River Blackwater, Cavan and Meath

River Blackwater (Leinster/Kells) An Uisce Dubh
River Blackwater Bridge carrying the R164 over the Blackwater at Moynalty
Country	Ireland
Basin features
Main source	South County Cavan
River mouth	Irish Sea via River Boyne
River system	Boyne
Basin size	733 km2 (283 sq mi)
Physical characteristics
Length	68 kilometres (42 mi)
Discharge	Average rate: 15.08 m3/s (533 cu ft/s)

The River Blackwater (Irish: An Uisce Dubh), also called the Kells Blackwater or Leinster Blackwater, is a river that flows through the counties of Cavan and Meath in Ireland. It is a tributary of the River Boyne which flows into the Irish Sea at Drogheda. (This is one of two River Blackwaters which flow into the Boyne in County Meath, the other originates in County Kildare).

It has its source in the south of Cavan, near the town of Bailieborough. It flows through Lough Ramor at Virginia, County Cavan, past Kells, County Meath, before joining the River Boyne in Navan, County Meath.

Rivers of Ireland

Coordinates: 52°51′N 7°27′W / 52.850°N 7.450°W / 52.850; -7.450