At a glance
Llyn Brenig (LL21 9TT) is a large reservoir on Mynydd Hiraethog near Cerrigydrudion — 16-mile flat cycle/walk circuit, sailing, fishing, visitor centre, RSPB osprey watching and Bronze Age archaeology trail. Free reservoir access; car park charge. Near A5 between Corwen and Pentrefoelas. Car essential.
About Llyn Brenig
Mynydd Hiraethog — the long mountain or Denbigh Moors — is the upland plateau between the Vale of Conwy and the Clwydian Range, a landscape of open moorland, blanket bog and forestry that is one of the less-visited parts of North Wales despite its considerable wildlife and historical interest. Llyn Brenig, completed in 1976, occupies a shallow basin in this plateau and, despite being only 50 years old, has developed a settled character that sits naturally in the landscape.
The reservoir's recreational offer is genuinely good. The 16-mile tarmac circuit makes it one of the most accessible flat cycling routes in North Wales — families with young children can complete part or all of the route without significant challenge. The visitor centre (Natural Resources Wales) has café facilities, toilets and information on the local wildlife and archaeology. A sailing club offers wind sport on the exposed upland water.
The archaeological heritage is an unexpected highlight. Before the reservoir was filled, a team of archaeologists undertook a systematic survey of the plateau, recording a remarkable concentration of Bronze Age monuments — cairns, standing stones and ceremonial enclosures dating from roughly 2000 to 1000 BCE. Several sites were preserved above the waterline, and a heritage trail visits them as part of the reservoir circuit.
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Frequently asked questions
Llyn Brenig is a large upland reservoir on Mynydd Hiraethog (the Denbigh Moors) in Conwy County, completed in 1976. The reservoir covers approximately 920 acres and supplies water to the north-east Wales area. Despite being an artificial reservoir, it has developed significant wildlife value and recreational facilities that make it one of the better visitor destinations on the upland plateau between the Vale of Conwy and the Clwydian Range.
Yes — a 16-mile circular cycle and walking route runs around the entire reservoir on a well-surfaced tarmac path. The route is flat (the reservoir is on a moorland plateau) and suitable for cyclists of all abilities including families. Bikes are not available for hire at the reservoir itself — bring your own or hire in a nearby town. The path is also open to walkers and mobility scooters.
Llyn Brenig has been part of an RSPB osprey monitoring and viewing programme. Ospreys from Welsh nesting sites (including the well-known Glaslyn nest near Porthmadog) sometimes visit the reservoir to fish in summer. The visitor centre has had live CCTV feeds from nesting sites in previous years. Check the RSPB website or contact the visitor centre for current osprey viewing arrangements.
Yes — Llyn Brenig has a sailing club (Brenig Sailing Club) and the reservoir is used for dinghy sailing, windsurfing and kayaking. Permits are required — contact the visitor centre or the sailing club for access arrangements. The exposed upland position of the reservoir means wind can be reliable for sailing but also strong and cold — suitable kit and experience is required.
Before the reservoir was filled in 1976, archaeologists excavated a remarkable concentration of Bronze Age monuments on the moorland — cairns, standing stones and ritual sites dating from approximately 2000–1000 BCE. The most important finds were recorded and several monuments were preserved. A heritage trail around the reservoir visits some of these Bronze Age sites, which give the reservoir plateau an archaeological depth that adds to its interest.