Overview
Tucked into the deep green folds of the Glenasmole Valley, about 15 km southwest of Dublin city centre, Bohernabreena Reservoir is a striking pair of lakes framed by evergreen and deciduous woodlands. Managed by Dublin City Council, the twin lakes form a vital part of the capital’s water infrastructure, supplying drinking water to roughly 35,000 households across South Dublin. Sitting on the border between the Dublin Mountains and the edge of Wicklow National Park, the reservoirs offer sweeping views of peaks like Seefingan, Corrig and Kippure. The surrounding landscape is a designated Area of Special Conservation, making it a quiet haven for walkers, birdwatchers and anyone looking to escape the city without a long drive.
History & The Waterworks
The twin lakes were engineered during the Industrial Revolution, with construction beginning in the 1880s and finishing in 1887. They were built to solve three pressing local issues: provide a reliable drinking-water source for a growing Dublin, supply water to the numerous mills that once lined the Dodder valley, and control frequent flooding in the area.
The engineering remains impressive today. Water collected from the lower, non-peaty slopes fills the upper lake, keeping it clear and suitable for drinking. This water then flows through a distinctive stone-faced channel into the lower lake, which holds more peaty water historically used for the mills. From there, it travels 7.5 km to the treatment works at Ballyboden. You can still see the impressive overflow system at the upper reservoir, a reminder of the careful planning that went into the site. The valley itself was carved out by glaciers during the last Ice Age, leaving a dramatic U-shaped profile that still defines the terrain.
Walking Trails & Routes
The reservoir offers two main loop walks, both well-surfaced and suitable for most fitness levels.
Upper Reservoir Loop (8.5 km) This easy-going circuit starts at the original Bohernabreena North Car Park off the Ballinascorney Road. The trail follows the road alongside the Dodder, passes the lower lake, and loops around the upper reservoir. Waymarked in orange, it takes roughly 60 to 90 minutes to complete and climbs just 15 metres. The route offers several vantage points to take in the surrounding peaks and the stone-lined channel that feeds the lower lake.
Lower Reservoir Loop (≈4 km) Often preferred by visitors for its compact length and varied scenery, this shorter walk starts from the newer, paid car park. It circles the lower lake and passes the historic St Ann’s graveyard before returning along the same road. Allow 1 to 1.5 hours for a leisurely pace. If you prefer to avoid the longer approach road, this loop delivers the best views in less time.
Both routes connect to the Dublin Mountains Way, a national trail that threads through the shoreline and links the reservoir to a wider network of mountain paths.
Wildlife, Nature & St Ann’s Graveyard
The reservoir park is a registered Area of Special Conservation, and the planting schemes from the early 20th century have matured into a rich mix of larch, Scots pine, Corsican pine, Douglas fir, hazel, birch, ash and sycamore. In spring, the surrounding meadows put on a show with wild orchids and molinia grasses.
Birdwatchers frequently spot kingfishers flashing along the water’s edge, alongside dippers, grey wagtails, herons and moorhens. The lakes support a modest trout fishery, though angling requires a permit from local clubs.
Along the western shore of the upper lake sits St Ann’s graveyard, the quiet remains of a church that served the local community until the mid-16th century. You can access the graveyard by following the Dublin Mountains Way’s yellow markers down toward Castlekelly and back along the road. It’s a peaceful spot to pause and reflect on the valley’s long history of human settlement.
Getting There & Parking
By Car From Dublin city centre, head out on the N81 toward Tallaght. Take the Oldbawn exit (R113), turn right at the crossroads onto Bohernabreena Road (R114), and take the left turn just after Fort Bridge into the waterworks entrance. The site is clearly signposted and easy to navigate with GPS.
By Public Transport The TFI Local Link SD3 bus runs between Tallaght Luas and Ballinascorney, stopping at Glenasmole and Upper Reservoir. It’s a convenient option for avoiding parking queues, especially on weekends. Check the TFI website for the latest timetables and live tracking.
Parking Options
- Original Car Park (Bohernabreena North): Free, but limited to just 15 spaces. It fills quickly on weekends and bank holidays. Arrive early or visit during weekdays to secure a spot. Do not park along the narrow access road, as vehicles are liable to be towed.
- Upper Lake Car Park (Recommended): A newer, secure facility costing €5 to park. It includes toilet facilities and a small weekend coffee kiosk. This is the starting point for the shorter 4 km loop and is generally less stressful to access.
Practical Information
- Opening Hours: The park is open year-round with unlimited access. There are no gates or formal closing times.
- Admission: Free entry to all walks, picnic areas and viewpoints.
- Dogs: Welcome on all trails. Keep them on a lead while passing through the farm sections near the entrance and around the water’s edge to protect wildlife. Once you reach the open areas around the reservoir, dogs can be let off to explore.
- Facilities: Picnic tables are scattered around both lakes. The paid car park has toilets and a weekend coffee stand. There are no permanent facilities at the original car park or along the trails.
- Contact: For general enquiries, call the local information line at +353 86 882 8415.
Nearby Attractions
If you want to extend your day, the surrounding area offers excellent options. A 20-minute drive takes you to Cruagh Wood, where forest trails lead up to Cruagh summit for panoramic views over the city. Head south to the lakeside town of Blessington, a popular stop for walkers offering cafes, a chippy and access to the Blessington Greenway. Both make ideal post-walk destinations to stretch your legs further or enjoy a proper meal.
Bring sturdy shoes, pack a light snack, and aim for early morning or late afternoon to catch the best light on the water and avoid the midday crowds. The reservoir rewards quiet observation, whether you’re tracking a kingfisher’s dive or simply watching the mist roll over the Dublin Mountains.