The River Stour is a river in Suffolk, England. It is 76km (47 m) long and forms most of the county boundary between Suffolk and Essex. It rises in eastern Cambridgeshire, passes though Haverhill, Cavendish, Suffolk, Sudbury and the Dedham Vale, and it joins the North Sea at Harwich.

RSPB Stour Estuary is a nature reserve managed by the Royal Society for the Protection of Birds.

The Stour valley has been portrayed as a working river by John Constable, Thomas Gainsborough and Paul Nash.

The River Stour Trust, a waterway restoration group, was set up in 1968 and has restored the Gasworks Cut and the 19th century Granary Building, now used as the Trust's Headquarters.

See also