Lake Michigan and Huron jumped a stunning 13.4 inches in April, the biggest April rise since record-keeping began in 1918, after rapid snowmelt teamed up with heavy rain. From Milwaukee down to Chicago, shoreline communities are eyeing bluffs, beaches, and basements for signs of erosion and flooding, even as overall lake levels sit near seasonal averages in early May.
Record jump documented by binational board
The International Joint Commission reported that the lakes rose 34 centimeters, about 13.4 inches, from the beginning of April to the beginning of May, the largest April increase in the 109-year record. The board said snowmelt runoff, combined with significant rainfall tracking directly over the basin, drove the spike, according to the International Joint Commission.
Heavy rain and fast snowmelt
Federal climate data show the Upper Midwest slogged through an exceptionally wet April, with roughly twice its normal precipitation that primed rivers and tributaries to funnel extra water into the lakes. That soggy stretch piled on top of lingering snowpack in parts of the basin, a one-two punch of rain on snow that amplified runoff, according to NOAA's National Centers for Environmental Information.
What officials are saying
Hydrologists in the Detroit District called the jump unusual. Keith Kompoltowicz, chief of hydraulics and hydrology for the U.S. Army Corps of Engineers' Detroit District, said, "The lakes are typically rising in the spring due to rainfall and snowmelt runoff, but obviously we hadn’t seen a rise of this magnitude." A Corps chart and reporting put Michigan–Huron at about 579.10 feet and Lake Superior at about 601.57 feet as of May 6, figures reported by Wisconsin Public Radio.
Milwaukee shoreline and storm response
In Milwaukee, heavy mid-April rains triggered sewer overflows and localized flooding that left some neighborhoods and roadways more vulnerable to higher lake levels. The Milwaukee Metropolitan Sewerage District told state regulators it logged overflow volumes after the April storms and says it is accelerating flood-management projects to protect neighborhoods and the lakefront. National coverage also documented flash flooding that swamped parts of Milwaukee's freeway network during the same storm system, according to Weather.com.
Outlook for the next months
Despite April's rapid climb, forecasters say the lakes started May close to their long-term seasonal averages and, barring another unusually wet stretch, are not expected to revisit the record highs of 2020. The International Joint Commission warned that much wetter weather could still push levels higher, but under near-average conditions Michigan–Huron is projected to rise only modestly over the coming weeks. The board also noted planned outflow adjustments on the St. Marys River to help manage risks, according to the International Joint Commission.
