A “200-year storm” along a narrow band from northern Minnesota into Northwestern Wisconsin brought flooding to parts of Aitkin, Pine, Carlton and Douglas counties Monday.
“Carlton County is experiencing a significant rain event,” Sheriff Kelly Lake said in a news release. “There is flooding in the southeastern part of the county. … Sheriff’s deputies and county road crews are assessing damage and closing roads when they find hazards.”
Steve Gohde, hydrologist with the National Weather Service in Duluth, said radar indicated rainfall totals of between 5-6 inches within six hours from the northeastern corner of Mille Lacs Lake to the Pattison Ridge area of Douglas County. It was the intensity of the rainfall that made it a 200-year storm along that line, he said.
The most rain recorded in a gauge was 5.07 inches in Moose Lake, followed by 5 inches at Kettle River, 4.7 inches near Solon Springs and 4.3 inches near Holyoke.
The headwaters of the Nemadji River near Pleasant Valley “staged a very dramatic rise,” Gohde said, from 6.4 feet to 17.1 feet in a short amount of time.
The river was expected to crest in Superior on Tuesday morning and remain high throughout the day, Gohde said, but isn’t expected to have a significant impact.
Culverts and other infrastructure are designed to survive a 50- to 100-year storm, Gohde said, so problems were expected in areas that received the heaviest rainfall.
“We rearranged a lot of gravel and tested a lot of sump pumps today,” he said.
Flood warnings remained in effect in Carlton, southern Aitkin and northern Pine counties as well as along the Nemadji River basin, Gohde said.
He urged motorists to heed signs warning that roads are closed, even more so at night when drivers won’t be able to see if water is over the road.
Strong to severe storms are possible Monday night, he said, but will be isolated and should move through quickly.