Thick Ice on Wisconsin Rivers Could Lead to Ice Jams This Spring

Mar 3, 2014

Milwaukee River upstream from Humboldt Avenue.
Credit Susan Bence

This year’s spring thaw, when it begins, could produce hazardous conditions on some waterways in Wisconsin - ice jams.

If warmer temperatures mix with strong rain, the combination could crack loose large slabs of ice. They could threaten everything nearby, according to Bill Sturdevant, a safety engineer and watershed expert with the Wisconsin DNR.

Ice buckling on the Milwaukee River.
Credit Susan Bence

He says when chunks of ice suddenly break apart, they can jam into each other as they move down the river and form a dam. The water behind then finds a way to get around the ice. Sturdevant says the water can climb up the banks, weaken bridges or carve out a deeper river bed, and in areas that are not flood plains.

Sturdevant says the threat of ice jams is greater than usual this year because our cold temperatures have created thick ice on rivers. Some areas of northern Wisconsin are reporting depths of 30 to 48 inches. He says the waterway that most frequently experiences ice jams is the Wisconsin River, near Portage.

Watershed scientists are monitoring state and local rivers.