Nicholas O’Dwyer Ltd. June 2014
APPENDIX I: SITES SYNOPSES
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SITE SYNOPSIS
SITE NAME: CARLINGFORD SHORE
SITE CODE: 002306
Carlingford Shore stretches for approximately 15 km along the shoreline to the LWM
of Carlingford Lough which is also the estuary of the Newry River. It is flanked by
glacial moraines and mountains - the Mourne Mountains to the north and Carlingford
Mountain to the south-west. The underlying rock within the SAC is mainly
carboniferous limestone. This outcrops over sections of the SAC in the form of
bedrock shore or reefs. Granite boulders are occasionally found. Intertidal mudflats
and sand/gravel banks also occur.
The site is a candidate SAC selected for perennial vegetation of stony banks and drift
lines, both habitats listed on Annex I of the E.U. Habitats Directive.
The stony banks or shingle found along much of the site vary in width from less than a
meter to approximately 50 m south of Ballagan Point. The best examples are found in
this area. The perennial vegetaion of the upper beach of these shingle banks is widely
ranging, well developed and often stable. In places lichens encrust the stones farther
back from the sea. Typical species present throughout the site include Oraches
(Atriplex spp.), Sea Beet (Beta vulgaris), Wild Carrot (Daucus carota), Red Fescue
(Festuca rubra), Sea-milkwort (Glaux maritima), Lyme-grass (Leymus arenarius) and
Wild Radish (Raphanus raphanistrum). This grades landward into lowland dry
grassland mainly though there are patches of wet grassland.
The vegetation of the stony banks is often interspersed with the vegetation occupying
accumulations of drift material and gravels rich in nitrogenous organic matter. The
vegetation is sparse. Species seen include Saltwort (Salsola kali), Sea Rocket (Cakile
maritima), Sea Sandwort (Honkenya peploides), Sea Spurge (Euphorbia paralias),
Sea Mayweed (Matricaria maritima)and Oraches. The Red Data Book Species the
Oyster Plant (Mertensia maritima) is also found. This plant is protected under the
Flora Protection Order 1999.
There are small patches of saltmarsh on the drier sections of outcropping reefs and at
the landward edge of the site. Species present include Sea Aster (Aster tripolium),
Sea Purslane (Halimione portulacoides), Lax-flowered Sea Lavender (Limonium
humile), Common Saltmarsh-grass (Puccinellia maritima), Sea Arrowgrass
(Triglochin maritima) and Sea Plantain (Plantago maritima). In areas which are more
regularly flooded is Sea Blite (Suaeda maritima). A small brackish lake is present on
the landward side of the railway line.
Relatively extensive expanse of intertidal flats - more a sand rather than mud
dominant type - occur, particularly between Greenore Point and Carlingford Harbour.
The flats in this area are broken by outcropping reefs and some shingle deposits and
saltmarsh on the drier higher rocks. These flats are very important feeding grounds
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for wildfowl and waders. Patches of green algae (filamentous, Ulva sp. and
Enteromorpha sp.) and Lugworm casts occur in places, while fucoid seaweeds are
common on the more stony flats. Abundant Barnacle shells and Lichens are also
present on many of the rocks. Eelgrass (Zostera) beds are found on the flats - the
main food source for the internationally important population of Pale-bellied Brent
Geese at the site. Small tufts of Cord-grass (Spartina) are also found.
The threshold for internationally important numbers of birds within the site has been
exceeded in single years, by some species such as Pale-bellied Brent Geese in the 80’s and
94/95. The site is nationally important for a number of species such as Great Crested Grebe,
Cormorant, Ringed Plover and Red-Breasted Merganser. This classification is based on
species which attained interim all-Ireland importance on the basis of the three year mean
maximum counts for the winters 94/95-96/97. There are a number of bird species recorded
including, Golden Plover and Bar-tailed Godwit, which are listed under Annex I of the E.U.
Birds Directive. The intertidal flats between Greenore and Carlingford have been designated
a Special Protection Area under the EU Birds Directive.
Black Guillemots (6) were recorded in pairs nesting in wooden breakwater in Greenore and
8 birds were seen at the breakwater. A colony of Terns in Northern Ireland feed in the SPA
particularly Sandwich Tern with some Common Tern.
Grey Seals also use the site. Approximately 25-30 haul out on reefs between Greenore and
Carlingford. This seal is listed in Annex II under the E.U. Habitats Directive.
The principal activity in the site is recreational usage and shellfish production.
Almost the entire area at the MLWM between Carlingford Harbour and Greenore is
under production of Oyster and some small amount of Clams.
Carlingford Shore has a wide diversity of habitats including very good examples of
perennial vegetation of stony banks and drift lines. The presence of the Red Data Book
Species adds to the ecological interest. The wide area of mud and sand flats within the site
is internationally important for birds and is designated as a Special Protection Area. Grey
Seal, an Annex II species under the E.U. Habitats Directive adds to the conservation value
of the site.
23.10.2002
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SITE SYNOPSIS
SITE NAME: CARLINGFORD LOUGH SPA
SITE CODE: 004078
The site comprises part of the southern sector of Carlingford Lough, Co. Louth,
extending from the harbour at Carlingford to Greenore Point. It includes all of the
intertidal sand and mud flats to the low tide mark. Much of the shoreline is artificially
embanked.
The site supports part of a nationally important population of wintering Cormorant
(233 average maximum, 1995/96-1999/00). A range of other waterfowl species
occurs, notably Brent Goose (175), Oystercatcher (172), Dunlin (267), Bar-tailed
Godwit (25), Redshank (35) and Turnstone (19). The intertidal flats provide feeding
areas for the wintering birds.
While the numbers of wintering birds are relatively low, the site does support a good
range of species. The presence of Bar-tailed Godwit is of particular note as this
species is listed on Annex I of the E.U. Birds Directive.
8.2.2004
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