J. Gregory Keyes, The Waterborn

[ellarien]

Interesting and unusual fantasy in a pantheistic world, where every wood and stone has its own god -- except in the areas where people have driven them out. The greatest god of all is the River, but a rash young hero, in love with a tributary stream-goddess, sets out to kill him anyway. Along the way, he learns a lot about the nature of heroism (which isn't all it's cracked up to be) and friendship. Far away, a lonely young princess strives to find out what happened to a beloved cousin, and may one day happen to her, but it is her almost involuntary wish that tangles her fate with that of the journeying hero.

I enjoyed this a lot, under the impression it was a standalone. It could stand as one, but in fact there's a sequel, The Blackgod, and it's even still in print, so I promptly ordered it.