River Itchen, Hampshire

Itchen Alre (see tributary so-named)
The Itchen near Avington
Map of the River Itchen, in dark blue, and its principal tributary, the Alre, in grey. Canal sections of the Itchen Navigation in green.
Etymology	Unknown
Location
Country	England
County	Hampshire
City	Winchester Southampton
Physical characteristics
Source
• location	south of New Cheriton, Kilmeston, Hampshire, England
• coordinates	51°02′33″N 1°09′37″W / 51.0426°N 1.1603°W / 51.0426; -1.1603
Mouth	Southampton Water
• location	Southampton, Hampshire
• coordinates	50°54′19″N 1°23′08″W / 50.9052°N 1.38565°W / 50.9052; -1.38565
• elevation	0 metres
Length	26 miles (42 km) or unconventionally: 88 km (55 mi) (including all anabranches)
Basin size	119.619 km2 (46.185 sq mi)
Discharge
• location	Riverside Park, Bitterne Park
• average	5.3 m3/s (190 cu ft/s)
• minimum	1.75 m3/s (62 cu ft/s)14 August 1995
Discharge
• location	Highbridge, Hampshire
• average	5.4 m3/s (190 cu ft/s)
Discharge
• location	Easton, Hampshire
• average	4.3 m3/s (150 cu ft/s)
Basin features
Tributaries
• left	Candover Brook River Alre Nun's Walk Stream Monks Brook
• right	Cheriton Stream

The River Itchen in Hampshire, England, rises to the south of New Alresford and flows 26 miles (42 km) to meet Southampton Water below the Itchen Bridge. The Itchen Navigation was constructed in the late 17th and early 18th centuries to enable barges to reach Winchester from Southampton Docks, but ceased to operate in the mid-19th century and is largely abandoned today.

The river is one of the world's premier chalk streams for fly fishing,^[1] amenable to dry fly or nymphing. The local chalk aquifer has excellent storage and filtration and the river has long been used for drinking water. Watercress thrives in its upper reaches.^[2]

Much of the river from its source to Swaythling is classified as a 748.5-hectare (1,850-acre) biological Site of Special Scientific Interest (SSSI),^[3][4] and a Special Area of Conservation,^[5] of which the 9-hectare (22-acre) Hockley Meadows nature reserve is a part.^[6] The Itchen estuary is part of the separate Lee-on-The Solent to Itchen Estuary SSSI.^[7]