Ice season on Minnesota lakes is 2 weeks shorter than it was 50 years ago, and likely won't stop shrinking

PLYMOUTH, Minn. — The typical length of ice season on Minnesota lakes has dropped by 10 to 14 days over the past half-century, according to data released Friday, Dec. 10, by the state's environmental agency.

A new report from the Minnesota Pollution Control Agency shows lakes aren't freezing over as early as they used to, and the average freeze-over date is nine days later than it was in 1967. While the entire state is seeing lake ice seasons shorten, the decline is most significant lakes farther north in the state.

Data shows Lake Bemidji has seen its average ice season decline by nearly 19 days over the past half-century. Lower Hay Lake, about 20 miles north of Brainerd lost 15.1 days. Detroit Lake lost nine and a half days.

The data is largely provided by volunteers who log ice-in and ice-out dates, according to Assistant State Climatologist Pete Boulay, who says the shrinking ice season is a strong visual reminder of a warming climate and a sign that the state is experiencing fewer days of extreme cold than it did in the past.

Officials with the pollution control agency and the Department of Natural Resources say the trend driven by human-caused climate change could pose a threat to traditional cold-weather activities in the state.

"We've all seen dramatic footage of massive chunks of glaciers breaking off," MPCA Commissioner Katriana Kessler told reporters at a Friday news conference at an iced-over Medicine Lake in the western Twin Cities suburb of Plymouth. "In our own backyard, climate change is chipping away at the lake ice season."

Shorter ice seasons on lakes could mean negative economic impacts for Minnesota communities that depend on winter activities such as ice fishing, according to Minnesota Department of Natural Resources Commissioner Sarah Strommen, who said recreational fishing contributes more than $2 billion to the state's economy each year.

"We are already seeing the impact of climate on our Minnesota way of life, which includes our natural resources, our outdoor activities and our economy," she told reporters. "We all know Minnesota is the land of 10,000 lakes, the state of hockey, the state of fishing, and these unique qualities of our state's identity face an uncertain future because of warming temperatures and shorter ice seasons."

State officials did not provide an exact dollar amount for how much shorter ice seasons affect the tourism industry in the state, but Kessler said ice fishing generates a significant amount of tourism activity at a time that is typically slow for many communities.

Later freeze times have already been impacting fishing across the state said Woman Anglers of Minnesota President Michelle Morey.

"The 10-14 day reduction of ice can definitely be felt by our ice anglers especially now as the southern part of the state anxiously awaits our lakes to freeze," she said, adding that a shorter ice season can also have safety implications.

Anglers who bring ice houses or vehicles onto lakes may face thinner ice, and dangerous and slushy conditions often come earlier in the season. Morey said that's one reason her group is moving its in-person fishing tournament typically held in the first week of March one week earlier.

Rising water temperatures could also mean declines in native fish species, more opportunities for algae blooms, and increased growth of invasive aquatic plants such as Eurasian watermilfoil, according to the DNR.

"Warming waters are having negative impacts on Minnesota's state fish: the walleye," the DNR's Strommen said. Many lakes that were once managed for walleye no longer support conditions that are suitable for this species."

Follow Alex Derosier on Twitter @xanderosier or email aderosier@forumcomm.com .