Lengths obtained from the
Ordnance Survey of Ireland:
Rivers and their Catchment Basins 1958 (Table of Reference), and for the rivers Bann and Erne –
Notes on River Basins by Robert A. Williams
TABLE 1 a • The length of the
River Shannon from the
Shannon Pot to
Limerick City is 11 km (7 mi) longer than the
Shannon Pot source. • The River Shannon's overall length (to Loop Head), using the
Boyle River's furthest source, is , making the
Boyle-Shannon river the
longest natural stream flow (source to sea) in Ireland, 31.6 km (19.5 mi) longer than the
Shannon Pot source. • The
River Shannon is a traditional freshwater river for just about 45% of its total length. Excluding the tidal estuary from its total length of , if one also excludes the lakes (
L. Derg ,
L. Ree ,
L. Allen plus
L. Boderg,
L. Bofin,
L. Forbes,
L. Corry) from the Shannon's freshwater flow of , the Shannon as a freshwater river is only about long.
b • The total basin area of the
Three Sisters (Barrow, Nore and Suir) is 9,207 km2.
c • The traditional length given for the
River Bann is 80 miles (129 km) which is the combined total length of Upper and Lower Bann rivers and doesn't include Lough Neagh. • The total length of the
Ulster Blackwater from its source to the sea via
L. Neagh and the
Lower Bann is 186.3 km (115.75 mi), surpassed, in Ireland, only by the
Shannon and
Barrow rivers. This is the longest stream flow (source to sea) in
Ulster.
d • The total basin area of the 6 km
River Corrib is 3,138 km2 This is the longest stream flow (source to sea) within the
Corrib Basin. == Largest Irish Rivers (by flow) ==