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Great Lakes Article:

Lake level plunging near record
By Eric Carlson
The Leelanau Enterprise

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 year’s level at this time, and 24 inches below its long term average.

Harbormasters at Leelanau County’s municipal marinas have reported that lower water levels haven’t 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 Army’s 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 Ontario’s 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 year’s level.

Lake Superior’s 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. Mary’s 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.

Plenty of rain has fallen downstate recently, but very little has fallen on northwestern lower Michigan over the past several weeks.

Although the current near-drought conditions in the northern lower peninsula may benefit from projected rain, the amounts of precipitation forecast almost certainly won’t be enough to affect lake water levels.

According to the National Weather Service, a 60-percent chance of rain was expected Wednesday evening. For today, Thursday, the forecast called for another 60-percent chance of isolated thunderstorms with scattered showers overnight.

Temperatures were expected to remain relatively mild, with highs around 70 through Friday. Another chance of showers was expected Friday, with the sky clearing on Saturday.

Partly cloudy skies were forecast for Sunday, with temperatures rising. The forecast for Monday called for another day of partly cloudy skies and high temperatures around 77 degrees.

Another chance for rain may emerge on Tuesday, according to the National Weather Service forecast.

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