Mitheithel

The long river that rose in the icy north of Middle-earth, in the Misty Mountains about a hundred miles north of Rivendell. It flowed southwestwards through the lands that had once been held by the kingdom of Rhudaur, round the woodland region of the Trollshaws. Passing beneath the Last Bridge on the East-West Road, it flowed on into the south, until it met the Glanduin above Tharbad to form the River Gwathló (or Greyflood).

The river's Mannish name was Hoarwell, a free translation of the Elvish Mitheithel. The Elvish name for the river contains the components mith 'grey' and eithel 'spring, well'.