Not really a fishing question, but y'all are going out on ice already so this would be the best place to find out. What's been the ice thickness of the lakes you've been on? Only asking because with the extreme cold we've had and the pending "warmup" I've been trying to get some guys together to play some pickup pond hockey on a retention pond behind my apartment. Schaumburg puts flags out by pretty much all their ponds indicating whether ice is safe or not to trek onto, but after 3 years of living here I've yet to ever see a green flag. Come to find out, they don't ever put them up anymore and leave the red flags up as a "go out at your own risk" and liability reasons.
The pond is no more than a few feet deep and I wouldn't be shocked if it's iced through by now (zero indication of gilled life leads me to believe this is true). But my sheer lack of ice knowledge doesn't know if anything under 6" is safe for 6 to 10 guys to skate (and probably fall) on.
Lets Go Sharks!