Important Facts About Ice
- New ice is usually stronger than old ice. Four inches of clear, newly formed ice may support one person on foot, while a foot or more of old, partially thawed ice may not.
- Ice seldom freezes uniformly. It may be a foot thick in one location and only an inch or two just a few feet away.
- Ice formed over flowing water and currents is often dangerous. This is especially true near streams, bridges and culverts. Also, the ice outside river bends is usually weaker due to the undermining effects of the faster current.
- The insulating effect of snow slows down the freezing process. The extra weight also reduces how much weight the ice sheet can support. Also, ice near shore can be weaker than ice that is farther out.
- Booming and cracking ice isn't necessarily dangerous. It only means that the ice is expanding and contracting as the temperature changes.
- Schools of fish or flocks of waterfowl can also adversely affect the relative safety of ice. The movement of fish can bring warm water up from the bottom of the lake. In the past, this has opened holes in the ice causing snowmobiles and cars to break through.
Recommended Minimum Ice Thickness
2" or less - STAY OFF
4" - Ice fishing or other activities on foot
5" - Snowmobile or ATV
8" - 12" - Car or small pickup
12" - 15" - Medium truck
Note: These guidelines are for new, clear solid ice.
Many factors other than thickness can cause ice to be unsafe.
White ice or "snow ice" is only about half as strong as new clear ice. Double the above thickness guidelines when traveling on white ice.
Safety Tips for Traveling on Ice
The following guidelines can help you make wise choices:
- Check for known thin ice areas with a local resort or bait shop. Test the thickness yourself using an ice chisel, ice auger or even a cordless 1/4 inch drill with a long bit.
- Refrain from driving on ice whenever possible. If you must drive a vehicle, be prepared to leave it in a hurry--keep windows down and have a simple emergency plan of action you have discussed with your passengers.
- Stay away from alcoholic beverages. Even "just a couple of beers" are enough to cause a careless error in judgment that could cost you your life. And contrary to common belief, alcohol actually makes you colder rather than warming you up.
- Don't "overdrive" your snowmobile's headlight. At even 30 miles per hour, it can take a much longer distance to stop on ice than your headlight shines. Many fatal snowmobile through-the-ice accidents occur because the machine was traveling too fast for the operator to stop when the headlamp illuminated the hole in the ice.
- Wear a life vest under your winter gear. Or wear one of the new flotation snowmobile suits. And it's a good idea to carry a pair of ice picks that may be homemade or purchased from most well stocked sporting goods stores that cater to winter anglers. It's amazing how difficult it can be to pull yourself back onto the surface of unbroken but wet and slippery ice while wearing a snowmobile suit weighted down with 60 lbs of water.The ice picks really help pulling yourself back onto solid ice. Caution: Do not wear a flotation device when traveling across the ice in an enclosed vehicle.
Content courtesy of Minnesota Department of Natural Resources
Photo courtesy of Michigan Department of Natural Resources