Stwlan Dam and Llyn Stwlan - the battery in the mountains

By Dan | Oct 3rd, 2021 - 8:37pm

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At a glance

Key stats

Difficulty icon Difficulty: Intermediate
Distance icon Distance: 3.4 miles
Route icon Show Route

This is a point-to-point route, so the distance assumes you will retrace your footsteps

Brief Overview

Aside from a brief section of uneven rocky/muddy terrain that can be avoided by using the alternative parking, this is a route entirely on paved surfaces. Sections of the approach road can be steep. Extended walks may be muddy and rocky also.

Navigation

Navigate to: Cwmorthin, Cwmorthin Rd, Blaenau Ffestiniog, LL41 3SW
Latitude/Longitude: 52.990094, -3.963681
what3words: flank.juicy.inkjet

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Difficulty

Difficulty Icon

A rough estimate of difficulty, this does not factor in distance and is only based on the conditions of the route followed. A 20 mile walk on paved roads will be marked as beginner, whereas a 1 mile scramble up a mountain will be Advanced/Expert. Please consider both distance and difficulty when choosing a walk.

Beginner

Clearly marked routes that are easy going with smooth surfaces, little to no inclines or declines. Should be accessible to all.

Intermediate

May include some minor sections of uphill or downhill that could be a little challenging. Some surfaces may be loose or otherwise be difficult to pass. The vast majority of people should be able to tackle this walk, but good hiking shoes are absolutely recommended.

Advanced

Walks may be almost completely comprised of difficult terrain, be it up/downhill or difficult surfaces that are slippery or muddy. Some may struggle on this walk, hiking shoes and possibly hiking sticks are a must.

Expert

A very difficult walk, may require scrambling or climbing in parts. Appropriate preparation should be made before attempting these walks, as they may require additional equipment. These are very much for experienced walkers only and it may be worth having a guide who knows the area with you.


Length

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A rounded estimation for the distance of the route shown, remember to factor in the return journey! Obviously, circular routes will end with you where you started, but any point-to-point walks have been doubled assuming you are going to retrace your footsteps. If the articles includes any suggestions for extra walks they will not be included in this value.


Route

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The map displays a downloadable .GPX file that can be used in Satellite Navigation devices or apps. Walks shown will typically be the simplest route described in the article. Routes are for reference only, always remain on paths and be aware of your surroundings.


Navigation

We offer links to either copy or navigate to the destination, the navigate link should work on most modern platforms (If all else fails you can manually copy the text above the buttons!). It is recommended you use Latitude/Longitude rather than address whenever possible as it will be much more accurate and consistent across different navigation tools, but we understand that sometimes address is the only supported option so we include that too where applicable. Unfortunately, if your destination is in the middle of the countryside you may struggle to navigate by address.



Features

Parking available nearby Parking available nearby
Roadside and at Cwmorthin
Dogs welcome Dogs welcome
24-7 access 24-7 access

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I have already spent some time to extol the beauty and mysteries that can be found around the town of Blaenau-Ffestiniog, specifically in the long since retired Cwmorthin Slate Quarry. But beyond the sheer walls of the now silent mines are plenty of other spectacular viewpoints and amazing sights; today we are going to be taking a short stroll uphill to see Stwlan Dam and the lake by the same name. Nestled at the foot of Moelwyn Mawr, the highest peak in the area, this dam is a striking sight to behold as you first round the corner and see the colossal concrete structure jutting out from the jagged edges of the surrounding peaks. For such an ascent into the mountains, this is a surprisingly easy walk, but we will get into that shortly - firstly, let us get you there.

The easiest place to start the Stwlan Dam walk is from the same car park at Cwmorthin. The route up to the car park at Cwmorthin is easy enough to find, as you pass through Blaenau-Ffestiniog along the A496 to travel to Tanygrisiau - keep an eye out for the stone fence posts labelled "Gorsaf Bŵer Ffestiniog power station" and follow the road up the hillside. You can, alternatively, take the other road up through Tanygrisiau if you take the wrong turning but those roads are a little narrower and can be trickier to navigate when compared to the other route. The road we want to take will circle up past a large reservoir (Tanygrisiau Reservoir), which has convenient parking should you wish to take a walk over the dam there, past a café and up over train tracks before becoming narrower (albeit with plenty of passing places) as you make your way up to Cwmorthin car park. You cross over a bridge and take a left when you arrive at some houses, the car park will be at the end of this lane.

A view from the approach road

A spectacular waterfall on approach



Once settled in at the car park, pass through the kissing gate towards the bridge near Cwmorthin's welcome waterfall; obviously, you should take some time to enjoy the views, but once you are ready cross the bridge and start making your way up the path. This route is most likely going to be wet, muddy and rocky but it is only short and soon brings you out onto a perfectly smooth road. The good news is this smoothness will be with you all the way to the top, the bad news is there will be a few sections of steepness to contend with. The iconic approach road at Stwlan Dam is beautiful but will see you veering back and forth as you snake your way up the hillside, there are some sections where you can easily cut the corner once you are there, but at first, you just need to follow the road straight up. There is an alternative route that can avoid the wet, muddy section if needed - by parking roadside around this area instead of parking at Cwmorthin, or by walking back down the lane, you can follow the road all the way up; the entrance to the dam approach road is gated but has a kissing gate that should allow you through, this will overall be a slightly longer route than by parking at Cwmorthin but an all-round more accessible option.

The approach road is not without its own charm, there are a handful of streams and cascades as you venture onwards, plus the remnants of the area's mining history will keep you excited. As you get closer to the dam there are several walks that splinter away from the road, including one route across a small footbridge and over a stile which can become a larger circular with Cwmorthin, should the mood take you. Be sure to take a quick stroll down to the viewpoint marked on the map above to soak in the wondrous views out over Blaenau-Ffestiniog - the combination of towering mountains and active slate mines make for an amazing backdrop, no matter the weather. Once you have reached this viewpoint you will have also caught your first glimpse of the dam, it is a striking structure with an almost ominous presence; the cold black and white concrete of the dam almost feels like an evil lair against its beautiful natural backdrop - absolutely amazing!

Approaching the dam

Now its time to snake around, the sequence of S-bends is a stunning sight if you can catch a shot of them from above either from the mountainside or otherwise, like some kind of harsh black rope of asphalt draped up the mountainside if it were a public road it would be a petrolhead's dream. As you progress up you may be able to cut some of the corners to reduce the amount of meandering required but generally, you will be sticking to the path. If you fancy a breather as you ascend, just turn around and hopefully, those spectacular views behind you will keep you motivated. Before you know it you will be at the foot of the dam and feeling absolutely tiny in the face of the imposing structure, just the thought of the tremendous amount of water it is working hard to hold back is enough to turn the stomach slightly but it's a great photo opportunity that shouldn't be missed. Just be respectful of the restrictions imposed by the power station, as this is an active structure the last thing you want to do is trespass.

As you have taken the time to make the journey to Stwlan Dam, it is probably worth knowing a little bit about what you are looking at. Unlike many dammed reservoirs in the area, what you are looking at isn't drinking water but rather a giant battery. The Ffestiniog Power Station operates two dammed reservoirs, both Llyn Stwlan that resides behind this dam and the aforementioned Tanygrisiau Reservoir down the hill, these lakes combine with an underground pumping system to form what is known as pumped-storage hydroelectricity. This was the first of its kind in the United Kingdom and the concept is fairly straight forwards: at times where the national demand for electricity is low, the station pumps water up to Llyn Stwlan to store it, once the demand is high the water is released back to the lower reservoir where it passes through a turbine, generating electricity. Ffestiniog Power Station has a maximum capacity of 360 MW which can make a nice boost when the nation all decide to turn on their kettles at the same time.



A resting sheep in front of the dam

One of the many spectacular viewpoints

A cloudy view at the top

Speaking of the lake, you can continue up the hillside following the road to see the lake, but access is fairly limited - you cannot access the dam top, and there is only a small area to view the lake but it is only a short walk on from the base of the dam so you might as well go for it. There is also a toposcope that gives an overview of all the peaks and interesting landmarks you can (hopefully - weather permitting) see from this little viewing platform. It is a great little ending to this walk, a panoramic viewpoint to enjoy the views out over Snowdonia and then, as you descend back down the curvy approach road, you get to enjoy those views all the more.

So that is Stwlan Dam, the battery in the mountain. It is a great walk that is fairly accessible depending on the route you opt to take and offers a myriad of spectacular views and, of course, that unbelievable dam. If you are still hungry for more walking then you could either retrace your footsteps back to the car park or try to follow the circular walk in the mountains that will take you out to Cwmorthin - one of our favourites walks in all of Wales! This entire area is full of wonders that are worth seeing and the thing I love most about these cold slate mountains is they look spectacular come rain or shine. In fact, I'd go one step further and say this is a perfect day out for those rainy days, a bit of drizzle and some low hanging clouds make this one of the most awe-inspiring options that won't leave you sad that you got a little soggy.

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Cwmorthin Slate Quarry and Lake Cwmorthin Slate Quarry and Lake

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