Respect the ice: Here are signs that ice might not be safe

Hear this loud and clear: Heading out on a frozen lake or river to walk, skate, ski, snowshoe or fish is a risky venture. Ice is unpredictable and never 100 percent safe, especially during a winter like this one when the thermometer seems to have spent as much time above the freezing mark as it has below.

The Minnesota Department of Natural Resources (DNR) recommends a minimum ice depth of 4 inches before anybody steps on a frozen body of water and twice that depth when ice is old, has a white or gray tint or has partly thawed.

While most of us don't carry around drills and tape measures to check ice depths, experts do have some tips to help us spot good ice or know when it's best to remain a landlubber.

You can't judge the strength of ice simply by its appearance, but it's a good place to start, says Rick Slatten, captain of the St. Louis County Rescue Squad. Ice that is thick and blue is likely tried and true, but if it is thin and crispy, it's way too risky. Ice with a "dirty, cloudy look" (black or having a gray tinge) doesn't hold a load as well as clear ice. White ice is more porous due to air pockets and thus weaker. Good ice will "burp, squeak, groan and talk before it breaks. Rotten ice will fail without notice," Slatten said.

Cracks and fissures indicate weakening ice, Slatten said. Ice can lose 40 percent of its strength along a single crack. Ice in areas where two cracks intersect can lose up to 75 percent. Other indicators that it's time get off the ice or stay off in the first place: Appearance of pressure ridges, water at or near the edges of cracks and areas that are snow covered. Snow insulates and inhibits ice formation and masks the ice. "You can't tell if it's 2, 12 or 14 inches thick," said Hennepin County Sheriff Rich Stanek.

Oh yeah, obey those "Thin Ice" signs. "They are not lying," said Cmdr. Kelly McCarthy of the Lino Lakes Police Department.

Ice conditions change daily and from place to place says Dave Bergstrom, parks operations manager with the Minneapolis Park and Recreation Board, meaning ice may be thick in one spot and weak just few feet away. He recommends taking a stick and tapping the ice as you walk along. "A hollow or dull sound" means potential problems, he said. Slush on top may indicate ice is rotting below the surface. The DNR says to check the ice at least every 150 feet.

When on foot, travel in areas used by others, Slatten advises. And return to your starting point by retracing your steps instead of straying into unknown areas, he said.

Don't go on the ice alone. Even professionals take somebody with them, just in case. "We never do ice checks alone," Bergstrom said. "There is a sense of security knowing that somebody has your back."

Slatten said to tell a friend or family member when you plan to be off the ice. "Give them a panic time. If they don't hear from me at that time, it means I'm in trouble and call 911." If off-ice time is 5 p.m., the friend or family member should call for help at 5:01 p.m., he said. "That puts the onus on me to get to the phone."

Bait shop owners and ice fishermen usually are up to speed on ice conditions, so ask them. That's what organizers of the Minneapolis Loppet did when making the call on whether to hold their speed­skating races on Lake Calhoun. They used holes drilled by ice fishermen to check ice depths and determined conditions were favorable for the race.

Be prepared and follow your instincts. Slatten strongly recommends having ice picks at the ready to pull yourself out of trouble should the unthinkable happen. He also advises ice trekkers to dress in layers of polypropylene, polar fleece and outer windbreaker.

Bergstrom might have the best advice of all: If your gut tells you it's not safe, then don't go out. "A lot of it comes down to common sense," he said. "Respect the ice."

Tim Harlow • 612-673-7768