NOAA 2003-R507
Contact: Jana Goldman
NOAA News Releases 2003
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How high or low the water level is in the five Great Lakes has long been of interest to those who use the lakes for commercial and recreational boating and fishing, energy, and as a source of drinking water. The levels have been measured and forecast monthly for many years and NOAA scientists hit the bull’s-eye with their July forecast of the water level of Lake Michigan. NOAA is an agency of the U.S. Department of Commerce.

“We were within inches of the actual measurement,” said Cynthia Sellinger, deputy director of NOAA’s Great Lakes Environmental Research Laboratory in Ann Arbor, Mich.

GLERL uses meteorological forecasts from the National Weather Service to forecast the lake levels six months out. Back in January, GLERL’s Lake Michigan forecast was 176.61 meters - about 579 feet; in July the actual level was 176.65 meters -- approximately 2 inches higher than the forecast. Sellinger meets monthly with her colleagues from Environment Canada and the U.S. Army Corps of Engineers to forecast the levels.

Since 1997, Lake Michigan has dropped 4.1 feet, the largest drop in that short of time span since records have been kept. Lakes Michigan and Huron are often considered one body of water as they are connected by the Straits of Mackinac, located between the upper and lower peninsulas of the state of Michigan.

The other lakes are more difficult to forecast, because the water flow of Superior and Ontario are regulated by power companies and Erie gets 80 percent of its water from Michigan and Huron, Sellinger explained.

The Great Lakes - Superior, Michigan, Huron, Ontario, and Erie - are the major bodies of water within the Great Lakes Basin. The basin is located along the international boundary between Canada and includes portions of eight states and the provinces of Ontario and Quebec. Combined, these lakes make up the largest surface fresh water body in the world--they contain 90 percent of the U.S.'s fresh water and 20 percent of the world's fresh water.

The Great Lakes carry thousands of recreational and commercial ships annually. Lake levels are important to shippers, who must load the lake carriers with fewer goods when the levels are low and to recreational boaters, who often have to find dock space in deeper water. The Lakes provide drinking water to the 40 million residents as well as water to power and cool electric generating plants.

Lake levels have been dropping for the past six years and lake evaporation has increased significantly.

“The only good thing that comes out of lower lake levels is more beach for beach-goers,” according to Sellinger. But that also exposes and destroys some vital breeding habitat for lake wildlife.

Lake levels have been forecast before GLERL was formed in 1974. Part of the laboratory’s mandate is to provide the lake level forecasts, a task that was given to
GLERL when the research arm of the U.S. Army Corps of Engineers was transferred to the laboratory.

The Commerce Department's National Oceanic and Atmospheric Administration (NOAA) Office of Oceanic and Atmospheric Research is dedicated to enhancing economic security and national safety through research to better understand weather and climate-related events and to manage wisely our nation's coastal and marine resources.

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