Ballynafagh Lake () is a Special Area of Conservation and wildfowl sanctuary in County Kildare, Ireland, near the town of Prosperous. This site is also known as the Blackwood Reservoir, the Blackwood Lake or the Prosperous Reservoir.
Location The Ballynafagh Lake Special Area of Conservation is located in the townlands of Ballynafagh, Blackwood, Coolree, Garvoge, Graigues and Moods, approximately 2 km north of the town of Prosperous.
Special Area of Conservation: qualifying interests Ballynafagh Lake is of significant ecological interest as a Special Area of Conservation. Under the European Union Habitats Directive 92/43/EEC and the Irish regulations which implement this Directive (European Communities (Birds and Natural Habitats) Regulations 2011 (S.I. No. 477 of 2011), Ireland has a legal obligation to designate habitats and plant and animal species for conservation. To 2024, Ireland has designated approximately 13,500 km2, between terrestrial, freshwater and marine habitats. The lake itself is not a natural feature. The Natura 2000 information for the site describes it thus: ”The site comprises a former reservoir (generally called Ballynafagh Lake) and an associated canal feeder (Blackwood feeder), the latter now disused and mostly dry. The lake is shallow and is now very overgrown with various wetland vegetation types with only a small area of open water remaining. Fen is the predominant habitat, with reed-swamp, wet grassland and some bog or heath also occurring. A strip of deciduous woodland occurs on some drier ground. The main habitats along the canal feeder are dry grassland (partly improved), wet grassland, swamp vegetation and scrub.”
The lake itself is described as “a shallow alkaline lake with some emergent vegetation. The Blackwood Feeder, which connects Ballynafagh Lake to the Grand Canal, is also included in the site.” There are some calcareous springs, some of which are tufa-forming, at the site, mainly in the north-east of the site.
This site had been recognised as of significance and worthy of conservation in the latter half of the 20th century. In 1972, Roger Goodwillie, of An Foras Forbartha, noted that consideration should be given to passing a Conservation Order on Ballynafagh Lake (also called the Prosperous Reservoir), in order to protect the relatively high numbers of breeding birds from disturbance. The lake was rated at that time as of local importance (criteria: only area of its type in county/one of a few localities in province/ fine example of its kind/general educational importance) and priority level B (relative urgency necessary for protection of these areas, on a A-C scale).< The site is noted in An Foras Forbartha's 1981 text "Areas of scientific interest in Ireland: national heritage inventory" as being of ecological interest as a wildfowl feeding and breeding site, including several species not found elsewhere in the country. Ballynafagh lake was proposed as a Site of Community Importance (SCI) in August 2000 and designated as a Special Area of Conservation in November 2018.
Ballynafagh Lake qualifies for Special Area of Conservation status under three qualifying features, one based on habitat conservation and two based on species conservation. These features are: Alkaline fens (Natura 2000 code 7230) Desmoulin's Whorl Snail (Vertigo moulinsiana; Natura 2000 code 1016) Marsh Fritillary butterfly (Euphydryas aurinia; Natura 2000 code 1065)
Alkaline fens Alkaline fens are permanently waterlogged peat wetlands, which have an alkaline (non-rainfall) supply of water. They are highly specialised ecosystems with characteristic flora, and are considered Annex I habitats under the European Union Habitats Directive. The European Environmental Agency's EUNIS description of alkaline fens describes the alkaline fens habitat as: “Wetlands mostly or largely occupied by peat- or tufa-producing small sedge and brown moss communities developed on soils permanently waterlogged, with a soligenous or topogenous base-rich, often calcareous water supply, and with the water table at, or slightly above or below, the substratum.”
The Irish Office of Public Works report of 2009 noted that at the time of publication, Ireland had 19,621 hectares of fen land in 342 sites, of which 763 hectares is conserved. There were at that time 39 Special Areas of Conservation (SAC) sites which included alkaline fens as a qualification for conservation. This report noted that in the Republic of Ireland, there had been a 79% loss of fen habitat, with the causes listed as land reclamation, drainage, development and infilling. The National Parks & Wildlife Service (NPWS) Foss review of 2007 found that there were 380 alkaline fens in Ireland.
The Foss Report notes that there are a range of classification systems for fens. The EU Habitats Directive Annex I Alkaline fen habitat typically corresponds to the Heritage Council “rich fen” habitat. According to the NPWS site synopsis, Ballynafagh Lake is a shallow alkaline lake, surrounded by acid grassland, heath and bog. There are patches of emergent vegetation in the middle and at the shore of the lake. At the surface of the lake can be found common duckweed (Lemna minor) and liverwort Riccocarpus natans. Submerged flora include starworts (Callitriche spp.) and lesser bladderwort (Utricularia minor). At the edge of the lake, vegetation typical of alkaline fens can be found. This includes blunt-flowered rush (Juncus subnodulosus), black bog-rush (Schoenus nigricans) and species of sedge, such as Carex lepidocarpa and Carex rostrata. Other plant species to be found here include bulrush (Typha latifolia), marsh arrowgrass (Triglochin palustris), marsh-marigold (Caltha palustris), marsh lousewort (Pedicularis palustris) and water mint (Mentha aquatica). In the open water of the lake, stands of common reed (Phragmites australis), bulrush and bottle sedge (Carex rostrata) grow. To the western corner of the lake, a stand of great fen-sedge (Cladium mariscus) can be found.
While only one habitat is noted as a qualifying interesting for SAC status, the Natura 2000 and European Environmental Agency EUNIS webpages for the Ballynafagh Lake site also note that a second habitat of conservation interest occurs at this site, that is, Transition mires and quaking bogs (Natura 2000 code 7140). This habitat consists of 2.69 hectares of transition mire cover. Transition mires and quaking bogs are very wet mires which can be considered intermediate between rich or poor fens and bog habitats, with surface pH varying between distinctly acidic to slightly basic. Acid grassland, heath and bog occur around the lake. The flora in this habitat includes common bent (Agrostis capillaris), bog-myrtle (Myrica gale), bracken (Pteridium aquilinum), gorse (Ulex europaeus), heather (Calluna vulgaris) and purple moor-grass (Molinia caerulea). To the north-west of the lake, wet woodland of alder (Alnus glutinosa), birch (Betula spp.), and willow (Salix spp.).
Desmoulin's whorl snail The Ballynafagh Lake SAC is of conservation interest for a number of species, two of which are Annex II species. A population of the rare snail species, Desmoulin's whorl snail (Vertigo moulinsiana; Natura 2000 code 1016), occurs at the Blackwood Feeder (the channel that connects Ballynafagh Lake to the Grand Canal) and in wetland flora beside the lake. This species requires tall vegetation and stable hydrology. It has ‘Endangered’ status in Ireland and ‘Vulnerable’ status in Europe.
Wetland drainage has resulted in the decline of this species in Europe, and in Ireland the drainage of wetlands and the management of the banks and wetlands of the Grand and Royal Canal have removed the habitat it requires. The 2019 report by Long and Brophy notes that drying out, vegetation change and heavy overgrazing are risks to the Desmoulin's whorl snail population at Ballynafagh Bog, beside Ballynafagh Lake. Monitoring of the site for population and habitat showed a decline in the species, from status Green (Favourable) in 2007-2012 to status Red (Unfavourable) in 2013-2018. The assessment for future prospects for the species showed a decrease from status Green in 2007-2012 to Status Amber (Unfavourable-Inadequate) in 2013-2018. The report recommended an overall hydrological plan to increase/maintain water levels at the site, targeted scrub removal and a reduction in grazing at the Blackwater Feeder, to improve the status of the species at Ballynafagh.
The NPWS site synopsis notes that another rare mollusc species occurs at this site. This is Pisidium pseudosphaerium, a members of the pea-clam family. The site synopsis states that this species has only been recorded from sites along the Royal Canal and the NPWS species record appears to confirm this pattern. The species status in Ireland is ‘Endangered’.
Marsh fritillary butterfly The third qualifying feature for which Ballynafagh Lake is designated a Special Area of Conservation is the presence of the marsh fritillary butterfly, an Annex II Habitats Directive species, at the site. This species also is under protection via the Berne Convention on the Conservation of European Wildlife and Natural Habitats as an Annex II strictly protected species, and mentioned as an Annex I species under the 2011 revised Berne Convention listing the species requiring specific habitat conservation measures. It is Ireland's only protected insect and its status is ‘Vulnerable’, indicating that it is at risk of extinction. Ballynafagh Lake is designated as one of the 16 conservation sites for this species in Ireland. This butterfly may currently not be recorded at this location, however, the site must legally be managed for conservation of the species.
Wildfowl Ballynafagh Lake is an important ornithological site and the only national wildfowl sanctuary in County Kildare (wildfowl sanctuary code WFS-30). The designation as a wildfowl sanctuary indicates that shooting of game birds is not permitted at this site. The NPWS site synopsis notes that bird species known to breed at the lake include little grebe (Tachybaptus ruficollis), mallard (Anas platyrhynchos), moorhen (Gallinula chloropus), coot (Fulica atra), snipe (Gallinago gallinago) and water rail (Rallus aquaticus). Curlew (Numenius arquata), sedge warbler (Acrocephalus schoenobaenus), reed bunting (Emberiza schoeniclus), whitethroat (Sylvia communis), and the black-headed gull (Larus ridibundus) have been recorded at the site. Waterfowl known to winter at Ballynafagh Lake include whooper swan (Cygnus cygnus), teal (Anas crecca), mallard, golden plover (Pluvialis apricaria) and curlew.
The Birdwatch Ireland entry for Ballynafagh Lake notes that, in addition to the birds listed above, the site also hosts kingfisher (Alcedo atthis) and reed bunting (Emberiza schoeniclus). The European Environmental Agency EUNIS webpage for this SAC lists five Habitats Directive bird species protected at the site: teal, mallard, whooper swan, curlew, and lapwing (Vanellus vanellus).
Other species Other species noted on the Natura 2000 form for Ballynfagh Lake include the moths Apomyelois bistriatella subcognata and Ectoedemia argyropeza, the ground beetle Chlaenius tristis, the rove beetle Philonthus corvinus and the Common Frog (Rana temporaria).
Conservation objectives While there exists a management plan for nearby Ballynafagh Bog, no management plan has been developed to date for Ballynafagh Lake. The site-specific conservation objectives for the site were published in 2021. The overarching objectives are to restore the favourable conservation condition of the alkaline fens, to maintain the favourable conservation condition of Desmoulin's whorl snail (Vertigo moulinsiana) and to maintain the favourable conservation condition of marsh fritillary (Euphydryas aurinia) at Ballynafagh Lake Special Area of Conservation.