Enchanted Stream

[Gorthaur the Cruel]

Remember the Enchanted Stream in Mirkwood? Bombur fell into it and slept quite a long time due to the enchantment. My question is was it ever explained anywhere why it was enchanted and who caused it? I can't seem to find and reference about it.

Could it possibly be Thranduil (or his father)? Thranduil was of the Sindar who ruled the Silvan of Mirkwood. If he was Sindarin (with his father, former ruler of Mirkwood), then most likely a close associate of Thingol and Melian. And is it too far-fetched to suppose that Melian taught some enchantments to Thranduil (or his father)? After all, she did hallow Esgalduin, though the Girlde was the primary defense of Doriath. But the enchantment on the river seems too potent to cast even for a Sindarin elf. But what about Eol and his "enchantments" at Nan Elmoth? Or were those magicks already present before he took his abode there? I remember him casting some spell to snare Aredhel, a Calaquendi!
As said above, it's hard to associate Thranduil for the enchantment. Perhaps if he bore one of the Three Elven-rings... it could be possible. After all, Vilya allowed Elrond to enchant Bruinen, barring the Nazgul. The "sleep enchantment" could've been useful for Lorien, though, being nearest to Dol Guldor.

Other suspects would be Tom and Goldberry, as mentioned by other posters. Another aforementioned is Melian herself who probably travelled far and wide in Middle-Earth during the "Sleep of Yavanna."