We have a foot of ice on Lake Wausau, it is safe and getting safer with this cold snap. I've had my shack out there for almost 2 weeks. This last Sunday there were cars and trucks driving out.
As always, be safe. Check the local bait shop for conditions, and if you're not familiar with the area, go with someone who is, or at least go where the others are, and ask where there may be bad ice due to springs or a channel.