The Duke of Northumberland's River or D. O. N. River consists of separate upper and lower artificial watercourses in west London, United Kingdom. The older name Isleworth Mill Stream/River more accurately describes the economic motivation behind its construction. The first section draws water via a sluice from the Colne — a source river which has seven distributaries, many of which are man-made — today an extended distance of about 5 miles (8 km) into the Crane; its lower section of about 1.8 miles (2.9 km) draws water from that small river in Whitton, Twickenham and discharges it via neighbouring Isleworth, passing Mill Plat into the tidal Thames. A sluice underneath Mill Plat feeds the main lake in Syon Park.

The Colne is a river and a tributary of the River Thames in England. Just over half its course is in south Hertfordshire. Downstream, it forms the boundary between Buckinghamshire and the London Borough of Hillingdon. The confluence with the River Thames is on the Staines reach at Staines-upon-Thames.