I can kill two birds with one stone. The St Croix River which seems to have an avg depth of around 70 feet on most of the maps I look at freezes over most of the time so well it has been known to be used as a shortcut for many drivers trying to save time and not use the bridges located about 10 miles apart in one area (Hudson WS and Stillwater MN)
Where the St Croix River feeds into the Mississippi I have driven on it many times and put up ice houses. We've slept on it many night too which is scary because you can hear the ice periodically let out low distant rumbles and hear the ice crack and heave.
I was with my buddy one day when he was jigging with a minnow head off the bottom for walleye and pulled up a few small catfiish about two hours before sundown. So it was not a fluke.
I did see a picture in the paper of a guy about 15 miles down from where the St Croix feeds into the Mississippi with a monster flathead in the month of February. I believe it weighed around 70 pounds. But it is narrow faster moving open water there (never freezes) and he was in a boat.
So some rivers freeze good and others not so good and yes cats can be caught through the ice. The best ice thickness I think I can remember on the St Croix River was around 18" or tad more. Some years it never freezes over very well and no one drives on it. This year was looking good but then it warmed up.
Oh and the St Croix River is approx half a mile wide where I drive on it.
Here's a pic taken April 05 I believe. It's probably one of the 1st barges to come up river in spring time. I have taken a canoe in the spring and paddled up the St Croix River in the barge channels they cut thru the ice. The ice bergs are always good for a few gag pic of guys setting up tables and chairs and playing cards. I don't have any pics of that but every few years some idiots do it to get in the paper.