Celebrant (translated as Silverlode) was a stream rising in the eastern Misty Mountains from springs some way below the the Mirrormere in the Dimrill Dale. It then ran through Lothlórien where it was met by the Nimrodel river, and emptied into the Anduin.
In T.A. 2994, an army of orcs came up the Silverlode and wiped out the colony of Dwarves dwelling in Moria.
Around November T.A. 3018, Elladan and Elrohir, sent by Elrond to a secret errand, passed down the Silverlode into a "strange country" and were the last to return to Rivendell, in December.
The Fellowship of the Ring followed this river when they travelled from Moria to Lothlórien.