After the cold snap the last couple of days - my guess is all that slush hardened up and started making more ice.
I went spud-checking at Cottage Grove on Muskegon Lake this afternoon. Spud-checking soon went to power auger testing. I didn't measure, but if I still had my quadrunner, I'd say it was plenty safe for that (at least 6+ inches of white and black combined). I'm not sure what conditions are like on the rest of the lake but I saw shanties off the Sand Docks (where I heard they got limits of perch today) and off Johnson's Point and Second Street.