No deaths have been reported on Minnesota lakes and rivers so far this winter, but authorities have responded to several close calls and are urging people to stay off lakes and rivers that have been kept from fully freezing by atypically warm weather.

Many Twin Cities lakes and rivers still have open water, according to the DNR’s tracking of “ice-in” dates, when a lake is frozen over. Lake Minnetonka almost beat its record for latest ice-in, with the Freshwater Society declaring it frozen over on Dec. 31, just shy of the latest ice-in date of Jan. 2, recorded in 2002. It usually freezes over by Dec. 7.

The lake made history when the dam that controls water flowing into Minnehaha Creek closed Dec. 21 — the latest it’s ever operated in its 36 years, because 2015’s heavy rain and warm weather kept lake levels so high.

Now, with warmer-than-normal conditions starting 2016, DNR climatologist Pete Boulay said, those lakes aren’t likely to freeze over soon.

It isn’t safe to walk on ice, the DNR says, unless there’s at least 4 inches of ice.

“The ice is never 100 percent safe,” Lt. Jackie Glaser said.

The DNR recommends people wear a life jacket and bring ice picks when ice fishing or walking on frozen waterways. Last winter, five people died after falling through ice.

Authorities have responded to a few close calls. Last Tuesday, a snowmobiler fell through thin ice in Hennepin County before first responders rescued him.

On Dec. 24, an iceboat broke through Lake Minnetonka’s West Arm Bay, sending the boater into frigid water before he pulled himself onto ice and was rescued. In mid-December, about 50 people were rescued on Upper Red Lake in Beltrami County after the ice they were standing on broke loose from shore.

KELLY SMITH