MINNEAPOLIS (WCCO) — This year could be a record for latest ice-out on Lake Minnetonka. May 5th, 1857 is the latest date. The median date is April 13th. Every year, ice-out an important milestone for anglers, boaters and people who love a summer day on the water.

So, how is ice-out determined on Minnesota lakes? Good Question.

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Every day, a deputy from the Hennepin County Water Patrol heads out onto Lake Minnetonka.  On Monday, Deputy Alan Lang let WCCO ride along in an airboat that glides over the ice as he measured the ice thickness in Spring Park Bay. The air temperature was 80 degrees, but the ice was 15.5 inches thick.

“We had 23 inches last Wednesday,” Deputy Lang said. “We’ve lost quite a bit. It starts getting thinner at the shore, works its way to the middle and eventually the ice will be floating around.”

At that point, it’s at the mercy of the weather. Wind, rain and warmer temperatures mean ice-out can happen in days, or even hours.

The definition of ice-out on Lake Minnetonka is for the Hennepin County Water Patrol and Freshwater Society to be able to travel to any bay on any shore to every channel uninterrupted. That could mean a floating ice chunk or two, but nothing that obstructs a boat from getting by.

Once the Water Patrol knows ice-out is imminent, a representative from the Freshwater Society joins them on the water to make the official declaration. The Freshwater Society has been keeping track of the date since 1855.

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In 2017, the Minnesota Department of Natural Resources kept track of 614 Minnesota lakes. According to Assistant State Climatologist Pete Boulay, the information comes through Facebook, email, phone calls, letters, newspapers and the Minnesota Pollution Control Agency.

The Mille Lacs Messenger is the official tracker of ice-out on Lake Mille Lacs and uses information from satellite photos, resort owners and its reporters.

On White Bear Lake, local Jan Holtz Kraemer officially keeps track. She took over the duties from Ben Schmalzbauer, who had declared ice-out for 72 years.

Official ice-out on Lake Minnetonka doesn’t change how the Sheriff’s Office enforces the law. People are allowed on the lake before and after the ice-out. But, Sheriff Rich Stanek says having his deputies measure and monitor the water each day reminds everyone the ice is constantly moving and shifting.

“We want to check and make sure there aren’t any structures out there, people walking around or ATVs,” he said. “Plus it’s good practice and training for these airboats which are used year-round as well as getting to know people on the lake.”

Deputy Lang predicts this year’s Lake Minnetonka ice-out to be Sunday, May 6th, if the weather stays warm. But, he says that might won’t stop people from trying to get to the water before then. Last year, he stopped four or five kids trying to wake surf in the water while he was checking the ice.

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“They wanted to know why I was out and I wanted to know why they were out,” he says. “They all had dry suits. They were well-equipped but they wanted to be the first ones surfing on Lake Minnetonka.”

Heather Brown