Catchment facts

Catchment facts

The Tweed catchment in northeast Britain straddles the national and administrative border between English Northumberland and the Scottish Borders. The Tweed catchment is bounded to the north and west by the Lammermoor and Moorfoot Hills, and to the south by the Cheviots, which form part of Northumberland National Park. These upland areas are characterised by rounded hills with steep valleys, or cleuchs, eroded into their sides. The uplands eventually give way to the more open, rolling lowlands to the east, featuring flatter, more fertile land. The Borders is noted for its diverse and traditional landscapes which have helped sustain a rich variety of habitats and species. This is reflected in the designation of the River Tweed and its major tributaries as both a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SAC).

Today the Tweed is probably best known for its salmon, as it boasts one of the best wild stocks of Atlantic Salmon in Europe. The rod fishery for Tweed salmon, which is carefully managed by the River Tweed Commission, now catches well in excess of 7000 Salmon annually with the majority of Salmon being returned under the voluntary catch and release code. Salmon fishing on Tweed contributes around £24m per year to the local economy and supports over 500 jobs. This combined with the stunning scenery and the rich built and cultural heritage all help make tourism one of the mainstays of the region’s economy.

Some quick Tweed facts…

– The River Tweed is 160km (100 miles) long from its source at Tweed’s Well, high in the Lowther Hills, to the breakwater at Berwick Upon Tweed.
– The Tweed is the second largest river basin in Scotland (the Tay being the largest) and the sixth largest in mainland Britain after the Thames, Severn, Trent, Yorkshire Ouse and Tay.
– The total catchment area of the Tweed is 5000 square kilometres (1930 square miles) with approximately 4300 square kilometres (1660 square miles) in Scotland and approximately 680 square kilometres (260 square miles) in England.
– The Tweed is one of the least polluted rivers in the UK and a nationally important example of an easterly flowing eutrophic (nutrient-rich) river system.
– Average rainfall decreases markedly from west to east. Around its source in the Tweedsmuir Hills, average rainfall is 2000mm (80 inches) per annum, whilst around the lower reaches on the Merse of Berwickshire, average rainfall is 650mm (26 inches) per annum.
– Flow rates vary considerably, on the lower Tweed the average is 78 cubic metres per second (1480 million gallons per day) but in large floods they can exceed 1500 cubic metres per second (28500 million gallons per day), compared with less than 10 cubic metres per second (190 million gallons per day) during periods of low flow.
– The Tweed has several major tributaries: the largest nine, listed in descending order of catchment size, are:

TributaryCatchment size (km2)
River Teviot


River Till


Whiteadder Water


Ettrick Water


Leader Water


Yarrow Water


Gala Water


Lyne Water


Ale Water