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Lake Superior & Lake Huron Continue Seasonal Water-Level Declines for September

Lake Superior and Lake Michigan-Huron both continued their seasonal water-level declines in September.

As a result of the drier than average weather and water supply conditions, Lake Superior water levels have declined below the seasonal long-term average for the first time since April 2014.

Lake Michigan-Huron water levels have declined significantly from the record-high levels observed in recent years, but water levels remain above the seasonal long-term average.

Lake Superior outflows continue to be set in consideration of water levels upstream and downstream. The Board expects the total outflow to be 2,030 m3 /s (71.7 tcfs) in October, which is as prescribed by Lake Superior Regulation Plan 2012.

The gate setting at the Compensating Works will be maintained at the setting equivalent to one-half gate open in October (Gates #7 through #10 partially open 20 cm (7.9 in.)).

There will be no change to the setting of Gate #1, which supplies a flow of about 15 m3 /s to the channel north of the Fishery Remedial Dike. Weather and water supply conditions were drier than average in both the Lake Superior basin and the Lake Michigan-Huron basin in September.

As a result, Lake Superior declined 5 cm (2 in.) last month, while on average the lake declines 2 cm (0.8 in.) in September.

Lake Michigan-Huron declined 14 cm (5.5 in.) last month, while on average the lake declines 6 cm (2.4 in.) in September.

At the beginning of October, Lake Superior is 4 cm (1.6 in.) below the seasonal long-term average (1918-2020) and 31 cm (12.2 in.) below the level of a year ago.

Lake Michigan-Huron is 39 cm (15.4 in.) above average, 42 cm (16.5 in.) below the level of a year ago and 61 cm (24 in.) below the record-high level set at this time in 1986.

Lake Superior and Lake Michigan-Huron water levels typically decline in October. Depending on the weather and water supply conditions during the next month, Lake Superior may rise slightly or may decline by up to 10 cm (3.9 in.) in September.

Lake Michigan-Huron water levels could decline by as much as 15 cm (5.9 in.).

Shoreline businesses and property owners are reminded that the Great Lakes – St. Lawrence River Adaptive Management (GLAM) Committee continues to host an online questionnaire to allow for direct reporting on impacts related to high water conditions: https://ijc.org/glam/questionnaire

SOURCE – International Lake Superior Board of Control


International Lake Superior Board of Control


International Lake Superior Board of Control

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