|- location||Near Oulston Reservoir, Yearsley|
|- elevation||160 m (520 ft)|
|- location||River Ouse, York|
|- elevation||12 m (39 ft)|
|Basin size||118 square kilometres (46 sq mi)|
The River Foss is an improved river in North Yorkshire, England, and a tributary of the River Ouse. It rises in the Foss Crooks woods near Oulston reservoir close to the village of Yearsley and runs south through the Vale of York to the Ouse. The name most likely comes from the Latin word Fossa, meaning ditch and is mentioned in the Domesday Book. The York district was settled by Norwegian and Danish people, so parts of the place names could be old Norse. Referring to the etymological dictionary "Etymologisk ordbog", ISBN 82-905-2016-6 dealing with the common Danish and Norwegian languages – roots of words and the original meaning. The old Norse word Fos (waterfall) meaning impetuous. The River Foss was dammed, and even though the elevation to the river Ouse is small, a waterfall was formed. This may have led to the name Fos, and later changed to Foss.
The responsibility for the management of the river's drainage area lies with the Foss Internal drainage board (IDB). It has responsibility for the area from Crayke to the pre-1991 city boundary of York covering 9,085 hectares and 162.54 km of waterways. The Foss IDB is itself part of the York Consortium of Drainage Boards that oversees 10 IDB's in the Yorkshire region.
The typical river level range at the Foss Barrier is between 5.05m and 7.90m. The highest river level recorded at this location was 10.20 metres and the river level reached 9.34 metres on 23 January 2008.
The source of this river is a spring situated in the Howardian Hills adjacent to, and flowing into, Oulston Reservoir near Newburgh Priory, 4 miles (6.5 km) north of Easingwold. From there to the Blue Bridge in York, where it joins the River Ouse, it is 19.5 miles (31 km) in length. For part of its way it runs close to the B1363 between Brandsby and Stillington. The river flows in a series of wide meanders in southerly direction for most of its course towards York. As of 2010 the river is only navigable for some 1.5 miles (2 km) upstream of Castle Mills Lock. The bridges by Peasholme Green and Foss Bank restrict the headroom to an air space of 2.4 metres.
The Foss Barrier is built across the river near its mouth at Castle Mills. When closed, it prevents floodwater from the River Ouse forcing the flow of the Foss back on itself. When the river Ouse reaches a level of 7.4m above ordnance datum, the staff at the barrier are alerted. When the level reaches 7.8m AOD the barrier is then lowered, after running pumps for several minutes to clear silt and debris from the river bed. This provides a watertight fit. It takes four minutes to lower the barrier. To avoid the build-up of water behind the barrier causing the Foss to burst its banks, the water is pumped around the barrier and into the Ouse. This is done by eight pumps that pump water at 30 tonnes per second, this prevents the Foss flowing back on itself. The water pumped out should maintain a water level of 6.5m AOD behind the barrier. When the two sides of the barrier are equalised, the barrier is raised.
Castle Mills Lock is 34 metres long and 6 metres wide. There are mooring points in the lock basin on the River Ouse side with overnight mooring on the River Foss prohibited. Beyond Rowntree Wharf there are few opportunities for turning.
In 1069 William the Conqueror dammed the River Foss just south of York Castle, close to its confluence with the Ouse, to create a moat around the castle. This caused the river to flood further upstream in what is now the Hungate and Layerthorpe areas, forming a large lake that was known as the "King's Pool" or the "King's Fish Pond" and which provided fish for the markets. It was approximately 100 acres in size and fishing was only allowed by licence, except for the King's Men.
The King's Pool was an integral part of the city's inner defences during the Middle Ages as the marsh was virtually impassable. This explains why there is no city wall between Layerthorpe Postern and the Red Tower.
In the 17th century, the King's Pool and the Foss were in a state of decline because silt from upriver collected in the Pool, and not enough water came down to move it on, despite the main channel of the River Foss having been deepened in 1608. Eventually the lake was too shallow to remain viable as a defence of the city. In 1644 the lake was shallow enough for Parliamentarian forces under Sir Thomas Fairfax to consider crossing it on foot as a way of breaking the Siege of York during the English Civil War.
In 1727 an order was placed upon Arthur Ingram, 6th Viscount of Irvine to scour the River Foss from the Castle Mills to Foss Bridge, making it eight yards wide at the top and four yards at the bottom, and, in 1731 the Little Foss, an extension to enclose the Castle, was also drained. In the 18th century, the water was so low that marshy islands were created (hence the area's modern name of Foss Islands). Citizens used the river as a rubbish tip which became a health hazard. Acts of Parliament in 1793 and 1801 were enacted to make the Foss navigable and they effectively saw the end of the King's Pool. The Foss Navigation Company canalised the river from 1778, to make it navigable as far as Sheriff Hutton.
The York Drainage and Sanitary Improvement Act of 1853 meant that the York Corporation purchased the River Foss from the Foss Navigation Company. In 1859, the York Improvement Act was passed that saw the river above Yearsley Bridge abandoned as a waterway.
Stillington Hall was a mansion on the west side of the Foss and adjoining the village of the same name. It was the home of the Croft family, who are descended from a common ancestor with the house of Croft, of Croft Castle in Herefordshire.
Remains of Roman jetties, wharves and warehouses have been found by excavations and building works on the banks of the Foss, suggesting that water-borne transport and trade was important from early in the history of the city.
The modern Foss benefits most from leisure activity and several long distance walks cross its path. The Foss Walk follows much of the river course from Blue Bridge to Oulston Reservoir and then on to Easingwold, a distance of 28 miles (45 km). Part of the Howardian Way near Yearsley and both the Ebor Way and Centenary Way as far as West Lilling also follow the Foss for part of their way.
River Foss Barrier
Flooding of the River Ouse occurs periodically in York. This is part of a series of schemes designed by the Yorkshire Water Authority.
The River Foss is a left bank tributary of the River Ouse, situated near the York Castle.
In the years 1947,1978,1982 and end of 2015 flooding occurred causing many areas to be under water.
In 1982 a feasibility study which was undertaken which indicated flood levels in the River Foss are directly related to River Ouse levels.
A barrier was put forward as a solution to counteract the backwash of the river Ouse into the River Foss. In 2016 funds were allocated to upgrade the existing facilities to improve the pumping capacity.
Source for this section comes from the Ordnance Survey Open Source Mapping
There are many small streams that feed into the Foss north of Strensall. The main ones are:
- Eller's Beck, North-west of Crayke.
- Brandsby Beck, South-west of Crayke
- Farlington Beck, south of Farlington
- Whitecarr Beck, near Sherriff Hutton Bridge
- Howl Beck, near Sherriff Hutton Bridge
- Black Dike near Strensall
North to south, to the confluence with the Ouse, these are:
Bridges over the Foss
North to south, to the confluence with the Ouse, these are:
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- Ordnance Survey Open Viewer
- Media related to River Foss at Wikimedia Commons