Lake Michigan water levels have started the seasonal decline, decreasing 2 inches from August to September. Though Lake Michigan is now about 24 inches below the highest monthly water level recorded for August in 2020, the Lake is still about 9 inches above the long-term average water level. Water levels are expected to remain level until the seasonal decline in the fall.

Watch the USACE’s “On the Level” Youtube channel for monthly updates and information about the Great Lakes’ water levels and forecasts from Detroit District Hydraulics and Hydrology experts.

Water Levels on Lake Michigan-Huron

Here are four things to know about water levels on Lake Michigan for September 2022.

What are the current water levels on Lake Michigan?

The water level of Lake Michigan as of September 5, 2022, was at an elevation of 580.12 feet above sea level (from the International Great Lakes Datum). To put this level into perspective, here are some statistics for Lake Michigan relative to the period of water level records measured from 1918 to present (statistics from USACE’s Weekly Water Level Update and USACE’s Water Level Summary).

What is the outlook for future water levels?

Water levels on Lake Michigan have started their seasonal decline from August to September with approximately 2 inches of change. The USACE is projecting that water levels continue their seasonal decline and drop approximately 3 inches by October (see the water level forecast issued for August 2022 below). The dropping water levels are a seasonal occurrence in the fall due to increased evaporation. While in the spring, evaporation decreases due to the increasing air temperatures while the water is cool causing water levels to peak around mid-summer. In an average year, water levels vary seasonally by about one foot from a peak in summer to a low in winter, though every year is different. You can read more about this as well as other myths about water level fluctuations in this blog.

What is behind Great Lakes water level fluctuations?

The story of Great Lakes water level changes is told by Net Basin Supply. Net Basin Supply (NBS) accounts for the water going into a lake in the form of precipitation and runoff minus water leaving a lake due to evaporation of water from the lake surface. In general, when Net Basin Supply is positive, more water enters the lake than leaves, causing a rise in lake levels. When Net Basin Supply is negative, more water leaves the lake than enters, causing a drop in lake levels. (Click here for more detail).

Places you can find more relevant information:

1. Our Coastal Hazards page for details about the impacts of high water levels, including erosion, flooding, and navigation issues.
2. Our blog post Resources for Great Lakes Coastal Property Owners: Where do I start? has links to many resources to help
   • understand coastal hazards
   • weigh the risks coastal hazards pose to property
   • understand options for addressing these hazards
   • get started on implementing actions if necessary.
3. The Great Lakes Water Budgets from the University of Michigan gives more information about what makes the lakes go up and down.
4. The US Army Corps’ Great Lakes Information page has tons of details on view water level data, water level forecasts, basin conditions, outflows, etc.
5. Our Resource of the Month on US Army Corps of Engineers Monthly Bulletin of Great Lakes Water Levels.