I took it for the debuff. Could go well with your carrion creeper.
@Turbo_Starr
I have never even cared about the damage, but it does move around all over the place, and the damage is spread across its lifespan, which is pretty long. So, you probably aren't really leveraging or even seeing most of its damage potential.
I took it just because it looks so cool.
Lewis
Random AT Generation!
"I remember... the Alamo." -- Pee-wee Herman
"Oh don't worry. I always leave things to the last moment." -- The Doctor
"Telescopes are time machines." -- Carl Sagan
It's pretty much DoT damage that can lose some of its oomph as it tries to catch mobs.
A nice AoE Immob or Hold will take care of that though (or even a good AoE Slow or KD patch.
Apparently, I play "City of Shakespeare"
*Arc #95278-Gathering the Four Winds -3 step arc; challenging - 5 Ratings/3 Stars (still working out the kinks)
*Arc #177826-Lights, Camera, Scream! - 3 step arc, camp horror; try out in 1st person POV - 35 Ratings/4 Stars
Water Spout *does* do a lot of damage - but it delivers that damage in a DoT over its entire lifetime. And since it hurls things around and tends to switch targets a lot, it usually doesn't deliver that entire load of damage to any one target. In normal situations, it's not going to be an AoE damage dealer. However, you do have ways to leverage it - your AoE immob stops knockback for about 10 seconds after you use it, and also prevents the mobs from running away. If you use seeds of confusion to make the mobs clump up, immob them all in place, and *then* cast water spout it'll actually get a chance to hit more than one target, and do so for a while. Just make sure to keep casting roots to keep the -KB in effect. It'll still take a while to do the whole damage, but it *will* do it.
The other big use for water spout, imo, is on tough bosses or EBs. EBs are generally immune to knockback and fear (and bosses can be held/immob'd to render them stationary), so as long as you've cleared out the riff-raff water spout will grind on the boss/EB for the whole duration, doing a good amount of damage and debuffing their defense to boot. That's what I use it for most often on my ice/ice, since I already have a couple of decent AoEs from my secondary.
@MuonNeutrino
Student, Gamer, Altaholic, and future Astronomer.
This is what it means to be a tank!
Correct me if I am wrong (I don't have a Dominator with Water Spout) but wasn't it changed to a Knockup?
Favorite Hero: Computer (Empathy/Energy Blast Defender)
Favorite Villain: Gimp Computer (Fire Control/Psionic Assault Dominator)
Yes. Water spout flings the baddies in the air. At least I think so. I usually have my foes locked down with Fire Cages, but occasionally, someone is still alive after the 10 seconds of -knock from Fire Cages, and I seem to recall they go up. But its rare, so I'm not 100% sure. I usually have killed them all before that. 
Lewis
Random AT Generation!
"I remember... the Alamo." -- Pee-wee Herman
"Oh don't worry. I always leave things to the last moment." -- The Doctor
"Telescopes are time machines." -- Carl Sagan
It is knockup.
I took water spout and have been using it awhile, Mids says it does something like 250 damage... It doesn't seem to be doing much to me, definitely nothing like that... If mids is wrong, is it worth it? I really hate the fear portion, and mainly took it for more area damage on my plant/energy