Lake Superior, in this view of Keweenaw Bay from Michigan's Upper Peninsula, reached near record low water levels in 2007.
John Flesher / AP Enlarge
Don't look now, but Great Lakes water levels may be more stable this summer than they've been in recent years.
That's uplifting news for the region's $7 billion fishing industry, though hardly enough to make up for the biological train wreck that could be in the making if Asian carp colonize the lakes. Recent DNA evidence suggests they have slipped through a $9 million electrical barrier the U.S. Army Corps of Engineers built in Lockport, Ill., 20 miles southwest of Chicago.
Predicting water levels in the Great Lakes - which collectively hold six quadrillion gallons, more fresh water than anywhere else on Earth except Russia's Lake Baikal - is no easy task.
The lakes have shown themselves to be far more fickle than many people have realized since the federal government began keeping statistics on them in 1860.
Even though the Great Lakes hold 20 percent of the world's fresh surface water, they are prone to rising and falling without notice - with trends lasting up to 30 years, then suddenly reversing.
An inch or two up or down can affect property values, algae growth, beach access, marina sales, the cost of shipping goods across America's heartland, and the reproduction of sportfish as well as the ability of anglers to get to them.
While 2009 was a cruel year for North Americans in many respects, from a collapsed economy to an outbreak of deadly swine flu, it was one of the better years of late for the lakes, which are the source of drinking water for 33 million of the continent's people.
Records compiled by the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory in Ann Arbor and the U.S. Army Corps of Engineers' Detroit district office show that as of late December the lakes had rebounded close to their historical mean levels.
Lake Superior, which holds more water than all of the other four lakes combined and is largely responsible for replenishing them, has come back from its record low of August and September of 2007, Keith Kompoltowicz, a Corps meteorologist in Detroit, said.
Though it's still four inches below its historic average, Lake Superior was four inches higher last month than it was in December, 2008, he said.
The comeback has been slightly more impressive for lakes Michigan and Huron, which are hydrologically viewed as one body of water. Though five inches below their historic average, the Michigan-Huron pairing was 10 inches higher than it was in December, 2008, Mr. Kompoltowicz said.
Lake Erie is right about at its historic mean.
Eighty percent of Lake Erie's water comes down the Detroit River from Lake St. Clair and the three upper Great Lakes of Superior, Michigan, and Huron.
"We're expected to stay right at its long-term level for the next six months for Lake Erie," Mr. Kompoltowicz said. Lake Ontario finished 2009 three inches lower than it was in December, 2008.
The current era of low water levels came in the late 1990s, after 30 years of usually high water.
The fact that other 30-year eras preceded that one shows that at least part of the fluctuation is natural and occurs in cycles, scientists have said.
But experts say it's probably too soon to declare the latest decade-old era of low water levels over, especially with the Earth's climate warming and lower lake levels predicted as a consequence.
A study issued in the fall of 2007 by 75 area scientists from nearly 50 government, business, academic, and public-interest groups claimed warming and evaporation trends could cause Lake Erie water levels to drop 3.28 feet to 6.56 feet by 2066.
The estimates were based on findings by the Intergovernmental Panel on Climate Change, the world's most prestigious group of climatologists.
A subsequent paper that appeared in Environmental Science & Technology suggested Lake Erie and Lake Ontario water levels will become largely dependent on the rainfall they pick up from additional hurricanes and tropical storms. More violent weather is anticipated as the climate warms. Lakes Superior, Michigan, and Huron are too far north to pick up substantial amounts of rain from storms, the report stated.
The resurgence for the three Upper Great Lakes in 2009 is attributed to "some very active weather through the lakes the past two years," Mr. Kompoltowicz said.
That includes a larger snowpack on the Canadian side of Lake Superior than had been seen in years past. Snow holds a lot of water and is among the most efficient ways of recharging lakes.
But while the outlook is promising now for the summer of 2010, things could all come crashing down if more ice doesn't form soon - especially in western Lake Erie, the shallowest part of the Great Lakes region.
Unbeknownst to many, late fall and early winter are the cruelest times for lakes. Far more evaporation occurs then than in summer, because there is a greater disparity between the air and water temperatures when it's cold.
John Hageman, a longtime Lake Erie ice-fishing guide and manager of Ohio State University's Stone Laboratory near Put-in-Bay, said last week the "quiet water" near the Lake Erie Islands had started to freeze. "Everything west of the islands is frozen," he said.
Lake Erie has been freezing later and more infrequently in recent years. It failed to freeze over in 2002, 2004, and 2006, Mr. Hageman said. He said he does not consider a lake frozen until it has ice six to eight inches deep.
"I don't take anybody out [icefishing] until we have at least eight," Mr. Hageman said.
Jeff Reutter, director of NOAA's Ohio Sea Grant program and Ohio State University's Stone Laboratory near Put-in-Bay, said people shouldn't read too much into stabilized water levels.
Climate scientists have documented changes under way in the Great Lakes region, including a rise in evening temperatures over the past 20-some years.
They've documented less snow and ice over the past 20 years, too, notwithstanding Ontario's snowfall over the past two years.
In the future, they expect the Great Lakes regions to get more rain. But it's expected to come in the form of fast-moving storms and far short of what is needed to compensate for increased evaporation, Mr. Reutter said.
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