The groaning and cracking of ice does not necessarily mean that the lake is unsafe. As the temperature changes, there are tremendous forces at work on the massive ice sheet. The forces exhibited by lake ice are similar to those acting on the earth's crust. A sheet of ice can develop fault lines, and sudden shifts along these faults can cause the separated sheets to collide, pushing upwards, creating pressure ridges. These areas can be dangerous, particularly to vehicle traffic as they can cause injuries if someone were to collide with them. The potentially weakened ice underneath these ridges may also cause someone to break through and plunge into frigid waters of the lake below. Shifting ice can also push up along shorelines and form large, leaning ice heaves and potentially hazardous conditions. Parents should be careful that children do not play on or around these dangerous ice formations.

- Greg Spoden, DNR Division of Waters; Kim Elverum, DNR boat and water safety