Wildlife and weather officials are fond of quoting a rhyme when talking about ice conditions on Maine lakes and ponds: “Thick and blue, tried and true. Thin and crispy, way too risky.”

It’s a good rule of thumb, experts say. But when it comes to judging the safety of ice, outdoors enthusiasts should keep other factors in mind.

Day-to-day changes in the recent weather have resulted in dangerous ice conditions in some areas. Officials from the Maine Department of Inland Fisheries and Wildlife suggest that anglers, ice skaters, snowmobilers and boaters make sure the ice is solid before stepping, sliding or driving onto it.

According to the agency’s Web site, people should look for bluish ice that is at least 4 to 6 inches thick, in order to support people and their gear. Even if the weather has been below freezing for several days, don’t guess about ice thickness, they say.

Other tips include:

• Check ice in several places. Use an auger, chisel or ax to make a test hole, beginning at shore and continuing as you go out.

• If ice at the shoreline is cracked or squishy, stay off. Don’t go on the ice during thaws. Watch out for thin, clear or honeycomb-shaped ice. Dark snow and dark ice are other signs of weak spots.

• Choose small bodies of water. Rivers and lakes are prone to wind and wave action, which can break up ice quickly. Avoid areas with currents, around bridges and pressure ridges.

The American Pulpwood Association has published a hand reference chart that shows how much weight ice will support at various thicknesses.

This table is for clear, blue ice on lakes. Reduce the strength values by 15 percent for clear, blue river ice. Slush ice is only one-half the strength of blue ice. The table does not apply for parked loads.



Ice thickness: Permissible load

2 inches: One person on foot

3 inches: Group in single file

7.5 inches: Passenger car (2 tons gross)

8 inches: Light truck (2 tons gross)

10 inches: Truck (3 tons gross)

12 inches: 7 to 8 tons gross

15 inches: 10 tons gross

20 inches: 25 tons gross

25 inches: 45 tons gross

Source: The American Pulpwood Association