The Shanganagh River is the largest watercourse system in Dún Laoghaire–Rathdown (in southern County Dublin).

[1]: 174–175 [2] The Three Rock Mountain source of the river begins as Bride's Glen Stream in the townland of Ballyedmonduff, with small inflows near Kilternan Abbey, and what may be a former millrace near the former Ballycorus Lead Mines complex.

[2] The northern Loughlinstown River forms from multiple streams, rising in an arc from Foxrock to Three Rock Mountain.

Forming between Ballyogan Grove and Glenamuck Road, the Carrickmines runs through the area of the same name, meeting a southern tributary as it enters Lehaunstown.

One branch of the Ballyogan Stream passes through the Fernhill Gardens public park, while tributaries come from Kilgobbin.