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Lake level plunging near record low

Lake Michigan water levels were reaching their seasonal peak this week and were expected to remain steady through the month of July, according to the Army Corps of Engineers.

However, water in the Lake Michigan-Huron basin is a full 13 inches below last years level at this time, and 24 inches below its long term average.
Harbormasters at Leelanau Countys municipal marinas have reported that lower water levels havent been much of a problem so far this year. Most marinas in the county have been dredged within the past two years.
However, projections provided this week by the Army Corps of Engineers show that water levels could close in on their all-time low later this year.

Generally, Lake Michigan water levels begin an annual decline around August and reach a low point around March. The Armys projections extend into December 2003, when levels could come within two inches of an all-time low recorded in 1964.

The most likely scenario, however, is that water levels will dip to within about five inches of the all time low, according to the Corps projection.
Currently, water levels in Lake Michigan are some nine inches above the 1964 low. In fact, the water is almost exactly at its chart datum level, the level at which most nautical charts depict water depth. The chart datum level is 577.5 feet above sea level for the Lake Michigan-Huron basin.
Elsewhere in the Great Lakes, Lake Superior water is 12 inches below its long-term average level. Lakes St. Clair and Erie are 12 and 16 inches below averages, respectively.

Lake Ontarios level, on the other hand, is four inches above the long-term average. However, all of the Great Lakes, including Lake Ontario, are below last years level.

Lake Superiors water level is forecasted to continue its seasonal rise in the next four weeks. While Lake Michigan and Huron are reaching their seasonal plateau, Lakes St. Clair, Erie and Ontario are already into their seasonal declines.

Part of that fluctuation is related to flows through channels connecting the lakes, according to the Army Corps. The Lake Superior outflow through the St. Marys River into Lake Huron is expected to be below average during the month of July. Flows in the St. Clair and Detroit Rivers are also expected to be below average, while flows in the Niagara and St. Lawrence Rivers are expected to be near average in July.

Fluctuating water levels are also related to the amount of ice that forms on the lakes over the winter. Although heavy ice was reported on the Great Lakes this winter, it was not enough to significantly affect the amount of water that evaporated from the lakes.

More significantly, the overall amount of precipitation in the Great Lakes region has been relatively low this year.

Thu, 7/10/2003

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