River Nidd
Railway Viaduct over the River Nidd in Knaresborough 54°10′23″N 1°59′53″W / 54.17306°N 1.99806°W / 54.17306; -1.99806
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Etymology	Probably a Celtic word meaning "bright, brilliant, shining"
Location
Country	England
Physical characteristics
Source
• location	Nidd Head Spring, 1.3 km north of the summit of Great Whernside
• elevation	595 metres (1,952 ft)
Mouth
• location	River Ouse, Nun Monkton
• coordinates	54°0′51″N 1°13′8″W / 54.01417°N 1.21889°W / 54.01417; -1.21889
• elevation	13 metres (43 ft)
Length	94.45 kilometres (58.69 mi)
Basin size	516 square kilometres (199 sq mi)
Basin features
River system	Swale–Ouse

v t e River Nidd
Legend
Nidd Head Straight Dike Craven Sike Long Hill Sike Crook Sike Stone Beck Angram Reservoir Scar House Reservoir Twizzling Gill Maddering Gill Foggyshaw Gill Mere Dike Flooding route (above ground) Manchester Pot (subterranean) Limley Gill Goydon Pot (subterranean) How Gill (occupies River Nidd Bed) Intake Gill (Lofthouse) How Stean Beck Nidds Head (waters resurface) Blackston Gill Wath Road Ramsgill Beck Lul Beck Byerbeck Gill Gouthwaite Reservoir Dauber Gill Foster Beck B6265 road Rash Dike Fosse Gill Byril Beck Fell Beck Mill race Loftshaw Gill B6451 road Darley Beck Fingill Dike Lolly Bog Dike Slack Dike Cockhill Beck Ripley Beck A61 road Killinghall Bridge Newton Beck Oak Beck Nidd Viaduct Bilton Beck A59 road Harrogate Line Holbeck A658 road Crimple Beck A168 road A1(M) Harrogate Line A59 road River Ouse

The River Nidd is a tributary of the River Ouse in the English county of North Yorkshire. It rises in Nidderdale at Nidd Head Spring on the slopes of Great Whernside. In its first few miles it has been dammed three times, creating Angram Reservoir, Scar House Reservoir and Gouthwaite Reservoir, which attract a total of around 150,000 visitors a year.^[1] It joins the River Ouse at Nun Monkton.

The upper river valley, Nidderdale, was designated as an Area of Outstanding Natural Beauty in 1994.^[2]

The Yorkshire Dales Rivers Trust has a remit to conserve the ecological condition of the River Nidd from its headwaters to the Humber estuary.

The Nidd rises in Nidderdale at Nidd Head Spring on the slopes of Great Whernside in the Yorkshire Dales. It flows east into Angram and Scar House reservoirs before turning south just downstream of Newhouses. In normal conditions the river disappears underground into the sinkhole known as Manchester Hole. If Scar House reservoir overflows, water flows past Manchester Hole to Goyden Pot, another sinkhole. In severe floods, the river flows past Goyden Pot down the valley. The water sinking into the Nidderdale caves reappears at the rising Nidd Head to the south of the village of Lofthouse.

Below Lofthouse the river is joined by How Stean Beck, and turns south-south-east towards Ramsgill before flowing into Gouthwaite Reservoir. Continuing on the same heading, the first major settlement is reached at Pateley Bridge. Turning more south-easterly, it flows past Glasshouses and Summerbridge, where it turns south again past Dacre Banks. Passing by Darley, the river turns east before reaching Birstwith, where it flows south-east to Hampsthwaite. A series of large bends in the river take the flow north, east and then south, and east again, to enter Nidd Gorge.

Below the gorge, the river meanders south-east through the town of Knaresborough, heading north and looping south again as it enters flatter terrain. Near Little Ribston it meanders south-easterly and easterly, crossing underneath the A1 and the A1(M) near the small village of Cowthorpe. The river continues meandering past Cattal north-easterly towards Moor Monkton, towards its junction with the River Ouse at Nun Monkton.

• Low and high water levels are an average figure.

The two most northerly reservoirs on the course of the river were built to provide water to the Bradford area in the early 1900s by way of the Nidd Aqueduct. As of 2017, they are maintained by Yorkshire Water.^[4]

The reservoir takes its name from Angram, a settlement in the township of Stonebeck Up, submerged when the reservoir was built. Completed in 1919 with a dam height of 61 metres (200 ft) covering 34 hectares with a volume of 1,041 million gallons and a depth of 33.4 metres (110 ft).

A temporary village was built at Scar House to house the workers building the reservoirs and some remains can still be seen. The old Village Hall was moved to Darley, where it now serves as the local Village Hall. The dam at Scar House was completed in 1936. The dam height is 71 m (233 ft) with the reservoir covering area 70 hectares and a depth of36.3 metres (119 ft) giving a volume of 2,200 million gallons. The reservoir is fed almost exclusively from the Angram dam.

Gouthwaite reservoir is designated a Site for Special Scientific Interest.^[5] It provides a compensation release for the river.^[6] It covers an area of 312 acres (126 ha).^[7]

The Nidd can overflow the reservoirs, flooding the caves in the valley.^[8][9] In such cases the river overflows into the normally dry river bed past Lofthouse through to Gouthwaite Reservoir.

The head of the river is located on moorland and the river character is affected by the run-off levels from the three reservoirs. The upper valley is primarily millstone grit with fluvioglacial deposits. The overlying soil is prone to water-logging due to its slow permeability, being composed of loamy soils on top of clay with peat on the top layer. Around Lofthouse there are outcrops of Upper Yoredale limestone, which is more permeable than millstone grit and has created the Nidderdale Caves, where the river flows underground.

Lower down on the flood plain, the nature of the underlying ground is Magnesian Limestone over alluvium and terrace drift deposits. On top of this is a combination of slowly permeable and well drained fine loam over clay.^[10][11]

Where the river passes through the Nidd Gorge, Carboniferous (Namurian) and Upper Permian rock is exposed.^[12]

The etymology of the name remains unknown but the name is either Celtic or Pre-Celtic (as with most rivers in Western Europe). A derivation from Celtic meaning brilliant or shining has been suggested (as in Old Irish níamda),^[13] as has a link to the older Indo-European root *-nedi, simply meaning river.^{[14][15][16][17]}

The Nidd likely shares this etymology with the river and town of Neath (Welsh Nedd) in South Wales and the town of Stratton in Cornwall (originally named Strat-Neth), and with many other rivers across Europe, such as the Nete in Belgium, the Nied in France, Neda in Galicia (NW Spain), the Nethe, Nidda and Nidder in Germany, and the Nida in Poland.^{[18][16][19][20]}

Along the river valley can be found the Nidderdale Museum, which is located in Pateley Bridge, and features sections about the traditional agriculture, industries, religion, transport and costume of Nidderdale.

Lower down the river is the town of Knaresborough, which is home to Knaresborough Castle and Knaresborough Museum.

There are many way-marked walking routes throughout the river valley, including the Nidderdale Way, a 55-mile circular walk whose usual starting point is Ripley.

• 
  River Nidd less than 0.6 miles (1 km) from the source
• 
  River Nidd at Lofthouse
• 
  River Nidd near West House Farm
• 
  River Nidd near Pateley Bridge
• 
  River Nidd at Glasshouses
• 
  River Nidd below Dacre
• 
  River Nidd between Birstwith and Hampsthwaite
• 
  River Nidd from Killinghall Bridge
• 
  The River Nidd at Knaresborough
• 
  River Nidd near Tockwith Road

Ordnance Survey Maps

• Lower Wharfedale & Upper Washburn Valley (297)
• Nidderdale (298)
• Yorkshire Dales – Northern & Central Areas (OL 30)