The Afon Tarell is a river in Powys

Powys

Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...

, Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

, which rises to the west of the Brecon Beacons

Brecon Beacons

The Brecon Beacons is a mountain range in South Wales. In a narrow sense, the name refers to the range of popular peaks south of Brecon, including South Wales' highest mountain, Pen y Fan, and which together form the central section of the Brecon Beacons National Park...

 in Brecon Beacons National Park  and flows north, then north-east, for 14 miles (22.5 km) into the River Usk

River Usk

The River Usk rises on the northern slopes of the Black Mountain of mid-Wales, in the easternmost part of the Brecon Beacons National Park. Initially it flows north into Usk Reservoir, then east by Sennybridge to Brecon before turning southeast to flow by Talybont-on-Usk, Crickhowell and...

 

The river is followed for its entire length through Glyn Tarell (the Tarell valley) by the A470 road, passing by the hamlets of Libanus

Libanus, Powys

Libanus is a village in the Brecon Beacons National Park, in the county of Powys, Wales, United Kingdom.It lies on the A470 road approximately 1 mile north-east of its junction with the A4215 road, and approximately 5 miles south-west of Brecon....

 and Tai'r Bull and entering the Usk at Llanfaes

Llanfaes

Llanfaes is a small village on the island of Anglesey, Wales, located on the shore of the eastern entrance to the Menai Strait, the tidal waterway separating Anglesey from the north Wales coast.- History :...

 on the southern edge of Brecon

Brecon

Brecon is a long-established market town and community in southern Powys, Mid Wales, with a population of 7,901. It was the county town of the historic county of Brecknockshire; although its role as such was eclipsed with the formation of Powys, it remains an important local centre...

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The most significant tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the river is Nant Cwm Llwch, which enters the Tarell on its right bank between Tai'r Bull and Llanfaes. This secondary river emerges from the glacial lake of Llyn Cwm Llwch

Llyn Cwm Llwch

Llyn Cwm Llwch is a lake in the Brecon Beacons National Park in Powys, Wales. It is a small lake of glacial origin occupying a rock hollow beneath the peaks of Pen y Fan and Corn Du in the central Brecon Beacons...

 beneath Pen y Fan

Pen y Fan

Pen y Fan is the highest peak in South Wales and southern Britain, situated in the Brecon Beacons National Park. At above sea-level, it is also the highest peak in Britain south of the Snowdonia mountain range...

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The name may have its origins in the old Welsh language

Welsh language

Welsh is a member of the Brythonic branch of the Celtic languages spoken natively in Wales, by some along the Welsh border in England, and in Y Wladfa...

 words tarddu, "to bubble out", and tarddell, "a spring or source".

The Afon Tarell, in common with the Usk and its other tributaries, is designated as a special area of conservation

Special Area of Conservation

A Special Area of Conservation is defined in the European Union's Habitats Directive , also known as the Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora...

 for its three species of lamprey

Lamprey

Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...

, twaite shad, European bullhead

European bullhead

The bullhead is a freshwater fish that is widely distributed in Europe, mainly in rivers. It is a member of the Cottidae family, a type of sculpin...

, Atlantic salmon

Atlantic salmon

The Atlantic salmon is a species of fish in the family Salmonidae, which is found in the northern Atlantic Ocean and in rivers that flow into the north Atlantic and the north Pacific....

 and otter

Otter

The Otters are twelve species of semi-aquatic mammals which feed on fish and shellfish, and also other invertebrates, amphibians, birds and small mammals....

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