Overview
Nestled about 15 km southwest of Dublin city, Glenasmole Valley is a quiet, glacially‑carved landscape that cradles the twin Bohernabreena Reservoir reservoirs. Managed by Dublin City Council, the reservoirs supply drinking water to roughly 35,000 households in South Dublin and form a designated Area of Special Conservation (ASC) rich in wild orchids, molinia meadows and petrifying springs. The valley sits between the Wicklow National Park and the Dublin Mountains, making it a perfect base for a leisurely ramble or a longer trek along the Dublin Mountains Way.
History & Landscape
The valley’s geology dates back to the last Ice Age, when glaciers gouged out the deep, narrow lower valley and a broader upper basin. In the late 19th century (1883‑1887) the Bohernabreena Waterworks were constructed to provide water for the mills that once dotted the River Dodder and to tame a flood‑prone area. Two reservoirs – the Upper (clear, non‑peaty water) and the Lower (more peaty) – are linked by a stone‑lined channel that feeds the treatment works at Ballyboden, 7.5 km away.
Beyond their utilitarian role, the reservoirs sit within a thriving ecosystem. The ASC status protects rare plant species and supports a variety of birds and insects. Remnants of St Ann’s Churchyard, used until the mid‑16th century, lie on the lower‑reservoir loop, offering a quiet historic waypoint.
Flora & Fauna
The meadows around the reservoirs are noted for their spring display of wild orchids, including early purple orchid and frog orchid. The damp, peat‑rich soils also support mosses, liverworts and the distinctive petrifying springs where calcium‑rich water creates mineral deposits. Birdwatchers can spot meadow pipits, skylarks and, in winter, waders such as curlews and snipe. The mix of open water and mixed woodland provides habitat for dragonflies, butterflies and a range of small mammals.
What to See & Do
The Reservoir Walks
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Short Loop (Lower Reservoir) – 4 km, 1–1.5 hrs. Starts from the paid Upper‑Lake car park (see table). The route circles the lower reservoir, passes the St Ann’s Churchyard ruins and returns via a well‑marked clockwise path. A weekend coffee stall (Goughie’s) operates near the car park, perfect for a quick break.
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Long Loop – 8.5 km, about 2 hrs. Begins at the Bohernabreena North Car Park (the original 15‑space lot). Walks past the lower reservoir, continues to the upper reservoir and follows the stone‑lined channel back. The terrain is gentle; the main challenge is the initial country‑road stretch.
Both routes are easy‑going, suitable for families and casual walkers. The scenery alternates between open water, mixed evergreen‑deciduous woodlands and sweeping valley views.
Nearby Highlights
- Cruagh Wood (20‑minute drive) – Offers the Slí na Sláinte loop and a summit view of Dublin from 522 m.
- Blessington (25‑minute drive) – Lakeside town with the Blessington Greenway and the stately Russborough House.
- Ticknock (30‑minute drive) – Home to the Fairy Castle passage tomb and panoramic vistas of Dublin Bay.
Dublin Mountains Way – Stage 8
Stage 8 of the 42.6 km Dublin Mountains Way threads through Glenasmole Valley, providing a 6 km, roughly 2‑hour segment from Glenasmole to Tallaght. Walkers on this national way‑marked trail enjoy additional viewpoints of the reservoirs and can link to the longer Bohernabreena loop for an extended day out.
Practical Information
| Facility | Details |
|---|---|
| Parking – Original | 15 spaces, free. Very limited; arrive early or use off‑peak times. No roadside parking allowed (risk of towing). |
| Parking – New Upper‑Lake | €5 fee, secure, toilets, weekend coffee stall. Closest entry to the short loop. |
| Access | Unlimited – the park is open 24 hours. No entry fee. |
| Toilets | Available at the new Upper‑Lake car park. |
| Map & Directions | Google Maps – Upper Lake Car Park – also shows the loop walk entry point. |
| Phone | +353 86 882 8415 (local information centre). |
Getting There
The valley is accessed via the R114, about 3.5 km southwest of Tallaght. For drivers, the new Upper‑Lake car park is the recommended entry point; for walkers preferring a quieter start, the original 15‑space lot works well if you can be there early. Public transport options are limited, but the Local Link Kildare South Dublin route SD03 stops at Upper Reservoir Gate and Glenasmole Community Centre on Saturdays.
Amenities
The new car park provides clean restroom facilities and a small coffee kiosk (operational weekends). The Glenasmole Community Centre, 9 km from Tallaght, offers tea, coffee and additional toilets on weekdays (09:00‑17:00). No dedicated visitor centre exists, but information boards near the car parks outline the walk routes and highlight the ASC status.
Dog‑friendly & Accessibility
Dogs are welcome on the trails but must be kept on a leash to protect wildlife and other visitors. The Upper‑Lake car park area has a flat, paved path suitable for wheelchairs to reach the reservoir edge; however, the remainder of the loops involve uneven ground and may be challenging for wheelchair users.
Visitor Tips
- Arrive early in the summer months; the free original car park fills quickly.
- Bring a water bottle and sturdy shoes – the paths can be boggy after rain.
- Check the weekend coffee stall opening times before you go.
- Bird‑watchers should carry binoculars; early morning offers the best sightings.
- If you plan a longer hike, pack a snack and a map; mobile signal can be patchy in the valley.
Seasonal Notes
The valley’s flora is at its most vibrant in late spring when wild orchids bloom across the meadows. The stone‑lined channel between the reservoirs remains clear year‑round, offering a striking visual contrast against the surrounding peatland.
Whether you’re seeking a short, family‑friendly loop, a longer lakeside hike, or a segment of the Dublin Mountains Way, Glenasmole Valley delivers tranquil water‑edge scenery, subtle historic intrigue and the satisfaction of walking in a protected natural haven just a short drive from Dublin’s bustling centre.