The Farmington Hills Fire Department wants all residents to know that when it comes to judging whether a frozen pond or lake is safe, there really is no sure answer.
You can't judge the strength of ice just by its appearance, age, thickness, temperature or whether or not the ice is covered with snow. Strength is based on all of these factors, plus the depth of water under the ice, size of the water body, water chemistry and currents, the distribution of the load on the ice, and local climatic conditions.
Some Cold 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 formed by melted and refrozen snow appears milky, is porous, and is very weak.
- Ice seldom freezes uniformly. It may be a foot thick in one location and only an inch or two thick 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 on 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, and should be considered unsafe. Also, ice near the shore can be weaker than ice that is further out.
- Booming and cracking ice isn't necessarily dangerous. It only means that the ice is expanding and contracting as the temperature changes.
Checking Ice Thickness
Ice thickness should be checked prior to beginning any activity. If you have not done so, consider yourself in harm’s way. This can be done easily by using any of the following tools:
For new, clear, solid ice, the following general guidelines may be used:
2 inches or less - STAY OFF
4 inches - Ice fishing or other activities on foot
8 inches - Snowmobile or ATV
Never venture onto the ice alone or without telling your plans to a responsible adult.
Avoid crossing frozen bodies of water in a single file.
Look for large cracks or depressions in the ice.
Never drive a car or truck on the ice.
Avoid standing or walking in areas with a group of people.
Always wear a life jacket when on the frozen surface of a lake or river.
Learn and practice rescue techniques by using ropes, boats, ladders, etc.
Consider carrying a pair of ice picks. These are designed for a self rescue and are two handles with a nail device in one end attached to each other by a length of rope.
Remember - clear ice is the strongest.
Do not hesitate to call 9-1-1 immediately if you or someone else is in need of help.
Lieutenant Larry M. Gauthier is a fire and safety educator with the Farmington Hills (MI) Fire Department. Contact him at 248-871-2820 or LGauthier@fhgov.com.
Sources: Michigan DNR, Minnesota DNR, Haddams-Killingworth Patch