It's for an Erudite quest where you get a poison and hand it to the "River Source" in order to poison the kobolds' water supply. Check the quest listings for the Warrens and you'll find it. As I recall, the result is sorely outdated and there's no real reason to try the quest any longer.
actually, there is, faction boost is huge. also, for anyone heavily into lore, having the Leggings--think that's the reward--is neat as they're Ridosan's.
but you are correct in thatthey're woefully outdated.