Despite living here for over 14 years I had never been up close to the Grwyne Fawr reservoir, I had only ever seen it from a distance from the tops of the Black Mountains. I was spurred into action when my friend Danny appeared on a rainy Wednesday from Bristol to go for a walk. Time to go and have a look at the dam I thought.
This huge piece of engineer was completed in 1928 with the purpose of supplying clean water to the South Wales valleys. There was quite a large temporary village established for the workforce when work started in 1912 and remains of buildings still surround the site At one stage over a thousand people lived up here and some labourers made the eight mile trip to Talgarth daily on foot.
The route is a simple one. Drive up to the car park at SO 252 285, this is lovely drive from Gliffaes and is around 12 miles. Walk along the rough landrover track up to the top of the dam wall, a distance of about two miles and parallels the tarmac road to the base of the dam. The past few days having been very wet meant that a good deal of water was cascading over the top of the dam and made an impressive sight. Take time to explore at the top of dam, you can walk across the top to have a look down over the edge. (This is the site where Princes William & Harry were caught making an ‘unauthorised’ absail in 1998 while under the charge of their nanny,Tiggy Legge-Bourke.)
Follow the path pass the reservoir and up the valley NNE all the time following the line of the stream that feeds the reservoir. At the head of the reservoir is a small mountain bothy maintained by the Mountain Bothy Association, not easily seen from the path.The path can be wet and is almost a small stream in itself during wet weather. After crossing the stream you come out on top of the ridge in the area of the path junction at SO 204 327.
Head SSE on the oppersite side of the valley to which you came up on top of the ridge towards the peak Waun Fach (the highest point in the Black Mountains). Be warned it is VERY boggy around Waun fach and is best avoided by staying off the ridge and following your nose about 500 hundred meters below the ridge (along the 750m contour). The country side up here is bleak and wet and all we saw was a pair of grouse.
When you reach the northern edge of the Mynydd Du forest follow the spur west down hill back towards the road and the stream. Once at the bottom of the hill where the corner of the wood meets the stream (SO 247 291) cross the small stream to your right and follow the Grwynwe Fawr river through the woods for a short distance until you come to a foot bridge enabling you to cross the river to get back on to the metalled road and back to your car.
This took us just over 4 hours but we went pretty slowly and spent around 40 minutes at the damn wall. Of course we will be happy to mark up your map for you and send you on your way with a pack lunch.