The Three Sisters
The Three Sisters are three rivers in Ireland: the River Barrow, the River Nore and the River Suir. The Suir and Nore rise in the same mountainous area in County Tipperary, near the Devil's Bit, while the Barrow rises in the Slieve Bloom Mountains in County Laois. All three join the sea in the same bay south-east of the city of Waterford. In between, they fan out to drain a large portion of the southern part of the island, including the counties of Tipperary, Carlow, Kilkenny, Wexford and Waterford, among others.
The combined catchment area of the Three Sisters is 3,555 square miles, made up of the Suir's 1,394 sq miles, the Barrow's 1,184 square miles and the Nore's 977 square miles.
The combined long-term average flow rate of the Three Sisters into Waterford Harbour is 205 cubic yards per second, almost half of which is made up of the Suir's (100 cu. yds/s), followed by the Nore's (56 cu. yds/s) and the Barrow's (49 cu. yds/s).
The Barrow Bridge crosses two of the Three Sisters, the Nore and the Barrow. They then join the River Suir just downstream of the bridge. This place is known in the Irish language as Cumar na dTrí Uisce, "the confluence of the three waters". The Nore joins the Barrow some two miles north of New Ross and the combined waters of the three sisters that can be seen from Cheekpoint. The combined waters of all three sisters are then visible all the way down the estuary from Cheekpoint on.
In ancient times, the area bounded by the Suir and the Barrow formed the Kingdom of Ossory. This name is retained today for dioceses in both the Roman Catholic Church and the Church of Ireland.
- South Eastern River Basin District Management System. Page 38 
- South Eastern River Basin District Management System. Page 38