|Location||Central Rohan, flowing past Edoras|
|Description||Boundary between East and Westfold|
The Snowbourn was a river in Rohan that originated beneath the Starkhorn in the northern White Mountains. Its course flowed north down Harrowdale past the courts of Edoras then, after a sharp bend, east to meet the Entwash among the grassy plains of Eastfold.
The deep valley above Edoras was called Harrowdale and between its walls the Snowbourn loudly rushed over stones. It was fed by a lesser stream from the west that had cascaded near a mountain path. After making its right turn just beyond Edoras it flowed twelve leagues to its confluence with the Entwash, which was in willow-thickets.
The Snowbourn served as the border between the Westfold and the Eastfold. It was also, in conjunction with the Entwash north of their confluence, the boundary between the military districts of the West-mark and East-mark.
After the Battle of the Hornburg, King Théoden and his riders took a mountain path that led down into Harrowdale. On 9 March T.A. 3019, they descended into the valley following a stream that finally joined the Snowbourn. The next day the Host of the Mark mustered in the fields beside the river and then followed the path of the river as it passed Underharrow and Upbourn. The Host camped in the willow-thickets where the Snowbourn met the Entwash. From there the riders continued on to Minas Tirith.
- J.R.R. Tolkien, "Unfinished index for The Lord of the Rings", in Wayne G. Hammond and Christina Scull (eds), The Lord of the Rings: A Reader's Companion, p. 538
- J.R.R. Tolkien, The Lord of the Rings, The Return of the King, "Map of Rohan, Gondor, and Mordor"
- J.R.R. Tolkien, The Lord of the Rings, The Return of the King, "The Muster of Rohan"
- J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "The Battles of the Fords of Isen", "Appendix (i)", footnote after East-mark in the first paragraph
- J.R.R. Tolkien, The Lord of the Rings, Appendix B, "The Great Years"
- J.R.R. Tolkien, "Nomenclature of The Lord of the Rings" in Wayne G. Hammond and Christina Scull (eds), The Lord of the Rings: A Reader's Companion, p. 776