The River Seph (or River Sep) is a tributary of the River Rye (itself a tributary of the River Derwent) in

North Yorkshire North Yorkshire is the largest ceremonial counties of England, ceremonial county (lieutenancy area) in England, covering an area of . Around 40% of the county is covered by National parks of the United Kingdom, national parks, including most of ...

, England. The river flows for down

Bilsdale Bilsdale is a dale in the western part of the North York Moors in North Yorkshire, England. The head of the dale is at Hasty Bank, and the dale extends south to meet Rye Dale near Hawnby. The dale is the valley of the River Seph, formed wher ...

and meets the Rye near the village of

Hawnby Hawnby is a small crossroads village and civil parish in Rye Dale in the North York Moors National Park, North Yorkshire, England. The village is about north-west of Helmsley. History The village is mentioned twice in the ''Domesday Book'' a ...

. The name derives from Old Swedish and means either ''Slow Stream'' or ''Calm''. When the surrounding land was owned by Roger de Mowbray, the river was referred to as the ''Sep''.

Course

The river starts in Bilsdale at the village of

Chop Gate Chop Gate ( ) is a small village in the Hambleton district of North Yorkshire, England. The village lies within the North York Moors National Park. Historically part of the North Riding of Yorkshire, the village is situated south east of Stokes ...

where the waters of the Bilsdale and Raisdale Becks meet, though some of the sources start on

Urra Moor Urra Moor is the highest moor in the North York Moors, North Yorkshire, England. At above sea level it is the highest point in Hambleton District and the North York Moors National Park, and the fourteenth most prominent hill in England. The n ...

. The river from source to where it meets the River Rye at Seph Mouth, is long. Historically, parts of the river were the delineating boundaries between ancient parishes. Bilsdale is narrow and densely wooded at the head of the valley, but further down becomes wider and the water meanders before it joins the Rye.

Natural History

The river has suffered with invasive species such as

Himalayan balsam ''Impatiens glandulifera'', Himalayan balsam, is a large annual plant native to the Himalayas. Via human introduction it is now present across much of the Northern Hemisphere and is considered an invasive species in many areas. Uprooting or cutt ...

and

Japanese Knotweed ''Reynoutria japonica'', synonyms ''Fallopia japonica'' and ''Polygonum cuspidatum'', is a species of herbaceous perennial plant in the knotweed and buckwheat family Polygonaceae. Common names include Japanese knotweed and Asian knotweed. It is ...

which have been the subject of various programmes to eradicate them. The river has also benefitted from a government grant to help fish navigation and a reduction in pollution. It was known to be a good trout stream in the late 19th/early 20th centuries, and various agencies came together in 2015 to improve fish passages on the watercourse to allow the migration of trout from the River Rye. The river flows across the south western edge of the North York Moors and as such has limestone, gritstone, mudstone and siltstone as its bedrock. During dry summers, the waters disappear into the bedrock and the river becomes totally subterranean. The sides of Bilsdale where the Seph meanders, are lined with ancient Oak trees and the

North York Moors National Park Authority The North York Moors is an upland area in north-eastern Yorkshire, England. It contains one of the largest expanses of Calluna, heather moorland in the United Kingdom. The area was designated as a national parks of England and Wales, National P ...

were granted

Heritage Lottery Fund The National Lottery Heritage Fund, formerly the Heritage Lottery Fund (HLF), distributes a share of National Lottery funding, supporting a wide range of heritage projects across the United Kingdom. History The fund's predecessor bodies were ...

ing in 2017 to protect the land and study the wildlife along the upper reaches of the River Rye. This will include the Seph and will look at some of the native species which make use of the watercourse such as the alcathoe bat and the

white-clawed crayfish ''Austropotamobius pallipes'' is an endangered European freshwater crayfish, and the only crayfish native to the British Isles. Its common names include white-clawed crayfish and Atlantic stream crayfish. Distribution It is found from the eas ...

Settlements

Bilsdale is a remote valley populated mainly with hamlets as opposed to villages and towns. From the source of the Seph downstream, these are; * Seave Green *

* Cross Holme * Fangdale Beck

References

External links

{{authority control Seph Ouse catchment