Increasingly larger storms, more frequent heavy rains and higher water levels — likely spurred by global climate change — are not only roiling the waters of Lake Superior but also damaging the big lake’s water quality.
That’s the analysis of a “white paper’’ report released Tuesday by researchers at Northland College’s Mary Griggs Burke Center for Freshwater Innovation in Ashland.
The problem is especially pronounced along the South Shore, where erodible clay soils are sloughing into the lake, increasing sedimentation and contributing to the first widespread algae blooms ever noticed in Lake Superior.
Scientists began paying closer attention to so-called super storms in the Northland after the 2012 flood event in Duluth, when nearly 10 inches of rain fell in one June storm. Similar “1,000-year’’ or “500-year” storms hit parts of the region again in 2016 and 2018.
Those rainstorms resulted in widespread urban flooding, blown-out bridges and culverts, sewer system overflows, agricultural runoff and more than $150 million in damages combined, the report noted.
And in the past three years, fall and spring windstorms have combined with near-record high Lake Superior water levels to cause millions of dollars of damage to shoreline infrastructure as well as constant flooding headaches for some shoreline residents that continue today.
“We weren’t even thinking about super storms and algal blooms in Lake Superior until a few years ago,” said Matt Hudson, associate director of the Burke Center, in releasing the report. “Since 2012, we’ve been served a new reality and a new set of challenges.”
The report is the result of a daylong summit at Northland College in September to discuss water quality concerns with the International Joint Commission, a bi-national organization charged with assessing water quality goals set out in the 1972 Great Lakes Water Quality Agreement between the U.S. and Canada. The Burke Center convened a mix of experts from city and tribal governments, state and federal agencies and academia to examine water quality issues along the south shore of Lake Superior.
“This new normal of extreme weather events is something we’re just starting to understand,” said Valerie Damstra, operations manager with the Burke Center, in a statement.
And among the more noteworthy developments in this storm-driven “new normal” is the appearance of potentially toxic blue-green algal blooms. Brenda Lafrancois, an aquatic ecologist for the Midwest Region of the National Park Service, reported that until 2012, the only reports of algal blooms in western Lake Superior were few and anecdotal.
The 2012 bloom spread along parts of the south shore of Lake Superior in Wisconsin during warm July weather and just a few weeks after the 500-year-storm in Duluth. Then in 2018, following the 1,000-year-storm near Ashland, another bloom stretched roughly 80 miles from Duluth to areas near Ashland.
For more information go to northland.edu/watersummit.