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News
By Vicki Browne
Iron County Lakes and Streams Partnership
For the last month on Chicaugon Lake, we have heard gurgly digestive moans as well as pops and cracks that signal changes in ice conditions. Each warm day produces a bit of shore lead (opening between the shore and the ice) in several places that close as the nighttime temperatures dip below freezing. The lack of snow cover, combined with stretches of unseasonably warm temperatures, may mean we can expect early ice out in Iron County.
John Downing, director of the Minnesota Sea Grant, hosted a webinar on Friday, March 8 to discuss both this year’s predictions for ice out on Minnesota lakes as well as the radically different winter conditions between 2022–23 and 2023–24.
Downing and his colleagues at the University of Minnesota-Duluth have created an ‘ice-out clock’ that uses various parameters to predict when ice will be off lakes (z.umn.edu/mnsg-mnlakes-iceoutclock).
“Decades of historic climate data and ice-out dates for hundreds of lakes across the state were statistically analyzed to come up with an equation that ‘fits the data’,” reads the ice-out clock’s website. “This equation is used to predict this year’s ice-out based on the current winter’s climate data.”
Michigan does not have a predictive tool like this; however, Iron County’s proximity to both Lake Superior and Minnesota mean their findings can inform our estimates. Downing mentioned several times that latitude is one of the important factors for predicting ice out because of the position of the sun. Iron County’s latitude is approximately 46.27ºN. This puts it roughly in line with Brainerd, Minnesota where the latitude is 46.35ºN.
Another factor is lake size. Downing says that for every power of 10 increase in lake acreage, two days are added to the ice-out prediction. Downing’s calendar predicts ice out in Brainerd on March 25 for 100-acre lakes and March 27 for 1000-acre lakes. If these estimates hold, it’s not too early to tune up the boat and get back into swimsuit shape!
The comparison to winter 2022–23 is stunning. Snowfall totals last winter were between 53.4 inches and 88.5” in Iron County. To date, the website ‘Fun in the UP’ lists the snow total for Stambaugh as 22.4 inches. At this time last year there was snow on the ground and 17 more snow events to come including a heavy snowstorm from March 31–April 1. During the webinar, Downing showed a map where most of Minnesota is currently in ‘mud season’ — no snow on the ground and thawing that creates muddy conditions on unpaved roads.
Downing described 2023–24 as a “curveball year.”It was less cold, had almost no snow and more early warming. Lake ice was thin and “warm.” He cautioned those who like to fish and recreate on lake ice to stay off because the quality of the ice is deteriorating and conditions make it unsafe.
Downing talked about the upsides of early ice out:
• A longer summer is good for tourism, hospitality industries, sporting goods retailers and boating/fishing license revenues.
• Early open water means lakes can mix, reoxygenating the water for fish.
• ‘Short’ ice tends to produce less ice scour and bottom freezing.
• Deeper lakes experience stronger summer stratification — separation into three distinct layers with a warmer top, a middle layer where the temperature drops steeply, and a cold bottom. This is important for anglers because many fish thrive in that middle layer.
On the downside:
• Aquatic invasive species which outcompete native species, and are better equipped to capitalize on early opportunities, will be more plentiful.
• Waters that will be up to 10 degrees warmer as the summer season progresses can generate more algae growth and potentially more harmful blooms of cyanobacteria later in the season.
• Aquatic species (zooplankton, macroinvertebrates, fish) may be out of sync with their sources of food. Downing specifically mentioned concerns about walleye spawning early and their larvae not finding available zooplankton.
• The longer there is open water, the more likely lake levels will be affected by evaporation.
On March 10, a driving tour showed:
• Lake Antoine in Dickinson County (748 acres and max depth 40 feet) was open.
• Wildwood Lake off US2 (98 acres and max depth 17 feet) showed a band of open water.
• Indian Lake near Camp Batawagama (196 acres and max depth 36 feet) was still iced up but had a crack from shore to shore.
With predictions for ice out just around the corner, 2024 will definitely be a year for the record books!