Serni

The Serni was a short river of southern Gondor; it rose beneath the eastern White Mountains, and flowed southwestward through Lebennin until it met the River Gilrain at Linhir. Then it opened into a delta, joining the larger Ethir Anduin. That mouth was blocked with shingles, and ships that entered the Ethir Anduin preferred to enter it east of Tol Falas.
The river Serni was found in Lower Lebennin in the region of Central Gondor. As its name indicated, it was strewn with rocks. There were two fords, with the western one being south of the town of "Malbarth" and the eastern one south of "Ost Anglebed". The Serni was the domain of the stern River-maid Grey-eye, one of the Five Sisters, though she and her sisters were widely considered a myth by the time of the War of the Ring.