Office of Public Works Arterial Drainage Maintenance Works - Glyde and Dee Arterial Drainage Scheme Stage 2: Natura Impact Statement 2018 to 2022 April 2018 Office of Public Works Main Street Headford Co Galway Ireland JBA Project Manager Tom Sampson 24 Grove Island Corbally Limerick Ireland Revision History Revision Ref / Date Issued Amendments Issued to Draft V1.0 Report / Tony Brew December 2017 Final Report V2.0 Included OPW Invasive Tony Brew April 2018 Species procedures, winter survey results and concluding statement. Contract This report describes work commissioned by the Office of Public Works, by a letter dated 31/08/2017. The Office of Public Works’ representative for the contract was Tony Brew. Niamh Sweeney, Patricia Byrne and Fiona Byrne of JBA Consulting carried out this work. Prepared by .................................................. Patricia Byrne BSc PhD CIEEM Ecologist Reviewed by ................................................. Laura Thomas BA MRes PGCert CEcol MCIEEM Chartered Senior ecologist Purpose This document has been prepared as a Final Report for the OPW. JBA Consulting accepts no responsibility or liability for any use that is made of this document other than by the Client for the purposes for which it was originally commissioned and prepared JBA Consulting has no liability regarding the use of this report except to the OPW. 2017s6456 Glyde and Dee NIS v2.0 i Copyright © Jeremy Benn Associates Limited 2018 Carbon Footprint A printed copy of the main text in this document will result in a carbon footprint of 396g if 100% post- consumer recycled paper is used and 504g if primary-source paper is used. These figures assume the report is printed in black and white on A4 paper and in duplex. JBA is aiming to reduce its per capita carbon emissions. 2017s6456 Glyde and Dee NIS v2.0 ii Contents 1 Introduction ............................................................................................................ 1 1.1 Background ........................................................................................................................ 1 1.2 Legislative Context ............................................................................................................. 1 1.3 Appropriate Assessment Process ...................................................................................... 1 1.4 Methodology....................................................................................................................... 3 2 Arterial Drainage Maintenance .............................................................................. 5 2.1 Background ........................................................................................................................ 5 2.2 Drainage Maintenance Activities ........................................................................................ 5 2.3 The Glyde and Dee Arterial Drainage Scheme .................................................................. 10 2.4 Drainage Maintenance Works Proposed for the Glyde and Dee Arterial Drainage Scheme 11 3 Screening Assessment Results ............................................................................. 13 3.1 Introduction ........................................................................................................................ 13 3.2 Screening Assessment Conclusions .................................................................................. 19 4 Existing environment ............................................................................................. 21 4.1 Methodology....................................................................................................................... 21 4.2 Results ............................................................................................................................... 21 5 Natura 2000 sites within the Zone of Influence of Drainage Maintenance Activities ............................................................................................................................... 42 5.1 Introduction ........................................................................................................................ 42 5.2 Dundalk Bay SAC (000455) ............................................................................................... 42 5.3 Dundalk Bay SPA (004026) ............................................................................................... 47 5.4 Stabannan-Braganstown SPA (004091) ............................................................................ 49 6 Appropriate Assessment........................................................................................ 51 6.1 Introduction ........................................................................................................................ 51 6.2 Identification of Potential Sources of Impact ...................................................................... 51 6.3 Cumulative and in-combination impacts ............................................................................. 54 6.4 Impact Assessment ............................................................................................................ 57 7 Avoidance and Mitigation Measures ...................................................................... 63 7.1 Introduction ........................................................................................................................ 63 8 Conclusions ........................................................................................................... 65 A Appendices ............................................................................................................ 68 References.......................................................................................................................... 87 2017s6456 Glyde and Dee NIS v2.0 List of Figures Figure 1-1: The Appropriate Assessment Process (from: Appropriate Assessment of Plans and Projects in Ireland - Guidance for Planning Authorities, DoEHLG, 2009).. 2 Figure 1-2: Screening assessment process ...................................................................... 4 Figure 2-3: Map of the Glyde and Dee Arterial Drainage Scheme .................................... 11 Figure 3-1: Channels and embankments with potential impacts via surface water pathways ........................................................................................................................... 14 Figure 3-2: Channels and embankments with potential impacts via land and air pathways ........................................................................................................................... 17 Figure 4-1: Lower weir on River Glyde separating depositing/lowland river habitat from tidal river habitat. ....................................................................................................... 23 Figure 4-2: Reed and large sedge swamps FS1 on the River Dee .................................... 24 Figure 4-3: Riparian woodland WN5 on left bank of River Glyde ....................................... 24 Figure 4-4: Tall-herb swamp adjacent to River Glyde ........................................................ 25 Figure 4-5: Tidal river habitat CW2 with mud shores (left) and mud and cobbles with attached seaweed (right). .................................................................................. 25 Figure 4-6: Area of upper saltmarsh CM2 on River Glyde ................................................. 26 Figure 4-7: Lower saltmarsh CM1 habitat on River Glyde. ................................................ 27 Figure 4-8: Annex 1 saltmarsh habitat and Perennial vegetation on stony banks [1220] at the mouth of the Glyde/Dee Estuary ................................................................. 28 Figure 4-9: Glyde and Dee Estuary MW4 opening onto mud and sandflats with mixed sediment shores ................................................................................................ 29 Figure 4-10: Drainage ditch adjacent to OPW embankment on right bank of River Dee. .. 30 Figure 4-11: Mixed woodland WD1 on right bank of River Glyde. ..................................... 31 Figure 4-12: Cleared area of woodland on left bank of River Glyde below upper weir. ..... 32 Figure 4-13: Areas of wet grassland adjacent to the River Glyde ...................................... 32 Figure 4-14: Scrub WS1 on left embankment of River Dee ............................................... 33 Figure 4-15: Egret roosting site .......................................................................................... 34 Figure 4-16: Badger droppings (left) and Otter spraint (right) ............................................ 34 Figure 4-17: Water Fern Azolla filiculoides on the River Glyde .......................................... 35 Figure 4-18: Japanese Knotweed on landward side of embankment adjacent to the River Glyde ................................................................................................................. 36 Figure 4-19: Giant Hogweed (potential) ............................................................................. 37 Figure 4-20: Drainage ditch at Stabannan ......................................................................... 38 Figure 4-21: Mixed species treeline at Stabannan ............................................................. 39 Figure 4-23: Badger holes on E3, River Glyde ................................................................... 41 List of Tables