Record Low Waters Possible on Great Lakes this Summer

MADISON , Wis. ( 2/20/03 )—Unusually low water levels in the Great Lakes for this time of year may combine with lingering El Nino conditions to yield the lowest summertime water levels in decades, according to Philip Keillor, coastal engineering specialist at the University of Wisconsin Sea Grant Institute.

“This is the first time since the 1960s we’ve had such low late-winter water levels on Lake Michigan coinciding with El Nino conditions,” Keillor said. “The last time that happened, we had some of the lowest water levels on record.”

[Keillor maintains a web site on lake levels:  click here to view.]

 

El Nino conditions occur every three to four years, and they usually bring warmer and drier-than-average weather.   That’s been the case so far this winter, Keillor said, and it will probably hold true into spring, keeping water levels down.

 

As of last week, all of the lakes were lower than last year at this time, according to Marie Strum, water resource engineer with the U.S. Army Corps of Engineers in Detroit .   Lake Michigan was six to seven inches below last year’s levels and 22 inches below average for February.   Lake Superior was two inches lower than last year and eight inches below average for February.

 

Water on the Great Lakes normally cycles from a low in the winter to a peak in the summer.

 

The Corps of Engineers predicts Lake Michigan will peak this summer between six inches above and two inches below its 2001 high water mark, which was its lowest since the 1960s. The lake generally peaks around mid July.

 

Lake Superior is predicted to peak within five inches of its 2000 high water mark, which was the lowest peak for that lake since the 1920s.   Lake Superior usually peaks in late August.

During most springs, the lakes rise from melting snow and rain. But both sources of water may be in short supply this spring.

 

So far this winter, little snow has fallen in the Great Lakes basin. Precipitation across the basin was 25 percent below average in November, 29 percent below average in December and 41 percent below average in January, the corps reported. 

Compounding the problem are very dry soils in much of the Great Lakes basin, according to Mark Svoboda of the National Drought Mitigation Center at the University of Nebraska in Lincoln .     Dry soil will absorb more melted snow and rainwater than usual, leaving less to replenish the lakes, Svoboda said.

 

High rates of evaporation this winter have contributed to the current low lake levels.   This winter’s warm weather has been punctuated by several bursts of very cold, dry weather, producing ideal conditions for evaporation.   Evaporation on the lakes is greatest when the water is warm and overlying air is cold and dry.

The mild winter has also limited ice cover on the lakes, further promoting evaporation.

For More Information:

Philip Keillor, coastal engineering specialist, University of Wisconsin Sea Grant Institute, (608) 263-5133

 

John Karl , science writer, University of Wisconsin Sea Grant Institute, (608) 263-8621

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Conceived in 1966, Sea Grant is a national network of 30 university-based programs of research, outreach and education dedicated to the protection and sustainable use of the United States' coastal, ocean and Great Lakes resources. The National Sea Grant Network is a partnership of participating coastal states, private industry and the National Sea Grant College Program , National Oceanic & Atmospheric Administration , U.S. Department of Commerce. The University of Wisconsin Sea Grant College Program is administered by the Sea Grant Institute on the UW-Madison campus in Madison, Wisconsin.

 

 

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last updated 20 February 2003

http://www.seagrant.wisc.edu/communications/news_releases/2002/KellyApp.html