Loch Sloy

Loch Sloy is a man-made reservoir in Argyll and Bute, western Scotland, north of Helensburgh and close to Arrochar and Inveruglas on Loch Lomond. It lies inside Loch Lomond & The Trossachs National Park. A concrete dam holds back the Inveruglas Water here, and the stored water still feeds one of the largest conventional hydro stations in the SSE fleet.

What is Loch Sloy?

The loch is a high-glen storage reservoir holding roughly 36 million cubic metres of water, tucked between the ridges of several Munros. It was built as part of the Loch Sloy Hydro-Electric Scheme in the years after the Second World War. Work began in 1945, was slowed by labour shortages and poor weather, and involved German prisoners of war on site. Power generation started around 1950. Water leaves the loch through a tunnel inside the mountain and drops to a power station on the shore of Loch Lomond.

What kind of dam is it?

It is often called a gravity dam, but it is really a buttress dam. It stands about 56 m tall and runs for about 357 m along its crest. The buttressed design needed noticeably less concrete than a solid wall, roughly a fifth less according to published descriptions. Historic Environment Scotland lists the structure, and Canmore holds a record for it. Sources disagree on the station's output, quoting figures between about 130 and 152 MW, so check the operator for the current number.

How do you get to Loch Sloy?

Start from the Inveruglas car park and visitor centre beside the A82 on Loch Lomond. The service road to the dam has a locked gate, so there is no driving up it and the approach is on foot. You pass hydro infrastructure on the way and reach the dam after a walk of a few dozen minutes. The nearest railway station is Arrochar & Tarbet, a few kilometres from Inveruglas.

What can you see and do here?

Most visitors come for the hills. Just beyond the dam, a small cairn marks the start of the climb to Ben Vorlich, while a fork in the road leads towards Ben Vane. Walkers' reports describe round trips of roughly 13 to 15 km with around 950 to 1,000 m of ascent. Ground is boggy in places and some stretches have no clear path, so navigation skills help. If you just want atmosphere, a walk to the dam alone gives you a wild mountain setting without the summit effort.

When should you visit?

Late spring to early autumn is best, when paths are drier. Highland weather turns quickly, so carry waterproofs, a map and sturdy boots. In winter the slopes can be icy and call for proper experience.

Frequently asked questions

Can I drive up to the dam?

No. The access road is gated, so the final stretch from Inveruglas is on foot.

Is Loch Sloy a natural loch?

No. It became a reservoir when the dam was built in the mid-twentieth century, and it exists to generate electricity.

Which hills start from here?

Routes to Ben Vorlich and Ben Vane begin near the dam. Both are demanding and cross wet ground.

Is there anything else nearby?

Yes. Inveruglas has a visitor centre with views over Loch Lomond, and the villages of Arrochar and Tarbet are close.