What's it like
The Powerhouse run on the Snoqualmie is a short class II run, followed by a class I section down to Fall City. Most people get out at the fishing access below the class II section. However, there is one nice wave formed as the river takes a bend against a cliff. It has eddies on both sides, but the eddy on river left is better.
The first wave is large and glassy. On the second wave it's possible to get some enders and pirouettes.
This wave only really forms from levels 2000 cfs to 2500 cfs.
How to get there
Drive across I-90 to Fall City, take the Preston/Fall City exit. Drive through Fall City, cross the bridge, and take the first available right turn down to Fish Hatchery Road. Follow the road to either the put in at the Powerhouse, or start from the takeout of the Powerhouse run at the fishing ramp. You must have a conservation license to park here, which costs $10 (and it's a big fine if you don't have one). The easiest access to this wave is by paddling down a couple of miles of class I water.
For park-n-play, you can drive to right above the drop on river left, by taking the road before the Fall City bridge. Run the drop and then carry back up to your car on the gravel bar. Make sure not to cross anyone's private property, though! (Otherwise, float on down to Fall City and get out there).
Canoeists, inner tubers. Do not under any circumstances leave anything valuable in your car at either put-in, as this is a well known local hunting ground for thieves.