Signs are mounting that Lake Michigan’s already-low water levels are taking a turn for the worse. The big lake is a foot lower now than it was this time last year. And on Sunday, its level briefly dipped below a record low, according to federal monitoring data.
Water levels are down in wetlands and rivers, environmental experts say, and the latest decline is more bad news for ships, boats and lake and river marinas already suffering from nine years of sinking levels.
November was especially hard on lakes Michigan and Huron, which geologically are considered one lake. Instead of a normal seasonal drop of 2 inches in November, the lakes dropped 6 inches. For the Lake Michigan-Huron watershed, it was the driest November since 1908, according to U.S. Army Corps of Engineers data. Army Corps hydrologists and engineers blame excessive evaporation caused by cold air sucking moisture from the relatively warm lake.
Carl Woodruff, a hydraulic engineer, said it is unusual when evaporation outpaces the water runoff into the two lakes, which happened last month. As a rule of thumb, the two generally match each other over a year’s time.
Dry weather may be only one reason behind the plunging levels.
More than 90 years of historical water-level data suggest the lakes may fluctuate on a 30-year cycle, going from low to low. Lakes Michigan and Huron were low in the mid-1930s, the mid-1960s and began the latest decline in 1998.
Some of the other Great Lakes, particularly Erie and Ontario, have benefited from tropical storms and hurricanes out of the south that brought rain in recent years, including Katrina, Dennis and Arlene.
December 6, 2007
Lake Michigan water levels nearly scrape bottom
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