|Location||Central Rohan, flowing from Fangorn to Nindalf and Anduin|
The Entwash was a great river in Rohan, notable for its huge inland delta.
The sources of the Entwash were springs whose waters fell from Methedras, the southernmost peak of the Misty Mountains. Where they coalesced into one stream the collected waters flowed just south of Wellinghall, Treebeard's home. At its origin the Entwash was a noisy stream that cascaded over rocks and then hurried down the sloped terrain of Fangorn. From there the stream coursed eastward through Fangorn to the south-east corner of the forest.
Upon leaving the forest the river was still swift-flowing and its banks were deeply carven. Leaving the woods, the river flowed past the Wold of Rohan, and then headed south. As the river passed southward across Rohan its flow became more sluggish and the banks became fens. At some point it was traversed by the Entwade ford. At the latitude of Edoras it was joined by the river Snowbourn from the west; at their confluence great thickets of willows grew.
Turning east, the Entwash flowed towards Anduin, which it joined just south of the Falls of Rauros, in the huge inland delta known as the Mouths of Entwash. The splitting of the river marked the border of Rohan. The Mering Stream (or Glanhír) met the southernmost of the Entwash's arms there. The delta where the Entwash widened and joined the Anduin was a land of marshes that travelers were advised to avoid. The influx of water was so great that across the Anduin the marshes of Nindalf (Wetwang) arose.
In T.A. 2510, when the Steward Cirion granted the land of Calenardhon to Eorl the Young to be the realm of Rohan, the two leaders (along with the Prince of Dol Amroth and Éomund, the chief captain of the host of the Éothéod) defined the borders of their respective domains. The border ran along the Mering Stream from the Firien Wood to the southernmost arm of the Entwash, west up this waterway to the beginning of the delta, and then east along the northernmost arm of the Entwash to the Anduin.
After the Breaking of the Fellowship, Orcs carried Merry and Pippin to the point where this river exited Fangorn Forest, followed by Aragorn, Legolas, and Gimli. The Orcs were stopped just short of Fangorn by riders from Rohan. Merry and Pippin found the opportunity to escape and they followed the river into the woods, and taken by Treebeard the Ent west along the stream to his home. In the meantime the Three Hunters followed the tracks along the river and into the forest, where they met Gandalf the White.
When Éomer became King of Rohan he discarded the old offices of Second and Third Marshals of Rohan and instead created the positions of Marshal of the West-mark (the first of whom was Erkenbrand) and Marshal of the East-mark (the first of whom was Elfhelm).
Entwash was a translation of the Sindarin name Onodló, named for the Ents (Onodrim) of Fangorn Forest, but the origin of the name was largely forgotten by the Rohirrim. Onodló comes from Onod "Ent" and ló "stream".
Entwash is a modernization of Old English Entwaesc (waesc "flood water"), so modernised because it was recognisable by speakers of Westron. Gondorians used that name, assimilated to their own language.
- J.R.R. Tolkien, The Lord of the Rings, The Two Towers, "Treebeard"
- J.R.R. Tolkien, The Lord of the Rings, The Two Towers, "The Uruk-hai"
- J.R.R. Tolkien, The Lord of the Rings, The Two Towers, "The Riders of Rohan"
- J.R.R. Tolkien, The Lord of the Rings, The Return of the King, "The Muster of Rohan"
- J.R.R. Tolkien, The Lord of the Rings, The Fellowship of the Ring, "Farewell to Lórien"
- J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "The West of Middle-earth at the End of the Third Age" [map]
- J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "Cirion and Eorl and the Friendship of Gondor and Rohan"
- 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 West of Middle-earth at the End of the Third Age" [map]
- J.R.R. Tolkien, The Lord of the Rings, The Two Towers, "The White Rider"
- J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "The Battles of the Fords of Isen"
- J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "Cirion and Eorl and the Friendship of Gondor and Rohan", note 46
- J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, Index, entry "Enyd"
- Paul Strack, "S. Onodló loc.", Eldamo - An Elvish Lexicon (accessed 2 May 2019)
- 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, pp. 769-70