Great Lakes Region

high water level

High waves in Lake Michigan along the Chicago shoreline, October 31, 2014
(Credit: L.S. Gerstner)

Great Lakes Water Levels

The Great Lakes, a massive system of freshwater seas, are home to 40 million people who rely on the them as a source of drinking water, recreation, and natural beauty. The water levels of the lakes fluctuate on different time scales; monitoring and analysis of these cycles is an important part of NOAA’s mission to understanding and predicting changes in climate, weather, oceans, and coasts. Beginning in 1890, there is an incredibly rich data set available regarding the Great Lakes that provides important context for planning and management. The data is essential for supporting international navigation, planning for coastal development, and for monitoring the Great Lakes water budget to improve predictive models.

Historic Water Levels

The best way to access lake-wide average levels and forecasts is via the Great Lakes Water Levels Dashboard. This easy to use data portal allows you to view, download, and print images of Great Lakes water levels from 1860 to present.  If you are interested in comparing plots of water levels with water budget components (precipitation, modeled evaporation, and runoff), try the Great Lakes Hydro-Climate Dashboard.

Since September of 2014, all of the Great Lakes have been above their monthly average levels for the first time in 15 years. This period of below-average levels on Lake Superior, Michigan and Huron caused challenges for boaters, small harbor towns, commercial shipping, and hydropower. After a new record low level was set on Lakes Michigan and Huron in January 2013,  wet conditions of 2013 and 2014 (1) brought a dramatic end to the long period of low water levels.

low water level

Lake Erie low water levels from Aquatic Visitors Dock, February 19, 2013 (Credit: K. Hart, Ohio Sea Grant).

Although fluctuation in Great Lakes water levels is an annual occurrence, long periods of either high or low levels can impact sectors of the population in different ways. High water levels are advantageous to boaters, commercial shipping, and hydropower; however, coastal erosion, flooding and property damage along the shoreline are likely to result (1).

Water Level Monitoring

Water level monitoring stations are operated by NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS) on U.S. coastlines, and the Department of Fisheries and Ocean’s Canadian Hydrographic Service on Canadian coastlines. 53 water level stations operated by NOAA’s National Ocean Service CO-OPS are distributed throughout the Great Lakes region. The map below depicts these stations, as well as the stations on the Canadian coast. . The NOAA stations record a 3 minute average water level every 6 minutes, and the data are recorded in hourly, daily and monthly averages. Click here to view the NOAA station data.


Water Level Forecasting

Lake Level Rebound Graphic

Record-Setting Water Level Rise Infographic (Credit: NOAA-GLERL).

Short-term forecasts

If your needs for water level information are cite specific and real time, the tool you need is the Great Lakes Coastal Forecast System (GLCFS). This well-documented query tool, developed at GLERL and operationalized by NOS, gives access to both nowcasts and forecasts (up to 5 days) for water levels, wave heights, wind speed, currents, air and water temperature, and ice.

GLCFS (research version)

GLOFS (operational version)

Seasonal forecasts

Computer simulation models, such as the   Advanced Hydrologic Prediction System (AHPS), developed by NOAA-GLERL, are used to forecast monthly-averaged water levels. AHPS  uses historical meteorological data, mathematical models and climate forecasts to simulate multiple variables; these simulated variables include precipitation, evaporation and rainfall-induced runoff. The “net” supply of water to the basin is used to produce probability-based water level predictions. AHPS is an important component of the official seasonal forecast produced jointly by the U.S. Army Corps of Engineers and Environment Canada each month.

Link to Corps forecast: Monthly Forecast Bulletin (Army Corps of Engineers)

Link to AHPS: GLERL-Advanced Hydrologic Prediction System

Multi-Decadal forecasts (climate studies)

Long-term projections for future Great Lakes water levels are highly uncertain. Many studies have been published in the past several decades that use global climate models to assess the impact that future climates will have on Great Lakes water levels. Although a thorough understanding of each study will require reading the source material, the Great Lakes Hydro-Climate Dashboard allows us to put these different projections side by side for visual comparison.

Water LevelsWhere can I find more information on Great Lakes Water Levels?

View NOAA-GLERL’s webpage on Great Lakes Water Levels to learn more about how Great Lakes water levels are measured, examine current and historical water level conditions, and browse through seasonal and multi-decadal projections of Great Lakes water levels.


Water Levels in the Great Lakes, February 2015


Monitoring Network factsheet

Water Level Dashboard factsheet

Hydro-Climate Dashboard factsheet

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