English: Willow - The Ouse Washes at Sutton Gault, near to Mepal, Cambridgeshire, Great Britain. The Ouse Washes is an area of seasonally flooding wet grassland (washland) lying between the Old and New Bedford Rivers. These are derived from the River Ouse, a major tributary of East Anglia's Wash. They were cut in the 17th century (and earlier) by the Dutch engineer Cornelius Vermuyden as part of the programme to drain the fens of floodwater for agriculture. In 1630, King Charles I granted a drainage charter to the 4th Earl of Bedford who engaged the Dutch engineer Cornelius Vermuyden to construct the two Bedford rivers. The purpose of the new rivers was to facilitate drainage of the Great Ouse between Earith and Downham Market. The area between the rivers is 20 miles (32 km) long and almost a mile wide and acts as washland, i.e. a floodplain during the winter and, increasingly, also in summer.