For the first time in nearly half a century, the ice is out on Lake Minnetonka in May. But which day in May is still up for debate.

As snow fell Wednesday, the Hennepin County Sheriff’s Office declared the ice-out after a Water Patrol boat was able to navigate from Spring Park through several channels to Big Island at 4 a.m.

But the Freshwater Society, an Excelsior nonprofit that has tracked ice-out since 1857, wasn’t calling the much-anticipated milestone.

So who is right on the springtime ritual? Turns out, it’s not so easy to determine a universal ice-out definition in the Land of 10,000 Lakes. Everyone and every lake defines ice-out differently.

At the Department of Natural Resources, state climatologist Pete Boulay relies on the Freshwater Society’s declaration for Minnetonka and gathers data from lake residents, pilots flying overhead, even Facebook posts to determine lake ice-outs statewide.

“I think it’s important to a lot of people,” Boulay said of the data, adding that the DNR’s site on ice-outs is the second-most-viewed site this week, getting thousands of views each day. “It’s a sign of spring.”

But on Minnetonka, the state’s ninth-largest lake is more complicated than a lake with a single bay. Last year, the county declared ice-out March 20, a day before the Freshwater Society did.

“Clearly, we have different standards,” Freshwater Society spokesman Pat Sweeney said.

His group defines ice-out as a small boat’s ability to travel from one shoreline to another. The county has long had its Big Island tradition, spokeswoman Lisa Kiava said. And years ago, residents would put a car on the lake and declare ice-out when it fell through.

No matter what, a May ice-out is rare on Lake Minnetonka, which usually sees ice retreat in mid-April. This year marks the fifth May ice-out since 1857, when the lake had its latest ice-out of May 5, according to the Freshwater Society. Now, with anglers, boaters, sailboat racers and residents eager to get on the water, the Sheriff’s Office is issuing a warning about navigational buoys not being all in place. Boaters should wear life jackets because hypothermia can happen quickly in the low water temperatures.

To view up-to-date ice-out data for Minnesota lakes, go to