Dargle Catchment
The Dargle catchment covers an area of approximately 128 square kilometres.
The River Dargle flows in a north-easterly direction from the Wicklow Mountains, reaching the sea at Bray.
This catchment’s geology is mixed between granite, slate, shale and schist, with the land used mainly for agriculture. Significant urban activity is present towards the mouth at Bray.
Portions of this catchment’s most southern and western headwaters are situated within the Wicklow Mountains Special Area of Conservation.
Waters within the Dargle Catchment:
River Dargle
Irish: An Deargail (meaning “little red spot”, so called with reference to the prevailing tint of its rocks)
The River Dargle rises in the Wicklow Mountains of Ireland on the northern slopes of Djouce Mountain and flows over the highest waterfall in Ireland, falling 121 metres (398 feet) at Powerscourt Waterfall.
It then flows through the Glencree Valley where it is fed by the River Glencree before flowing east for a further 13 kilometres (8.1 miles) where a small tributary, the Swan River, joins opposite the People’s Park in Little Bray.
The Dargle then flows for a final kilometre (0.62 miles) to reach the Irish Sea at Bray Harbour.
Tributaries:
Glencree
Irish: Abhainn Ghleann Crí
The Glencree valley is a glacial valley which lies at the north eastern edge of the Wicklow mountains. The Glencree river, which flows through the valley, is a good example of a fast flowing upland river with many boulders and often brown peaty coloured water.
The river valley includes three areas of deciduous woodland which flank the river. The main tree species in the woods is Oak (Quercus petraea), with Ash (Fraxinus excelsior) and Birch (Betula pubescens) locally abundant. The shrub layer in the woods is variable. Holly (Ilex aquifolium), Birch (Betula pubescens) and young Beech (Fagus sylvatica) are the most common species. The field layer is generally sparse, and includes Wood-sorrel (Oxalis acetosella), Bracken (Pteridium aquifolium) and Wood-rush (Luzula sylvatica).
Mosses are fairly abundant – these form carpets over the boulders. The moss species include Polytrichum commune, Rhytidiadelphus spp. and Thuidium tamarascinum. In places Hazel (Corylus avellana) is common and here the field layer is more diverse with Bluebells (Hyacinthoides non-scripta), Ramsons (Allium ursinum), Dog Violet (Viola riviniana), Herb Robert (Geranium robertianum) and Germander Speedwell (Veronica chamaedrys). Patches of Willow (Salix spp.) are found in the wetter areas.
Regeneration in the woods is generally poor due to grazing. of the woods has taken place in some areas, notably with Hemlock (Tsuga heterophylla) and Scots Pine (Pinus sylvestris). On the south side of the river between the wooded areas there are species-rich boggy flushes with clumps of Sphagnum moss (Sphagnum spp.) and areas dominated by Sedges (Carex spp.) and Rushes (Juncus spp.). Other species include Bog Asphodel (Narthecium ossifragum), Butterwort (Pinguicula vulgaris), Devils-bit Scabious (Succisa pratensis), Milkwort (Polygala vulgaris) and occasional low hummocks of Heather (Calluna vulgaris), Bilberry (Vaccinium myrtillis) and Cross-leaved Heath (Erica tetralix).
The bird life of the valley has been examined recently. Dipper and Grey Wagtail breed along the river, while Jay, Long-eared Owl, Woodcock and Blackcap are present in the woods.
Lough Bray
Lough Bray Upper and Lower are corrie lakes, gouged out by the retreating glaciers of the last ice age. The stream which drains the lower lake rushes across the valley to join the Glencree River.
Glencullen
Irish: Abhainn Ghleann Cuilinn
Glencullen is the most northerly of the eastern Wicklow Mountains’ glens. The river valley runs for a distance of 9.5km in a northwesterly direction from Enniskerry, crossing the county boundary to Tibradden, Co. Dublin.
The valley floor is partially filled with glacial till and glaciofluvial gravels. The greater extent of the valley sides is vegetated (gorse, bramble, and broadleaf deciduous woods). Nearer the riverbank, the terrain is vegetated with wet woodland, heath and a number of tufa (springs and seepage areas). Knocksink Wood is a popular amenity area running along the glen.
The Glencullen joins the River Dargle just west of Bray near the N11.
Kilmacanogue
Irish: Cill Mocheanóg (Mocheanóg’s church)
Two small streams join in Kilmacanogue, behind the old Post Office,, to form the Kilmacanogue River. This river flows into the River Dargle near the old “Silver Bridge” at Kilbride approximately two miles to the north. These watercourses once held a good population of trout but increasing urbanisation led to a deterioration in water quality.