Why a waterfall? They look really cheesy unless you actually have the terrain that will make them look as though they are only one element in the landscape. Why not exploit the use of the deck and have a preformed barrel liner with a spillway that flows into the pool.
http://www.amazon.com/Products-BL15-S-Barrel-Liner-Spillway/dp/B001D27WH8/ref=pd_sim_dbs_ol_1
You could drop it right into the deck and then build a neat looking cover for a faucet that would sit by the barrel liner that you could turn on to cause water to fall into the pool or use for an outlet on a pump pulling water out of the bottom of the pool. All as an extension of the deck. This would make a more interesting statement for your yard.

i agree with t-man that waterfalls that suddenly pop up in the middle of a flat area look very strange. there is no way to make them look natural without first building some kind of rocky hill behind them. in your situation, he has an excellent suggestion for you.
min

Dig the Skippy down into the ground and have a short but wide waterfall.

I disagree with "pop-up" waterfalls looking strange, but I happen to have one and I like how it looks. Mine ain't even real rocks, it's the plastic top of a small fountain minus the base.

It's down in this post:
http://forums2.gardenweb.com/forums/load/ponds/msg0413425823292.html?1

It is not part of the filter system, it is just decorative. The barrel filter mentioned would be good for the filter system.

I describe what I do for my filter there too. Your pond ain't much bigger then mine is (but I'm still jealous!)

ernie- i can't get your photo. there were no matches to the url.
can you post the photo here? min