Appropriate Assessment Report

Assessment of the likely effects of dredging of the navigation channel in harbour on the integrity of the Cummeen Strand / Bay SAC and the Cummeen Strand SPA

Project Description:

Sligo County Council proposed to carry out capital and maintenance dredging works in a 5.3Km stretch of the navigation channel between Oyster Island and the Barytes Jetty in Sligo Harbour. The areas to be dredged are shown on Drawing No. IBE0440 Attachment 3(i), dated 8/10/2012 that accompanied the application..

For the Capital dredging element of the proposed works it is intended to dredge the channel to a depth of -3.0m CD and it is estimated that the total volume of material to be dredge will be 250,000m3. The dredging will be carried out using either a Suction Dredger or a Backhoe Dredger but the exact dredger type to be used will not be known until a Contractor has been appointed. It is intended that all the dredged material will be disposed of at sea, subject to a Dumping at Sea Permit being granted by the EPA, at a site located some 63 Km from the deep water jetty in Sligo Harbour, approximately 31.5 Km southwest of Malin More Head.

Given the shallow water depths in the existing channel it is anticipated that the dredger will have to “dig its way upstream” and thus will only be able to carry out dredging during the upper half of the tidal cycle. It is estimated that the dredger will only be able to operate for a period of 70 – 80 minutes during each tide. The remainder of the time would be spent steaming to and from the dump site. It is anticipated that the dredging operation will take 4 – 8 months to complete.

Capital dredging to -3.0m CD is proposed to give vessels with a draught of 5.9m a 3 hour window at high tide during which they could complete the passage through Sligo harbour into the Port.

It is also intended to carry out maintenance dredging, using Water Injection Dredging (WID) of an area within the Sligo Port as shown on Drawing No. IBE0440 Attachment 3(i), dated 8/10/2012. This will involve the removal of some 5,500m3 of material from the area around the channel to the Deepwater jetty and berths at both Deepwater and Barytes Jetties. It is intended that WID will be carried out on an ebbing tide in order to ensure that suspended particles are transported away from the Port area and it is anticipated that the WID operation would be completed within 5 -6 tides.

Details of the proposed works are shown the following Drawings submitted by the applicant in support of the application:

o Drawing No IBE 0440-Attachment 3(i) ‘’A3 Overview Navigation Channel Dredging Areas(OS) o Drawing No IBE 0440 Attachment 3(ii) ‘’A3 Overview Navigation Channel Dredging Area(Admiralty Chart 2852) o Drawing No IBE 0440/500-Rev 0- ‘’Plan Overview of Dredging Cross Section Locations o Drawing No’s IBE 0440/500_1, IBE 0440/500_2 and IBE 0440/500_3-Rev 0- ‘’Dredging Cross Sections’’

The total area of foreshore involved is estimated to be 28.3Ha.

The area of the proposed works is within the Cummeen Strand / Drumcliff Bay SAC (Site Code 000627) and the Cummeen Strand SPA (Site Code 004035).

A Natura Impact Statement to inform Appropriate Assessment, dated October 2012 prepared by AquaFact International Services Ltd was submitted by the applicant.

Cummeen Strand / Drumcliff Bay SAC

This large coastal site extends from Cullamore in the north-west to Killaspug in the south-west, and from Sligo town in the south-east to Drumcliff village in the north-east. It encompasses two large, shallow bays (Drumcliff Bay and Sligo Harbour), Ardboline and Horse Islands, sand dunes and sand hills at , Killaspug, Yellow Strand and Coney Island, grassland at Ballintemple and Ballygilgan (Lissadell) and a variety of other habitats (woodland, salt marsh, sandy beaches, boulder beaches, shingle, fen, freshwater marshes, rocky sea cliffs, lakes).

The dominant habitats on the site are estuaries and intertidal sand and mud flats. Sligo Harbour receives the waters of the Garavogue River, which flows from Lough Gill, while Drumcliff Bay receives the Drumcliff River which flows from . At low tide extensive areas of intertidal flats are exposed in both of these sheltered estuarine bays. The intertidal flats support a diverse macrofauna, with invertebrate species such as lugworm (Arenicola marina), cockles (Cerastoderma edule), sand mason (Lanice conchilega), Baltic tellin (Macoma balthica), spire shell (Hydrobia ulvae) and mussels (Mytilus edulis) being frequent. Of particular note is the presence of eelgrass (Zostera noltii and Z. angustifolia) beds in both bays. Both estuaries and intertidal flats are of conservation significance and are listed on Annex I of the EU Habitats Directive. Areas of salt marsh fringe both bays in places.

At least five species listed on Annex II of the EU Habitats Directive are found within this site. Drumcliff Bay is important for the presence of a breeding population of Common Seal. Ardboline and Horse Islands on the western side of the site are also important as haul-out areas for this species. Sea Lamprey and River Lamprey have been recorded in the Garavogue River, and River Lamprey are also known from further upstream in the tributaries of Lough Gill. The Marsh Fritillary butterfly is found at Rosses Point, while the rare snail, Vertigo angustior has recently been recorded from sand dunes at Killaspugbrone.

Cummeen Strand/Drumcliff Bay () is an important site of high conservation significance, which includes a wide variety of habitat types, including several listed on Annex I of the EU Habitats Directive, several species listed on Annex II of this directive, large and important populations of waterfowl and seabirds, and several rare plant species.

As set out in the NPWS (2013)1 the key Conservation Objectives for this site are :

 To maintain the favourable conservation condition of Estuaries in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To maintain the favourable conservation condition of Mudflats and sandflats not covered by seawater at low tide in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To maintain the favourable conservation condition of Embryonic shifting dunes in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To restore the favourable conservation condition of Shifting dunes along the shoreline with Ammophila arenaria ('white dunes') in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To restore the favourable conservation condition of Fixed coastal dunes with herbaceous vegetation ('grey dunes') in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To restore the favourable conservation condition of Juniperus communis formations on heaths or calcareous grasslands in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To maintain the favourable conservation condition of Petrifying springs with tufa formation (Cratoneurion) in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To maintain the favourable conservation condition of Narrow-mouthed Whorl Snail in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To restore the favourable conservation condition of Sea Lamprey in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To maintain the favourable conservation condition of River Lamprey in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC  To maintain the favourable conservation condition of Harbour Seal in Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC

Impact of Project on key species and key habitats

Considering the location, nature and scale of the proposed works it is considered that no direct or indirect effects are likely on the following species / habitats

o Embryonic shifting dunes along the shoreline with Ammophila arenaria ('white dunes') o Fixed coastal dunes with herbaceous vegetation ('grey dunes') o Juniperus communis formations on heaths or calcareous grasslands o Narrow-mouthed Whorl Snail

Noise associated with the works could result in the disturbance and displacement of Harbour seal and other marine mammals.

Noise and resuspension of sediments during the dredging operation, could impact on the passage of migratory fish including river lamprey and sea lamprey.

1 NPWS (2013) Conservation Objectives: Cummeen Strand/Drumcliff Bay (Sligo Bay) SAC 000627. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht. Resuspension of sediments during dredging with subsequent resettlement could have an indirect effect on Mudflats and sandflats not covered by seawater at low tide

The dredging operation, both capital and maintenance, as proposed will have a direct impact on circa 28.3 Ha of the following habitats “Estuaries” habitat.

Harbour seal (Phoca vitulina), is a species listed in Annex II of the EU Habitats Directive and is a qualifying feature/interest for the Cummeen Strand/Drumcliff Bay Special Area of Conservation. Drumcliff Bay is important for the presence of a breeding population of Common Seal while Ardboline and Horse Islands on the western side of the site are also important as haul-out areas for this species. There are, however, no known seal breeding or haul-out areas in the areas to be dredged. Other marine mammal species, including the cetacean species Bottle nose dolphin and Harbour porpoise have been sighted in the Sligo area but are not known to be resident within the Sligo Harbour area. All cetaceans are listed under Annex IV the Habitats Directive. The interaction with marine mammals will be mitigated by the employment of a Marine Mammal Observer and the use of “soft start” procedure. The Marine Mammal Observer will undertake 30 minutes of survey prior to commencement of the soft-start procedure to ensure that no marine mammals are within 50m of the works area.

The noise producing works will not be continuous.

Any increase in water column turbidly will be temporary, localised and within the natural range of variability caused by current induced sediment resuspension. Prior to the commencement of any dredging activity agreement on timing of the works with Inland Fisheries Ireland, with a closed period as appropriate, will ensure that any impacts on river and sea lamprey are minimised.

Sediment transport models predict that deposition of sediment as a result of the dredging activity, will be low (<2mm). The fauna found on the sandflats in the majority of the Sligo Harbour /Cumeen Strand area would be considered highly tolerant of such levels of sedimentation. Model results show that the maximum final deposition depth following completion of operations will not exceed 1mm in the majority of the harbour area. The impact on the “Mudflats and sandflats not covered by seawater at low tide” habitat type is therefore not considered likely to be significant.

There will be a direct impact on the habitat within the dredged areas as a result of the proposed works. This will have a slight adverse impact on the Conservation Objectives for the “Estuary” habitat types. The total area of the “Estuary” habitat in the SAC is 1258 Ha. Given that the total area that will be impacted is 28.3 Ha, or 2.25% of the total “Estuary” habitat within the SAC it can be concluded that the overall effect on this habitat will not be significant. There will not be significant disturbance to key habitats or species. Additionally there will be no habitat or species fragmentation and the overall integrity of the site will not be affected.

There will be no direct discharge of pollutants into the environment during the works and water quality will not be affected.

Cummeen Strand SPA (Site Code 004035).

Cummeen Strand is a large shallow bay stretching from Sligo town westwards to Coney Island. It is one of three estuarine bays within Sligo Bay, with Drumcliff Bay to the north and Bay to the south. The Garavogue River flows into the bay and forms a permanent channel. At low tide, extensive sand and mud flats are exposed. These support a diverse macro- invertebrate fauna which provide the main food supply for the wintering waterfowl. Areas of salt marsh fringe the bay in places and provide roosting sites for birds during the high tide periods. There are sand dunes at Killaspug Point and Coney Island, with a shingle spit at Standalone Point near Sligo town.

Cummeen Strand is of ornithological importance as it supports important concentrations of wintering waterfowl. The site supports an Internationally Important flock of Brent Geese and Nationally Important populations of a further two species – Oystercatcher and Redshank Other species which occurred in significant numbers included Shelduck Wigeon Teal Mallard Red- breasted Merganser, Golden Plover, Lapwing, Knot, Sanderling, Dunlin, Bar-tailed Godwit, Curlew, Greenshank and Turnstone. Whooper Swans also occur though they are not regular visitors. The presence of Golden Plover, Bar-tailed Godwit and Whooper Swan is of particular note as these species are listed on Annex I of the EU Birds Directive.

As set out in NPWS (2013)2 the key Conservation Objectives for this site are to: o maintain the favourable conservation condition of Light-bellied Brent Goose in Cummeen Strand SPA o maintain the favourable conservation condition of Oystercatcher in Cummeen Strand SPA o maintain the favourable conservation condition of Redshank in Cummeen Strand SPA o maintain the favourable conservation condition of wetland habitat in Cummeen Strand SPA as a resource for the regularly occurring migratory waterbirds that utilise it

Impact of Project on key species and key habitats

There are no areas of saltmarsh or habitats of a similar nature located in the works area and no significant loss of potential feeding area for waterbirds will occur. There will be no direct discharge of pollutants into the environment during the works and water quality will not be affected.

2 NPWS (2013) Conservation Objectives: Cummeen Strand SPA 004035. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht. There will be no direct impact on the “Mudflats and sandflats not covered by seawater at low tide” habitat Sediment transport models predict that deposition of sediment as a result of the dredging activity, will be low (<2mm). The fauna found on the sandflats in the majority of the Sligo Harbour /Cumeen Strand area would be considered highly tolerant of such levels of sedimentation. Model results show that the maximum final deposition depth following completion of operations will not exceed 1mm in the majority of the harbour area. The impact on the “Mudflats and sandflats not covered by seawater at low tide” habitat type is therefore not considered likely to be significant. It is also considered that the intertidal macrobenthos which serves as a food source for birds are not likely to be significantly impacted.

There is the potential for disturbance to birds during the dredging operation. As the capital dredging works will only take place for a period of 70 – 80 minutes during each tide, any disturbance is likely to be localised and temporary. Similarly, as the maintenance dredging works will only be carried out during an ebbing tide and will be completed within 5-6 tides the noise disturbance will not be continuous, will be localised and temporary.

Conclusion

Based on the above it is concluded that the proposed dredging of the navigation channel in Sligo Harbour is not likely to have an adverse impact on the Conservation Objectives of the Cummeen Strand / Drumcliff Bay SAC and the Cummeen Strand SPA and that the integrity of these sites will not be affected.

Prepared by Marine Institute, on behalf of the MLVC 07 May 2014