Severe drought on Lake Superior’s western shores brought the big lake’s water level down in August, dropping below the normal seasonal average for the first time in more than seven years.
Lake Superior dropped 1.2 inches in August, when it goes up by about a half-inch on average, according to the International Lake Superior Board of Control.
That left the lake nearly a half-inch below normal Sept. 1 and 10.2 inches below the level at this time in 2020.
The last time Lake Superior was below normal was April 2014, said Charles Sidick, analyst for the U.S. Army Corps of Engineers in Detroit.
The seven-year high-water period, while not historically the longest since accurate records have been kept starting in 1918, saw some historic high-water marks. Lake Superior set monthly high-water records in July, August and September 2019, but fell just shy of the all-time high mark set in October 1985.
The recent streak of high water was also the root cause of millions of dollars in damage along the western tip of Lake Superior. The combination of high water during high-wind storm events caused erosion of clay banks on Wisconsin’s South Shore and of sand along Duluth’s Park Point. They also trashed Duluth's Brighton Beach and sent waves rising up to smash Duluth’s Lakewalk trails and flood Canal Park streets.
The summer drought in northern Minnesota saw some of Lake Superior’s tributaries dry to just a trickle, with some streams not running at all. The St. Louis River, the largest U.S. tributary to Lake Superior, was running last month at just 10% of its normal August flow.
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With the lake now down more than a foot since the highest levels in 2019, that’s billions of gallons less water across Lake Superior’s 31,700 square miles. Not only does the lake drop vertically, but the water’s edge pulls farther out from shore, creating noticeably wider beaches and offering more buffer when storms occur.
“More damage occurs during high-water periods, definitely,’’ Sidick said.
Sidick said that communities and residents along the lake should continue to take action to “build resilience” against the next round of high water, whenever that might occur.
“We will never be able to control the water levels to the extent that some people would like us to, so the answer is resilience,’’ Sidick said.
Forecasters say there’s little chance of another high-water period coming anytime soon. The six-month forecast for Lake Superior heading into winter is for near average water levels, said Deanna Apps, lead forecaster for the U.S. Army Corps of Engineers in Detroit.
The seven years of above-normal water levels came after an unusually long below-normal period that lasted from about 1998 to 2014, bottoming out with record monthly low water levels in fall 2007, when Great Lakes freighters were having a hard time accessing some ports, with some running at reduced capacity.
Lake Superior generally rises from April through August and then slowly drops from September to March.
Meanwhile, the Lakes Michigan-Huron watershed saw higher than normal rainfall in August and dropped less than its usual amount. The lakes now sit 17.7 inches above the long-term average for Sept. 1, but are 15.7 inches below the record-high level set Sept. 1, 2021.