The River Itchen rises near Wormleighton at grid reference SP 447 541 and flows into a broad valley to the northeast of a range of ironstone hills which border Warwickshire and Northamptonshire.

A mile-and-a-half north of Bishops Itchington, the River Itchen passes under Deppers Bridge which gives its name to the neighbouring hamlet.

A mile north of Bascote, the Grand Union Canal crosses the Itchen valley on a half-mile-long embankment, and is carried over the river on an aqueduct.

In 2009 thousands of fish were killed in the River Itchen when poisonous chemicals washed off neighbouring farmland.

There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish.