Great Lakes Water Levels

Great Lakes Water Levels are rising to a record high since record lows of 2012 and 2013.

According to the National Weather Service and the National Oceanic and Atmospheric Administration, “the water level of Lake Michigan continues to rise after generally staying below long term average values for over a decade…”

For the combined Lake Michigan/Lake Huron Basin…it adds up to 20.17 trillion gallons,” – NOAA.

The peak water levels of this summer (2019) were 2.13 feet higher than the average peak of record low level summers (2012/ 2013). “For Lake Michigan alone… that’s 9.95 trillion gallons of water more than 2012/2013. For the combined Lake Michigan/Lake Huron Basin…it adds up to 20.17 trillion gallons,” – NOAA.

“Great Lakes Water Levels are continuously monitored by U.S. and Canadian federal agencies through a binational partnership,” – NOAA. That binational partnership uses the International Great Lakes Datum (IGLD of 1985); a reference system which is adjusted every 25 to 35 years.

Great Lakes
Photo by Melanie Wupperman on

According to the Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data, “the harmonious use of these waters requires international coordination of many aspects of their management” … the common datum is periodically revised “due to isostatic rebound, sometimes referred to as crustal movement. Isostatic rebound is the gradual rising or ‘bouncing back’ of the earth’s crust from the weight of the glaciers that covered the Great Lakes – St. Lawrence River region during the last ice age.” This movement causes benchmarks to shift. However, the data shows that from 1955 to 1985 the low water datum levels for Lakes Michigan and Huron were increased from just 576.77 ft. to 577.43 ft.

…water levels on Crooked Lake are raised to elevation 595.4 ft (IGLD 1985) by May 27th.

The U.S. Army Corps of Engineers uses the IGLD of 1985 to raise and lower lake level elevations along the Inland Waterway. Specifically, water levels on Crooked Lake are raised to elevation 595.4 ft (IGLD 1985) by May 27th and held to 595.4 ft, or as near as possible, through Sept. 30th. After Nov. 1st, the locks are opened and the lake is drawn “down to the maximum possible, leaving the gates fully open throughout the winter as long as conditions allow,” according to the US Army Corps of Engineers.

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For comparison, as of January 20th, 2020, the water levels on the downstream sensor show the water levels at 595.30 ft (indicating higher than usual water levels). Meanwhile, the water level in Mackinaw City was 581.43 on IGLD.

“Lake Michigan-Huron is forecasted to begin its seasonal decline and fall to be below its record high August levels by 2 inches. Over the forecast period, the levels are projected to remain below record high levels by 2- 12 inches and above their levels from last year by 7 to 15 inches. Likewise, levels are expected to remain above their long-term average by 28 to 31 inches,” – The US Army Corps of Engineers; July 2019 Great Lakes Water Level Summary.

For more information, the US Army Corps of Engineers updates their site weekly on Great Lakes Water Levels. Click here for a link to the weekly forecasts.

Lakes Michigan-Huron Water Levels January 2020
Lakes Michigan-Huron Water Levels January 2020 provided by the Army Corps of Engineers.

Printable version – Lakes Michigan-Huron Water Levels January 2020 PDF



Watch the video series to understand more about the measurement of the Great Lakes.

Water Levels as of 2022 show a decline since the original post. “Forecasted water levels for May 13th are below water levels from a year ago on all lakes…”

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