The River Stour is a 60.5 mile (97 km) long river which flows through Wiltshire and Dorset in southern England, and drains into the English Channel. It is sometimes called the Dorset Stour to distinguish it from rivers of the same name. The source of the river is at Stourhead, in Wiltshire, where it forms a series of artificial lakes which are part of the Stourhead estate owned by the National Trust. It flows south into Dorset through the Blackmore Vale and the towns of Gillingham and Sturminster Newton. At Marnhull the Stour is joined by the River Cale and then (two miles downstream) by the River Lydden. At Blandford Forum the river breaks through the chalk ridge of the Dorset Downs, and from there flows south east into the heathlands of south east Dorset. At Wimborne Minster it is joined by the River Allen, and at its estuary at Christchurch it is joined by the River Avon before it flows through the harbour into the English Channel. The Stour Valley Way is a designated long distance footpath that follows almost all of the course of the river.