River Loudwater

Note that the positioning of the river Greyflood here is open to debate¹

The Mannish name for the river the Elves called Bruinen, named for the loudness of its running waters. Its sources were in the western Misty Mountains near the High Pass, and from there it ran southwestwards, forming the deep ravine where Rivendell was built, and from which that refuge took its name. Beneath Rivendell, the Loudwater could be crossed at the Ford of Bruinen, and from there it flowed on for some hundred and fifty miles until it met the Hoarwell, and the two rivers combined to create the Greyflood that ran out to the Sea at Lond Daer.

Historically, the Loudwater was a border river, marking the eastern extent of the Mannish lands of Eriador beyond which lived the Elves of Rivendell and Hollin. In the Third Age, it formed part of the eastern boundary of Arnor, and after the break-up of that land, it bordered the realm of Rhudaur. It was also important in the history of the Hobbits: after the Stoors came over the Misty Mountains into Eriador, they followed the river southwards. Many settled in the narrow Angle of land it formed with the Hoarwell, and further south still, though many of these settlers later moved back northwards.