Lake levels declining more than average

Dry conditions in November resulted in the levels of the Great Lakes declining more than the

seasonal average.

That’s the word from the International Lake Superior Board of Control in its latest update. Lake

Superior declined by 3.9 inches last month. The seasonal long-term average pattern is for

Superior to decline by 2 inches, the board said.

At the same time, Lake Michigan-Huron declined by 3.9 inches last month. The seasonal long-

term average pattern is for Lake Michigan-Huron to decline by 1.6 inches in November,

according to the board.

Water supply conditions were quite dry in Lakes Superior Michigan-Huron basins in

November, the board said.

At the beginning of December, the lake-wide average water level of Lake Superior was

2 inches below the seasonal long-term average (1918-2022) and 8.7 inches below the level of a

year ago. At the beginning of December, the lake-wide average water level of Lake Michigan-

Huron was 3.1 inches above the seasonal long-term average (1918-2022) and 1.6 inches below

the level of a year ago.

As for the forecast outlook, the board noted both Lake Superior and Michigan-Huron are in

their seasonal decline.

• If weather and water supply conditions are near average, both Lake Superior and Lake

Michigan-Huron are expected to decline in December by 3.1 inches and 2.4 inches,

respectively.

• If conditions are wetter than average, Lake Superior may decline by 1.6 inches and Lake

Michigan-Huron may rise slightly by 0.4 inches.

• If conditions are drier than average, the water level of Lake Superior is expected to

decline by as much as 5.1 inches, and Lake Michigan-Huron is expected to decline by as

much as 4.7 inches.

The board said an adjustment to the gate setting on the St. Marys River compensating works

will take place this week, with the gate setting being lowered to approximately one-half gate

fully open with the water flow being 74,900 ft 3 /s, as prescribed by a regulation plan from 2012.

Actual day-to-day flows may vary depending on conditions, as well as variations in flow from

the hydropower plants.

International Lake Superior Board of Control