The Army Corps of Engineers office in Detroit has predicted that water levels in Lake Michigan could decline six inches more than the normal seasonal decline this winter because of decreased precipitation and increased evaporation.

In addition, lake water levels are nearing record low levels, according to a report released last week by Army hydrologists.

Because they are connected, the waters of Lake Michigan and Lake Huron are considered one body. The Michigan/Huron basin last month continued its period of seasonal decline and reached a level about 25 inches below average.

Water levels in November were also about 10 inches below “chart datum,” meaning that the water is lower than the minimum level noted on nautical charts. Whenever water levels fall below the “chart datum,” mariners are cautioned to pay close attention to their vessels’ draft so as not to run aground.

Precipitation last month was about an inch below average. For the year, precipitation over the basin has been about 2.4 inches below average while evaporation has been above average, the Army report noted.

“Because of large differences between air and water temperature, the months of November and December on average have the largest evaporation rates,” the report stated.

Army predictions call for the lake level to fall to about 27 inches below the long term average level recorded between 1918 and 2006 this winter. Levels will likely be somewhere between nine and 15 inches below last year’s levels, the report said. Water levels are expected to remain below the chart datum through May 2008.

“If the lake experiences very dry conditions, water levels could approach record lows in the January through May timeframe,” Army hydrologists said.