Once a lake loses its ice, spring can begin (or, sometimes, summer)

Each year, Minnesotans have 11,842 opportunities to proclaim "ice-out" on the state's official lakes, marking the moment when water again laps the shore, reflects the sun and welcomes swimmers.

People have been keeping records for years, as if we can't help our desire to compare, which leads to theorizing. Also, occasionally, betting.

"It's just an interesting realm of citizen science," said Steve Woods, executive director of the Freshwater Society in Excelsior, which for decades has marked ice-out dates on Lake Minnetonka.

Society founder Dick Gray, who died last year, had compiled the lake's ice-out dates for years from his own observations, as well as pioneer records and old diaries.

Yet there is no single definition for an open lake.

During the first half of the past century, a common measure was when a junker car parked on the ice sank from view, often with some raffle winnings on the line. Eventually, more environmentally wise heads prevailed.

Today, some watchers make the call only when a lake is 90 percent ice-free; others settle for 80 percent.

To ease confusion, the county and the society now make the determination together.

"What we're looking for is that you're able to get into all the bays of the lake by boat," Woods said. Minnetonka, with an estimated 125 miles of shoreline, has 37 numbered bays. While you might expect the more windswept main lake to open first, small bays often lead the way if they're fed by creeks, Woods said.

Last year, though, a strong south wind drove the last of the ice into tiny Tanager Bay, which then remained iced-in until April 24.

On most lakes, ice-out dates are less about saying goodbye to winter than saying hello to walleyes, even though last year's deep cold held the ice on many northern lakes long past the fishing opener on May 10.

The governor caught a break, fishing at the relatively clement Gull Lake near Brainerd. This year, however, the guv's party will fish at Lake Vermilion on the Canadian border, currently reported as "ice-covered." (You can check conditions on several webcams via www.lakevermilionresorts.com/webcams.)

You can also monitor the progression of open lakes on the DNR's ice-out map by visiting www.dnr.state.mn.us/ice_out/index.html.

Several lakes in southwestern Minnesota are open, and Lake Minnetonka's ice is starting to break up from the west, Woods said. Once the breakup starts, the ice can go fast.

"This year, we'll be lucky to make it into April at all."