September 2010 Minnesota-Wisconsin flood
|Date||September 23rd - October 9th|
|Location||Minnesota and Wisconsin|
September 2010 flash flooding in Minnesota and Wisconsin put towns underwater and forced evacuations in southern Minnesota and central Wisconsin. A strong system caused the heavy rain and flash flooding in the Upper Midwest.
Several waves of thunderstorms associated with a slow-moving warm front produced unusually heavy rainfall throughout the region beginning in the early afternoon of September 22 and continuing until the evening of September 23. Tropical moisture moving northward from remnants of tropical storm Georgette in the eastern Pacific and Hurricane Karl in the Gulf of Mexico contributed to heavy rainfall. The highest rainfall reported for the two-day period in Minnesota was 11.06 inches (281 mm), recorded by a volunteer observer near Winnebago in Faribault County. The highest official National Weather Service report was 10.68 inches (271 mm), observed at Amboy in Blue Earth County. Most locations in southern Minnesota reported more than 4 inches (100 mm), with numerous locations recording 6 inches (150 mm) or more. The areal extent of extreme rainfall was unusually large; more than 5,000 square miles (13,000 km2) in Minnesota received more than 6 inches (150 mm).
River stages and flooding
Soil moisture levels in the affected region were high prior to the storms, increasing runoff. Water levels in area rivers rose beginning on September 23rd and for several days thereafter, with some of the highest water levels occurring a week after the heavy rains. The Minnesota River crested at a record-high stage at Henderson, Minnesota, and near-record river stages were recorded on the Minnesota River at New Ulm, Mankato, St Peter, Jordan, Shakopee, and Savage. Records were also broken on the Cannon River and the Zumbro River in Minnesota and Yellow River at Babcock, Wisconsin, near-record flood crests were recorded on the Black, Trempealeau, and Wisconsin Rivers in Wisconsin. On September 29, the Mississippi River at St. Paul rose above flood stage, marking the first time since record-keeping began in 1893 that the river exceeded flood stage during the autumn months. River flooding in the region is typically associated with spring snowmelt.
Flooding forced evacuations in communities including New Richland, Owatonna, Pine Island, Zumbro Falls, Hammond, and Waseca, Minnesota, and Arcadia and Black River Falls, Wisconsin. Some major roads, including portions of Interstate 35 and roads in the southwestern Twin Cities metropolitan area, were closed due to high water levels on rivers. As floodwaters moved downstream, high water levels on the Wisconsin River closed some major roads in and around Stevens Point in central Wisconsin.
As of September 24, there had been no deaths or injuries from the flooding. However, the heavy rainfall and flooding caused significant adverse effects on crop production in the region by delaying fall harvesting and reducing crop yields. University of Minnesota Extension estimated that over 100,000 acres (400 km2) of the state's corn and soybean fields were covered by standing water for several hours or longer. In Wisconsin, the September rains and flooding contributed to a poor quality potato crop and the failure of a large fraction of the state's cabbage crop.
As of September 29, Wisconsin authorities reported that flooding had destroyed three homes and caused more than $4.6 million in damages to public infrastructure. A preliminary assessment of damages in Minnesota estimated their total cost as $64.1 million and identified 80 homes as having been destroyed. 
On October 13, 2010, the U.S. federal government declared the flooding to have been a "major disaster" in a 21-county region of Minnesota. Eight additional Minnesota counties were added to the disaster area declaration on October 19. Nine Wisconsin counties were included in a disaster declaration on October 21. These declarations made local governments and some nonprofit organizations in the affected region eligible for Federal Emergency Management Agency financial assistance to cover 75 percent of their costs for emergency work and repair or replacement of damaged facilities.
- Chris Dolce, Flooding Hits the Upper Midwest, Weather.com, September 26, 2010
- Heavy Rainfall - September 22-23, 2010, Minnesota Climatology Working Group, State Climatology Office, DNR Division of Ecological and Water Resources, University of Minnesota. Accessed February 12, 2011
- September 22-23, 2010: Significant Rainfall and Widespread Flooding Across Southern Minnesota and Wisconsin, National Weather Service Central Region Headquarters. Accessed February 12, 2011.
- Significant Flooding and Heavy Rain of September 22-23, 2010, National Weather Service Weather Forecast Office, LaCrosse, Wisconsin. Updated October 7, 2010. Accessed February 12, 2011.
- Significant Flooding in Central Wisconsin on September 23, 2010, National Weather Service Weather Forecast Office, Green Bay, Wisconsin. Updated October 5, 2010. Accessed February 12, 2011.
- Associated Press, Flooding Eases in Parts of Minnesota and Wisconsin, But Some Communities Still Struggle, September 25, 2010. Retrieved from FoxNews.com, February 12, 2011.
- Flooding Forces Evacuations, Road Closures in Southern Minnesota, September 23, 2010
- Karen Scullin, Flood Damage, Disruption in Southern Minnesota; I-35 closed, more flooding expected, FOX 9 News, September 24, 2010
- Moni Basu, Severe floods hit Midwest; areas downriver get ready, CNN, September 24, 2010
- Seth Naeve and Bruce Potter, Flood effects on Minnesota soybeans: 2010 edition, Minnesota Crop News, September 29, 2010
- Sara Schoenborn, 2010 a year of difficulty for Wisconsin fruits and vegetables, Agri-View, January 27, 2011
- Wisconsin reports $4.6 million in flood damage, LaCrosse Tribune, September 29, 2010
- Special Legislative Session Called To Address Flood Relief In Minnesota, GovMonitor, October 15, 2010
- Sarah Elmquist, Who to call if you need help after the September floods, Winona (Minnesota) Post, October 6, 2010
- Tim Nelson, Pawlenty declares state of emergency in flood zone, Minnesota Public Radio, September 23, 2010
- Governor Doyle Declares State of Emergency for Columbia County, NBC-15, September 27, 2010
- Mark Guarino, Swamped Midwestern towns prepare for more flooding, Christian Science Monitor, September 25, 2010
- President Declares Major Disaster For Minnesota, press release, Federal Emergency Management Agency, October 13, 2010
- Eight Additional Counties Now Eligible For Federal Aid, press release, Federal Emergency Management Agency, October 19, 2010
- President Declares Major Disaster For Wisconsin, press release, Federal Emergency Management Agency, October 21, 2010