Llangollen Canal: Water Supply, Horseshoe Falls and an Engineered Welsh Landscape

Most canals are still water. The Llangollen Canal moves. Walk its towpath west of Llangollen and you can see the current running gently eastward, because this narrow waterway in north-east Wales was built not only to carry boats but to carry water itself, drawn from the River Dee at a curved weir called Horseshoe Falls and sent some 46 miles across the Welsh border to the Cheshire plain. Understanding how that water arrives, and why it still flows two centuries later, explains why the canal survived when so many others were abandoned. On the sixth day of our Canals and Railways in the Industrial Revolution tour, the group sees Horseshoe Falls and the Llangollen Canal before travelling along it by longboat.

Why the Llangollen Canal depends on a reliable water supply

Every canal loses water. Each time a boat passes through a lock, a lockful of water drains downhill to the next level, and more is lost through leaks, seepage and evaporation. A canal that crosses high ground therefore needs a constant supply delivered to its summit, or it slowly empties. Engineers solved this with reservoirs, streams and pumping engines, and the search for water shaped routes as much as the search for trade did. Our wider guide to canals and the Industrial Revolution explains why Britain built so many of them in the late eighteenth century; the Llangollen Canal is a clear case of what happens when the water question comes first.

The waterway began as part of the Ellesmere Canal, authorised by Act of Parliament on 30 April 1793. Its promoters, industrialists with works around Ruabon, wanted to link the Mersey, the Dee and the Severn. William Jessop was appointed engineer, and Thomas Telford was engaged later that year to oversee the works. The tour passes through the market town of Ellesmere, where Telford lived while the canal was being built between 1793 and 1805.

The grand plan was never finished. In 1800 Jessop abandoned the planned line north from Trevor to Chester, which left the canal company with a magnificent aqueduct at Pontcysyllte, Telford’s canal in the air, and a network that reached it, but with no dependable source of water at its western end. The answer was to go further west, into the valley of the Dee.

Horseshoe Falls and the River Dee

The Ellesmere Canal, Railway and Water Supply Act of 1804 authorised a navigable feeder running from the north end of Pontcysyllte through Llangollen to Llantysilio, about two miles upstream of the town. There the company built a weir across the Dee. Jessop had first promoted the idea in 1795, and Telford built it as chief engineer between 1804 and 1806. The feeder opened in 1808, and from then on the system was not short of water.

The weir, known in Welsh as Rhaeadr y Bedol, is about 140 metres long and sits at a sharp bend in the river above a stretch of rapids. Its upstream face slopes, its downstream face drops vertically about 1.2 metres, and its crest is built of large squared stones capped with bullnosed cast-iron sections. Despite its name it is not a true horseshoe: the line curves in a long J-shaped crescent, a form that spreads the pressure of the water along its whole length. Jessop’s crescent followed an earlier weir by his former tutor, John Smeaton, at Acklington Mill in Northumberland in 1776. The cast-iron edging was added in 1822, after floods in the winter of 1820 to 1821 damaged the stonework.

Is Horseshoe Falls a natural waterfall?

No, it is a man-made weir, built between 1804 and 1806 to hold back the River Dee so that water could be drawn off into the canal. The “falls” are the even sheet of water spilling over its crest, little more than a metre high. Before the weir was built, the riverside here was already a well-known beauty spot, and the curving line of water against the wooded hillside has kept that reputation. It is listed at Grade II as an early example of a river regulation scheme.

Feeder, channel and controlled flow

Behind the weir, the river forms a broad, slow pool that acts as the canal’s reservoir. On the eastern bank, the river’s edge was extended into a stone-lined pound with sluices, so that the company could control how much water entered the canal rather than leaving it to the whims of the Dee. Wooden planks were originally slotted in to raise or lower the level at the intake. A grating fitted in 1810 was meant to keep salmon fry out of the canal; when the company removed some of its bars in 1874 because of weed, it was prosecuted and had to put them back. A small gauge house, built in 1947, now measures the water flowing into the canal.

The quantities are considerable. The Canal & River Trust puts the flow at about 12 million gallons a day, enough to give the canal a current of roughly two miles an hour. Jessop’s scheme also looked further upstream: in 1795 he proposed sluices at Llyn Tegid, the lake at Bala, so that the river feeding the weir could be regulated from a distance. The river bed itself became part of the canal’s water storage.

Why does the water in the Llangollen Canal flow?

Because the canal is a water channel as well as a navigation, and it is constantly carrying water east. The supply taken in at Horseshoe Falls travels the length of the canal, over the aqueducts at Pontcysyllte and Chirk, through Ellesmere and across the border into Cheshire, until it reaches Hurleston Reservoir near Nantwich. Walkers on the towpath can often see leaves and twigs drifting with the current, something that seldom happens on other British canals.

Why can’t motor boats reach Horseshoe Falls?

Because the last stretch of the feeder is too narrow and shallow for them to pass or turn. Above Llangollen, sections of the channel are only wide enough for one boat, and boats drawing more than about 21 inches of water are advised not to attempt them. Powered craft are not allowed beyond the entrance to Llangollen Marina. The final section is used only by horse-drawn trip boats from Llangollen Wharf, a tradition first offered to visitors in 1884.

Ellesmere, Llangollen and the wider system

Followed eastward from the weir, the Llangollen Canal reads as a single engineered line. It runs for about 46 miles from Llantysilio to Hurleston Junction, where it meets the Shropshire Union main line, and climbs or falls through 21 locks along the way. Most of those locks lie in the English section: at Hurleston four locks lift the canal 34 feet in quick succession, and at Grindley Brook three single locks and a three-chamber staircase together raise it almost 39 feet. In Wales, by contrast, the canal holds its level along the valley side and crosses valleys rather than descending into them.

Between Llangollen and the border, the line crosses the Dee on Pontcysyllte, then passes through the Whitehouses and Chirk tunnels, which opened in June 1802, before crossing the Afon Ceiriog on Chirk Aqueduct. Begun in 1796, the aqueduct is about 600 feet long, with ten masonry arches carrying the canal some 70 feet above the river. On the tour, the group views Chirk Aqueduct and visits Chirk Castle on the way to Llangollen.

Further east, at Frankton Junction, the Montgomery Canal branches south, and a short tunnel past Blake Mere leads to Ellesmere. Here the Canal & River Trust’s maintenance depot, with its workshops and dry dock beside a short canal arm, is regarded as the best-preserved canal maintenance yard in Britain. It is a reminder that a waterway this long needed constant care to keep both boats and water moving.

At the far end, Hurleston Reservoir receives the water through a side channel with sluices and a weir above the top lock. It holds about 85 million gallons, and it supplies both the Shropshire Union main line and a drinking-water treatment works run by United Utilities. The water that spills into the canal at Llantysilio ends its journey as part of the public supply in Cheshire.

Water saved the canal

That role turned out to matter more than anyone in 1808 could have foreseen. Commercial traffic beyond Frankton to Llangollen ended in 1937, and the Frankton to Hurleston section fell out of use after 1939. In 1944 an Act obtained by the London Midland and Scottish Railway sanctioned the abandonment of much of the Shropshire Union network. The Hurleston to Llangollen line was kept, because it was the main water supply for the rest of the system. A canal that might otherwise have been drained and filled in survived as a water channel that boats could still use.

The Transport Act 1968 then designated the branch from Hurleston to Llantysilio a cruiseway, securing it for leisure boating. In 2009 UNESCO inscribed an 11-mile stretch, from Gledrid Bridge near Chirk to Horseshoe Falls, as the Pontcysyllte Aqueduct and Canal World Heritage Site. It covers both aqueducts, the tunnels and the feeder to the weir, and it recognises the canal as a whole engineered landscape rather than a single monument.

How the canal works with its Welsh landscape

West of Llangollen, the canal hugs the steep side of the Dee valley, with the river running below and a rocky, wooded hillside rising above. The engineers kept the line on the contour wherever they could, cutting a shelf into the slope rather than climbing with locks, so the feeder threads through the landscape at an almost constant level. Close to the falls, King’s Bridge, a five-arched road viaduct built between 1902 and 1906, crosses both river and canal, and nearby the Chain Bridge, first built in 1817 and rebuilt over the years with its original chains, was reopened in 2015. Above the weir stands St Tysilio’s Church, much of it fifteenth-century.

The canal also explains the industries around it. It carried slate and limestone from the quarries of the upper Dee valley across the aqueducts into Shropshire, linking this corner of Wales to the wider economy of industrial England. On the day before the group reaches the canal, the tour rides the Ffestiniog Railway, built to carry slate from the mountains of Snowdonia to the sea at Porthmadog; seen together, the two routes show how differently engineers answered the same Welsh terrain.

Can you walk from Llangollen to Horseshoe Falls?

Yes. The towpath runs from Llangollen Wharf to Horseshoe Falls, a distance of about two miles (3.2 kilometres) each way. Most of the route is level towpath, but there is a short stretch past Ty-Craig Bridge where walkers share a road leading to the Chainbridge Hotel, and the final approach to the falls is narrow and wooded. Llangollen Wharf sits on the hillside above the town, so the return from the canal into Llangollen is uphill.

How much walking does the Llangollen day involve?

Expect a moderate day on your feet, with the longboat journey giving a seated stretch. The tour as a whole is rated Level 2 (Moderate): most days involve three to five hours of activity, the equivalent of walking up to 8 kilometres, sometimes on uneven ground, and travellers need to manage stairs and carry their own luggage. Towpaths can be muddy after rain, so comfortable, sturdy shoes are worth bringing.

Following the water on the tour

The Llangollen Canal rewards travellers who look at it as a system. Start at the weir, watch the water pass through the sluices, follow the current along the hillside and across the aqueducts, and the purpose of every structure along the way becomes clear. Our overview of Britain’s canals, railways and industrial heritage places Llangollen alongside the other engineering landmarks on the route, from Pontcysyllte to the Scottish canals.

The Canals and Railways in the Industrial Revolution tour passes through Ellesmere and Chirk, then spends a day at Llangollen to see Horseshoe Falls, cross Pontcysyllte and travel along the canal by longboat, in a small group of 6 to 14 travellers departing in April and September 2027.