Usk Reservoir

Map: OS (1:25K) Explorer 12 Brecon Beacons West and Central (1:50K) Landranger 160 Brecon Beacons

Linear walk, although circular variations are possible

Start Point: Car Park at SN820271

End Point: Trecastle (SN880291)

Distance: 16.0km / 10 miles (approx 6 hours) Ascent: 435m Descent: 527m

Walking Directions

From the car park at SN820271, head north into the forest, before heading in a clockwise direction around the reservoir. However, before getting to the narrowest point of the resevoir tail, cross the fence and head up the hill onto the ridge and the Cairns at SN796289. Follow the ridge to the northeast, before turning right at the bridle way junction (SN814301) back towards the reservoir. You can always detour to the location of the Roman Fortlet if desired.

Once back in the forest, take one of the tracks to the reservoir at SN824294. Continue around the reservoir, either on the track or along the shoreline before crossing the dam. Follow the road down the hill for approx 500m until SN837290. Head up the hill (through the gate) and along the bridleway. Follow the bridleway until near the road, before making an abupt turn at SN841280 through the field. The turn is not necessarily obvious, so if you reach the road you have gone too far. It'll be found along the line of trees behind you! Before the bottom of the field, you need to go down the bank and across the stream before going through the gate onto the road.

At Cwmwysg, you can either follow the quiet road to Trecastle, or if feeling more adventurous, take the road heading southeasterly, before taking a left at the next junction (SN856278). At the river (SN861276), take the bridleway northwards until another bridleway crosses at SN866285. Take this new bridleway (and track) eastwards, passing around the house (this is marked on the ground), through the fields until joining the track at SN873284. Follow the track until the sharp right turning (it also heads downhill), and instead hop over the stile (SN876287) and follow this footpath into Trecastle.

Hike Profile

Hike Gradient


A simple circular walk, taking in the reservoir and the ridge is possible. Once across the dam, the circular route diverges from the linear route. Turning right and following the road (right at next junction) brings you back to the car park. A distance of 11.1km and 283m ascent/descent.

Maps provided by under a Creative Commons license

Notable Features and Highlights

Mynydd Myddfai

The route outlined follows the ridge of Mynydd Myddfai to the northeast of Usk Reservoir. This follows a roman road direct to the Roman Fortlet at SN821310. Roman Camps were found at Y Pigwn beyond this (SN828312)

Pen y Fan

To the southwest, Corn Du (873m) and Pen y Fan (886m) are clearly visible. Pen y Fan is the highest peak in Southern Wales and England.

© Rhodri L T Bevan