River Dwyryd facts for kids

The River Dwyryd (called Afon Dwyryd in Welsh) is a river in Gwynedd, Wales. Its name means "river of two fords." It mainly flows westwards and empties into Tremadog Bay, which is south of Porthmadog.

Journey of the River Dwyryd

The River Dwyryd starts high up in the hills north of Ffestiniog. Water from a mountain called Moelwyn Mawr flows into the Tanygrisiau Reservoir. The water leaving this reservoir forms the beginning of a stream called Afon Goedol. This stream then joins another river, the River Bowydd.

Further downstream, the Dwyryd meets the Afon Cynfal. This river flows from the east through a deep, wooded gorge. Here, you can see the amazing Rhaeadr Cynfal, which is a beautiful waterfall south of Ffestiniog.

The main river then flows through a wide valley called the Vale of Ffestiniog. This valley was shaped by ancient glaciers (huge sheets of ice). Its flat bottom is made of rocky material left by glaciers and river gravel. Many farms are in this valley, but it often experiences flooding in winter.

About one mile downstream, another stream called the Afon Tafarn-helyg joins the Dwyryd. This stream starts south of Gellilydan and north of the Llyn Trawsfynydd reservoir, but it doesn't take water from the reservoir itself.

There are also several small lakes and reservoirs hidden in the woods north of Plas Tan y Bwlch. These lakes, including Llyn y Garnedd, Llyn Hafod y Llyn, and Llyn Mair, also flow south into the Dwyryd.

The River Meets the Sea

When the Dwyryd reaches Maentwrog, it becomes a long, sandy estuary. An estuary is where a river meets the sea, and the water becomes a mix of fresh and salt water. The river flows under the road and railway line at Pont Briwet. After this, it joins the estuary of the River Glaslyn before finally flowing into Porthmadog Bay.

A stream called Afon y Glyn flows into the southern side of the Glaslyn estuary. This stream drains water from Llyn Tecwyn Uchaf and Llyn Tecwyn Isaf. It enters the estuary near a large area of salt marsh called Glastraeth, which means "green beach." The village of Portmeirion is located opposite this salt marsh.

River Health and History

The land around the Dwyryd is made of very old rocks. Over the last 100 years, much of the area has been used for growing trees for wood. Because of this, and because of acid rain (pollution in the air that makes rain acidic), some of the smaller streams that feed the Dwyryd have become quite acidic. This can make it harder for fish and other living things to thrive in these waters.

In the past, activities like metal mining and slate mining also took place in the area. These activities, along with others, sometimes affected the river's water quality.

Afon Prysor: A Major Branch

The Afon Prysor is the biggest stream that joins the Dwyryd. It flows into the Dwyryd's left bank in the tidal part of the river, downstream from Maentwrog.

The Afon Prysor starts in the hills east of Trawsfynydd. It flows past the village and into Llyn Trawsfynydd. This is a large reservoir near the A470 main road. Before a dam was built here in the 1920s for hydro-electric power (making electricity from water), the river used to wander across a big marshy area.

Llyn Trawsfynydd is special because it's the only inland water in the UK that was used to cool a nuclear power station. Most of the water from the reservoir now goes through a power station near Maentwrog to make electricity. This water then rejoins the Afon Prysor just before it meets the Dwyryd. The Afon Prysor then flows through a steeply wooded valley called Ceunant Llennyrch, which is a protected national nature reserve.

River Use in the Past

The River Dwyryd is not deep enough for large ships to sail on. However, in the late 1700s, several small docks were built west of Maentwrog. From these docks, small boats would carry wood and, later, slate (a type of rock used for roofs) to bigger ships waiting in deeper water. These bigger ships would then take the cargo to other places.

The river was so shallow that boats could only carry goods during spring tides, which are the highest tides. Some of these old docks are still there today and are used by people who like to fish.

When the Ffestiniog Railway opened in 1836, it became much easier to transport slate by train. This meant fewer and fewer boats used the Dwyryd. By 1860, river traffic on the Dwyryd had completely stopped.

Images for kids

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  The River Dwyryd at Maentwrog