Unusual ice heave on Otter Tail County lakes, Minnesota

Ice damage on Otter Tail Lake mostly has been concentrated on the south shore of the lake, according to Dave Sethre, President of the Otter Tail County Coalition of Lake Associations

Ice is a normal part of winter along Minnesota's lakes. However, this year, some property owners on Otter Tail County lakes are dealing with more ice, and damage, than usual.

Dave Sethre, president of the Otter Tail County Coalition of Lake Associations, called the ice on one of the biggest lakes -- Otter Tail -- "pretty radical" this year.

"This is turning out to be the winter of the ice heave on many of our larger Otter Tail County lakes," Sethre wrote in a March newsletter. "Estimates are that expansion has been 150 to 200 percent at some locations."

According to the Minnesota Department of Natural Resources, ice heaves and ridges are caused by caused by the pushing action of a lake's ice sheet against the shore.

"This is especially true in years that the ice sheet lacks an insulating snow cover," the department added. When lake ice cracks for whatever reason, water rises into the cracks and freezes, gradually expanding the sheet.

Fluctuating temperatures can worsen this problem by causing additional expansion, the DNR said, which exerts a tremendous thrust against the shore. Alternate warming and cooling of the ice sheet leads to additional pushing action, causing the ice to creep shoreward and scrape, gouge, and push soil and rock into mounds (called "ice ridges").

Sethre said he has seen the most damage on Otter Tail Lake on the southern shore.

© Eric Hendrickx/FOCUS

Ice along the shore of Otter Tail Lake has been pushing up against the shoreline again this year. This picture, taken by the public lake access along State Highway 78 and across from the Pelican Bay Pier, shows a group of trees as no match for the heaped-up ice.

"I don't think it's because of high water," Sethre responded, when asked if he thought the summer's precipitation made for more problems this winter.

Instead, he said, the water level actually seems to be lower, based on outflow near the lake's weir.

"At times in the past, major ice breakers with mid-lake pushups have occurred to relieve the impact to shoreline areas," Sethre said. "Unfortunately, we have not seen this in recent years... with ice thickness about 24 inches now; there will be little hope for any stress relief to occur with a mid-lake ice breaker from here on to the end of the winter."

Ross Hagemeister, a professional fishing guide who is often on Otter Tail Lake, said he thinks the lake's shallow shoreline also contributes to the problem, acting as a sort of an ice ramp.

Hagemeister also agreed that the ice heave seems to be more dramatic in some areas this year.

While it isn't out of the ordinary to find heaves on the lake, he said, where about 10 feet of push-up might be average, it appears closer to 20 feet this year.

"The ice just needs somewhere to go," Hagemeister said,as the ice grows during warmer spells.

"But, I'm not a hydrologist," Hagemeister said. "It's just observation."