When I drilled a hole the water started running in like a flushed toilet.
See video: http://www.youtube.com/watch?v=Hs1PwCCRuLE
I have a 7 inch auger. After ~ 5hours of water flushing down the hole the holes were pushing 10 inches in diameter. The ice was ~28 inches thick but after 5 hours of water flushing down the hole in etched out a large cavity between layers of ice. I stuck my slush spoon down the hole and it appeared that there was about 8 inches of ice, about 12 inches of void/water, and then more ice. From what I could tell, the blue ice under all the white ice appears to be gone. I don't expect Cascade to be fishable much longer.
If you decide to go, be careful. I won't be going again until next winter.
BTW, I brought home about 15-17 keepers and flushed back a 12-14 inch trout and several perch under 12 inches. Found the active fish in about 15-17 FOW. I believe they are going to be spawning very soon.
Keep your gun powder dry and your fishing hooks wet....