On thin ice

Falls through Wisconsin’s ‘frozen’ lakes are becoming more common. There’s more than just warm weather to blame.

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When Alec Hembree fell through the ice on Lake Wingra last winter, he remembered, “it was instantaneous.”

It was just after dark on Jan. 20. The temperature was around 2 degrees. Hembree was riding his bike across the frozen lake from Madison’s east side to his west-side home, a commute he had tried successfully for the first time the previous week. When he fell in, his feet couldn’t touch the bottom. He barely had time to be scared.

“I think there were a couple people on the lake,” Hembree said. “They wouldn’t have been able to get to me before I got out.”

The air was so cold, Hembree’s leather gloves immediately froze to the icy surface of the lake when he tried to pull himself out. After about 30 seconds in the water, he was able to pull himself and his bike out. It all happened so fast, he wasn’t sure how he did it. He thinks his Eagle Scout training helped. 

“Everything was in an ice shell at that point,” he said. He biked 10 minutes to a co-worker’s house, where he used a hair dryer to thaw his jacket zipper and get out of his frozen clothes before his co-worker gave him a ride home.

Hembree’s experience is becoming more common on Wisconsin’s lakes. For some, falls prove deadly. The Department of Natural Resources last winter recorded five people statewide who died falling through the ice on off-highway vehicles across the state. Between 2020 and 2024, similar accidents accounted for a total of seven deaths.

According to the Madison Fire Department, the Lake Rescue Team was dispatched four times to rescue people who fell through the ice this past winter and six times the previous winter, though only once in 2023. The department has responded to 39 incidents of people falling through the ice since 2016. On Dec. 27, the department rescued another individual who had fallen through the ice on Lake Mendota.

But those are only the incidents where the Lake Rescue Team was dispatched, so the stories of Hembree and others who fell through the ice and managed to escape aren’t included.

“This (past) year has probably been one of the more dangerous years on ice that I can remember,” says Lt. Jacob Holsclaw, the Wisconsin DNR’s off-highway vehicle administrator.

Treading on Wisconsin’s frozen lakes has gotten more dangerous, creating cost for taxpayers and business owners and calling into question the future of an important state pastime.

A growing trend

Trekking on Dane County’s frozen lakes is a common winter activity for southern Wisconsin residents.

“Walking on frozen lakes” was the most common activity on the lakes among respondents to a 2010 Dane County Land & Water Resources Department survey. At 28%, that was more common than swimming, kayaking, boating, or fishing from a boat or pier. Other ice-related activities such as skating and fishing were more popular than water skiing, jet skiing and sailing. The study authors estimated that close to 110,000 Dane County residents — more than a fifth of the population — walked on the county’s frozen water bodies at least once in 2010.

The heavy usage of the frozen lakes provides a revenue stream for numerous Dane County businesses and nonprofits. For example, the Clean Lakes Alliance hosts the annual Frozen Assets Festival, in which hundreds of participants take part in a fundraising 5K on frozen Lake Mendota and others enjoy scientific demonstrations, ice skating, kiting, boating and other ice-related activities.

But the future of frozen recreation in Dane County is in peril. Madison winters are getting shorter and less predictable. And falls through the ice are becoming more common.

Ron Blumer, a Madison Fire Department division chief who heads the department’s Lake Rescue Team and has been with the city since 1995, says in recent years his team has conducted “a lot more responses” to calls to rescue people who fell through the ice.

Part of the uptick can be attributed to climate change and the shrinking number of days of 100% ice cover on the Yahara lakes. Since 1855, when the Wisconsin State Climatology Office began consistently tracking Lake Mendota’s freezing and thawing dates, the lake has stayed frozen for an average of 102 days every winter. But only in four of the last 25 years has Mendota been frozen that long. During the 2023-24 winter, the lake was frozen for 44 days — a more than 20-year low. Last winter it froze for 69 days.

There’s no ‘safe’ ice

While information about how thick ice should be for walking or driving varies between sources, there is some consensus: No ice is ever completely safe.

“We really shy away from saying that there’s ever any ice that’s 100% safe,” Holsclaw says. The DNR’s website offers no hard and fast rules for what’s considered a “safe” thickness.

“You cannot judge the strength of ice by one factor like its appearance, age, thickness, temperature or whether the ice is covered with snow,” the website reads. “Ice strength is based on a combination of several factors.”

Air temperature is just one of those factors. But others include wind, sunlight, whether the ice is near a spring or other moving water, and whether the ice is frozen water (black ice) or mixed with snow (white ice).

“Black ice can withstand a lot more force (than white ice),” says Adrianna Gorsky, a freshwater and marine sciences Ph.D. candidate at UW-Madison. “Even if you have really thick white ice, it might not be as strong as if you had black ice only.”

Fluctuations in temperature during winter can also have a marked effect on ice thickness and quality. In January and February of 2025, it wasn’t uncommon for temperatures to fluctuate by tens of degrees within a single week in Dane County. On Jan. 21, the day after Hembree fell through the ice, Madison temperatures were in the single digits. A week later, on Jan. 28, the high temperature was 49 degrees. This frequent melting and thawing back and forth, Gorsky says, could result in mixed layers of black and white ice that would compromise the ice’s structural integrity.

Variations in temperature can also make lake ice expand or contract, causing pressure heaves or large cracks to form in the surface of the ice.

“And there will be a gap in there where there’s thin ice or no ice at all,” says Jon Mast, a lieutenant on MFD’s Lake Rescue Team. These areas can be especially dangerous to walk near.

For as much that is known about factors affecting ice thickness and qualities, “there is a lot of unknown,” says Gorsky. That’s because winter limnology is relatively understudied compared to other areas of marine science.

“There’s a lot of things we still don’t know and a lot of theory that we’ve based off summer open water season that doesn’t really hold true for winter,” Gorsky says.

Increasingly visible effects of climate change on lake ice have precipitated “a cry for more research” in winter limnology, Gorsky adds. And it can’t come soon enough — falls through the ice are costing local businesses, nonprofits and taxpayers money.

The cost of thin ice

In Madison, there are no fines associated with being rescued from falling through the ice. Because, Blumer says, “we want people to enjoy the lakes and to have fun.” But that fun still comes at a cost.

Businesses and organizations that rely on the ice for income are feeling the strain of weakening lake ice too.

In 2024 the Clean Lakes Alliance canceled all on-ice events for its Frozen Assets Festival, including the annual 5K. According to Sarah Skwirut, the Clean Lakes Alliance’s marketing coordinator, only around 200 participants participated in the on-land “winter workout” the organization hosted in lieu of the 5K, down from 800 who ran the 5K the previous winter, which generated around $30,000 for the nonprofit.

“If the lack of ice becomes more common in the future,” Skwirut says in an email, “we will need to adapt and find new ways to engage the community and promote our work.”

Small businesses are equally if not more affected by the phenomenon. In 2022, Pat Hasburgh purchased D&S Bait and Tackle in Madison, “very aware of what I was getting myself into as far as climate change and running a business that kind of depends on ice,” Hasburgh says. He admits the recent, mercurial winters have made it difficult to plan for the ice fishing season.

“I mean, I had a pile of augers waist high in 2022,” Hasburgh says, noting that people are less likely to need such a high-powered tool to break through the ice in warmer winters. And 2024 was even worse.

“We had four weeks of ice, as opposed to three months,” he says. “That was a rough one to try to make it through as a business.” Hasburgh is used to around a third of his business coming from ice fishing, but guessed that it was probably less than a quarter in 2024.

Beyond Madison

The increase in falls through the ice is easier to see in a populous part of the state like Dane County. But the trend is apparent across Wisconsin. And in many cases, the cost is more than just lost business or an icy bike ride.

The five deaths this past winter happened in Pewaukee, Kenosha, Fond du Lac, Superior and Westfield, an hour north of Madison, where a man died on Jan. 6, after falling through the ice on Lawrence Lake while riding a UTV.

In a Facebook post, the Marquette County Sheriff’s Office urged the public “to avoid venturing onto frozen lakes or rivers unless they have confirmed the ice is thick enough for safe activities.” The temperature in Westfield on Jan. 6 was below freezing and had been every day the previous week.

An October 2024 study published in Nature Reviews Earth & Environment warned that lakes between 40 and 45 degrees north latitude — a range that includes all of Wisconsin south of Wausau — could lose all safe ice for the winter sometime this century.

A solution may lie in more research. Gorsky says predicting the future of what winter is going to look like for lakes “is a really big research topic.”

For Hembree’s part, he considers himself lucky to be alive. But he has “no concerns” about going back on the ice. He’s enjoying it while he still can: “If I do go out commuting on the lake again I will be, certainly, more cautious.” 

This story was produced in partnership with UW-Madison’s Investigative Journalism class taught in the School of Journalism and Mass Communication. Wisconsin Watch is a nonprofit, nonpartisan investigative news outlet.