Appendix 16C Baseline Data

A5 Western Transport Corridor Volume 3 – Appendices APPENDIX 16C BASELINE DATA Surface Water Designations There are a number of areas in close proximity to the proposed route which support important habitats and wildlife, including areas requiring special protection under national or European legislation. A number of these designated sites are dependent on the quality of the water environment and are detailed in Table 16C.1 Table 16C.1 Designated Sites Dependent on the Quality of the Water Environment Name Basis of Designation River Foyle & Tributaries The SAC is designated for its habitats of plain to montane levels with the Ranunculion SAC fluitantis and Callitricho-Batrachion vegetation and the largest population of Atlantic Salmon in Northern Ireland (15% of the estimated national spawning numbers). The river is notable for the physical diversity and naturalness of the banks and channels, especially in the upper reaches, and the richness and naturalness of its plant and animal communities. The presence of otter is a subsidiary qualifying feature. River Finn SAC The River Finn SAC is located adjacent to the River Foyle & Tributaries SAC, within the same watercourse, comprising the designated area on the Republic of Ireland side of the border. The SAC is designated for its habitats of Oligotrophic Waters, Wet heath, Blanket Bogs, Transition Mires, as well as its Atlantic Salmon and Otter species. The northern section of this site also comprises the River Foyle, Mongavlin to Carrigans Proposed Natural Heritage Area (pNHA). McKeans Moss ASSI The most north-western example of lowland raised bog in Northern Ireland. The intact bog surface exhibits a well defined dome with characteristic vegetation and structural features, including hummock and lawn complexes and small shallow pools. Sphagnum species are well represented. The periphery of the bog has been extensively cut for turf in the past. The cutover area is now dominated by mature woodland and scrub. Strabane Glen ASSI Strabane Glen is a narrow valley supporting a calcareous wet woodland which is atypical of this region and its presence is related to the underlying geology. Tully Bog SAC & ASSI Tully Bog is an isolated lowland raised bog lying in a shallow hollow within the former floodplain of the Fairy Water River. The central intact dome supports a small pool system with a good hummock and hollow development on the bog plain. The centre of the bog has a small raised drumlin, with birch woodland growing on it. The rare bog- mosses Sphagnum imbricatum and S. fuscum are present. © Mouchel 2016 A.16C-1 A5 Western Transport Corridor Volume 3 – Appendices Name Basis of Designation Grange Wood ASSI Grange Wood is a calcareous wet woodland occurring on the north-eastern flank of Bessy Bell Mountain and partially overlying an isolated outcrop of Dungiven limestone. The wood is largely comprised of a low, multi-stooled Hazel canopy with occasional Ash standards over a diverse base-rich ground flora. Frequent exposed rocky outcrops and boulders are covered by a luxuriant growth of mosses, particularly on the upper slopes. The lower slopes are waterlogged with extensive flushing and in these areas Willow and Alder predominate. Under the Water Framework Directive the major rivers and their tributaries have also been classified in terms of their ecological status, with classifications ranging from ‘Good’ to ‘Poor’. Surface watercourse catchments The main surface water catchments with which the Proposed Scheme would interact, are described below. These are shown on Figure 16.1 and in more detail on Figures 16.2-16.18. Lower Foyle Catchment The River Foyle catchment area is approximately 2,890km2 and extends into the counties of Londonderry, Tyrone and Donegal. The major tributaries of the Foyle include the Burn Dennet, Glenmornan, Finn, Mourne, Strule, Owenkillew, Derg, Fairy Water, Camowen and Drumragh Rivers. The northern section of the proposed route lies within the Lower Foyle Catchment, where the Mourne River and the Finn River converge at Strabane to form the River Foyle. From Strabane, the Foyle flows north to Londonderry and Lough Foyle. The lough is tidal and exerts a tidal influence up the River Foyle as far as Strabane. The tidal reach of the Foyle, shown in Photograph 16C.1 has a tidal range of approximately 3m and is up to 750m wide in places. © Mouchel 2016 A.16C-2 A5 Western Transport Corridor Volume 3 – Appendices Photograph 16C.1 River Foyle, looking upstream from Drumenny The main tributaries to the Foyle in the vicinity of the route are discussed in the following sections. However, there are also a substantial number of smaller tributaries which the route crosses. These tributaries are generally large man-made field drains and small streams which have been heavily modified / straightened where they pass through villages and agricultural land as shown in Photograph 16C.2. Classified as a heavily modified water body by NIEA due to flood defences. Photograph 16C.2 Left - Typical field drain/modified stream running through agricultural land. Right - Upstream view of the culverted/channelised section of the Blackstone Burn in Magheramason. © Mouchel 2016 A.16C-3 A5 Western Transport Corridor Volume 3 – Appendices Burn Dennet Catchment The Burn Dennet has a catchment area of approximately 150km2 and rises in the Sperrin Hills, flowing 35km west to the River Foyle. The catchment is predominantly agricultural, although there are significant sand and gravel quarrying sites close to the lower reaches of the river. The route crosses the Burn Dennet in the vicinity of Burn Dennet Bridge, in this area the river is approximately 15m wide with typical transitional (piedmont) river characteristics i.e. lower gradient, relatively unconfined valley, wider floodplain, riffle/pool sequences and meandering channel pattern (see Photograph 16C.3). Photograph 16C.3 Burn Dennet Approx 2km Upstream of Burn Dennet Bridge, Looking Upstream © Mouchel 2016 A.16C-4 A5 Western Transport Corridor Volume 3 – Appendices Glenmornan Catchment The Glenmornan River has a catchment area of approximately 35km2 and rises in the foothills of the Sperrin Hills. From source the river is approximately 16km long and drains westwards to the River Foyle. Although the river rises on peat-covered hills the majority of the catchment is agricultural, with some sand and gravel workings adjacent to the middle reaches of the river. The river, shown in Photograph 16C.4, also passes through Artigarvan and Ballymagorry villages. Where the route crosses the catchment the river channel is between 4m and 20m wide and displays typical transitional characteristics (as described above for the Burn Dennet). Photograph 16C.4 Glenmornan River at Ballymagorry, Looking Upstream Finn Catchment The Finn River headwaters are in the upland area surrounding Lough Finn in County Donegal, flowing from Lough Finn eastward for 60km to Strabane, where it joins with the Mourne River. The Finn River becomes tidal upstream of Strabane, the Finn has a catchment area of 495km2, upstream of tidal influence. The route runs along the eastern bank of the lower reaches of the river, which by this point is a mature lowland river, with a wide unconfined valley and floodplain that is relatively deep and slow Photograph 16C.5 Finn River Immediately Upstream of Strabane, Looking Upstream © Mouchel 2016 A.16C-5 A5 Western Transport Corridor Volume 3 – Appendices Mourne Catchment The Mourne River forms the middle section of the main spine of the Foyle Catchment and has a catchment area of 1,860km2. The Mourne, shown in Photograph 16C.6, is formed at the confluence of the River Strule and Derg River near Ardstraw. The river flows north to Strabane where it merges with the Finn River to form the River Foyle. The existing A5 crosses the Mourne River in Strabane, where the channel width is approximately 80m. The Mourne is a transitional river with numerous riffle and pool sequences, which flow in a relatively unconfined valley within a large floodplain. At Sion Mills the river channel and has been heavily modified, where a large weir was historically constructed. As the Mourne River passes through Strabane the channel has been modified by various flood defences. The route runs parallel with the western bank of the Mourne River. Photograph 16C.6 Mourne River at Victoria Bridge, Looking Downstream. Classified as a heavily modified water body by NIEA due to flood defences. © Mouchel 2016 A.16C-6 A5 Western Transport Corridor Volume 3 – Appendices Derg Catchment The Derg River rises in the Killeter Uplands and flows eastwards to its confluence with the River Strule near Ardstraw. The upper reaches of the catchment are characterised by peatlands, while the lower reaches flow predominantly through farmland. The main stream length of the Derg River is 53km, with a catchment of approximately 440km2 The route crosses the lower reaches of the Derg close to the confluence, see Photograph 16C.7. Within the vicinity of the Proposed Scheme the Derg River is a transitional (piedmont) river characterised by a well developed valley, reasonably large floodplain and variable substrate with riffle and pool sequences. Photograph 16C.7 Downstream View of Confluence Between Derg River (Foreground) And River Strule. Strule Catchment The River Strule forms the upper section of the main spine of the Foyle Catchment, and has a catchment area of 1,340km2. The Strule is formed by the confluence of the Camowen and Drumragh rivers in the centre of Omagh. The Strule flows northwards for approximately 21km before merging with the Derg River to form the Mourne River. The Strule has two major tributaries, the Owenkillew which joins the Strule from the east at Newtownstewart and the Fairy Water which joins to the north of Omagh. The Strule is a transitional river with variable bed materials, riffle and pool sequences, an unconfined valley and floodplain (Photograph 16C.8).

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