The Brent Reservoir (popularly called the Welsh Harp) is a reservoir in North West London. It straddles the boundary between the boroughs of Brent and Barnet and is owned by the Canal & River Trust. The reservoir takes its informal name from a public house called The Welsh Harp, which stood nearby until the early 1970s. It is a 68.6-hectare (170-acre) biological Site of Special Scientific Interest (SSSI), the only SSSI in either borough and among more than 30 SSSIs in Greater London.