Lake Levels End Three-Year Decline

The water level of Lakes Michigan and Huron remained unusually steady during the last half of 2001, ending--at least temporarily--a three-year pattern of net declines. The two lakes are connected through the Straights of Mackinac and always have the same level.

In the last half of 2001, water levels remained close to their mid-summer peak, in contrast to the large declines seen since 1997. As a result, the level of the two lakes was nine inches higher at the beginning of 2002 than one year earlier.

Monthly means graph from NOAA/NOS CO-OPs web site. Click for larger version.

Similar end-of-the-year plateaus have occurred only six times since accurate water level records were first kept in 1860: 1881, 1928, 1941, 1959, 1992, and 1996. In five of those years, water levels the following spring rose more than the one-foot average. The exception was in 1881, when the lakes rose six inches the following year.

Although water levels remain below average, the increase over last year’s level will be encouraging news to harbor, marina, and boat operators on the lakes, for whom shallow waters mean inaccessible docks and slips, reduced cargos, and increased hazards. How long this improvement lasts, however, depends upon evaporation and precipitation during the remainder of winter and through the spring. The U.S. Army Corps of Engineers is forecasting an average rise in the level of the two lakes this spring.

For more information, see “Lake Level Update.”

- John Karl

Last updated 24 April 2002 by Karl
All contents copyright 2001 University of Wisconsin Sea Grant Institute

http://www.seagrant.wisc.edu/Communications/news/LD_stories/2002/LakeLevels.html