We found the key to catching perch was being RIGHT on the bottom no matter the depth and using cutbait. Oh, and spring bobbers, look them up.
6" of ice near the dam
3-4" of clear ice near lava, but it's making a ton of creepy noises and will run big cracks every time you drill a hole
We didn't make it to hot springs, but hear 8" there, wow.
Near West Resort and the main body is still thin or open and way to scary to try yet.