Parts of southern Minnesota, Wisconsin and northern Iowa are at risk of rare winter floods as the Mississippi River runs faster and higher than it ever has this early in the year.
The U.S. Army Corps of Engineers has told cities along the river from Winona, Minn., to Guttenberg, Iowa, to monitor and brace for potential flooding in the weeks and months ahead, an unusual concern for late January.
“We’re seeing flows we might normally see in late spring,” said Dan Fasching, Upper Mississippi River water manager for the Corps’ St. Paul District. “And it doesn’t seem to be wanting to slow down.”
Much of the precipitation that made 2019 the wettest year in Minnesota’s history is still emptying out through the river, Fasching said. All that water has caused the river to rush about three times its normal strength in southern Minnesota, roaring at a record-high rate of 43,000 cubic feet of water per second. The typical river flow for January is about 15,000 cubic feet per second, Fasching said.
Fluctuating temperatures have compounded the problem, preventing the upper Mississippi from forming a solid, thick layer of ice. As temperatures have bounced above and below freezing, chunks of ice break off and get carried away by the water’s high flow.
That ice is eventually pushed into a bend, high point or pinch of the river, where it gets stuck and packed into place. The ice builds up there until it starts to act like a dam, pooling the water until it floods over the banks.
“It’s at the point now where we are just below the cusp of where we would get concerned,” Fasching said.
Two pools of the river that are particularly at risk of flooding are near Winona and near Clayton County, Iowa, Fasching said.
In Winona, the river has started to bleed over into some back areas, City Manager Steve Sarvi said.
“We’re certainly keeping our eye on it,” Sarvi said. “Hopefully this dry spell will continue and the river will get a little lower. But if it doesn’t, our pumps and our operators are ready to go.”
Farther to the north in Champlin and Anoka, ice jams caused the river to crest, briefly closing city parks and walkways this month. As a precaution, Champlin city officials made sandbags available to residents on Jan. 14, but they weren’t needed, said City Administrator Bret Heitkamp.
The record-setting volume of water that has been flowing in the Mississippi River over the last 13 months can be hard to comprehend.
In 2019, a total of 77 million acre feet of water passed through Lock and Dam 10 — the St. Paul District’s southernmost point on the Mississippi River. That shattered the previous record of just 59 million acre feet, which had stood since 1993, Fasching said.
The difference between those two years — 18 million acre feet of water — is enough to fill all 207 square miles of Lake Mille Lacs six and a half times over, he said.
The conditions could make for a particularly bad spring flooding season.
“If we add that new snowmelt on top of what we’re still trying to get rid of from this winter, and if you put these ice jams in there, it could be a very unpredictable spring,” Fasching said.
While the current conditions are ominous, the severity of any spring flooding will mostly depend on how much snow comes down between now and April and how quickly the snowpack melts, said Chris O’Brien, meteorologist for the National Weather Service.
“That’s the part we don’t know yet,” O’Brien said. “But right now everything is running high, and we’ve got a decent snowpack with a good amount of water in it. It’s definitely a year to keep a close eye on things.”