The Boyle River has its origins in the rivers Lung and Breedoge which flow into Lough Gara. The 29km (18mi) Lung River is fed by Urlaur Lough and Errit Lough on the Mayo/Roscommon border.
On the bridge at Knockvicar
The river flow from the furthest reaches of the Boyle catchment to Limerick city has a measurement of 290 km (180ml). When added to the Shannon's 97 km estuary this gives a total river flow of 387 km (240 ml), which makes it the longest river within the River Shannon basin (from source to mouth) - 26 km (16 ml) longer than the Shannon Pot source.
Lung River at Crunnaun Bridge near Ballaghadereen Co. Roscommon