Its two upper branches unite in Bartley from where it flows north-east to Eling where it becomes a narrow tidal estuary into the Southampton Water which is an arm of the Solent.
The tidal part of the river (but not the natural low water flow) drives the working historic Eling Tide Mill at Eling, where a toll road crosses the river.
The river is also an important recreational and wildlife haven, especially at the tidal, Eling end of the river.
Despite being shallow in many places the stream is home to brown and rainbow trout that average about 10 to 12 inches (25 to 30 cm) long.
Its farthest source is the Mill Stream, which is the main contributor to its south branch and rises north-west of Lyndhurst, Hampshire.
References
^Ordnance Survey: Landranger map sheet 196 The Solent & Isle of Wight (Southampton & Portsmouth) (Map). Ordnance Survey. 2015. ISBN9780319231425.