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A 15-year stretch of record low water levels in Lake Superior and the rest of the Great Lakes has ended. But it's unclear whether levels will remain high. 

Scientists with the National Oceanic and Atmospheric Administration say heavy rain and snowfall are the major reasons for the rapid rise.

"The January 2013 through November 2014 rise on Lake Superior is the highest net rise we have in recorded history on Lake Superior," said Drew Groenwold, a research hydrologist with NOAA's Great Lakes Environmental Research Laboratory. Since January 2013, Groenwold said, the lake has risen about 2.3 feet.

Lakes Michigan and Huron rose more 3.2 feet during that same time. At no other point in recorded history have water levels risen so quickly in so short a period of time. 
 
Data shows precipitation in the Lake Superior and Lake Michigan-Huron basins was about 10 percent above long-term averages in both 2013 and 2014.

NOAA researchers expect levels to stay above average through at least the winter and spring of next year. 

Gronewold and Keith Kompoltowicz of the U.S. Army Corps of Engineers said the recovery is due primarily to heavy rain and snowfall in the region over the past two years.

They predict that levels will remain above normal for the next six months on all the Great Lakes except Lake Ontario, which may be a couple of inches below normal.

Beyond that, "it becomes difficult for us to predict whether or not water levels might drop again, stay at this level or go higher," Gronewold said.

It's tough to predict whether water levels will remain high or return to record-setting lows, scientists say. Part of that uncertainty comes from the challenge of predicting the lakes' precipitation and evaporation rates. It's also challenging to predict the kinds of long-term climate trends, like last winter's so-called polar vortex, that influence those rises and falls.

The recovery is good news for commercial shippers, recreational boaters and others who have had to worry about running around in harbors and shallow channels. But Kompoltowicz says some owners of shoreline property are concerned about erosion.

The Associated Press contributed to this report

Environmental News

Dan Kraker

Author

The slump began in the late 1990s. It continued for 15 years, culminating early last year when Lake Michigan and Lake Huron set low-water records. Since then, levels have sharply rebounded.

Great Lakes water level slump over, future unclear

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