St Gormans Well, Enfield, Co. Meath.

Survey site description 

St. Gorman's Well, Enfield has the appearance of an unaltered natural pond. The warm spring forms a pool of water at the surface covering an area of approximately 40 m² at times of high discharge. When flowing strongly the spring overflows into a swamped area adjacent to the spring from where it eventually flows into the local ditch drainage network. Substratum in the spring is comprised primarily of large limestone fragments and some gravel. The extent of the spring basin is delineated by a change in vegetation from fringing reed and weed to terrestrial grassland. The geological boundary between Middle and Lower Carboniferous limestone passes very close to the spring. This spring is seasonal, drying up completely for a period towards the end of the summer season each year. 

(photos: St. Gormans well, from top to bottom, condition of the warm spring in spring, summer and autumn when the spring was dry)

Macroinvertebrate / faunal survey 

St Gorman's well was sampled during the spring and summer surveys (when a notable decrease in water level was observed). The spring was completely dry in autumn when sampling was attempted. In both spring and summer surveys, the water louse Asellus aquaticus was the most abundant organism, comprising over 80% of the total number of organisms. The pond snail Lymnaea stagnalis was also present in spring but absent from summer sampling. One damselfly nymph Pyrphasoma nymphula, and one cased caddis larva Limnephilus flavicornis, were recorded in the spring sample. Summer sampling revealed a richer fauna which included the molluscs Lymnaea peregra, Anisus leucostoma, Planorbis sp. and bivalves Sphaeridae indet. The following taxa were also recorded, although many as small numbers or solitary specimens; midge larvae, chironomidae, water beetles Haliplus sp., waterbugs Micronecta poweri, and water mites, suborder Hydracarina. The smooth newt, Trituris vulgaris, was abundant at this site in spring and was recorded again (but in lower numbers) in summer. Newts were not found in the vicinity of the dry spring basin in autumn.

Physico-chemistry 

Water temperature ranged between 12 and 25oC, conductivity was recorded as 413 and 464 µS/cm in spring and summer respectively, pH was 7.8 on both occasions and oxygen concentration was measured at 7.9 mg/l and 83% saturation in spring and 5.8 mg/l and 62% saturation in summer. A local borehole containing water was investigated when the spring itself was dry in autumn - here water temperature was recorded at 18.8oC, pH was 7.2 and oxygen concentration was measured at 3 mg/l and 31% saturation.

Aquatic macrophyte survey 

St. Gorman's spring exhibited the highest plant species richness recorded in this survey. 11 species in total were recorded from the spring (spring and summer). Abundant species included a species of Charophyte, water cress - Rorippa microphylla, water plantain - Alisma plantago, and the water dock - Rumex hydropathum. The ivy leaved duckweed (Lemna trisulca) was recorded as 'frequent' in both surveys. Other species were recorded as occasional or rare including the algae Cladophora sp., Closcerium sp., the Bryophytes Brachythecium plumosum and Rhynchostegiella tenella, and the vascular plants Callitriche stagnalis, and Polygonium amphibium.

Other notable features: A light tufa deposition was noted on some spring basin submerged flora and substratum. A local stream to the northwest of the site is also known to be tufa depositing (EcoServe, 2001).

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