The River Dodder () is one of the three main rivers in Dublin, Ireland, the others being the Liffey, of which the Dodder is the largest tributary, and the Tolka. Course and system The Dodder rises on the northern slopes of Kippure in the Wicklow Mountains and is formed from several streams. The headwaters flow from Kippure Ridge, and include, and are often mapped solely as, Tromanallison (Allison's Brook), which is then joined by Mareen's Brook, including the Cataract of the Brown Rowan, and then the combined flow meeting the Cot and Slade Brooks. In the river's valley at Glenasmole are the two Bohernabreena Reservoirs, a major part of the Dublin water supply system. The Dodder is long. It passes the Dublin suburbs of Tallaght and then Firhouse, travels by Templeogue, passes Rathfarnham, Rathgar, Milltown, Clonskeagh, and Donnybrook, and goes through Ballsbridge and past Sandymount, before entering the Liffey near Ringsend, along with the Grand Canal, at Grand Canal Dock. There is a weir just above the bridge at Ballsbridge and the river becomes tidal roughly where the bridge at Lansdowne Road crosses it. The Dodder and the River Tolka are Dublin's second-largest rivers, after the Liffey. Tributaries The Dodder's main tributaries after Glenasmole, in and prior to which many streams join, are the Jobstown (or Whitestown) Stream, the Owendoher River and its tributary the Whitechurch Stream, the Little Dargle River (with Castle Stream and other tributaries), the Slang or Dundrum River, the Swan River (or Water), and the small Muckross Stream. Link with the Poddle The River Poddle, a tributary of the Liffey in its own right, was linked with the River Dodder from a large weir, in Balrothery, north of Firhouse village, from the 13th century. This weir, variously called the City, Great, Balrothery or Firhouse Weir, facilitated the offtake of part of the Dodder flow through a sluice and canal structure, known as the "City Watercourse," which ran through part of Templeogue. This link formerly provided much of Dublin City's water supply. It was partly piped in the mid-20th century, and the connection was later broken by housing development. All that remains now are a small channel from the weir, dead-ending less than 100m from the weir, and some unseen underground flows. History The Dodder lay well beyond the original city of Dublin but began to have an important impact in the 13th century when water from