The Gwathló
the Greyflood; the great river of the fens
Names
The Gwathló, the Greyflood, is the great river of the fens of the middle lands; in the wisest tongues ‘‘gwath’’ carried the sense of shadow and ‘‘lô’’ meant fenland, so that the name spoke of the “shadowy river from the fens”; in Adûnaic it was called Agathurush.
Geography
The Gwathló was made of the junction of the Mitheithel (Hoarwell) and the Bruinen (Loudwater), above the lands of the middle of Eriador, and ran down south-westward through the waste between the dark forests and the sea, past the ford and town of Tharbad.
History
In the Second Age the Númenóreans of the ships cut down the great forests along the Gwathló for their fleets, clearing the uplands of Minhiriath and Enedwaith; and the river remained for long the great way of those regions, and the crossing of the King’s road over its waters the gate between the North and the provinces of the South-kingdom.